The laboratory of Zhixi Tian works on the functional genomics of soybean. The main research projects are identification of gene network controlling important agronomical traits in soybean and evolutionary analyses of polyploidy soybean genome.

1. Identification of gene network controlling important agronomical traits in soybean

Soybean (Glycine max [L]. Merr.) is one of the most economically important leguminous seed crops that provide the majority of plant proteins, and more than a quarter of the world’s food and animal feed. It is suggested that soybean was domesticated from its annual wild relative, G. soja Sieb & Zucc, in China approximately 5,000 years ago, resulting in a multitude of soybean landraces that were adapted to various climate environments. But till now, approximate 80% of soybean consumed in China is imported from other countries. The big gap between production and consummation generates potential crisis for our country. The research on soybean in China lags behind other major crops. A better understanding of soybean genetics and genomics will advance breeding varieties with improved yield, quality, and stress tolerance. Our lab will combine association mapping, QTL mapping, map-based cloning along with comparative genomic approaches, as well as construction and utilization of omics to identify gene network controlling important agronomical traits and to apply them into the soybean breeding, which will facilitate soybean germplasm enhancement and benefit soybean production. The work is supported by NSFC and the Chinese Academy of Sciences.

2. Evolutionary analyses of polyploidy soybean genome

Whole-genome duplications (i.e., polyploidy) is a common phenomenon, particularly rampant in plants, which has led many researches to investigate the fate of duplicated gene pairs. Thus, the importance of the evolution of gene pairs and its effect on adaption have been continuously reviewed and emphasized, but the understanding of the selective and evolutionary mechanisms is fragmented. The soybean (Glycine max) genome has putatively processed two rounds of whole genome duplications (WGD) and many tandem duplications within the last 60 million years, which results in a highly duplicated genome with nearly 75% of the genes present in multiple copies. After numerous chromosome rearrangements, duplicated gene pairs are highly diversified, with about 25% of the soybean gene duplicates having been silenced and lost, and many new genes created, which indicated that the soybean genome is quickly evolving. A systematic analysis the diversity of soybean duplicated gene pair, and its relationship with abiotic adaption at a whole genome wide level will benefit our understanding of the mechanism of genome evolution during the selective adaption process. We will combine the approaches of genomics and transcriptomics to investigate the nucleotide diversity of duplicated gene pairs and their expression during different developmental stages and under abiotic stress, and check the relationship of these diversities with the changes of gene expression pattern. Our goal is to illuminate how the soybean genome evolves to adapt environment changes through polyploidy, which will provide a fundamental base for soybean functional genomics. The work is supported by NSFC and Ministry of science and technology project 973 fund.