Prioritization of Candidate Genes in QTL Regions for Physiological and Biochemical Traits Underlying Drought Response in Barley (Hordeum vulgare L.)

Drought is one of the most adverse abiotic factors limiting growth and productivity of crops. Among them is barley, ranked fourth cereal worldwide in terms of harvested acreage and production. Plants have evolved various mechanisms to cope with water deficit at different biological levels, but there is an enormous challenge to decipher genes responsible for particular complex phenotypic traits, in order to develop drought tolerant crops. This work presents a comprehensive approach for elucidation of molecular mechanisms of drought tolerance in barley at the seedling stage of development. The study includes mapping of QTLs for physiological and biochemical traits associated with drought tolerance on a high-density function map, projection of QTL confidence intervals on barley physical map, and the retrievement of positional candidate genes (CGs), followed by their prioritization based on Gene Ontology (GO) enrichment analysis. A total of 64 QTLs for 25 physiological and biochemical traits that describe plant water status, photosynthetic efficiency, osmoprotectant and hormone content, as well as antioxidant activity, were positioned on a consensus map, constructed using RIL populations developed from the crosses between European and Syrian genotypes. The map contained a total of 875 SNP, SSR and CGs, spanning 941.86 cM with resolution of 1.1 cM. For the first time, QTLs for ethylene, glucose, sucrose, maltose, raffinose, α-tocopherol, γ-tocotrienol content, and catalase activity, have been mapped in barley. Based on overlapping confidence intervals of QTLs, 11 hotspots were identified that enclosed more than 60% of mapped QTLs. Genetic and physical map integration allowed the identification of 1,101 positional CGs within the confidence intervals of drought response-specific QTLs. Prioritization resulted in the designation of 143 CGs, among them were genes encoding antioxidants, carboxylic acid biosynthesis enzymes, heat shock proteins, small auxin up-regulated RNAs, nitric oxide synthase, ATP sulfurylases, and proteins involved in regulation of flowering time. This global approach may be proposed for identification of new CGs that underlies QTLs responsible for complex traits

Drought-Stress Induced Physiological and Molecular Changes in Plants 2.0

Plant adaptation to soil drought is a topic that is currently under investigation [...

Participation of Wheat and Rye Genome in Drought Induced Senescence in Winter Triticale (X <em>Triticosecale</em> Wittm.)

The aim of the study was to identify the regions of triticale genome responsible for senescence under drought induced during the generative stage. We performed quantitative analysis of chlorophylls (a and b), carotenoids, soluble carbohydrates, and phenolic compounds. QTL (Quantitative Trait Loci) calculations were based on a previously developed and characterized genetic map involving 92 lines of doubled haploid derived from F1 hybrid ‘Hewo’ × ‘Magnat’ and two DH parental lines (‘Hewo’ and ‘Magnat’). We identified seven QTLs, including four on chromosome 2A, one on chromosome 1R, and two on chromosome 6R. Only three loci, QSPh.2A.1, QSC.2A.2 and QSC.2A.4 mapped single traits, i.e., the content of soluble phenolics and carbohydrates. Single QTL (QCSPh.1R) was responsible for changes in the levels of chlorophyll a and b, carotenoids and soluble phenolics. The remaining three loci, QCSPhC.2A.3, QCSPhC.6R.1 and QCSPhC.6R.2 controlled changes in the entire set of investigated traits. We also identified candidate genes for the investigated traits. The loci on chromosome 2A encoded proteins responsible for oligosaccharide transportation and mechanical properties of xylem and the genes regulating carbohydrate metabolism. The chromosomes 1R and 6R contained functional genes possibly associated with carbohydrate and phenolic metabolism

Physiological markers of stress susceptibility in maize and triticale under different soil compactions and/or soil water contents

Differences between two maize and two triticale genotypes grown in low soil compaction (LSC), moderate soil compaction (MSC) and severe soil compaction (SSC) and with a limited (D) or excess (W) soil water content were observed as a decrease in shoot (S) and root (R) biomass, leaf greening (SPAD) and increase in membrane injury (LI), root and leaf water potential (ψ), photosynthesis (Pn), transpiration (E) and stomata conductance (gS). Close correlations between ψL and ψR, and between differences ψL and ψR (Δψ) were found. Drought or waterlogging with LSC conditions in both maize genotypes resulted in higher WUE than in control plants (LSC C), but under the SSC WUE declined. However, for triticale differences in WUE, between treatments were small and insignificant. In general, changes in markers were greater for genotypes sensitive to the soil compaction (Ankora, CHD-12) than in resistant ones (Tina, CHD-247) and were higher in seedlings grown under SSC conditions. Abbreviations: ψR, ψL: root and leaf water potential; C: control; D: drought; E: transpiration rate; FWC: field water capacity; gS: stomatal conductance; LSC, MSC, SSC: low, moderate and severe soil compaction; Pn: photosynthesis rate; W: waterloggin