Mapping QTLs For Traits Associated With Stomatal On Spikelet In Wheat(Triticum Aestivum L.)

The sources of photosynthetic materials in wheat yield formation, in addition to the leafs, include spike organs of non-leaf organs. Wheat spike organs not only have a function of photosynthetic production, but also do protect the grains from light damage, and maintain the humidity and temperature of microenvironment in which grains grow, and thus play an important role in the grain formation. Investigation of the genetic variations of stomata-related traits in wheat spike organs can provide a basis for revealing relationships between spike stomata-related traits and between those and leaf stomata-related traits and revealing genetic regulatory networks. In this study, materials for genetic study were DH population derived from common wheat Hanxuan 10 and Lumai 14 hybrids, a total of 150 lines. In two years we observed spike's stomatal density and size three days after flowering, calculated the potential conductance index (PIC), stomatal length/stomatal width (L/W) and stomatal apertura (SA), relative stomatal area per spike (RSA), and analyzed QTLs for above-mentioned traits. The results were as follows:(1)The stomatal arrangement and the stomatal distribution in the spike organs were different in different parts. Stomata on apex of glume and lemma were dense. Relatively less stomata were on middle of glume and lemma. Basically there were no stomata on down of lemma. And stomata on palea were only found in the crease of the edge. Potential conductance index is consistent with stomatal density. Stomatal width/stomatal length on lemma is larger than that on glume, which may because of longer and narrower stomata on lemma and shorter and wider stomata on glume. Environmental conditions can significantly affect stomatal density and width, stomatal density and width in 2012 was significantly greater than in 2013, the impact of the environment on the stomatal length, PCI, L/W, SA and RSA is rather small.In both environments, the stomatal density in different parts of wheat spike organs has significantly or very significantly negatively correlation with corresponding stomatal length, but not significant with the stomatal width; the stomatal length has significant or highly significant positive correlation with stomatal width in 2012, and highly significant positive correlation in 2013 except in middle of lemma, apex and down of glume.In both environments, the stomatal apertura, relative stomatal area per spike and potential conductance index of the various parts showed significant positive correlations respectively. Stomatal length/stomatal width has significant negative correlation with stomatal apertura except in two years' palea,2012'apex of lemma glume; stomatal length/stomatal width has significant or highly significant negative correlations with relative stomatal area per spike, except in palea. stomatal length/stomatal width has significant positive correlations with potential conductance index, except in 2013'middle of lemma, two years' middle and down of glume.In 2012, stomatal density with RSA and PCI, stomatal length with L/W, PCI, SA and RSA(except apex of palea and lemma), stomatal width with SA, RSA and PCI(except middle of lemma and apex of glume) had significant or highly significant positive correlations; stomatal density with L/W and SA (except middle of palea and lemma), stomatal width with L/W had significant or highly significant negative correlations. In 2013, stomatal density with RSA (except palea, apex of lemma and glume) and PCI (except palea, apex of lemma and glume), stomatal length with SA, stomatal width with SA had significant or highly significant positive correlations; stomatal density with SA (except palea, middle of lemma and apex of glume) had significant or highly significant negative correlations.QTL analysis for spike stomata-related traits under two environments was carried out and 36 additive QTLs were detected and distributed on 1B, 1D,2A,3B,4A,4B,5A,5D,6A and 7B chromosomes, with variations explained ranged from 1.04% to 11.11%. In which eight and five QTLs were located on marker interval Xgwm291-Xgwm410-WMC340 and WMC410-WMC74-Xgwm291 on chromosome 5A,3 QTLs were located on marker interval P8143.2-P3713 on chromosome IB. In 36 additive QTLs, the variations explained by only QDGsd-5A was greater than 10%.45 pairs of epistatic QTLs for stomata-related traits were detected in two years, distributed on the 20 chromosomes except ID, and with variations explained ranged from 0.79% to 17.01%. In which the variations explained by only 8 pairs were greater than 10%, indicating that the traits are mainly controlled by the minor-polygenes. Except spike stomatal density, the rest traits are controlled by additive and epistatic QTL together.QTL mapping displayed that QALsd-A, QMLsd-5A, QAGsd-5A, QMGsd-5A and QDGsd-5A controlling stomatal density and QAGsl-5A and QDGsl-5A controlling stomatal length are located on marker interval Xgwm291-Xgwm410-WMC340 on chromosome 5A, and have contrary additive effect. This provides a genetic basis for the negative correlations between stomatal density and stomatal length of various parts in two years.