Abstract：23.5 kD small heat shock protein is an important anther differentially expressed protein between male sterile line and its conversion line in wheat BNS(Bainong sterility). In order to validate the relationship between this protein and BNS male sterility, the differentially expressed mRNA of this protein's gene, hsp23.5, was examined by means of fluorescent Real-time quantitative PCR taking the anthers of BNS as materials at three key developmental stages(tetrad phase, uninucleated period and binucleated period)．The results showed that the expression quantities of the hsp23.5 mRNA in three developmental stages were continuously rised in conversion line, but down-regulated significantly in sterile line. The amount of down-regulated in sterile line was as many as the times of 3.8, 20.0 and 4.6 in the three developmental periods comparing to that in conversion line, respectively. The result of sequencing indicated that the numbers of bases of hsp23.5 cDNA segment cloned by RT-PCR were 82.56% homologous wheat sequences from NCBI. By BLAST alignment and phylogenetic tree analysis, there were the biggest segment sequence identities of 94%, and the nearest genetic distance of <0.05, between the BNS hsp23.5 and common wheat(Triticm aestivum) hsp23.6 ，and between the BNS hsp23.5 and cone wheat(T. turgidum) hsp23.5. It was also found that the mRNA expression quantity of the gene was up-regulated in sterile line in binucleated period because of higher atmosphere temperature appearance in this period. These results suggested that the hsp23.5 gene expressed constitutive in BNS conversion line, and inducible by higher temperiture in sterile line. It may be the characteristic of sensitive-temperature that regulated the down-regulated expression of the gene in sterile line. It also implied that hsp23.5 may be one of the important relation sterile gene.
