title: Ascorbic acid deficiency leads to increased grain chalkiness in transgenic rice for suppressed of L-GalLDH.
abstract: The grain chalkiness of rice (Oryza sativa L.), which determines the rice quality and price, is a major concern in rice breeding. Reactive oxygen species (ROS) plays a critical role in regulating rice endosperm chalkiness. Ascorbic acid (Asc) is a major plant antioxidant, which strictly regulates the levels of ROS. l-galactono-1, 4-lactone dehydrogenase (L-GalLDH, EC 1.3.2.3) is an enzyme that catalyzes the last step of Asc biosynthesis in higher plants. Here we show that the L-GalLDH-suppressed transgenic rice, GI-1 and GI-2, which have constitutively low (between 30% and 50%) leaf and grain Asc content compared with the wild-type (WT), exhibit significantly increased grain chalkiness. Further examination showed that the deficiency of Asc resulted in a higher lipid peroxidation and H2O2content, accompanied by a lower hydroxyl radical scavenging rate, total antioxidant capacity and photosynthetic ability. In addition, changes of the enzyme activities and gene transcript abundances related to starch synthesis were also observed in GI-1 and GI-2 grains. The results we presented here suggest a close correlation between Asc deficiency and grain chalkiness in the L-GalLDH-suppressed transgenics. Asc deficiency leads to the accumulation of H2O2, affecting antioxidant capacity and photosynthetic function, changing enzyme activities and gene transcript abundances related to starch synthesis, finally leading to the increased grain chalkiness.
authors.affiliation: College of Life Sciences, Zhaoqing University, Zhaoqing 526061, People's Republic of China.
authors.forename: Le
authors.initials: L
authors.lastname: Yu
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.affiliation: College of Life Sciences, South China Normal University, Guangzhou 510631, People's Republic of China.
authors.forename: Lina
authors.initials: L
authors.lastname: Lu
authors.affiliation: College of Life Sciences, South China Normal University, Guangzhou 510631, People's Republic of China.
authors.forename: Qilei
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Zhaoqing University, Zhaoqing 526061, People's Republic of China.
authors.forename: Yezheng
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Life Sciences, Zhaoqing University, Zhaoqing 526061, People's Republic of China.
authors.forename: Liping
authors.initials: L
authors.lastname: Zhou
authors.affiliation: College of Life Sciences, Zhaoqing University, Zhaoqing 526061, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Chen
authors.affiliation: College of Life Sciences, South China Normal University, Guangzhou 510631, People's Republic of China. Electronic address: pengchl@scib.ac.cn.
authors.forename: Changlian
authors.initials: C
authors.lastname: Peng
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D002523:Edible Grain / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D012275:Oryza / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013213:Starch / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D012333:RNA, Messenger; D002734:Chlorophyll; D017665:Hydroxyl Radical; D008315:Malondialdehyde; D013213:Starch; D006861:Hydrogen Peroxide; D044925:Oxidoreductases Acting on CH-CH Group Donors; C093910:galactonolactone dehydrogenase; D012273:Ribulose-Bisphosphate Carboxylase; D001205:Ascorbic Acid
keywords: Antioxidant; Ascorbic acid; Grain chalkiness; Rice; Starch; l-Galactono-14-lactone dehydrogenase