Temperature fine-tunes Mediterranean Arabidopsis thaliana life-cycle phenology geographically.

To understand how adaptive evolution in life-cycle phenology operates in plants, we need to unravel the effects of geographic variation in putative agents of natural selection on life-cycle phenology by considering all key developmental transitions and their co-variation patterns. We address this goal by quantifying the temperature-driven and geographically varying relationship between seed dormancy and flowering time in the annual Arabidopsis thaliana across the Iberian Peninsula. We used data on genetic variation in two major life-cycle traits, seed dormancy (DSDS50) and flowering time (FT), in a collection of 300 A. thaliana accessions from the Iberian Peninsula. The geographically varying relationship between life-cycle traits and minimum temperature, a major driver of variation in DSDS50 and FT, was explored with geographically weighted regressions (GWR). The environmentally varying correlation between DSDS50 and FT was analysed by means of sliding window analysis across a minimum temperature gradient. Maximum local adjustments between minimum temperature and life-cycle traits were obtained in the southwest Iberian Peninsula, an area with the highest minimum temperatures. In contrast, in off-southwest locations, the effects of minimum temperature on DSDS50 were rather constant across the region, whereas those of minimum temperature on FT were more variable, with peaks of strong local adjustments of GWR models in central and northwest Spain. Sliding window analysis identified a minimum temperature turning point in the relationship between DSDS50 and FT around a minimum temperature of 7.2 °C. Above this minimum temperature turning point, the variation in the FT/DSDS50 ratio became rapidly constrained and the negative correlation between FT and DSDS50 did not increase any further with increasing minimum temperatures. The southwest Iberian Peninsula emerges as an area where variation in life-cycle phenology appears to be restricted by the duration and severity of the hot summer drought. The temperature-driven varying relationship between DSDS50 and FT detected environmental boundaries for the co-evolution between FT and DSDS50 in A. thaliana. In the context of global warming, we conclude that A. thaliana phenology from the southwest Iberian Peninsula, determined by early flowering and deep seed dormancy, might become the most common life-cycle phenotype for this annual plant in the region.

Effectiveness of manual therapy versus surgery in pain processing due to carpal tunnel syndrome: A randomized clinical trial.

BACKGROUND: People with carpal tunnel syndrome (CTS) exhibit widespread pressure pain and thermal pain hypersensitivity as a manifestation of central sensitization. The aim of our study was to compare the effectiveness of manual therapy versus surgery for improving pain and nociceptive gain processing in people with CTS. METHODS: The trial was conducted at a local regional Hospital in Madrid, Spain from August 2014 to February 2015. In this randomized parallel-group, blinded, clinical trial, 100 women with CTS were randomly allocated to either manual therapy (n = 50), who received three sessions (once/week) of manual therapies including desensitization manoeuvres of the central nervous system, or surgical intervention (n = 50) group. Outcomes including pressure pain thresholds (PPT), thermal pain thresholds (HPT or CPT), and pain intensity which were assessed at baseline, and 3, 6, 9 and 12 months after the intervention by an assessor unaware of group assignment. Analysis was by intention to treat with mixed ANCOVAs adjusted for baseline scores. RESULTS: At 12 months, 95 women completed the follow-up. Patients receiving manual therapy exhibited higher increases in PPT over the carpal tunnel at 3, 6 and 9 months (all, p < 0.01) and higher decrease of pain intensity at 3 month follow-up (p < 0.001) than those receiving surgery. No significant differences were observed between groups for the remaining outcomes. CONCLUSIONS: Manual therapy and surgery have similar effects on decreasing widespread pressure pain sensitivity and pain intensity in women with CTS. Neither manual therapy nor surgery resulted in changes in thermal pain sensitivity. SIGNIFICANCE: The current study found that manual therapy and surgery exhibited similar effects on decreasing widespread pressure pain sensitivity and pain intensity in women with carpal tunnel syndrome at medium- and long-term follow-ups investigating changes in nociceptive gain processing after treatment in carpal tunnel syndrome.

