Map-based Cloning And Cytological Study Of The Male Sterility Gene Ms6044 In Maize

Plants male sterility (ms) is widely found in flowering Plant. Plant male sex organs develops abnormally and is unable to produce functional male gametes (pollen),the female organ,however, develops normally and is able to accept normal male gamete and be fertilized, corn is one of the best crops in the utilization of heterosis. Improving seed quality and reducing seed production cost are the major objectives of corn seed production. The use of corn male sterility is the most effective way to achieve the objectives. In this paper, corn male sterile line ms6044 was studied in the following areas:1. Cytological observation of genic male sterility mutant ms6044. Compared with the normal fertile plants, nuclear sterility mutant ms6044 was not observed dyad, and microspore cells gradually degrade, so we speculate that regulating the period before the dyad by ms6044 gene, lead to abnormal changes in the period of the dyad, and anther can not develop normally, showing the abortive.2. Fine mapping of ms6044 gene. Two BC1F1 populations, ms6044//B73/ms6044 and ms6044//Z58/ms6044, were developed for map based cloning. Total 8896 individuals were tested and ms6044 were mapped in a 140kb interval of the B73 reference sequence (B73 RefGen_v2) between 80.96cM and 81.108cM on chromosome 1.3. Gene prediction and cloning. Four genes were predicted in this interval. Only one of them has different sequences between ms6044 mutant and fertile siblings. A 1.3kb transposon insertion in the 2nd exon of this gene was detected in mutant. In fertile individuals, this gene was specifically expressed in male meiosis process, and could not be detected under other stages and in any other tissues. So it will be the candidate gene of ms6044. The transposon insertion might cause the loss of function of this gene, which further lead to male sterility.4. Gene function validation. We constructed two vectors for maize transformation. A forward expression vector was introduced into Hi II and then will be cross back to ms6044 mutant to exam whether this gene can recover its phenotype. On the other hand, a RNAi vector was transformed and then will be cross back to several male fertile inbred lines to detect if the expression interference of this candidate gene could lead to male sterility in maize. In addition, an allele of ms6044, ms6034 was obtained from Maize Genetics Cooperation Stock Center. The allelic test is underway.