| To establish mutant libraries for wheat functional genomics, the tetraploid wheat accession Khapli was treated with fast neutron (FN) and ethylmethane sulfonate (EMS).443 mutants involved in most of the phenotypes from EMS-treatment and 61 from FN-treatment were identified by phenotypic evaluation of M2 plants and M3, M4, M5 progenies. These mutants distributed all through the whole growth period of tetraploid wheat, and most mutant phenotype appeared since their early vegetative growth. According to phenotype characters, these mutants could be classified into 13 major category including maturity, leaf, plant type, spike, sterility, root, response to stress and so on, and even 104 subcategory. Most mutants had changed in more than one character. More than 70%of them showed plant height or type variation. And more than 60%were growth vigour or leaf morphology related. Spike morphology related mutants accounted for about 38%. In this mutant pool, eight salinity tolerance related mutants had been identificated. There were also thirteen mutants showing variable degree of susceptibility to powder mildew. In addition, a BR-insensitive mutant showing erect leaf over its life was also identified.Characterization of yield trait mutants is important to understand the regulation of grain yield formation of staple food crops. Meh0239 is a yield trait-related mutant that created by EMS treatment of dry seeds of common wheat cultivar Wangshuibai. To shed some light on the nature of this mutation, it was investigated morphologically, physiologically, anatomically and genetically. The mutant plant shows obvious phenotypical difference from the wild type starting at the seedling stage. It has a reduced plant height, wider and shorter leaves, shortened spikes, spikelets and grains, and a more compact spikelet distribution. Seeds produced in the mutant germinated slower. Meh0239 contains a significantly higher level of abscisic acid (ABA) but a lower level of indole-3-acetic acid (IAA), methyl jasmonate (MeJA) or zeatin riboside (ZR) in flag leaves. Cells of all types in the leaf epidermis appeared shorter along the axial direction. The bulliform cells and long cells on the adaxial leaf surface were abnormal in shape. Genetic analysis using two F2 segregating populations indicated that a single recessive mutation on wheat chromosome 7DS, about 3.1cM distal from Xwmc506, causes these variations. Because of the pleiotropic nature of this gene and its relations with yield trait formation, we named it Ytl for yield trait-related 1.A documented recessive powdery mildew resistance gene pm2026 had been identified in einkorn accession TA2026, and had been located on 5AmL by primary mapping. For fine mapping and cloning of pm2026, three more closely linked STS-CAPS markers of MAG5222-MspI, MAG5067-MspI and MAG5066-AluI, were developed based on the colinearity of wheat, rice and Brachypodium in this chromosome region. And an enlarged F2:3 segregating population containing about 4000 lines was constructed.44 resistant recombinants were identified by flanking markers of MAG 1491 and MAG4586. Through these recombinants and those developed STS-CAPS markers, pm2026 was located in a genetic region of 0.2cM finally and was consegrated with Xmag5066 and Xmag5067. The genomic BAC library of TA2026 was screened by MAG5222 and MAG2170 through PCR, and four positive clones of 27L13,438013,330P9 and 178016 had been identified. Then the restriction enzyme finger printing, sequencing of positive BAC clones and genetic analysis by markers derived from BAC sequence in these recombinants had been done alternately. Finally, pm2026 was restricted to a physical range of 15kb. |
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