Dehydration response in Stylosanthes scabra: Transcriptional, biochemical, and physiological modulations.

Stylosanthes scabra, popularly known as stylo, is native to the Brazilian Caatinga semiarid region and stands out as a drought-tolerant shrub forage crop. This work provides information about the plant response during the first 48 h of water deficit, followed by a rehydration treatment. Besides root transcriptomics data, 13 physiological or biochemical parameters were scrutinized. Additionally, RNA-Seq annotated transcripts not associated with the "Viridiplantae" clade were taxonomically categorized. It was found that S. scabra quickly perceives and recovers from the oscillations of the imposed water regime. Physiologically, mechanisms that minimize evapotranspiration or protect the photosynthetic apparatus stood out. Biochemically, it was found that the root tissue invests in synthesizing compounds that can act as osmolytes (proline and sugars), emphasizing the importance of osmoregulation to water deficit acclimation. Consistently, transcriptome and qPCR analyses showed that a set of enriched biological processes with upregulated (UR) transcripts were involved in protective functions against reactive oxygen species or encoding enzymes of important metabolic pathways, which might contribute to S. scabra response to water deficit. Additionally, several UR kinases and transcription factors were identified. Finally, in an innovative approach, some naturally occurring microbial groups (such as Schizosaccharomyces, Bradyrhizobium, etc.) were identified in the S. scabra roots. This study reveals insights into the physiological, biochemical, and molecular mechanisms underlying the S. scabra response to water deficit and provides candidate genes that may be useful in developing drought-tolerant crop varieties through biotechnological applications.

Salt tolerance of Calotropis procera begins with immediate regulation of aquaporin activity in the root system.

The ability to respond quickly to salt stress can determine the tolerance level of a species. Here, we test how rapidly the roots of Calotropis procera react to high salinity conditions. In the first 24 h after saline exposure, the plants reduced stomatal conductance, increased CO2 assimilation, and water use efficiency. Thus, the root tissue showed an immediate increase in soluble sugars, free amino acid, and soluble protein contents. Twelve aquaporins showed differential gene expression in the roots of C. procera under salinity. Transcriptional upregulation was observed only after 2 h, with greater induction of CpTIP1.4 (fourfold). Transcriptional downregulation, in turn, occurred mainly after 8 h, with the largest associated with CpPIP1.2 (fourfold). C. procera plants responded quickly to high saline levels. Our results showed a strong stomatal control associated with high free amino acid and soluble sugar contents, regulated aquaporin expression in roots, and supported the high performance of the root system of C. procera under salinity. Moreover, this species was able to maintain a lower Na+/K+ ratio in the leaves compared to that of the roots of stressed plants. The first response of the root system, after immediate contact with saline solution, present an interesting scenario to discuss. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-00957-9.

Corrigendum: Ecophysiological Traits of Invasive C3 Species Calotropis procera to Maintain High Photosynthetic Performance Under High VPD and Low Soil Water Balance in Semi-Arid and Seacoast Zones.

[This corrects the article DOI: 10.3389/fpls.2020.00717.].

Ecophysiological Traits of Invasive C3 Species Calotropis procera to Maintain High Photosynthetic Performance Under High VPD and Low Soil Water Balance in Semi-Arid and Seacoast Zones.

The evergreen C3 plant Calotropis procera is native to arid environments. Thus, it grows under high vapor pressure deficit (VPD), intense light, and severe drought conditions. We measured several ecophysiological traits in C. procera plants growing in semi-arid and seacoast environments to assess the attributes that support its photosynthetic performance under these contrasting conditions. Gas exchange analysis, primary metabolism content, nutrients, the antioxidant system, and leaf anatomy traits were measured under field conditions. In the semi-arid environment, C. procera was exposed to a prolonged drought season with a negative soil water balance during the 2 years of the study. Calotropis procera plants were exposed to a positive soil water balance only in the rainy season in the seacoast environment. The leaves of C. procera showed the same photosynthetic rate under high or low VPD, even in dry seasons with a negative soil water balance. Photosynthetic pigments, leaf sugar content, and the activity of antioxidant enzymes were increased in both places in the dry season. However, the anatomical adjustments were contrasting: while, in the semi-arid environment, mesophyll thickness increased in the driest year, in the seacoast environment, the cuticle thickness and trichome density were increased. The ability to maintain photosynthetic performance through the seasons would be supported by new leaves with different morpho-anatomical traits, with contrasting changes between semi-arid and seacoast environments. Furthermore, our results suggest that an efficient antioxidative system and leaf sugar dynamics can contribute to protecting the photosynthetic machinery even under severe drought.

