Physiological and Molecular Biological Analyses of seed Germination Ecology in Echinochloa crus-galli (L.) Beauv., a weed in flooded rice

耐涝和感病的棘豆品种美人。(1)耐淹种子萌发的生理和分子分析；(2)淹水条件下种子呼吸代谢规律的研究。耐淹种子萌发的生理和分子分析耐淹品种在N_2下吸胀的种子表现出高的I/N商数和加速糖酵解，同时产生大量等摩尔的CO_2和乙醇，这表明种子具有巴斯德效应，可以在厌氧条件下萌发。相反，感涝品种的种子只能通过常规的好氧呼吸在有氧条件下发芽，而不能通过酒精发酵进行厌氧呼吸发芽。淹水条件下种子呼吸的代谢调节在土壤淹水的稻田中，水稻种子最初通过酒精发酵厌氧呼吸发芽，当种子到达水面时，种子将发酵转换为常规的好氧呼吸。这种转换被发现由氧诱导的内源性ADH抑制蛋白调节。

Flooding-tolerant and -susceptible varieties of Echinochloa crus-galli (L.) Beauv. were used to study (1) physiological and molecular analyses of the flooding tolerant seed germination and (2) metabolic regulation of seed respiration under flooding.1. Physiological and molecular analyses of flooding-tolerant seed germinationIn flooding-tolerant variety, seeds imbibed under N_2 could exhibited large I/N quotient and accelerated glycolysis and concomitantly produced large and equimolar quantities of CO_2 and ethanol, suggesting that the seeds operated the Pasteur effect and could germinate under anaerobic conditions. In contrast, seeds of the flooding-susceptible variety were capable of germinating only under aerobic conditions through the conventional aerobic respiration, but unable to anaerobically respire to germinate through the alcohol fermentation.2. Metabolic regulation of seed respiration under floodingIn a rice field where the soil is flooded, seeds of E.oryzicola anaerobically initially respire through alcohol fermentation to germinate and the seedlings switch the fermentation to the conventional aerobic respiration when they reach the water surface. This switching was found to be regulated by an endogenous ADH-inhibiting protein that is induced by oxygen.