水稻铁害和应激乙烯释放的关系

IRON TOXICITY AND STRESS ETHYLENE PRODUCTION IN RICE

摘要:

在热带地区的水稻栽培中，常遇到水稻青铜病（ｂｒｏｎｚｉｎｇ）的危害．已知它是由水田中高浓度的亚铁离子所引起，故又叫铁害．但至今没有可靠的生理诊断指标用于抗性品种的筛选．本文研究了铁害与应激乙烯释放的关系，试图以应激乙烯的释放作为铁害的生理诊断指标．试验用两种方法模拟水稻致病．第一种方法是将水稻离体叶片的剪口端浸入ＦｅＳＯ４溶液中，靠叶片蒸腾作用吸收Ｆｅ＋＋而致病．另一种方法是在水培培养液中加入ＦｅＳＯ４通过水稻根系吸收Ｆｅ＋＋而致病．研究结果表明，当处理离体叶片时，发病强度和应激乙烯释放量呈显著相关，但叶片内铁含量的增加与发病强度和应激乙烯释放都没有相关性．而处理完全植株时，叶片中乙烯释放几乎不受影响．当部分或全部切除根时，叶片中乙烯释放则可被亚铁离子激发。表明水稻根系限制了Ｆｅ＋＋的吸收速率，而Ｆｅ＋＋进入叶组织的速率又决定应激乙烯的释放和组织的伤害程度．因此，叶片应激乙烯的释放作为铁害的生理诊断指标只有在当根系受到某种伤害时才可能适用，譬如移栽和毒性土壤等因素造成的根系的伤害．

Abstract:

The relationship between Fe++-induced bronzing and stress ethylene production (SEP)was investigated both in detached rice (Oryza sativa L.)leaves and in whole plants.Fe++ was applied to the detached leaf through a transpiration stream and to whole plants through roots in culture solution.The SEP from detached leaves differed with leaf position,growth stage, and genotype.Correlation between SEP and bronzing was significant for the leaves of 16 tested genotypes(r=0.659**),but the iron concentration increment(ICI)of the detached leaf correlated neither to the bronzing nor to the SEP, suggesting that leaf tissue tolerance, not ICI, controls the bronzing deveiopment and the SEP.When the Whole plant was treated by increasing Fe++ concentration in culture solution,the SEP was negligibly small. By partially or entirely de-rooting the plant, however,stress ethylene was evoked bythe Fe++ treatment,indicating that roots limited the Fe++-induced SEP.