title: Genomic regions, cellular components and gene regulatory basis underlying pod length variations in cowpea (V. unguiculata L. Walp).
abstract: Cowpea (V. unguiculata L. Walp) is a climate resilient legume crop important for food security. Cultivated cowpea (V. unguiculata L) generally comprises the bushy, short-podded grain cowpea dominant in Africa and the climbing, long-podded vegetable cowpea popular in Asia. How selection has contributed to the diversification of the two types of cowpea remains largely unknown. In the current study, a novel genotyping assay for over 50 000 SNPs was employed to delineate genomic regions governing pod length. Major, minor and epistatic QTLs were identified through QTL mapping. Seventy-two SNPs associated with pod length were detected by genome-wide association studies (GWAS). Population stratification analysis revealed subdivision among a cowpea germplasm collection consisting of 299 accessions, which is consistent with pod length groups. Genomic scan for selective signals suggested that domestication of vegetable cowpea was accompanied by selection of multiple traits including pod length, while the further improvement process was featured by selection of pod length primarily. Pod growth kinetics assay demonstrated that more durable cell proliferation rather than cell elongation or enlargement was the main reason for longer pods. Transcriptomic analysis suggested the involvement of sugar, gibberellin and nutritional signalling in regulation of pod length. This study establishes the basis for map-based cloning of pod length genes in cowpea and for marker-assisted selection of this trait in breeding programmes.
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.|State Key Lab Breeding Base for Sustainable Control of Plant Pest and Disease, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Xu
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Botany and Plant Sciences, University of California-Riverside, Riverside, CA, USA.
authors.forename: María
authors.initials: M
authors.lastname: Muñoz-Amatriaín
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Baogen
authors.initials: B
authors.lastname: Wang
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Wu
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Yaowen
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Nematology, University of California-Riverside, Riverside, CA, USA.
authors.forename: Bao-Lam
authors.initials: BL
authors.lastname: Huynh
authors.affiliation: Department of Botany and Plant Sciences, University of California-Riverside, Riverside, CA, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Close
authors.affiliation: Department of Nematology, University of California-Riverside, Riverside, CA, USA.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Roberts
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Zhongfu
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.|State Key Lab Breeding Base for Sustainable Control of Plant Pest and Disease, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Guojing
authors.initials: G
authors.lastname: Li
mesh_terms: D000349:Africa; D002681:China; D018506:Gene Expression Regulation, Plant; D005828:Genetics, Population; D055106:Genome-Wide Association Study; D000071184:Pharmacogenomic Variants; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D000070658:Vigna / Q000235:genetics*
keywords: 
  GWAS
  ; Cowpea; Domestication; Pod length; Selection; Transcriptome