Evaluation For Seeding Drought Resistance Of Different Maize Inbred Lines And QTLs Identification On Yield-related Traits In Maize

In the spring and summer of each year, the main maize production regions of Chinaare always affected by drought, then drought is the most abiotic stress factor for maizeseedling growth and yield. Screening and determining drought-resistant germplasmresources and ultimately improving the drought tolerance level of maize in seedling stagehave already been a main task for maize breeders. High yield is a primary goal for maizebreeding in our country and ear is an important part of maize yield. QTL mapping formaize yield related traits using molecular marker technology could provide theoreticalbasis for high yield breeding.In the present study, a total of five index, plant height, stem diameter, free proline (Pro)content, malondialdehyde (MDA) content and peroxidase (POD), was measured for100maize inbred lines during seeding stage under drought stressed condition simulated byhypertonic solution of20%polyethylene glycol (PEG-6000), and methods of averagesubordinative function, principal components analysis and cluster analysis was used toevaluate drought resistance levels based on drought resistance coefficient regard to eachtrait.Additionally, a total of173F2:3families derived from maize inbred lines Zheng22and Dan599was used for the measurement of fifteen yield related traits (plant height, earlength, ear diameter, cob diameter, row number per ear, grain number per row,hundred-grain weight, volume-weight, panicle weight, grain weight per spike) andultimately QTL detection using composite interval mapping. The main results are asfollows:Under drought stressed condition simulated by hypertonic solution of20%polyethylene glycol (PEG-6000),100maize inbred lines used were classified into fivedrought resistance levels, that is extreme drought resistant material containing32inbredlines, strong drought resistant material containing22inbred lines, medium droughtresistant material containing31inbred lines, weak drought resistant material containing13inbred lines and pianissimo drought resistant material containing2inbred lines.An F2:3population of Zheng22×Dan599was used in quantitative trait loci (QTL)analysis for15traits of agronomic importance, mainly including yield-related traits. A totalof38QTL controlling10traits were detected with a genetic linkage map constructed by96 SSR makers under two environments of Handan and Baoding in China, of which29werefound in Handan and9were found in Baoding, and all the QTL distributed onchromosomes of1to8, explaining0.01%to31.97%of phenotypic variance. The numberof QTL detected from most to least was8for hundred-grain weight;6for volume-weight;4for plant height, ear length and ear diameter one each;3for cob diameter, row numberper ear and tasseling date one each;2for grain number per row; and1for grain weight perspike, Bare Ear length one each. Totally,21major QTL were discovered based on theirphenotypic variance were greater than10%.Altogether,8QTL-rich regions involving22QTL mapped on chromosome1,2,3,4,6and7were revealed by the present study and QTL accounted for the largest phenotypicvariance for each trait were located in the QTL-rich regions. The number of QTL includedin11QTL-rich regions accounted for54.5%of total QTL discovered, and57.9%of majorQTL were mapped on QTL-rich regions. A significant correlation for traits associated withQTL contained in QTL-rich regions was found, indicating the pleiotropism phenomenonfor QTL-rich regions.