Speaker Introduction: Rui Xia, PhD, Professor at South China Agricultural University. Dr. Xia obtained his PhD degree from Virginia Tech (USA) and had postdoctoral trainings at the University of Delaware and Donald Danforth Plant Science Center (USA). His research focuses on genomics of horticultural plants, flower and fruit development, plant small RNAs and bioinformatics.

Topic Introduction: The decoding of haplotypic genomes of lychee provides novel insights into its domestication history and uncovers the underlying genetics of flowering regulation.

Description: Lychee is an exotic tropical fruit with distinct flavor. The genome of cultivar ‘Feizixiao’ was assembled into 15 pseudo-chromosomes, totaling ~470 Mb. High heterozygosity (2.27%) resulted in two complete haplotypic assemblies. 13,517 allelic genes (42.4%) were differentially expressed in diverse tissues. Analyses of 72 re-sequenced lychee accessions revealed two independent domestication events. The extremely early maturing cultivars (EEMC) preferentially aligned to one haplotype were domesticated from a wild population in Yunnan, whereas the late-maturing cultivars (LMC) mostly mapped to the second haplotype were independently domesticated from a wild population in Hainan. Early maturing cultivars were likely developed in Guangdong via hybridization between EEMC and LMC individuals. Variable deletions of a 3.7 kb region encompassed by a pair of CONSTANS-like genes likely regulate fruit maturation differences among lychee cultivars. These genomic resources provide insights into the natural history of lychee domestication and will accelerate the improvement of lychee and related crops.In this session, you will learn: How to resolve haplotypes of a highly heterozygous genome like lychee and how the haplotypes help to trace back its evolution history. How to utilize population resequencing data to restore origin, domestication and cultivation of lychee. How to find key genes of lychee fruit maturation when data mining.