Tiller number is altered in the ascorbic acid-deficient rice suppressed for l-galactono-1,4-lactone dehydrogenase |
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Authors: | Yonghai Liu Le Yu Jianhua Tong Junhui Ding Ruozhong Wang Yusheng Lu Langtao Xiao |
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Affiliation: | 1. College of Life Sciences, Zhaoqing University, Zhaoqing 526061, People''s Republic of China;2. Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha 410128, People''s Republic of China;3. College of Life Sciences, South China Agricultural University, Guangzhou 510642, People''s Republic of China |
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Abstract: | The tiller of rice (Oryza sativa L.), which determines the panicle number per plant, is an important agronomic trait for grain production. Ascorbic acid (Asc) is a major plant antioxidant that serves many functions in plants. l-Galactono-1,4-lactone dehydrogenase (GLDH, EC 1.3.2.3) is an enzyme that catalyzes the last step of Asc biosynthesis in plants. Here we show that the GLDH-suppressed transgenic rices, GI-1 and GI-2, which have constitutively low (between 30% and 50%) leaf Asc content compared with the wild-type plants, exhibit a significantly reduced tiller number. Moreover, lower growth rate and plant height were observed in the Asc-deficient plants relative to the trait values of the wild-type plants at different tillering stages. Further examination showed that the deficiency of Asc resulted in a higher lipid peroxidation, a loss of chlorophyll, a loss of carotenoids, and a lower rate of CO2 assimilation. In addition, the level of abscisic acid was higher in GI-1 plants, while the level of jasmonic acid was higher in GI-1 and GI-2 plants at different tillering stages. The results we presented here indicated that Asc deficiency was likely responsible for the promotion of premature senescence, which was accompanied by a marked decrease in photosynthesis. These observations support the conclusion that the deficiency of Asc alters the tiller number in the GLDH-suppressed transgenics through promoting premature senescence and changing phytohormones related to senescence. |
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Keywords: | ABA, abscisic acid Asc, l-ascorbic acid Car, carotenoids Chl, chlorophyll Ci, intercellular CO2 concentration DHA, dehydroascorbate l-GalL, l-galactono-1,4-lactone GI, GLDH-suppressed transgenic rice GLDH, l-galactono-1,4-lactone dehydrogenase JA, jasmonic acid MDA, malondialdehyde PC, principal component PCD, programmed cell death ROS, reactive oxygen species TCA, trichloroacetic acid Tr, transpiration rate |
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