Drought is a major environmental stress that limits faba bean growth, leading to considerable reduction in their productivity. Two genotypes (Giza 3 and Hara) were evaluated under three water treatments (90%, 60% and 30% field capacity). The results showed that water stress affects negatively chlorophyll fluorescence parameters at different levels of water deficit and the variations of Fv/Fm, ΦPSII and electron transport rate in Giza 3 were largely higher than those in Hara. Drought preferentially enhanced the activities of superoxide dismutase, catalase and guaiacol peroxidase whereas it did not affect ascorbate peroxidase activity. Real-time reverse transcriptase-polymerase chain reaction results demonstrated that the expression of aquaporin (PIP), myeloblastosis (MYB), nine-cis-epoxycarotenoid dioxygenase, late embryogenesis abundant, dehydrins (Dhn), heat shock protein (HSP) and APETALA2/ethylene-responsive factor was modified in response to drought conditions and that all genes were differentially expressed in Hara and Giza 3. The observed expression patterns of these genes might be due to water deficit intensity according to cultivar’s tolerance to drought. Hara with the highest level of antioxidant enzyme activities, the accumulation of proline content and the expression level of Dhn, HSP and MYB gene throughout all conditions tested is reported more drought tolerant than Giza 3. This study should contribute to explaining the physiological, biochemical and molecular mechanism tolerance drought stress and improving breeding program in faba bean.

Barley is characterized by a rich genetic diversity, making it an important model for studies of salinity response with great potential for crop improvement. Moreover, salt stress severely affects barley growth and development, leading to substantial yield loss. Leaf and root transcriptomes of a salt-tolerant Tunisian landrace (Boulifa) exposed to 2, 8, and 24 h salt stress were compared with pre-exposure plants to identify candidate genes and pathways underlying barley’s response. Expression of 3585 genes was upregulated and 5586 downregulated in leaves, while expression of 13,200 genes was upregulated and 10,575 downregulated in roots. Regulation of gene expression was severely impacted in roots, highlighting the complexity of salt stress response mechanisms in this tissue. Functional analyses in both tissues indicated that response to salt stress is mainly achieved through sensing and signaling pathways, strong transcriptional reprograming, hormone osmolyte and ion homeostasis stabilization, increased reactive oxygen scavenging, and activation of transport and photosynthesis systems. A number of candidate genes involved in hormone and kinase signaling pathways, as well as several transcription factor families and transporters, were identified. This study provides valuable information on early salt-stress-responsive genes in roots and leaves of barley and identifies several important players in salt tolerance.

Salt stress negatively impacts crop production worldwide. Genetic diversity among barley (Hordeum vulgare) landraces adapted to adverse conditions should provide a valuable reservoir of tolerance genes for breeding programs. To identify molecular and biochemical differences between barley genotypes, transcriptomic and antioxidant enzyme profiles along with several morpho-physiological features were compared between salt-tolerant (Boulifa) and salt-sensitive (Testour) genotypes subjected to salt stress. Decreases in biomass, photosynthetic parameters, and relative water content were low in Boulifa compared to Testour. Boulifa had better antioxidant protection against salt stress than Testour, with greater antioxidant enzymes activities including catalase, superoxide dismutase, and guaiacol peroxidase. Transcriptome assembly for both genotypes revealed greater accumulation of differentially expressed transcripts in Testour compared to Boulifa, emphasizing the elevated transcriptional response in Testour following salt exposure. Various salt-responsive genes, including the antioxidant catalase 3, the osmoprotectant betaine aldehyde dehydrogenase 2, and the transcription factors MYB20 and MYB41, were induced only in Boulifa. By contrast, several genes associated with photosystems I and II, and light receptor chlorophylls A and B, were more repressed in Testour. Co-expression network analysis identified specific gene modules correlating with differences in genotypes and morpho-physiological traits. Overall, salinity-induced differential transcript accumulation underlies the differential morpho-physiological response in both genotypes and could be important for breeding salt tolerance in barley.

Phytohormones are of great significance in plant growth, development, immunity, and stress responses. As one of the promising phytohormones, salicylic acid (SA) is a natural phenolic compound synthesized from chorismate through two distinct pathways mediated by isochorismate synthase and phenylalanine ammonia-lyase, respectively. It plays crucial roles in regulating various biological processes related to plant growth and development, as well as in response to diverse biotic and abiotic stresses. Pathogens and herbivores are the most confronting biotic factors that pose severe threats to plant fitness and crop yield. The significance of SA in defense responses against these biotic stresses has been well addressed in the past decades. This review pays attention to the biosynthesis, metabolism, and signaling pathways of SA, and SA-mediated defense responses against pathogens and herbivores, thereby providing theoretical perspectives on the regulatory mechanism of SA-mediated immunity under biotic stress and improving the plant fitness and resistance to diseases caused by biotic factors.

Description of the subject. Drought is one of the major abiotic factors affecting growth and productivity of plants by imposing certain morphological, physiological and biochemical changes at different growth stages. Objectives. The objective of this work is to study key morphological, physiological and biochemical responses of faba bean (Vicia faba L. var. ‘minor’) to soil water deficit stress and to assess the contribution of genetic factors in improving faba bean tolerance to water deficit. Method. Plants of 11 faba bean cultivars were grown in the greenhouse and subjected to three levels of water deficit (90, 50 and 30% of field capacity [FC]) in a simple randomized design for 20 days. Water deficit effects on plant growth, relative water content (RWC), gas exchange, chlorophyll a (Chla) and chlorophyll b (Chlb) content, osmoprotectant accumulations (such as proline and soluble sugars), antioxidant enzyme activities and grain yield were determined. Results. Soil water deficit stress reduced growth and affected physiological parameters, especially antioxidant enzyme activities. Water deficit also increased proline, soluble sugars and protein contents. The studied cultivars significantly differed in their responses to water deficit stress. Photosynthetic parameters were less affected in the ‘Hara’ cultivar. Furthermore, this cultivar produced the highest value of grain yield at 30% FC, and showed higher antioxidant enzyme activities (CAT, GPX and APX), osmoprotectant accumulations, Chlb and RWC. The ‘Hara’ cultivar was found to be more tolerant to water deficit stress than the other cultivars. Conclusions. Our methodology can be used for assessing the response of faba bean genetic resources to soil water deficit. The identified tolerant cultivar can be utilized as a source for water stress tolerance in faba bean breeding programs aimed at improving drought tolerance.