QTL Mapping Of Shattering And Candidate Gene Cloning Of Zmsh1-1.3 In Maize

Since 6,000-10,000 years ago, maize(Zea Mays) was domesticated from the annual teosinte in Mexico, along with the development of human beings. Maize has been planted in the whole world since 500 years ago when Columbus found it during travel around the world, thus brought a great change for human life and production. The maize underwent two bottlenecks, domestication and improvement, each bringing extraordinary change of genome, which now became one of the major food crops world-wide. Non-shattering is very important for human to collect more food for consumption, and it has been selected by our ancestors during the early domestication. There are 13 shattering genes have been found in rice, sorghum, wheat, maize and foxtail millet, part of them with clear function. Shattring1(SH1) of rice, sorghum, maize and foxtail millet belong to YABBY family. The genes of YABBY family control the organ abaxial, such as the blade and inflorescence in maize, arabidopsis and tobacco. In our study we explored a homologous gene of Os SH1 and Sb SH1(Zm Sh1-1.3) in maize, which was identified within a QTL on chromosome 1, based on linkage analysis on the BC2F6 RIL population derived from a cross between a Zea.mays ssp. mexicana(complete shattering) and a maize inbred line MO17(non-shattering). The main research results as follow:1. The TM population(n = 191) was planted in five environments across two years. There are two main-effect QTL on chromosome 1 and one main-effect QTL on chromosome 2, and some minor-effect QTL on chromosome 4, chromosome 5, chromosome 6 and chromosome10.2. Two homologous genes of SH(ie., Os Sh1 and Sb Sh1) were found within the QTL on chromosome 1, they are Zm Sh1-1.2 and Zm Sh1-1.3. The Zm Sh1-1.3 is assigned as the candidate gene for its higher homology in amino acid sequence.3. Rre-sequencing ZmSh1-1.3 in the parents of TM population showed that there are two indels in exon 2 and exon 3, and a string of nonsynonymous mutation in exon 3, and a 1,009 bp indel in the 3’ UTR. The indels and nonsynonymous mutation give rise to the change of structure of YABBY domain. Especially, the 9 bp indel in exon 2 exists in only eight of 120 teosinte(teosinte is heterozygous, so we got 211 teosinte sequences from 120 teosintes), which exist in all 64 maize lines.4. ANOVA analysis on the shattering phenotype and genotype in two new BC1F1 populations(B73/TEO(Z.parviglumis) and MO17/TEO(Z.parviglumis)) isnon-significant. It may be due to the different backgrounds of populations have different effects on shattering, or it may imply this site is not the functional site.5. The HKA-test, Tajima’s D test and DNA diversity analysis of candidate gene Zm Sh1-1.3 showed that the DNA sequences of 5’ UTR and exon 2 between maize and teosinte are different. It verifies that this selection was truly happened during the domestication. Therefore, our study illustrates that the gene Zm Sh1-1.3 may relate to shattering in maize.