Cambios espirométricos tras la aplicación de un programa de cinesiterapia en la espondilitis anquilosante: estudio piloto / Spirometric changes after applying a kinetic therapy program in ankylosing spondylitis: A pilot study

ObjetivoEl objetivo del presente estudio piloto fue evaluar los cambios obtenidos en los volúmenes espirométricos y la movilidad costal tras la aplicación de un protocolo de reeducación postural global (RPG) o un protocolo convencional de fisioterapia.Material y métodosSe estudiaron 20 pacientes con espondilitis divididos en 2 grupos: control y experimental. Al grupo experimental se le aplicó un programa de cinesiterapia basado en el método de RPG, mientras que al grupo control se le aplicó un protocolo clásico de fisioterapia. El estudio duró 3 meses, en los cuales los pacientes recibieron 12 sesiones semanales de tratamiento. Se realizó una espirometría para el cálculo de varios volúmenes (capacidad vital forzada [FVC], volumen espiratorio forzado en el primer segundo [FEV1] y cociente FEV1/FVC) y la expansión costal. Ambas mediciones se realizaron antes y después de los tres meses de tratamiento. Se realizó un análisis de la varianza de medidas repetidas por cada variable estudiada.ResultadosEl análisis de la varianza encontró diferencias significativas para el factor tiempo en la FVC (F=7,133; p<0,01), el FEV1 (F=16,47; p<0,001) y la expansión torácica (F=28,17; p<0,001), pero no para el cociente FEV1/FVC (F=2,807; p=0,1). A su vez, se encontró una interacción entre el factor tiempo y el factor grupo para el cociente FEV1/FVC (F=5,25; p=0,03), pero no para el resto de las variables. Por tanto, la FVC, el FEV1 y la expansión torácica mejoraron por igual en ambos grupos, mientras que el cociente FEV1/FVC incrementó más en el grupo experimental. Aunque se encontraron diferencias estadísticas, el efecto clínico (EfC) fue pequeño (EfC<0,2) para los volúmenes espirométricos, mientras que fue largo (EfC>1) para la expansión costal(AU)

ConclusionesLos resultados del presente estudio piloto sugieren que la aplicación de un protocolo de fisioterapia, tanto convencional como basado en el método de RPG, puede inducir cambios en la espirometría en pacientes con espondilitis anquilosante, aunque futuros estudios son necesarios para objetivar la significación clínica de estos cambios(AU)

ObjectiveThe current pilot study aimed to evaluate changes in Spirometric volumes and rib mobility after application of a physical therapy program based on a Global Posture Re-education protocol or a conventional exercise program.Material and methodsTwenty patients diagnosed with Ankylosing Spondylitis were divided into a control and experimental group. The experimental group was treated with a Global Posture Re-education Method based protocol whereas the control group was treated with a conventional exercise program. During a 3-month treatment period, patients received 12 sessions of supervised physical therapy. A spirometric analysis was performed to assess Forced Vital Capacity (FVC), Forced Expiratory Volume during the First Second (FEV1) and the FEV1/FVC coefficient and rib mobility pre-intervention and after the 3-month intervention period. An analysis of variance for repeated measures was used for the statistical analysis of each variable studied.ResultsSignificant differences were found with the analysis of variance for time factor in FVC (F=7.133; P<0.01), FEV1 (F=16.47; P<0.001), and rib mobility (F=28.17; P<0.001), but not for FEV1/FVC coefficient (F=2.807; P=0.1). Interaction between group and time was also found for FEV1/FVC (F=5.25; P=0.03) but not for the remaining variables: FVC, FEV1. Furthermore, rib mobility improved the same in both groups whereas the FEV1/FVC had a greater increase in the experimental group. Nevertheless, effect sizes were small (EfS<0.2) for Spirometric volumes, but large (EfS > 1) for rib mobility.ConclusionsThe results from the present pilot study suggest that the application of a physical therapy exercise program, either conventional or based on the Global Posture Re-education Method, may induce changes in spirometry in Ankylosing Spondylitis. Future studies are required in order to determine the clinical relevance of these changes(AU)

Neck mobility and forward head posture are not related to headache parameters in chronic tension-type headache.

