Overexpression of beta-carotene hydroxylase enhances stress tolerance in Arabidopsis.
Plant stress caused by extreme environmental conditions is already a principal reason for yield reduction in crops. The threat of global environment change makes it increasingly important to generate crop plants that will withstand such conditions. Stress, particularly stress caused by increased sunlight, leads to the production of reactive oxygen species that cause photo-oxidative cell damage. Carotenoids, which are present in the membranes of all photosynthetic organisms, help protect against such light-dependent oxidative damage. In plants, the xanthophyll cycle (the reversible interconversion of two carotenoids, violaxanthin and zeaxanthin) has a key photoprotective role and is therefore a promising target for genetic engineering to enhance stress tolerance. Here we show that in Arabidopsis thaliana overexpression of the chyB gene that encodes beta-carotene hydroxylase--an enzyme in the zeaxanthin biosynthetic pathway--causes a specific twofold increase in the size of the xanthophyll cycle pool. The plants are more tolerant to conditions of high light and high temperature, as shown by reduced leaf necrosis, reduced production of the stress indicator anthocyanin and reduced lipid peroxidation. Stress protection is probably due to the function of zeaxanthin in preventing oxidative damage of membranes.
Robert Hill Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
P A
PA
Davison
C N
CN
Hunter
P
P
Horton
D000872:Anthocyanins / Q000032:analysis; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D002338:Carotenoids / Q000378:metabolism; D003624:Darkness; D015870:Gene Expression; D018869:Heat-Shock Response; D006358:Hot Temperature; D008027:Light; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009336:Necrosis; D018384:Oxidative Stress; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D024341:Xanthophylls / Q000378:metabolism; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives / Q000378:metabolism
D000872:Anthocyanins; D018749:RNA, Plant; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D002338:Carotenoids; D008315:Malondialdehyde; D006899:Mixed Function Oxygenases; C079232:beta-carotene hydroxylase