Characterization of the acetohydroxyacid synthase multigene family in the tetraploide plant Chenopodium quinoa

Background Currently, the technology called Clearfield® is used in the development of crops resistant to herbicides that inhibit the enzyme acetohydroxy acid synthase (AHAS, EC 2.2.1.6). AHAS is the first enzyme of the biosynthetic pathway that produces the branched-chain of the essential amino acids valine, leucine, and isoleucine. Therefore, multiple copies of the AHAS gene might be of interest for breeding programs targeting herbicide resistance. In this work, the characterization of the AHAS gene was accomplished for the Chenopodium quinoa Regalona-Baer cultivar. Cloning, sequencing, and Southern blotting were conducted to determine the number of gene copies. Results The presence of multiple copies of the AHAS gene as has been shown previously in several other species is described. Six copies of the AHAS gene were confirmed with Southern blot analyses. CqHAS1 and CqAHAS2 variants showed the highest homology with AHAS mRNA sequences found in the NR Database. A third copy, CqAHAS3, shared similar fragments with both CqAHAS1 and CqAHAS2, suggesting duplication through homeologous chromosomes pairing. Conclusions The presence of multiple copies of the gene AHAS shows that gene duplication is a common feature in polyploid species during evolution. In addition, to our knowledge, this is the first report of the interaction of sub-genomes in quinoa.

Expansins expression is associated with grain size dynamics in wheat (Triticum aestivum L.).

Grain weight is one of the most important components of cereal yield and quality. A clearer understanding of the physiological and molecular determinants of this complex trait would provide an insight into the potential benefits for plant breeding. In the present study, the dynamics of dry matter accumulation, water uptake, and grain size in parallel with the expression of expansins during grain growth in wheat were analysed. The stabilized water content of grains showed a strong association with final grain weight (r(2)=0.88, P <0.01). Grain length was found to be the trait that best correlated with final grain weight (r(2)=0.98, P <0.01) and volume (r(2)=0.94, P <0.01). The main events that defined final grain weight occurred during the first third of grain-filling when maternal tissues (the pericarp of grains) undergo considerable expansion. Eight expansin coding sequences were isolated from pericarp RNA and the temporal profiles of accumulation of these transcripts were monitored. Sequences showing high homology with TaExpA6 were notably abundant during early grain expansion and declined as maturity was reached. RNA in situ hybridization studies revealed that the transcript for TaExpA6 was principally found in the pericarp during early growth in grain development and, subsequently, in both the endosperm and pericarp. The signal in these images is likely to be the sum of the transcript levels of all three sequences with high similarity to the TaExpA6 gene. The early part of the expression profile of this putative expansin gene correlates well with the critical periods of early grain expansion, suggesting it as a possible factor in the final determination of grain size.

De novo sequencing and development of EST-SSR for Gevuina avellana (Proteaceae), a nut tree from South America.

UNLABELLED: • PREMISE OF THE STUDY: The aim of this study was to develop molecular tools to investigate the genetic structure and diversity of natural populations of Gevuina avellana (Molina, Proteaceae), the Chilean hazelnut. Simple sequence repeats (SSRs) derived from expressed sequence tags (EST-SSRs) were developed, optimized, and characterized. • METHODS AND RESULTS: The microsatellite-containing sequences were selected from a cDNA library developed from the nut. The eight marker loci showed two to seven alleles in 60 unrelated trees, from two different natural populations. The observed heterozygosity (H(o)) was 0.44, ranging from 0.07 to 0.92 for different loci. When the multilocus genotype of the eight EST-SSRs was considered, all trees could be differentiated. • CONCLUSIONS: The newly identified EST-SSRs in G. avellana and the multi-pooling strategy involving eight markers will facilitate future studies of clone identification, genetic structure, and diversity.

