SPX1 is an important component in the phosphorus signalling network of common bean regulating root growth and phosphorus homeostasis.
Proteins containing the SPX domain are believed to play vital roles in the phosphorus (P) signalling network in plants. However, the functions of SPX proteins in legumes remain largely unknown. In this study, three SPX members, PvSPX1-PvSPX3 were cloned from common bean (Phaseolus vulgaris L.). It was found that the transcripts of all three PvSPX members were significantly enhanced in both bean leaves and roots by phosphate (Pi) starvation. Among them, the expression of nuclear localized PvSPX1 showed more sensitive and rapid responses to Pi starvation. Consistently, only overexpression of PvSPX1 resulted in increased root P concentration and modified morphology of transgenic bean hairy roots, such as inhibited root growth and an enlarged root hair zone. It was further demonstrated that PvSPX1 transcripts were up-regulated by overexpressing PvPHR1, and overexpressing PvSPX1 led to increased transcripts of 10 Pi starvation-responsive genes in transgenic bean hairy roots. Taken together, it is suggested that PvSPX1 is a positive regulator in the P signalling network of common bean, and is downstream of PvPHR1.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China.
Zhu-Fang
ZF
Yao
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China.
Cui-Yue
CY
Liang
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China.
Qing
Q
Zhang
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China.
Zhi-Jian
ZJ
Chen
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China.
Bi-Xian
BX
Xiao
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China jtian@scau.edu.cn.
Jiang
J
Tian
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangzhou 510642, PR China.
Hong
H
Liao
D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D008969:Molecular Sequence Data; D027805:Phaseolus / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D010710:Phosphates / Q000172:deficiency / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000166:cytology / Q000235:genetics / Q000502:physiology; D017422:Sequence Analysis, DNA
D010710:Phosphates; D010940:Plant Proteins
Bean; SPX domain.; hairy roots; phosphate starvation; phosphorus homeostasis; root growth