Dihydroxyacid dehydratase is important for gametophyte development and disruption causes increased susceptibility to salinity stress in Arabidopsis.
Dihydroxyacid dehydratase (DHAD) catalyses a key step in the branched-chain amino acid (BCAA) biosynthetic pathway that exists in numerous organisms, including bacteria, fungi, and plants, but not humans. In Arabidopsis thaliana, DHAD is encoded by a single gene (AT3G23940), but its biological function in controlling plant development remains uncharacterized. In this study, we showed that DHAD is highly expressed in most vegetative and reproductive tissues. It is an essential gene, and complete disruption caused partial sterility in both male and female gametophyte phases. In addition, reduced expression of DHAD in knockdown mutants resulted in a reduction in the accumulation of all three BCAAs in roots and, as a consequence, led to a shorter root phenotype, which could be restored by an exogenous supplement of free BCAAs. Interestingly, the knockdown mutants became hypersensitive to salt stress, not to heavy metal stress, implying that BCAAs may act as osmolytes in salt tolerance. This would be the second amino acid shown to confer such a function in addition to the well-documented proline. Our results provide evidence that BCAA biosynthesis plays important roles in gametophyte and root development, and BCAA homeostasis contributes to the adaptation of Arabidopsis to salinity stress.
National Maize Improvement Centre of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China.
Chun
C
Zhang
Alkali Soil Natural Environmental Science Centre, Key Laboratory of Saline-alkali Vegetation Ecology Restoration in Oil Field, Northeast Forestry University, Harbin, Heilongjiang, China.
Qiuying
Q
Pang
National Maize Improvement Centre of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China.
Luguang
L
Jiang
National Maize Improvement Centre of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China.
Shoucai
S
Wang
Alkali Soil Natural Environmental Science Centre, Key Laboratory of Saline-alkali Vegetation Ecology Restoration in Oil Field, Northeast Forestry University, Harbin, Heilongjiang, China.
Xiufeng
X
Yan
Department of Biology, Genetics Institute, and Plant Molecular & Cellular Biology Program, University of Florida, Gainesville, Florida, USA yh352@cau.edu.cn schen@ufl.edu.
Sixue
S
Chen
National Maize Improvement Centre of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China yh352@cau.edu.cn schen@ufl.edu.
Yan
Y
He
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D055993:Germ Cells, Plant / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D006836:Hydro-Lyases / Q000235:genetics* / Q000378:metabolism; D054712:Salinity; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological
D029681:Arabidopsis Proteins; C000605625:dihydroxyacid dehydratase, Arabidopsis; D012965:Sodium Chloride; D006836:Hydro-Lyases
Arabidopsis; branched-chain amino acid (BCAA); dihydroxyacid dehydratase (DHAD); gametogenesis; root development; salt stress.