Recomendaciones para el diagnóstico y manejo práctico de la esofagitis eosinofílica pediátrica / Recommendations for the diagnosis and practical management of paediatric eosinophilic oesophagitis

La esofagitis eosinofílica es una enfermedad emergente, crónica, mediada por el sistema inmune y caracterizada por síntomas de disfunción esofágica e inflamación con infiltración eosinofílica aislada en el esófago. Es más frecuente en varones y en sujetos atópicos y los síntomas varían con la edad: en niños pequeños se manifiesta con vómitos, dolor abdominal y problemas con la alimentación y en niños mayores y adolescentes con disfagia e impactación alimentaria. El diagnóstico se basa en la presencia de síntomas e inflamación esofágica con ≥ 15 eosinófilos/campo de gran aumento, tras descartar otras causas de eosinofilia esofágica. Sin tratamiento, la enfermedad suele persistir y puede evolucionar a formas fibroestenóticas más frecuentes en el adulto. Las opciones terapéuticas incluyen inhibidores de la bomba de protones, dieta de eliminación empírica y corticoides deglutidos. Tras el tratamiento de inducción es aconsejable la terapia de mantenimiento. La dieta es el único tratamiento que se dirige a la causa de la enfermedad, al identificar los alimentos desencadenantes. La respuesta a los tratamientos requiere la evaluación histológica, por la escasa concordancia entre los síntomas y la inflamación esofágica. El manejo práctico de la esofagitis eosinofílica presenta desafíos debido, entre otras causas, a la falta de disponibilidad actual de fármacos específicos y a su abordaje con tratamientos dietéticos, en ocasiones, complejos. El presente documento, elaborado por el Grupo de Trabajo de Trastornos Gastrointestinales Eosinofílicos de la Sociedad Española de Gastroenterología, Hepatología y Nutrición Pediátricas, tiene como objetivo facilitar el abordaje diagnóstico y terapéutico de la esofagitis eosinofílica pediátrica, con base en las recientes guías de consenso basadas en la evidencia

Eosinophilic oesophagitis is an emerging and chronic disorder mediated by the immune system, and is characterised by symptoms of oesophageal dysfunction and inflammation with isolated eosinophil infiltration in the oesophagus. It is more common in males and in atopic subjects, and the symptoms vary with age. In younger children, there is vomiting, abdominal pain and dietary problems, with dysphagia and food impaction in older children and adolescents. The diagnosis is based on the presence of symptoms and oesophageal inflammation with ≥ 15 eosinophils / high power field, and after ruling out other causes of oesophageal eosinophilia. Without treatment, the disease usually persists and can progress to fibrostenotic forms more common in adults. The treatment options included proton pump inhibitors, empirical elimination diets, and swallowed topical corticosteroids. Maintenance therapy is advisable after the induction treatment. Diet is the only treatment that is directed at the cause of the disease, on identifying the triggering food or foods. The response to the treatments requires a histological assessment due to the poor agreement between the symptoms and the oesophageal inflammation. The practical management of Eosinophilic oesophagitis presents with challenges, due to, among other causes, the current lack of availability of specific drugs, and to its approach with, occasionally complex, diet treatments. The present document, prepared by the Working Group on Eosinophilic Gastrointestinal Disorders of the Spanish Society of Paediatric Gastroenterology, Hepatology and Nutrition, has as its objective to help in the diagnostic and therapeutic approach to paediatric eosinophilic oesophagitis, based on the recent evidence-based consensus guidelines

[Recommendations for the diagnosis and practical management of paediatric eosinophilic oesophagitis]. / Recomendaciones para el diagnóstico y manejo práctico de la esofagitis eosinofílica pediátrica.

Eosinophilic oesophagitis is an emerging and chronic disorder mediated by the immune system, and is characterised by symptoms of oesophageal dysfunction and inflammation with isolated eosinophil infiltration in the oesophagus. It is more common in males and in atopic subjects, and the symptoms vary with age. In younger children, there is vomiting, abdominal pain and dietary problems, with dysphagia and food impaction in older children and adolescents. The diagnosis is based on the presence of symptoms and oesophageal inflammation with ≥ 15 eosinophils / high power field, and after ruling out other causes of oesophageal eosinophilia. Without treatment, the disease usually persists and can progress to fibrostenotic forms more common in adults. The treatment options included proton pump inhibitors, empirical elimination diets, and swallowed topical corticosteroids. Maintenance therapy is advisable after the induction treatment. Diet is the only treatment that is directed at the cause of the disease, on identifying the triggering food or foods. The response to the treatments requires a histological assessment due to the poor agreement between the symptoms and the oesophageal inflammation. The practical management of Eosinophilic oesophagitis presents with challenges, due to, among other causes, the current lack of availability of specific drugs, and to its approach with, occasionally complex, diet treatments. The present document, prepared by the Working Group on Eosinophilic Gastrointestinal Disorders of the Spanish Society of Paediatric Gastroenterology, Hepatology and Nutrition, has as its objective to help in the diagnostic and therapeutic approach to paediatric eosinophilic oesophagitis, based on the recent evidence-based consensus guidelines.

Reference genes selection for Calotropis procera under different salt stress conditions.

