| Wheat is one of the major food crops in China. Drought is one of the most important abiotic stress factors that limit the yield and quality of wheat. Researches on genetic mechanism of drought resistance are important to the food security and sustainable development of China. The main aim of this study was to provide the basis for the study of drought resistance genetic mechanism and wheat breeding via QTL location of wheat seedlings drought related traits and drought gene cloning. The main result was as follow.1. Root number, maximum root length, seedling height, shoot fresh weight, root fresh weight, total fresh weight, shoot dry weight, root dry weight, total dry weight, shoot water loss rate, root water loss rate, relative water content, proline content, MDA content, soluble sugar content and POD activity was determined using a RIL population (Chuan 35050×Shannong 483) of wheat under the osmotic stress condition induced by PEG-6000 and normal water condition in nutrient solution. In both conditions, marked variability of characters was observed in the RIL population. The coefficient of variation of most traits were higher than 10% except for the leaf water loss rate and relative water content in normal water condition and plant height and leaf relative water content in stress condition. Most traits performance transgressive segregation, implying that RIL population has a relatively rich genetic variation, alleles for these traits contributed by parents were separated widely, the population had great potential for selection. Normal distribution was observed in most traits, indicating that these traits were quantitative traits that controlled by multiple genes, with complex mechanism.2. A total of 54 QTLs were detected on 14 chromosomes, 1A, 1B, 1D, 2A, 2B, 2D, 3B, 3D, 4A, 4B, 5A, 5D, 6D and 7A. Of which, 33 QTLs in OS and 21 QTLs in NW were determined, explaining 5.63-37.30% of the phenotypic variations. The additive effects for 22 QTLs were positive with Chuan 35050 increasing the effects, while 32 QTLs were negative with Shannong 483 increasing the effects. Three QTL clusters were located on chromosomes 1D and 5D, four co-located QTLs were detected on chromosomes 2A, 3B and 6D. QMrl.sdau-4A.OS, QRsfw.sdau-6D.2.OS, QTdw.sdau-4A.OS, and QPro.sdau -1D.OS were major QTLs, contributing 37.30, 30.84, 29.09, and 36.75% of the phenotypic variations, respectively.3. Betaine dehydrogenase gene (BADH) was isolated by homology cloning technology using the strong drought-resistant plants Xinjiang wild wheatgrass as material. The full length cDNA obtained was 1422bp, including a 1185bp open reading frame (ORF) that encoding 394 amino acids. Blast research was carried out using the deduced amino acid sequence in NCBI web site, conserved domains of the BADH gene were found, indicating that the sequence isolated was BADH gene sequence, open reading frame is correct. GenBank registrated number GU181396 was get after submit. Wheatgrass BADH gene attributable to the class of monocots, homology with barley and wildrye were 98% and 97%, respectively.4. BADH deduced protein was analyzed in Expasy website using online tools. Secondary structure prediction results showed that the protein is rich inα-helix, extended chain,β-turn and random coil. Hydrophilic predicted results showed that the protein formed a number of hydrophilic peak, and is conducive to the formation ofα-helix structure that can achieve the bound water molecules to protect cells from injury of water stress. |
