title: Tiller number is altered in the ascorbic acid-deficient rice suppressed for L-galactono-1,4-lactone dehydrogenase.
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 CO(2) 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.
authors.affiliation: College of Life Sciences, Zhaoqing University, Zhaoqing 526061, People's Republic of China.
authors.forename: Yonghai
authors.initials: Y
authors.lastname: Liu
authors.forename: Le
authors.initials: L
authors.lastname: Yu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Tong
authors.forename: Junhui
authors.initials: J
authors.lastname: Ding
authors.forename: Ruozhong
authors.initials: R
authors.lastname: Wang
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Lu
authors.forename: Langtao
authors.initials: L
authors.lastname: Xiao
mesh_terms: D001205:Ascorbic Acid / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D005838:Genotype; D012275:Oryza / Q000254:growth & development* / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D018520:Plant Shoots / Q000254:growth & development*; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000235:genetics; D013997:Time Factors
chemical_list: D010937:Plant Growth Regulators; D044925:Oxidoreductases Acting on CH-CH Group Donors; C093910:galactonolactone dehydrogenase; D001205:Ascorbic Acid