Natural variation of drought response in Brachypodium distachyon

Abstract

Brachypodium distachyon (Brachypodium) is a temperate wild grass species and is a powerful model system for studying grain, energy, forage and turf grasses. Exploring the natural variation in the drought response of Brachypodium provides an important basis for dissecting the genetic network of drought tolerance. Two experiments were conducted in a greenhouse to assess the drought tolerance of 57 natural populations of Brachypodium. Principle component analysis revealed that reductions in chlorophyll fluorescence (Fv/Fm) and leaf water content (LWC) under drought stress explained most of the phenotypic variation, which was used to classify the tolerant and susceptible accessions. Four groups of accessions differing in drought tolerance were identified, with 3 tolerant, 16 moderately tolerant, 32 susceptible and 6 most susceptible accessions. The tolerant group had little leaf wilting and fewer reductions in Fv/Fm and LWC, while the most susceptible groups showed severe leaf wilting and more reductions in Fv/Fm and LWC. Drought stress increased total water soluble sugar (WSS) concentration, but no differences in the increased WSS were found among different groups of accessions. The large phenotypic variation of Brachypodium in response to drought stress can be used to identify genes and alleles important for the complex trait of drought tolerance.

Genetic and phenotypic diversity for drought tolerance in perennial ryegrass (Lolium perenne L.)

“…In this study, genotypes of world-wide perennial ryegrass collection were compared under water deficit conditions in the controlled climatic chambers and classified into drought tolerant, drought medium tolerant and drought susceptible groups. Leaf wilting, F v /F m and re-growth after the stress provide rapid and easy measurements for the wholeplant responses (Luo et al, 2011;Jonavičienė et al, 2012), thus they were used to screen 104 accessions of perennial ryegrass and characterize drought tolerance at the whole-plant level. Leaf wilting, F v /F m and re-growth after the stress were found to be significantly correlated with each other; however, according to Mantel test, no significant correlation was detected between genetic diversity and phenotypic variation.…”

Natural genetic variation of root system architecture from Arabidopsis to Brachypodium : towards adaptive value

“…Phenotypic variation has already been found for diverse traits in a collection of Turkish accessions, indicating that this germplasm is suitable for natural variation analysis [32,34]. For example, substantial variation in flowering and vernalization time among Brachypodium accessions has been reported in one study [35], whereas broad diversity in drought tolerance was found in another [36]. Natural variation of Brachypodium root system architecture has not been investigated yet.…”

High-throughput imaging and analysis of root system architecture inBrachypodium distachyonunder differential nutrient availability

“…Similarly, wide variation in shoot biomass, flowering time and vernalization response was reported among 24 Brachypodium accessions from various geographic locations [59]. Most recently, an investigation of drought tolerance in 57 natural Brachypodium varieties demonstrated large differences in leaf water content and chlorophyll fluorescence when plants were drought-stressed [60]. Bd21 and Bd3-1 were among the varieties surveyed in the above-mentioned studies, and variation above ground was observed between these two accessions for flowering time, total biomass, plant stature and drought tolerance [52,59,60].…”

“…Most recently, an investigation of drought tolerance in 57 natural Brachypodium varieties demonstrated large differences in leaf water content and chlorophyll fluorescence when plants were drought-stressed [60]. Bd21 and Bd3-1 were among the varieties surveyed in the above-mentioned studies, and variation above ground was observed between these two accessions for flowering time, total biomass, plant stature and drought tolerance [52,59,60]. As plants are known to coordinate aerial and below-ground organ development to maintain a balance between the collection of light energy for photosynthate production, and the acquisition of important water and nutrients from the soil [61,62], we predicted that there would be differences in RSA between Bd21 and Bd3-1.…”