title: XIAO is involved in the control of organ size by contributing to the regulation of signaling and homeostasis of brassinosteroids and cell cycling in rice.
abstract: Organ size is determined by cell number and size, and involves two fundamental processes: cell proliferation and cell expansion. Although several plant hormones are known to play critical roles in shaping organ size by regulating the cell cycle, it is not known whether brassinosteroids (BRs) are also involved in regulating cell division. Here we identified a rice T-DNA insertion mutant for organ size, referred to as xiao, that displays dwarfism and erect leaves, typical BR-related phenotypes, together with reduced seed setting. XIAO is predicted to encode an LRR kinase. The small stature of the xiao mutant resulted from reduced organ sizes due to decreased cell numbers resulting from reduced cell division rate, as supported by the observed co-expression of XIAO with a number of genes involved in cell cycling. The xiao mutant displayed a tissue-specific enhanced BR response and greatly reduced BR contents at the whole-plant level. These results indicated that XIAO is a regulator of BR signaling and cell division. Thus, XIAO may provide a possible connection between BRs and cell-cycle regulation in controlling organ growth.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Yunhe
authors.initials: Y
authors.lastname: Jiang
authors.forename: Liang
authors.initials: L
authors.lastname: Bao
authors.forename: So-Yoon
authors.initials: SY
authors.lastname: Jeong
authors.forename: Seong-Ki
authors.initials: SK
authors.lastname: Kim
authors.forename: Caiguo
authors.initials: C
authors.lastname: Xu
authors.forename: Xianghua
authors.initials: X
authors.lastname: Li
authors.forename: Qifa
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D001483:Base Sequence; D060406:Brassinosteroids / Q000032:analysis / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics*; D035264:Flowers / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D006706:Homeostasis / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009929:Organ Size / Q000235:genetics; D009928:Organ Specificity; D012275:Oryza / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D010641:Phenotype; D010937:Plant Growth Regulators / Q000032:analysis / Q000378:metabolism*; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics
chemical_list: D060406:Brassinosteroids; D010937:Plant Growth Regulators; D018749:RNA, Plant