Working group session:
Functional Genomics
Presentation type:
oral
Authors:
Xueying, Guan; Pang, Xiongming; Nah, Gyoungju; Shi, Xiaoli ; Chen, Z. Jeffrey
Presenter:
Xueying, Guan
Correspondent:
Chen, Z. Jeffrey
Abstract:
Cotton is a good model for studying polyploidy effects on gene expression and fiber trait domestication. The most widely cultivated Upland cotton is an allotetraploid derived from A- and D- progenitor species, which diverged 10-12 million years ago. A-genome diploid progenitors produce spinnable fibers, while D-genome diploid progenitors bear very short and poor fibers. The superior fiber trait in the allotetraploid cotton is domesticated, which is subjected to changes in the expression of homoeologouse genes. One pair of the homoeologous genes, encoding the MYB-domain transcription factor MYB2, promotes fiber development in cotton and is functionally homologous to Arabidopsis glabrous1 (GL1) in trichome formation. MYB2A and MYB2D homoeologs in the allotetraploid cotton (AADD) are derived from A-genome and D-genome species, respectively. Overexpressing MYB2A but not MYB2D complemented the gl1 phenotype. This functional divergence of MYB2 homoeologs is associated with miR828 and miR858 preferentially targeting and the generation of trans-acting siRNAs (ta-siRNAs). Mutating the miR828-binding site or replacing its downstream sequence in MYB2D abolished ta-siRNA production and restored trichome development. Single nucleotide polymorphism (SNP) that is adjacent to the 3’ end of miRNA targeting site on MYB2 genes affects the homoeologs functional diversity by altering the miRNA accessibility and protein sequence. These data support a unique role for miRNAs in functional diversification of target homoeologous genes that are important to evolution and selection of morphological traits.