The relationship between the changes in forward head posture (FHP), neck mobility and headache parameters was analysed in 25 patients with chronic tension-type headache (CTTH) undergoing a physical therapy programme. Side-view pictures were taken to measure the cranio-vertebral angle in the sitting and standing positions. A cervical goniometer was employed to measure the range of all cervical motions. A headache diary was kept to assess headache intensity, frequency and duration. All patients received six sessions of physical therapy over 3 weeks. Outcomes were assessed at baseline, after treatment and 1 month later. Neck mobility and headache parameters showed a significant improvement after the intervention, whereas posture changes did not reach statistical significance. No correlations were found between FHP, neck mobility and headache parameters at any stage. Changes in these outcomes throughout the study were not correlated either. FHP and neck mobility appear not to be related to headache intensity, duration or frequency in patients suffering from CTTH. Although patients showed a reduction in the range of motion in the neck, it is uncertain whether this is consistent with TTH.

Myofascial trigger points in subjects presenting with mechanical neck pain: a blinded, controlled study.

The aim of this study was to describe the differences in the presence of myofascial trigger points (TrPs) in the upper trapezius,sternocleidomastoid, levator scapulae and suboccipital muscles between patients presenting with mechanical neck pain and control healthy subjects. Twenty subjects with mechanical neck pain and 20 matched healthy controls participated in this study. TrPs were identified, by an assessor blinded to the subjects' condition, when there was a hypersensible tender spot in a palpable taut band, local twitch response elicited by the snapping palpation of the taut band, and reproduction of the referred pain typical of each TrP. The mean number of TrPs present on each neck pain patient was 4.3 (SD: 0.9), of which 2.5 (SD: 1.3) were latent and 1.8 (SD: 0.8) were active TrPs. Control subjects also exhibited TrPs (mean: 2; SD: 0.8). All were latent TrPs. Differences in the number of TrPs between both study groups were significant for active TrPs (P < 0.001), but not for latent TrPs (P > 0.5). Moreover, differences in the distribution of TrPs within the analysed cervical muscles were also significant (P < 0.01) for all muscles except for both levators capulae. All the examined muscles evoked referred pain patterns contributing to patients' symptoms. Active TrPs were more frequent in patients presenting with mechanical neck pain than in healthy subjects.

Relación entre movilidad, funcionalidad y calidad de vida en pacientes con espondilitis anquilosante / Relationship among mobility, functionality and quality of life in subjects presenting with ankylosing spondylitis

Objetivo. La Espondilitis Anquilosante (EA) condiciona la calidad de vida (CV) de las personas afectadas, siendo la limitación de la movilidad una de las características más destacadas de la enfermedad. El objetivo del presente estudio fue comprobar si existe una relación entre la movilidad espinal, la funcionalidad y la CV en pacientes con EA. Pacientes y métodos. Estudio descriptivo en el que participaron 7 mujeres y 28 varones con EA. Para la medición de la movilidad, se escogieron las mediciones establecidas en el Índice de Movilidad para la EA del grupo de Bath (BASMI): distancia occipucio-pared, test de Schöber modificado, rotación cervical, latero-flexión lumbar y distancia intermaleolar. Para la funcionalidad y la actividad se emplearon el Índice de Funcionalidad para la EA (BASFI) y el Índice de Incapacidad Funcional para la EA (BASDAI) ambos del grupo de Bath. Finalmente para la CV se empleó el cuestionario SF-36. Se aplicó el coeficiente de correlación de Pearson (r) o la prueba rho de Spearman (rs) según la normalidad de las variables. Resultados. Las variables de movilidad medidas por el BASMI mostraron distintos grados de correlación entre ellas (r entre 0,43 y 0,8; p < 0,01). Destacar que la distancia occipucio pared presentó correlaciones negativas con el resto de variables de movilidad. Los índices BASFI y BASDAI mostraron diversas correlaciones con numerosas dimensiones del cuestionario SF-36. Finalmente, prácticamente ninguna de las variables de movilidad presentó relación alguna con ninguna de las dimensiones del cuestionario SF-36. Conclusiones. La calidad de vida no está relacionada con la pérdida de movilidad que acontece en la EA, mientras que la funcionalidad sí muestra relación con la CV

