Isolation And Analysis Of MALE STREILE 33 Gene In Zea Mays L

Lipid metabolism related genes play an important part in biosynthesis of pollen sporopollenin and anther cutin in high plants. Mutant in these genes often result in damage in pollen exine and anther cuticle development, and lead to microspore abortion and male sterile finally. Although a large number of male sterile mutants exist in maize, very few of them have been functionally characterized. A classical maize male sterile mutant ms33 was reported in 1995. This mutant showed stable sterile phenotype and has potential commercial value. However the related gene has not been identified before.In this study, we identified the maize MS33 gene via map-based strategy. And comprehensive analysis was conducted using various methods, including molecular genetics, cytobiology, developmental biology and analytic chemistry. As the first isolated GPAT coding gene, SA1/ MS33 showed an irreplaceable role in biosynthesis of maize anther related polyesters, directing the formation of anther cuticle and pollen extine. The main results are listed below:1. A male sterile mutant shrinking anther 1 (sa1) was identified by screening a MuDR library which was create in National Maize Improvemental Centre of China. This mutant exhibited normal vegetative development and no pollen grains were produced in anther. Analysis showed sal displayed defective pollen exine and anther cuticle development, as well as the consequent premature microspore degradation.2. Genetic test showed sal mutant was allelic to the classical maize mutant male sterile 33 (ms33). Through map-based cloning and sequencing, the related gene SA1/MS33 was isolated. SA1/MS33 encodes a putative glycerol-3-phosphate acyltransferase (GPAT), and this gene was the first reported GPAT gene in grasses.3. Data from qPCR and RNA-in situ indicated that SA1/ MS33 mainly expresses in roots and tapetal layers in developing anther. Gas chromatography-mass spectrometry (GC-MS) revealed dramatic reduction in lipidic polyester monomers in the anthers of the ms33 mutant. However, no obvious difference was detected in root polyester monomers content between wild type and ms33 mutant. It is suggested that MS33 might mediate pollen exine and anther cuticle formation by regulating biosynthesis of lipidic polyester in maize.In conclusion, this study demonstrated SA1/MS33 gene participates in anther related polyester biosynthesis which involves in the formation of anther cuticle and pollen extine. Disruption in this process might result in microspore abortion in early stage and lead to male sterile. These results have important significance in illustration of anther development and anther related lipid metabolism in maize, and provide new genetic resource for molecular breeding based on the utilization of male sterile related gene.