Fine Mapping Of SiMS1Male Sterile Gene In Foxtail Millet, Setaria Italica

This article focused on the study of mechanisms of a stable foxtail millet male sterile line J29A atcytological and molecular level. Morphological bases of male sterility of J29A mutant has beenanalyzed by approach of tissue sections. Sterile gene SiMS1, which caused the male sterility in J29A,was fine mapped by using Bulked Segregant Analysis (BSA) and Genome Scan Analysis (GSA). Theresults will lay a solid foundation for further research about the sterile mechanism of foxtail millet malesterile line J29A.. The main research achievements of this subject are as follows:Morphological observation between of J29A male sterile plant and its wild ones indicated that: itsagronomic traits was close to the wild-type Jingu29, average heading date are earlier than the wild-type,and seed setting rate is extremely low. Anatomical study of the flowers observed that: the J29A mutantanther was similar with wild-type. I2-KI staining study showed that pollens of J29A can not be normallycolored and pollen grains appear various malformations. Semi-thin section observation of J29A anthertissue showed that: tapetum cell of J29A can not be degradation normally in the process of microsporedevelopment and it arouse microspore nutritional deficiencies.Because the male sterility gene in J29A in this experiment was the first one indentified in foxtailmillet，this gene was named as SiMS1. A number of separation populations were constructed to mappingthe sterility gene. BSA experiment revealed that the male sterility gene SiMS1was located betweenmarker SIMS15254and SIMS15645. Two hundred and eighty individual F2plants were scanned usingmarkers of this area, and SiMS1was located between marker CAAS61001and CAAS61002. Then, afterscanning965F2sterile plant individuals, SiMS1was fine mapped to the region between theCAAS61001and CAAS61018, with a interval physical distance of12kb. Finally, we scanned the othertwo groups J29A×Bao213and J29A×Ji0515, the gene was located between the CAAS610028andCAAS61018, with a interval physical distance of12kb, and it contains the12kb.Sequences analysis of the119kb by Phytozome shows that there are26complete ORF in thisregion.Gene annotation of those26ORFs from the NCBI database identified that sequence identity ofthe Si013284m.g with the putative pollenless3gene in rice with a89%similarity. And Si013284m.gwas inclosed in between marker CAAS61001and CAAS61018.RT-PCR results show that: the two genes within the12kb was lowly transcripted in the J29A malesterility mutant and was highly transcripted in J29.Sequencing of the12Kb region that we fine mappedwas not completed, so far we got the sequence data of11.6kb. Severial SNP were identified between theJ29A and J29wild type, but further analysis of the sequence obtained with those sequence fromZhanggu, Yugu1, Daqingjie and N10, which are normal male fertile foxtail millet lines, did not findclear putation male sterile mutant sequence variation, although three mutant were identified in thedownstream noncoding region of Si015380m.g. Further analyses to identify the the causualmechanism of male sterile in J29A is needed.