Inheritance And Isolation Of Candidate Genes Controlling Thermo-photoperiod Sensitive Male Sterility In BS20 And BS210 Of Wheat (Triticum Aestivum L.)

The thermo-photoperiod sensitive male sterility in plant is controlled by factors ofinheritance and environment. Its performance of fertility and inheritance are muchmore complex than that.of male sterility controlled only by factors of inheritance. Inthis study, the fertility alteration and separation of cDNA fragments genes wereconducted in thermo-photoperiod sensitive male sterile lines BS20 and BS210, andinheritance models were analyzed using parents, F₁ and F₂ in crosses of BS210/Baiyu149 and BS210/O201. Major results are described below:1. Fertility AlterationThe study of fertility alteration was carried out in photo-thermo-controlled growthchambers and with different ecological regions and sow times. The results showed thatthe stage of photo-sensitivity and thermo-sensitivity was coincident from antherchamber formation to mononucleate. BS20 and BS210 showed sterility under theconditions of short day length and low temperature. Fertility alteration of BS20 wasinduced by photoperiod and temperature, but thermo-sensitivity played a leading role,and the critical point of temperature was 10-12℃. Below the critical temperature,BS20 kept the stable sterility, but not affected by the photoperiod. However, above thecritical temperature, the fertility of BS20 improved as the temperature rose. In thetemperature range of 12-14℃the fertility of BS20 improved significantly as thephotoperiod extended. Fertility alteration of BS210 was induced mainly bytemperature, and the critical point of temperature was 10-12℃.2. Inheritance of Photoperiod-temperature Sensitive Male SterilityInheritance of fertility from the crosses of BS210/Baiyu149 and BS210/O201 was investigatedby the mixed major gene plus polygenes inheritance model of quantitative traits. The resultsshowed that the two crosses were controlled by two additive-dominance-epistasis majorgenes+additive-dominance polygenes (E-1 model). The major sterile genes of BS210/Baiyu149& BS210/O201 were negative equal-additive effect and incomplete dominant. The major additiveand dominant effect of BS210/O201 was little higher than BS210/Baiyu149. The inherited modelsof major genes were almost identical in the crosses with same female parent and different maleparents, while polygenes had obvious differences. The heritabilities of major genes weresignificantly higher than that of polygenes. The heritabilities of major genes and polygenes were different in two crosses. Environment was an important effect factor on fertility of thephotoperiod-temperature sensitive genie male sterility. The variance of environmentwere 58.33% and 46.67% in above two crosses. It almost equaled to or even overthan variance of major genes. Therefore, the photoperiod-temperature sensitivemale sterility was called Environment Sensitive Male Sterile.3. Seperation of Candidate genes controlling Photoperiod-temperature Sensitive MaleSterilityDDRT-PCR was used to analyze the differential expression of genes of thephotoperiod-temperature sensitive genie male sterile lines of winter wheat, BS20 andBS210, which are two core female parents of two-line hybrid wheat. They wereplanted in Beijing (fertile environment) and Fuyang, Anhui (sterile environment) in2002-2003. The materials were collected in five stages, stamens/pistil differentiation,anther chamber formation, pollen mother cell formation, tetrad phase, andmono-nucleate phase. The different cDNA bands were identified with reverse Northernblot hybridization and 24 bands were sequenced. 6 candidate gene fragments werescreened including 8 cDNA sequences. The homology research indicated that the 5gene sequences were identical to the partial mRNA sequences of Oryza sativa(japonica cultivar-group) DNA repair-recombination protein (rad50), Triticumaestivum partial mRNA for receptor-like kinase with LRR repeats, Zea mays & Oryzasativa cell death suppressor protein llsl, Oryza sativa (japonica cultivar-group) HAP3genes and Triticum monococcum phosphatidylserine decarboxylase, and the identitieswere 88%,92%,88%,57% and 89%, respectively. The sixth candidate gene andother 16 sequences might represent new genes. In two of genes, rad50 gene and anew gene(the sixth candidate gene), the sequcences of 5' coding region of mRNA wereidentical while the sequences of 3' terminal non-coded regions were different betweenfertile environment and sterile environment. The studies of different researchersshowed different results. It maybe means photoperiod-temperature sensitive malesterile wheat involved a complex way of metabolism. The development mechanism ofphotoperiod-temperature sensitive genie male sterility could not yet be revealedcompletely in this paper.