PMID:20852032

Citation	Du, H, Wang, N, Cui, F, Li, X, Xiao, J and Xiong, L (2010) Characterization of the beta-carotene hydroxylase gene DSM2 conferring drought and oxidative stress resistance by increasing xanthophylls and abscisic acid synthesis in rice. Plant Physiol. 154:1304-18
Abstract	Drought is a major limiting factor for crop production. To identify critical genes for drought resistance in rice (Oryza sativa), we screened T-DNA mutants and identified a drought-hypersensitive mutant, dsm2. The mutant phenotype was caused by a T-DNA insertion in a gene encoding a putative β-carotene hydroxylase (BCH). BCH is predicted for the biosynthesis of zeaxanthin, a carotenoid precursor of abscisic acid (ABA). The amounts of zeaxanthin and ABA were significantly reduced in two allelic dsm2 mutants after drought stress compared with the wild type. Under drought stress conditions, the mutant leaves lost water faster than the wild type and the photosynthesis rate, biomass, and grain yield were significantly reduced, whereas malondialdehyde level and stomata aperture were increased in the mutant. The mutant is also hypersensitive to oxidative stresses. The mutant had significantly lower maximal efficiency of photosystem II photochemistry and nonphotochemical quenching capacity than the wild type, indicating photoinhibition in photosystem II and decreased capacity for eliminating excess energy by thermal dissipation. Overexpression of DSM2 in rice resulted in significantly increased resistance to drought and oxidative stresses and increases of the xanthophylls and nonphotochemical quenching. Some stress-related ABA-responsive genes were up-regulated in the overexpression line. DSM2 is a chloroplast protein, and the response of DSM2 to environmental stimuli is distinctive from the other two BCH members in rice. We conclude that the DSM2 gene significantly contributes to control of the xanthophyll cycle and ABA synthesis, both of which play critical roles in the establishment of drought resistance in rice.
Links	PubMed PMC2971608 Online version:10.1104/pp.110.163741
Keywords	Abscisic Acid/biosynthesis; Droughts; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Knockout Techniques; Mixed Function Oxygenases/genetics; Mixed Function Oxygenases/metabolism; Molecular Sequence Data; Mutagenesis, Insertional; Mutation; Oryza sativa/enzymology; Oryza sativa/genetics; Oxidative Stress; Photosynthesis; Photosystem II Protein Complex/metabolism; Plant Leaves/physiology; Plant Proteins/genetics; Plant Proteins/metabolism; Plant Stomata/physiology; Water/metabolism; Xanthophylls/biosynthesis
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ORYSJ:Q10SE7		GO:0009507: chloroplast	ECO:0000314:		C		Figure 4 A and C show by fluorescent microscopy and western blotting that DSM2 localizes to the chloroplasts.	complete CACAO 5542
ORYSJ:Q10SE7		GO:0016123: xanthophyll biosynthetic process	ECO:0000315:		P		Table 1 shows that dsm2 mutants have reduced xanthophyll and DSM2 overexpressors have increased xathophyll.	complete CACAO 5543
ORYSJ:Q10SE7		GO:0016119: carotene metabolic process	ECO:0000315:		P		Table 1 shows that dsm2 mutants have altered carotene content, and DSM2 overexpressors have reduced beta-carotene content, suggesting that DSM2 is involved in a carotene metabolic process.	complete CACAO 5544
ORYSJ:Q10SE7	part_of	GO:0009507: chloroplast	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
ORYSJ:Q10SE7	involved_in	GO:0016123: xanthophyll biosynthetic process	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
ORYSJ:Q10SE7	involved_in	GO:0016119: carotene metabolic process	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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