Objective. Ankylosing Spondylitis (AS) usually conditions the quality of life (QoL) of these patients. Restricted range of motion is one of the characteristics of AS. The aim of this study was to assess the correlation among mobility, functionality, and quality of life in subjects with AS. Patients and methods. A cross-sectional study was performed. Seven women and 28 men diagnosed with AS participated. Mobility outcomes were assessed by means of the Bath Ankylosing Spondylitis Metrology Index (BASMI): occiput-wall distance, modified Schöber test, cervical rotation, lumbar side-flexion and intermalleolar distance. The Bath Ankylosing Spondylitis Functional Index (BASFI) and the Bath Ankylosing Spondylitis Diasease Activity Index (BASDAI) assessed the functionality and activity of these patients. Quality of life was assessed with the SF-36 questionnaire. The Pearson test (r) or the rho Spearman tests (rs) were used depending on the normal distribution of the variables. Results. All mobility measures of the BASMI index showed correlations (r) among them ranging from 0.43 to 0.8; p < 0.01. Negative correlations ranging from ­0.43 to ­0.57; p < 0.01 were shown between occiput to wall distance and the remaining mobility measures. The BASFI and BASDAI indexes did correlate with several dimensions of the SF-36 questionnaire. Finally, few of the mobility measures did show correlation with any of the dimensions evaluated by the SF-36 questionnaire. Conclusions. Quality of life was not related to restricted mobility seen in AS subjects, whereas functionality was related with quality of life

Forward head posture and neck mobility in chronic tension-type headache: a blinded, controlled study.

Forward head posture (FHP) and neck mobility were objectively assessed in 25 patients with chronic tension-type headache (CTTH) and 25 healthy controls. Side-view pictures were taken in a sitting position to measure the cranio-vertebral angle. A cervical goniometer was employed to measure the range of all cervical motions. Patients with CTTH showed a smaller cranio-vertebral angle (45.3 degrees +/- 7.6 degrees) than controls (54.1 degrees +/- 6.3 degrees), thus presenting a greater FHP (P < 0.001). Patients also had lesser neck mobility for all cervical movements, except for right lateral flexion (P < 0.01). There was a positive correlation between the cranio-vertebral angle and neck mobility. Within the CTTH group, a negative correlation was found between the cranio-vertebral angle and headache frequency, but neck mobility did not correlate with headache parameters. Further research is needed to define a potential role of FHP and restricted neck mobility in the origin or maintenance of TTH.

Seguimiento a medio plazo de la mejora física y funcional tras tratamiento rehabilitador mediante el trabajo de cadenas musculares en la espondilitis anquilosante / Middle term follow-up of physical functional improvement after rehabilitation treatment by working the muscle chain in ankylosing spondylitis

Introducción. El objetivo de este trabajo es exponer el seguimiento a medio plazo (6 meses) en pacientes con espondilitis anquilosante (EA) que fueron tratados con un protocolo experimental de rehabilitación. Material y métodos. Estudio piloto, abierto y no controlado en el que se analizó el seguimiento durante 6 meses de 20 pacientes diagnosticados de EA según los criterios modificados de Nueva York. Los pacientes recibieron durante 4 meses, 1 sesión semanal de tratamiento rehabilitador (en total 15 sesiones), basado en un protocolo experimental. Se realizó un seguimiento a los 6 meses tras la finalización del tratamiento. La valoración de los cambios de movilidad, capacidad funcional y actividad se recogieron a través de cuestionarios específicos para la EA (Índice de Metrología de Bath para la Espondilitis Anquilosante [BASMI], Índice Funcional de Bath para la Espondilitis Anquilosante [BASFI] e Índice de Actividad de Bath para la Espondilitis Anquilosante [BASDAI]). Para el análisis de los datos se empleó el test no paramétrico de Wilcoxon para muestras relacionadas. Se consideraron valores significativos aquellos cuya p < 0,05. Resultados. Los resultados tras 4 meses de tratamiento, ya publicados previamente, mostraron una mejora significativa en el BASMI y el BASFI. Tras 6 meses de finalización del tratamiento, los pacientes conservan parte de esta mejora. Aunque presentan una disminución en la mejora obtenida con respecto a los valores postratamiento, los valores de movilidad medidos por el BASMI, y el valor del índice BASFI siguen siendo superiores a los 6 meses tras la finalización del tratamiento, que los valores pretratamiento (p < 0,05). Conclusiones. Los resultados muestran que los pacientes mantienen las mejoras, obtenidas en 15 sesiones semanales de tratamiento, 6 meses tras la finalización del mismo

