title: Plasticity and innovation of regulatory mechanisms underlying seed oil content mediated by duplicated genes in the palaeopolyploid soybean.
abstract: Many plants have undergone whole genome duplication (WGD). However, how regulatory networks underlying a particular trait are reshaped in polyploids has not been experimentally investigated. Here we show that the regulatory pathways modulating seed oil content, which involve WRINKLED1 (WRI1), LEAFY COTYLEDON1 (LEC1), and LEC2 in Arabidopsis, have been modified in the palaeopolyploid soybean. Such modifications include functional reduction of GmWRI1b of the GmWRI1a/GmWRI1b homoeologous pair relevant to WRI1, complementary non-allelic dosage effects of the GmLEC1a/GmLEC1b homoeologous pair relevant to LEC1, pseudogenization of the singleton GmLEC2 relevant to LEC2, and the rise of the LEC2-like function of GmABI3b, contrasting to its homoeolog GmABI3a, which maintains the ABSCISIC ACID INSENSITIVE 3 (ABI3)-like function in modulating seed maturation and dormancy. The function of GmABI3b in modulating seed oil biosynthesis was fulfilled by direct binding to a RY (CATGCA) cis-regulatory element in the GmWRI1a promoter, which was absent in the GmWRI1b promoter, resulting in reduction of the GmWRI1b expression. Nevertheless, the three regulators each exhibited similar intensities of purifying selection to their respective duplicates since these pairs were formed by a WGD event that is proposed to have occurred approximately 13 million years ago (mya), suggesting that the differentiation in spatiotemporal expression between the duplicated genes is more likely to be the outcome of neutral variation in regulatory sequences. This study thus exemplifies the plasticity, dynamics, and novelty of regulatory networks mediated by WGD.
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, IN, 47906, USA.
authors.forename: Dajian
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, IN, 47906, USA.
authors.forename: Meixia
authors.initials: M
authors.lastname: Zhao
authors.affiliation: College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, 266109, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, IN, 47906, USA.
authors.forename: Lianjun
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, IN, 47906, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, 266109, China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Cai
authors.affiliation: Genetics Laboratory, Indiana Crop Improvement Association, Lafayette, IN, 47909, USA.
authors.forename: Emily C
authors.initials: EC
authors.lastname: Dierking
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, IN, 47906, USA.|College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, 266109, China.
authors.forename: Jianxin
authors.initials: J
authors.lastname: Ma
mesh_terms: D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D020131:Genes, Duplicate / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000378:metabolism*; D013025:Glycine max / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
keywords: 
  Glycine max
  ; 
  Glycine soja
  ; palaeopolyploid; regulatory dynamics; regulatory pathways; regulatory plasticity; seed oil content; spatiotemporal expression