Evaluación del color y la posición de trampas en la captura de cicadélidos en Gaultheria phillyreifolia (Ericaceae) afectadas por fitoplasmas / Evaluation of trap color and position on the capture of cicadellids in Gaultheria phillyreifolia (Ericaceae) affected by phytoplasmas

Color sticky traps are one of the main alternatives to collect insect vectors, as they are easy to handle and are inexpensive. We aimed to compare the effect of color and height of the traps on the attractiveness to potential cicadellids vectors of plant pathogens. Yellow and green colored stick traps were placed at two different heights in plant of Gaultheria phillyreifolia. Seventeen leafhopper species were identified, with Ribautiana tenerrima Herrich-Shãffer (49 percent), Carelmapu ramosi Linnavuori & DeLong (33 percent), Carelmapu aurionitens Linnavuori (5 percent) and Atanus sp. (6 percent) being the most common. All these species were significantly attracted by yellow sticky traps. Ribautiana tenerrima was the only species affected by the height of the sticky traps. However, this was also dependent on the sampling season. The phytoplasma vector candidate, C. ramosi, showed two population peaks in early and late summer, which may indicate two different generations. Males of this species were more abundant than females on sticky traps, but were both similarly attracted to yellow sticky traps. No differences were detected in the capture efficiency of both sexes at any height of the traps. The high proportion of C. ramosi captured suggests that the yellow sticky traps can be an important element for monitoring this species.

Las trampas pegajosas de colores son una de las principales alternativas en la captura de insectos vectores, debido a su bajo costo y su fácil implementación. El objetivo fue comparar las preferencias a los colores y la altura de colocación de trampas para los posibles cicadélidos vectores de fitopatógenos. Trampas pegajosas amarillas y verdes fueron colocadas en plantas de Gaultheria phillyreifolia a dos distintas alturas. Se diferenciaron 17 especies de cicadélidos, siendo Ribautiana tenerrima Herrich-Shãffer (49 por ciento), Carelmapu ramosi Linnavuori & DeLong, Carelmapu aureonitens Linnavuori (33 y 5 por ciento), Atanus sp. (6 por ciento) las especies más comunes. Todas estas especies se vieron significativamente atraídas por trampas de color amarillo. Ribautiana tenerrima fue la única especie afectada por la altura de las trampas pegajosas, aunque este efecto fue influenciado por la temporada de colecta. La especie candidato a vector, C. ramosi, presentó dos curvas de crecimiento al inicio y finales del verano, lo cual puede representar la emergencia de dos generaciones distintas. Machos de esta especie fueron más abundantes que las hembras en las trampas pegajosas, pero ambos con una similar preferencia hacia el color amarillo. Además, no se detectaron diferencias en la posición de las trampas en la captura de ambos sexos. La alta proporción capturada de C. ramosi, sugiere que trampas de color amarillo pueden ser um elemento importante en el monitoreo de esta especie.

[Evaluation of trap color and position on the capture of cicadellids in Gaultheria phillyreifolia (Ericaceae) affected by phytoplasmas]. / Evaluación del color y la posición de trampas en la captura de cicadélidos en Gaultheria phillyreifolia (Ericaceae) afectadas por fitoplasmas.

Color sticky traps are one of the main alternatives to collect insect vectors, as they are easy to handle and are inexpensive. We aimed to compare the effect of color and height of the traps on the attractiveness to potential cicadellids vectors of plant pathogens. Yellow and green colored stick traps were placed at two different heights in plant of Gaultheria phillyreifolia. Seventeen leafhopper species were identified, with Ribautiana tenerrima Herrich-Shäffer (49%), Carelmapu ramosi Linnavuori & DeLong (33%), Carelmapu aurionitens Linnavuori (5%) and Atanus sp. (6%) being the most common. All these species were significantly attracted by yellow sticky traps. Ribautiana tenerrima was the only species affected by the height of the sticky traps. However, this was also dependent on the sampling season. The phytoplasma vector candidate, C. ramosi, showed two population peaks in early and late summer, which may indicate two different generations. Males of this species were more abundant than females on sticky traps, but were both similarly attracted to yellow sticky traps. No differences were detected in the capture efficiency of both sexes at any height of the traps. The high proportion of C. ramosi captured suggests that the yellow sticky traps can be an important element for monitoring this species.