Introduction. The present paper analyzes the results of a 6 months follow-up period in ankylosing spondylitis (AS) patients after finishing treatment with a specific experimental rehabilitation protocol. Material and methods. An open, non-controlled, physiotherapeutic pilot study was performed. A 6 month follow-up period was analyzed in 20 patients diagnosed of AS according to the modified criteria of New York. Patients received 15 weekly group sessions over 4 months. These sessions were managed by an experienced physiotherapist and based on an experimental protocol. After these 4 months of treatment, a 6 month follow-up period, in which the patients did not receive any type of treatment, was analyzed. Changes in disease, activity, mobility, and functional capacity were evaluated using the following previously validated scales for EA from the Bath group: BASMI, BASDAI, and BASFI. They were assessed 6 month after finishing the treatment. Data analysis was performed with the 2-tailed Wilcoxon ranged test. A p value less than 0.05 was considered as significant. Results. The results after 4 months of treatment that have been previously published showed a significant improvement in BASMI and BASFI indexes. After 6 months of follow-up, the patients maintained part of the improvement. Although, BASMI and BASFI scores at 6 month follow-up were less than post-treatment scores, theses values were significantly greater than pre-treatment values (p < 0.05). Conclusions. The results of the 6 month follow-up period showed that patients partially maintain the improvement obtained after 4 months of rehabilitation treatment with our experimental protocol

Repercusiones en la calidad de vida en pacientes con espondilitis anquilosante mediante tratamiento fisioterápico / Repercusions in the quality of life in patients with ankylosing spondilitis by physiotherapy

Fundamentos y objetivo. La Espondilitis Anquilosante (EA) condiciona la calidad de vida (CV) de las personas afectadas por la enfermedad, siendo el tratamiento fisioterápico un instrumento encaminado a la mejora de la misma. En el presente estudio se evalúan los resultados del tratamiento fisioterápico, mediante dos protocolos de cinesiterapia, en la CV en pacientes con EA. Material y métodos. Se estudiaron 29 pacientes con EA, los cuales fueron divididos en 2 grupos: grupo control y experimental. Al grupo control se le aplicó un protocolo clásico de fisioterapia mientras que al experimental se le aplicó un protocolo experimental basado en el método de Reeducación Postural Global. Se empleó el Cuestionario SF-36 para la valoración de la CV. Resultados. Los resultados mostraron una mejora en la CV en todos los pacientes independientemente del protocolo fisioterápico aplicado, especialmente en las dimensiones rol físico, función social y rol emocional. Por otro lado, no existieron diferencias significativas entre las mejoras en ambos grupos. Conclusiones. El tratamiento fisioterápico es una herramienta terapéutica indispensable en el tratamiento de la EA, ya que mejora la CV, además de la condición física, en este tipo de pacientes. Debido a las pocas investigaciones existentes en España sobre la CV en la EA, y menos aún en relación a los tratamientos fisioterápicos aplicadas a la misma, creemos que es necesario la realización de estudios que profundicen en este ámbito, mediante el empleo y la validación de instrumentos de CV específicos para la EA

Fundamentals and purpose. Ankylosing Spondylitis (AS) conditions the quality of life in these patients. Physical therapy treatment is a therapeutically instrument necessary in the management of these patients. In the present study there were evaluated the results from two physical therapy treatments measuring changes in quality of life. Material and methods. 29 patients diagnosed with AS according to the modified criteria of New York were divided into 2 groups: control, and experimental group. Control group was treated with a conventional protocol of physical therapy in AS, whereas experimental group was treated with the protocol suggested by our investigation group based on the Global Postural Reeducation method. The quality of life outcome measure was the SF-36 Spanish version. Results. The results showed a statistically improvement in all patients, independently of the physical therapy treatment. The greater improvement was in physical roll, social function, and emotional roll dimensions. However, there were no statistical differences between the improvement in both groups. Conclusions. Physical therapy treatment is a therapeutically instrument necessary in the management of these patient, because improves the quality of life and physical parameters. Due to the few Spanish researches about the quality of life in AS, and about physical therapy treatment, further trials are necessary. Moreover, the validation of specific quality of life questionnaires in AS is necessary in further studies

Pleiotropic effects of the Arabidopsis cryptochrome 2 allelic variation underlie fruit trait-related QTL.

