title: Concerted evolution of D1 and D2 to regulate chlorophyll degradation in soybean.
abstract: Polyploidy is a common phenomenon, particularly in plants. The soybean (Glycine max [L.] Merr.) genome has undergone two whole genome duplication (WGD) events. The conservation and divergence of duplicated gene pairs are major contributors to genome evolution. D1 and D2 are two unlinked, paralogous nuclear genes, whose double-recessive mutant (d1d1d2d2) results in chlorophyll retention, called 'stay-green'. Through molecular cloning and functional analyses, we demonstrated that D1 and D2 are homologs of the STAY-GREEN (SGR) genes from other plant species and were duplicated as a result of the most recent WGD in soybean. Transcriptional analysis showed that both D1 and D2 were more highly expressed in older tissues, and chlorophyll degradation and programmed cell death-related genes were suppressed in a d1d2 double mutant, this situation indicated that these genes are probably involved in the early stages of tissue senescence. Investigation of genes that flank D1 and D2 revealed that evolution within collinear duplicated blocks may affect the conservation of individual gene pairs within the blocks. Moreover, we found that a long terminal repeat retrotransposon, GmD2IN, resulted in the d2 mutation. Further analysis of this retrotransposon family showed that insertion in or near the coding regions can affect gene expression or splicing patterns, and may be an important force to promote the divergence of duplicated gene pairs.
authors.affiliation: State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Fang
authors.forename: Congcong
authors.initials: C
authors.lastname: Li
authors.forename: Weiyu
authors.initials: W
authors.lastname: Li
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Zhengkui
authors.initials: Z
authors.lastname: Zhou
authors.forename: Yanting
authors.initials: Y
authors.lastname: Shen
authors.forename: Mian
authors.initials: M
authors.lastname: Wu
authors.forename: Yunshuai
authors.initials: Y
authors.lastname: Wu
authors.forename: Guiquan
authors.initials: G
authors.lastname: Li
authors.forename: Ling-An
authors.initials: LA
authors.lastname: Kong
authors.forename: Cuimin
authors.initials: C
authors.lastname: Liu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Jackson
authors.forename: Zhixi
authors.initials: Z
authors.lastname: Tian
mesh_terms: D016923:Cell Death; D002734:Chlorophyll / Q000378:metabolism*; D019143:Evolution, Molecular; D020440:Gene Duplication; D018506:Gene Expression Regulation, Plant; D010641:Phenotype; D013025:Glycine max / Q000235:genetics* / Q000378:metabolism; D020079:Terminal Repeat Sequences
chemical_list: D002734:Chlorophyll
keywords: Glycine max [L.] Merr; duplicated genes; evolution; soybean; stay-green