Genetic and Physiological Architecture of Early Vigor in Aegilops tauschii, the D-Genome Donor of Hexaploid Wheat. A Quantitative Trait Loci Analysis

Abstract

Plant growth can be studied at different organizational levels, varying from cell, leaf, and shoot to the whole plant. The early growth of seedlings is important for the plant's establishment and its eventual success. Wheat (Triticum aestivum, genome AABBDD) seedlings exhibit a low early growth rate or early vigor. The germplasm of wheat is limited. Wild relatives constitute a source of genetic variation. We explored the physiological and genetic relationships among a range of early vigor traits in Aegilops tauschii, the D-genome donor. A genetic map was constructed with amplified fragment-length polymorphism and simple sequence repeat markers, and quantitative trait loci (QTL) analysis was performed on the F 4 population of recombinant inbred lines derived from a cross between contrasting accessions. The genetic map consisted of 10 linkage groups, which were assigned to the seven chromosomes and covered 68% of the D genome. QTL analysis revealed 87 mapped QTLs (log of the odds .2.65) in clusters, 3.1 QTLs per trait, explaining 32% of the phenotypic variance. Chromosomes 1D, 4D, and 7D harbored QTLs for relative growth rate, biomass allocation, specific leaf area, leaf area ratio, and unit leaf rate. Chromosome 2D covered QTLs for rate and duration of leaf elongation, cell production rate, and cell length. Chromosome 5D harbored QTLs for the total leaf mass and area and growth rate of the number of leaves and tillers. The results show that several physiological correlations between growth traits have a genetic basis. Genetic links between traits are not absolute, opening perspectives for identification of favorable alleles in A. tauschii to improve early vigor in wheat.

Combined Genetic and Modeling Approaches Reveal That Epidermal Cell Area and Number in Leaves Are Controlled by Leaf and Plant Developmental Processes in Arabidopsis

“…As described in the introduction of this article, it is often shown that there is a balance between both cell area and cell number in plants (Ter Steege et al, 2005;Ferjani et al, 2007). In the first general analysis, we found that it was not the case in the whole population studied here: Both variables were positively correlated with final leaf 6 area, but there was no correlation between them.…”

QTL mapping for germination of seeds obtained from previous wheat generation under drought

“…Various studies carried out, e.g. by [30] and [8] indicate a positive correlation between the germination capacity and the early vitality of grain. The germination capacity depends closely on the external conditions accompanying the processes of grain setting and filling, grain storage conditions [31][32][33][34] as well as grain size [35].…”

“…Wild species related to bread wheat show remarkable genetic diversity essential to the improvement of the quality of cultivated plants. The D genome originating from A. tauschii is considered a potential donor of traits associated with the vigour of grain, including germination capacity [30,41,42]. The principal regions on D genome associated with grain germination provide a common location for the genes coding for D-type cyclins (1D) and cytochrome 450 genes (P450 gene family), spermitine synthase 1 (SPDSY 1) (7D), and protein synthase gene.…”

Plasticity to soil water deficit in Arabidopsis thaliana: dissection of leaf development into underlying growth dynamic and cellular variables reveals invisible phenotypes

“…A negative relationship between cell number and cell size has been reported in cell cycle transgenic lines (Hemerly et al 1995) and in a population of recombinant inbred lines of Aegilops tauschii (Ter Steege et al 2005). The basis of these partial compensations are not known but they are probably under genetic control as the analysis of a population of recombinant inbred lines led to overlapping QTLs, with opposite effects for each couple of variables (Ter Steege et al 2005).…”