The previous molecular identification of a flowering time QTL segregating in the Arabidopsis L er x Cvi cross, demonstrated that natural allelic variation at the blue light photoreceptor CRY2 gene affects flowering time (El-Assal et al., 2001). In addition, previous works on the same cross have mapped several QTL affecting other unrelated life history traits in the CRY2 genomic region. In the present report, we have used a set of Arabidopsis L er transgenic plants carrying four different functional CRY2 transgenes for phenotypic analyses, with the aim of exploring the extent of pleiotropy of CRY2 allelic variation. It is concluded that previously identified QTL affecting fruit length, ovule number per fruit, and percentage of unfertilized ovules are caused by this same Ler/Cvi CRY2 allelic variation. In addition, dose effects of the CRY2-L er allele are detected for fruit length. A seed weight QTL at the map position of CRY2 could not be confirmed and also no effect on seed dormancy was observed. Thus, it is shown that transgenic plants carrying different alleles can be a useful tool to attribute QTL for different complex traits to a specific locus, even when the relationship among the traits has not been previously suggested.

Tratamiento fisioterapéutico en la espondilitis anquilosante mediante el trabajo de cadenas musculares / Physiotherapy in ankylosing spondylitis through exercising muscle chains

Introducción: En la actualidad existen múltiples protocolos de fisioterapia para el tratamiento de la espondilitis anquilosante (EA); sin embargo, si analizamos las repercusiones funcionales, podemos observar que no todos los ejercicios son los más convenientes para esta patología. El objetivo de este artículo es exponer los resultados obtenidos en un estudio piloto realizado en pacientes con EA en la Comunidad de Madrid, basado en la aplicación de un protocolo específico de fisioterapia y rehabilitación creado por nuestro grupo de trabajo. Material y métodos: Estudio piloto, abierto y no controlado, en el que se incluyeron todos los pacientes diagnosticados de EA según los criterios modificados de Nueva York, pertenecientes a dos asociaciones de la Comunidad de Madrid, que voluntariamente aceptaron participar en nuestro protocolo fisioterapéutico. El estudio incluyó 20 pacientes (15 mujeres y 5 varones) con una edad de 43 ñ 9 años. A todos los pacientes del estudio se les aplicó el protocolo fisioterapéutico experimental propuesto por nuestro equipo de investigación, y que se basa en el trabajo de las cadenas musculares y de la articulación sacroilíaca. Durante 4 meses los pacientes recibieron una sesión semanal en grupo (total, 15 sesiones), con una duración aproximada de 1 h cada sesión. Los cambios en la actividad de la enfermedad, movilidad y capacidad funcional fueron valorados antes y después del tratamiento a través de las escalas del grupo de Bath previamente validadas: BASDAI, BASFI, BASMI. Resultados: Los resultados obtenidos muestran al final del tratamiento una mejora significativa (p < 0,05) de todos los parámetros individuales de movilidad vertebral incluidos en el BASMI (mejora del 28 por ciento en la flecha nucal, del 35 por ciento en el test de Schöber y del 22 por ciento en la rotación cervical, entre los más destacados), así como de la capacidad funcional global valorada en el BASFI. Se observó también una discreta mejoría en la actividad de la enfermedad valorada por el BASDAI, aunque ésta no alcanzo significación estadística. Conclusiones: Los resultados de este estudio piloto sugieren la utilidad terapéutica de programas fisioterapéuticos específicamente diseñados para pacientes con EA, si bien se precisan estudios más amplios y controlados para confirmar definitivamente estos resultados (AU)

A QTL for flowering time in Arabidopsis reveals a novel allele of CRY2.

