Effect of Rice wx Gene on Carbohydrate Accumulation and Amylase Activity of Germinating Grain

Effects of rice wx gene on accumulation of carbohydrates during grain development and activitiesof amylases in germinating grains were studied using two pairs of waxy and nonwaxy near-isogenic lines Yuanfengzao and waxy-Yuanfengzao,Zhenzhu 19 and waxy-Zhenzhu 19(Oryza sativa L.subsp.indica).The wx led to 0.07～2.94 and 1.04～4.55 percentage point respectively more reducing and nonreducing sugars in waxy-Yuanfengzao than Yuanfengzao and 1.01～5.08 and 1.60～6.94 Percentage point respeCtively more in waxy-Zhenzhu 19 than Zhenzhu 19. Starch content was 0.34～5.01 and 0.72～6.59 percentage point lower in the waxy grains than in the nonwaxy grains respectively. It is suggested that the wx gene control the synthesis of amylopetin with stable high ratio since the early stage of grain development. Activities of β-amylasc and R-enzyme were higher, while α-amylase was lower activity in the germinating waxy grains than in the germinating nonwaxy grains. Electrophoresis of amylase isozymes indicated that the α-amylase band was more greatly affected by the ax gene. Higher α-amylase activity induced by GA3 was also observed in the nonwaxy grains than waxy grains.