水分胁迫对杂种马褂木与双亲重要生理性状的影响

CHANGES IN SOME IMPORTANT PHYSIOLOGICAL CHARACTERS OF THE HYBRID TULIP TREE AND PARENTS UNDER WATER STRESS

水分胁迫状态下鹅掌楸属 (Liriodendron)种间正反交F1 杂种及双亲的一些重要生理性状的研究表明 :水分胁迫状态下亲本与杂种叶片的相对含水量、叶绿素含量、蛋白质含量的降低速率和RNase活力的升高速率排序为马褂木 >北美鹅掌楸 >正交F1 >反交F1 ;短时间水分胁迫对马褂木伤害最大。3H Gly标记取得的直接证据证明 ,水分胁迫导致亲本与杂种RNase基因在翻译水平上表达而从头合成RNase ,RNase基因表达强度排序为马褂木 >北美鹅掌楸 >正交F1 >反交F1 。蛋白质生物合成抑制剂取得的间接证据表明 ,水分胁迫状态下双亲RNase活力升高除与细胞质mRNA翻译有关外 ,还可能涉及叶绿体和 或线粒体RNase的释放、活化和 或合成 ,而正反交杂种RNase活力升高可能主要来自细胞质mRNA的翻译而不涉及到叶绿体和 或线粒体。上述实验证据充分证明 ,杂种马褂木正反交F1 杂种具有对水分胁迫抗性的显著超亲杂种优势 ,而正反交杂种中反交F1 的抗性又强于正交F1 。研究结果从水分胁迫抗性差异角度揭示了杂种马褂木强大正向生长、适应性和抗性杂种优势现象形成的分子机理 ,并表明在杂种马褂木杂种优势固定利用实践中必须特别注意反交F1

Some important physiological characters of Liriodendron reciprocal hybrids and parents under water stress were studied.The results were as follows:The decrease rate of relative water content, chlorophyll content as well as protein content and increase rate of RNase activity in leaf blades under water stress were L.chinense (Hemsl.) Sarg.> L.tulipifera Linn.>plus crossing F\-1>minus crossing F\-1. L.chinense was severely damaged by short water stress. Direct evidences from 3H\|Gly labeling under water stress proved both that RNase genes of parents and hybrids were expressed in translation level as well as RNase were synthesized de novo and that intensity of RNase gene expression was L.chinense>L.tulipifera >plus crossing F\-1>minus crossing F\-1. Indirect evidences from protein synthetic inhabitor under water stress indicated that RNase activity increase of parents might be involved in cytoplasmic mRNA translation and RNase release, activation and/or synthesis of chloroplast and/or mitochondria, but RNase activity increase of hybrids might originate mainly from cytoplasmic mRNA translation, not from chloroplast and/or mitochondria. The above\|mentioned experimental evidences fully proved both that reciprocal hybrids displayed notable super\|parent heterosis of resistance to water stress and that minus crossing F\-1 possessed stronger powerful heterosis of resistance to water stress than plus crossing F\-1. The researches revealed molecular mechanism of powerful positive heterotic formation of growth, adaptability and resistance on the basis of the resistance to water stress and showed geneticists and breeders of forest\|tree who are engaged in fixation and utilization of heterosis of the hybrid tulip tree must lay special stress on clones of minus crossing F\-1.