Poster: Temperature Responses
Abs #
187: Occurrence and function of trehalose biosynthesis in chilling response of rice
The disaccharide, trehalose, is synthesized from UDP-glucose and glucose 6-phosphate in a two step process by trehalose 6-phosphate synthase (TPS) and trehalose 6-phosphate phosphatase (TPP). The compound is common in lower organisms where it serves as a reserve carbohydrate and/or stress protectant. However, the occurrence of trehalose in higher plants was ambiguous, except in resurrection plants. Recently, the genes for trehalose biosynthesis in Arabidopsis have been characterized, and trehalose has been hypothesized as a regulatory compound for sugar metabolism in plants. A cDNA microarray was utilized to screen for cDNA clones that are induced by chilling stress in rice roots. Two cDNAs clones involved in trehalose biosynthesis were identified as 12¡C-induced. Full-length cDNA clones (OsTPS1 and OsTPP1) were isolated from a root cDNA library. Southern blot analysis indicates that OsTPP1 is a single copy gene, while OsTPS1 may have similar genes in the rice genome. Northern blotting showed that both clones were rapidly induced within 1 to 4h of the chilling stress. This induction was transient and the signals disappeared after 6 to 10h of the chilling stress. Trehalose level was fairly low but increased rapidly and transiently in the cold-treated rice roots. Fructose and glucose levels consistently increased after a lag period of 5h. It appears that trehalose biosynthesis is transiently induced for chilling stress and may be involved in the regulation of sugar accumulation in the chilling stressed root tissues.