Variation of flowering time is found in the natural populations of many plant species. The underlying genetic variation, mostly of a quantitative nature, is presumed to reflect adaptations to different environments contributing to reproductive success. Analysis of natural variation for flowering time in Arabidopsis thaliana has identified several quantitative trait loci (QTL), which have yet to be characterized at the molecular level. A major environmental factor that determines flowering time is photoperiod or day length, the length of the light period, which changes across the year differently with geographical latitude. We identified the EDI locus as a QTL partly accounting for the difference in flowering response to the photoperiod between two Arabidopsis accessions: the laboratory strain Landsberg erecta (Ler), originating in Northern Europe, and Cvi, collected in the tropical Cape Verde Islands. Positional cloning of the EDI QTL showed it to be a novel allele of CRY2, encoding the blue-light photoreceptor cryptochrome-2 that has previously been shown to promote flowering in long-day (LD) photoperiods. We show that the unique EDI flowering phenotype results from a single amino-acid substitution that reduces the light-induced downregulation of CRY2 in plants grown under short photoperiods, leading to early flowering.

Genetic analysis of seed-soluble oligosaccharides in relation to seed storability of Arabidopsis.

Seed oligosaccharides (OSs) and especially raffinose series OSs (RSOs) are hypothesized to play an important role in the acquisition of desiccation tolerance and consequently in seed storability. In the present work we analyzed the seed-soluble OS (sucrose, raffinose, and stachyose) content of several Arabidopsis accessions and thus identified the genotype Cape Verde Islands having a very low RSO content. By performing quantitative trait loci (QTL) mapping in a recombinant inbred line population, we found one major QTL responsible for the practically monogenic segregation of seed stachyose content. This locus also affected the content of the two other OSs, sucrose, and raffinose. Two candidate genes encoding respectively for galactinol synthase and raffinose synthase were located within the genomic region around this major QTL. In addition, three smaller-effect QTL were identified, each one specifically affecting the content of an individual OS. Seed storability was analyzed in the same recombinant inbred line population by measuring viability (germination) under two different seed aging assays: after natural aging during 4 years of dry storage at room temperature and after artificial aging induced by a controlled deterioration test. Thus, four QTL responsible for the variation of this trait were mapped. Comparison of the QTL genetic positions showed that the genomic region containing the major OS locus did not significantly affect the seed storability. We concluded that in the studied material neither RSOs nor sucrose content had a specific effect on seed storability.

The late flowering phenotype of fwa mutants is caused by gain-of-function epigenetic alleles of a homeodomain gene.

The transition to flowering in Arabidopsis thaliana is delayed in fwa mutant plants. FWA was identified by loss-of-function mutations in normally flowering revertants of the fwa mutant, and it encodes a homeodomain-containing transcription factor. The DNA sequence of wild-type and fwa mutant alleles was identical in the genomic region of FWA. Furthermore, the FWA gene is ectopically expressed in fwa mutants and silenced in mature wild-type plants. This silencing is associated with extensive methylation of two direct repeats in the 5' region of the gene. The late flowering phenotype, ectopic FWA expression, and hypomethylation of the repeats were also induced in the ddm1 hypomethylated background. Mechanisms for establishment and maintenance of the epigenetic mark on FWA are discussed.

Naturally occurring variation in Arabidopsis: an underexploited resource for plant genetics.

The definition of gene functions requires the phenotypic characterization of genetic variants. Currently, such functional analysis of Arabidopsis genes is based largely on laboratory-induced mutants that are selected in forward and reverse genetic studies. An alternative complementary source of genetic variation is available: the naturally occurring variation among accessions. The multigenic nature of most of this variation has limited its application until now. However, the use of genetic methods developed to map quantitative trait loci, in combination with the characteristics and resources available for molecular biology in Arabidopsis, allow this variation to be exploited up to the molecular level. Here, we describe the current tools available for the forward genetic analysis of this variation, and review the recent progress in the detection and mapping of loci and the cloning of large-effect genes.

Natural allelic variation identifies new genes in the Arabidopsis circadian system.

