title: Expression of the Arabidopsis thaliana BBX32 gene in soybean increases grain yield.
abstract: Crop yield is a highly complex quantitative trait. Historically, successful breeding for improved grain yield has led to crop plants with improved source capacity, altered plant architecture, and increased resistance to abiotic and biotic stresses. To date, transgenic approaches towards improving crop grain yield have primarily focused on protecting plants from herbicide, insects, or disease. In contrast, we have focused on identifying genes that, when expressed in soybean, improve the intrinsic ability of the plant to yield more. Through the large scale screening of candidate genes in transgenic soybean, we identified an Arabidopsis thaliana B-box domain gene (AtBBX32) that significantly increases soybean grain yield year after year in multiple transgenic events in multi-location field trials. In order to understand the underlying physiological changes that are associated with increased yield in transgenic soybean, we examined phenotypic differences in two AtBBX32-expressing lines and found increases in plant height and node, flower, pod, and seed number. We propose that these phenotypic changes are likely the result of changes in the timing of reproductive development in transgenic soybean that lead to the increased duration of the pod and seed development period. Consistent with the role of BBX32 in A. thaliana in regulating light signaling, we show that the constitutive expression of AtBBX32 in soybean alters the abundance of a subset of gene transcripts in the early morning hours. In particular, AtBBX32 alters transcript levels of the soybean clock genes GmTOC1 and LHY-CCA1-like2 (GmLCL2). We propose that through the expression of AtBBX32 and modulation of the abundance of circadian clock genes during the transition from dark to light, the timing of critical phases of reproductive development are altered. These findings demonstrate a specific role for AtBBX32 in modulating soybean development, and demonstrate the validity of expressing single genes in crops to deliver increased agricultural productivity.
authors.affiliation: Monsanto Company, St. Louis, Missouri, United States of America. sasha.preuss@monsanto.com
authors.forename: Sasha B
authors.initials: SB
authors.lastname: Preuss
authors.forename: Robert
authors.initials: R
authors.lastname: Meister
authors.forename: Qingzhang
authors.initials: Q
authors.lastname: Xu
authors.forename: Carl P
authors.initials: CP
authors.lastname: Urwin
authors.forename: Federico A
authors.initials: FA
authors.lastname: Tripodi
authors.forename: Steven E
authors.initials: SE
authors.lastname: Screen
authors.forename: Veena S
authors.initials: VS
authors.lastname: Anil
authors.forename: Shuquan
authors.initials: S
authors.lastname: Zhu
authors.forename: James A
authors.initials: JA
authors.lastname: Morrell
authors.forename: Grace
authors.initials: G
authors.lastname: Liu
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Ratcliffe
authors.forename: T Lynne
authors.initials: TL
authors.lastname: Reuber
authors.forename: Rajnish
authors.initials: R
authors.lastname: Khanna
authors.forename: Barry S
authors.initials: BS
authors.lastname: Goldman
authors.forename: Erin
authors.initials: E
authors.lastname: Bell
authors.forename: Todd E
authors.initials: TE
authors.lastname: Ziegler
authors.forename: Amanda L
authors.initials: AL
authors.lastname: McClerren
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Ruff
authors.forename: Marie E
authors.initials: ME
authors.lastname: Petracek
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001683:Biological Clocks / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D012639:Seeds / Q000235:genetics* / Q000254:growth & development*; D013025:Glycine max / Q000235:genetics*; D013489:Suppression, Genetic
chemical_list: D029681:Arabidopsis Proteins; C568263:BBX32 protein, Arabidopsis; D002352:Carrier Proteins; D012333:RNA, Messenger