Calotropis procera is a perennial Asian shrub with significant adaptation to adverse climate conditions and poor soils. Given its increased salt and drought stress tolerance, C. procera stands out as a powerful candidate to provide alternative genetic resources for biotechnological approaches. The qPCR (real-time quantitative polymerase chain reaction), widely recognized among the most accurate methods for quantifying gene expression, demands suitable reference genes (RGs) to avoid over- or underestimations of the relative expression and incorrect interpretation. This study aimed at evaluating the stability of ten RGs for normalization of gene expression of root and leaf of C. procera under different salt stress conditions and different collection times. The selected RGs were used on expression analysis of three target genes. Three independent experiments were carried out in greenhouse with young plants: i) Leaf100 = leaf samples collected 30 min, 2 h, 8 h and 45 days after NaCl-stress (100 mM NaCl); ii) Root50 and iii) Root200 = root samples collected 30 min, 2 h, 8 h and 1day after NaCl-stress (50 and 200 mM NaCl, respectively). Stability rank among the three algorithms used showed high agreement for the four most stable RGs. The four most stable RGs showed high congruence among all combination of collection time, for each software studied, with minor disagreements. CYP23 was the best RG (rank of top four) for all experimental conditions (Leaf100, Root50, and Root200). Using appropriated RGs, we validated the relative expression level of three differentially expressed target genes (NAC78, CNBL4, and ND1) in Leaf100 and Root200 samples. This study provides the first selection of stable reference genes for C. procera under salinity. Our results emphasize the need for caution when evaluating the stability RGs under different amplitude of variable factors.

Photosynthetic limitation and mechanisms of photoprotection under drought and recovery of Calotropis procera, an evergreen C3 from arid regions.

Calotropis procera is a C3 plant native from arid environmental zones. It is an evergreen, shrubby, non-woody plant with intense photosynthetic metabolism during the dry season. We measured photosynthetic parameters and leaf biochemical traits, such as gas exchange, photochemical parameters, A/Ci analysis, organic solutes, and antioxidant enzymes under controlled conditions in potted plants during drought stress, and following recovery conditions to obtain a better insight in the drought stress responses of C. procera. Indeed, different processes contribute to the drought stress resilience of C. procera and to the fast recovery after rehydration. The parameters analyzed showed that C. procera has a high efficiency for energy dissipation. The photosynthetic machinery is protected by a robust antioxidant system and photoprotective mechanisms such as alternative pathways for electrons (photorespiration and day respiration). Under severe drought stress, increased stomatal limitation and decreased biochemical limitation permitted C. procera to maintain maximum rate of Rubisco carboxylation (Vc,max) and photosynthetic rate (Amax). On the other hand, limitation of stomatal or mesophyll CO2 diffusion did not impair fast recovery, maintaining Vc,max, chloroplast CO2 concentration (Cc) and mesophyll conductance (gm) unchanged while electron flow used for RuBP carboxylation (Jc) and Amax increased. The ability to tolerate drought stress and the fast recovery of this evergreen C3 species was also due to leaf anti-oxidative stress enzyme activity, and photosynthetic pigments. Thus, these different drought tolerance mechanisms allowed high performance of photosynthetic metabolism by drought stressed plants during the re-watering period.

Stress tolerance and ecophysiological ability of an invader and a native species in a seasonally dry tropical forest.

Ecophysiological traits of Prosopis juliflora (Sw.) DC. and a phylogenetically and ecologically similar native species, Anadenanthera colubrina (Vell.) Brenan, were studied to understand the invasive species' success in caatinga, a seasonally dry tropical forest ecosystem of the Brazilian Northeast. To determine if the invader exhibited a superior resource-capture or a resource-conservative strategy, we measured biophysical and biochemical parameters in both species during dry and wet months over the course of two years. The results show that P. juliflora benefits from a flexible strategy in which it frequently outperforms the native species in resource capture traits under favorable conditions (e.g., photosynthesis), while also showing better stress tolerance (e.g., antioxidant activity) and water-use efficiency in unfavorable conditions. In addition, across both seasons the invasive has the advantage over the native with higher chlorophyll/carotenoids and chlorophyll a/b ratios, percent N, and leaf protein. We conclude that Prosopis juliflora utilizes light, water and nutrients more efficiently than Anadenanthera colubrina, and suffers lower intensity oxidative stress in environments with reduced water availability and high light radiation.

Three cycles of water deficit from seed to young plants of Moringa oleifera woody species improves stress tolerance.

The main objective of this study was to assess whether recurring water stress occurring from seed germination to young plants of Moringa oleifera Lam. are able to mitigate the drought stress effects. Germination, gas exchange and biochemical parameters were analysed after three cycles of water deficit. Young plants were used 50 days after germination under three osmotic potentials (0.0, -0.3 and -0.4 MPa). For each germination treatment, control (irrigated) and stressed (10% of water control) plants were compared for a total of six treatments. There were two cycles of drought interspersed with 10 days of rehydration. The young plants of M. oleifera showed increased tolerance to repeated cycles of drought, maintaining high relative water content (RWC), high water use efficiency (WUE), increased photosynthetic pigments and increased activity of antioxidant enzymes. There was rapid recovery of the photosynthetic rate during the rehydration period. The stressed plants from the -0.3 and -0.4 MPa treatments showed higher tolerance compared to the control plants. The results suggest that seeds of M. oleifera subjected to mild water deficit have had increased the ability for drought tolerance when young plant.