We have analysed the circadian rhythm of Arabidopsis thaliana leaf movements in the accession Cvi from the Cape Verde Islands, and in the commonly used laboratory strains Columbia (Col) and Landsberg (erecta) (Ler), which originated in Northern Europe. The parental lines have similar rhythmic periods, but the progeny of crosses among them reveal extensive variation for this trait. An analysis of 48 Ler/Cvi recombinant inbred lines (RILs) and a further 30 Ler/Col RILs allowed us to locate four putative quantitative trait loci (QTLs) that control the period of the circadian clock. Near-isogenic lines (NILs) that contain a QTL in a small, defined chromo- somal region allowed us to confirm the phenotypic effect and to map the positions of three period QTLs, designated ESPRESSO, NON TROPPO and RALENTANDO. Quantitative trait loci at the locations of RALENTANDO and of a fourth QTL, ANDANTE, were identified in both Ler/Cvi and Ler/Col RIL populations. Some QTLs for circadian period are closely linked to loci that control flowering time, including FLC. We show that flc mutations shorten the circadian period such that the known allelic variation in the MADS-box gene FLC can account for the ANDANTE QTL. The QTLs ESPRESSO and RALENTANDO identify new genes that regulate the Arabidopsis circadian system in nature, one of which may be the flowering-time gene GIGANTEA.

Natural allelic variation at seed size loci in relation to other life history traits of Arabidopsis thaliana.

We have analyzed two Arabidopsis strains differing in the mean seed size and seed number they produced. The accession Cape Verde Islands (Cvi) yielded on average about 40% fewer seeds than the laboratory strain Landsberg erecta (Ler), but Cvi seeds were almost twice as heavy. Maternal and nonmaternal genetic factors were involved in the seed size variation, and interactions between both types of factors presumably occurred. The Ler/Cvi seed size difference increased through seed development from ovule maturation until seed desiccation, suggesting that multiple processes of seed development were affected. In addition, it involved changes in the final cell number and cell size of the seed coat and the embryo. Cell number variation was controlled mainly by maternal factors, whereas nonmaternal allelic variation mostly affected cell size. By using a recombinant inbred line population derived from Ler and Cvi, we mapped quantitative trait loci (QTLs) affecting 12 life history traits related to seed size, fruit size, seed number, and plant resources. Five of the seed size QTLs colocated with QTLs for other traits, suggesting that they control seed size via maternal components affecting ovule number and/or carpel development, ovule development, or reproductive resource allocation in the mother plant. The six remaining putative seed size QTLs did not show a significant effect on any other trait, suggesting that this allelic variation may be involved specifically in seed development processes.

Cytogenetics for the model system Arabidopsis thaliana.

A detailed karyotype of Arabidopsis thaliana is presented using meiotic pachytene cells in combination with fluorescence in situ hybridization. The lengths of the five pachytene bivalents varied between 50 and 80 microns, which is 20-25 times longer than mitotic metaphase chromosomes. The analysis confirms that the two longest chromosomes (1 and 5) are metacentric and the two shortest chromosomes (2 and 4) are acrocentric and carry NORs subterminally in their short arms, while chromosome 3 is submetacentric and medium sized. Detailed mapping of the centromere position further revealed that the length variation between the pachytene bivalents comes from the short arms. Individual chromosomes were unambiguously identified by their combinations of relative lengths, arm-ratios, presence of NOR knobs and FISH signals with a 5S rDNA probe and chromosome specific DNA probes. Polymorphisms were found among six ecotypes with respect to the number and map positions of 5S rDNA loci. All ecotypes contain 5S rDNA in the short arms of chromosomes 4 and 5. Three different patterns were observed regarding the presence and position of a 5S rDNA locus on chromosome 3. Repetitive DNA clones enabled us to subdivide the pericentromeric heterochromatin into a central domain, characterized by pAL1 and 106B repeats, which accommodate the functional centromere and two flanking domains, characterized by the 17 A20 repeat sequences. The upper flanking domains of chromosomes 4 and 5, and in some ecotypes also chromosome 3, contain a 5S rDNA locus. The detection of unique cosmids and YAC sequences demonstrates that detailed physical mapping of Arabidopsis chromosomes by cytogenetic techniques is feasible. Together with the presented karyotype this makes Arabidopsis a model system for detailed cytogenetic mapping.