不同锌效率水稻基因型及其杂种一代幼苗生长和抗氧化酶活性对Zn2+活度的反应

  为了解水稻耐低锌能力基因型差异的生理机制及F1杂种的耐低锌能力以提高水稻锌效率，解决水稻锌缺乏问题，选用耐低锌基因型水稻IR8192、IR36，锌敏感基因型水稻Ce 64、IR26及杂交后代IR36×IR8192、IR36×IR26和Ce 64×IR26为材料，进行低锌(pZn2+ 11.0)和正常锌(pZn2+ 9.7)营养液培养。结果表明：1)亲本和F1幼苗的株高，叶鞘高，地上部和地下部干质量及锌含量，叶片的叶绿素含量、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、过氧化物酶(POD)活性、丙二醛(MDA)含量在pZn2+ 11.0与pZn2+ 9.7条件下的相对值可作为耐低锌基因型水稻的筛选指标；2)在低锌条件下所有亲本及F1各项指标变化趋势相同，但IR8192、IR36、IR36×IR8192、IR36×IR26的叶绿素含量、SOD酶活性降幅较小，POD、CAT、APX活性升幅较大，MDA含量升幅较小，表明上述基因型水稻的耐低锌能力更强。 低锌胁迫下POD、CAT、APX活性增强，可以更有效地清除活性氧，SOD活性则最先下降；3)除根长、APX活性外，在低锌条件下，IR36×IR8192、IR36×IR26各项指标变化幅度均表现出超亲优势，而Ce 64×IR26则表现出偏中亲优势，推测水稻的耐低锌特性主要受基因的显性效应控制，并存在基因的叠加效应，可以通过耐低锌亲本间的杂交获得具有更强耐低锌能力的水稻基因型。

Responses of Seedling Growth and Antioxidase Activities of Different Zinc Efficient Rice Genotypes and Their F1 Hybrids to Zn2+ Activities

Studying the physiological mechanism of genotypic difference in tolerance and the tolerance of F1 hybrids to low zinc stress in rice is one basic work to improve rice zinc efficiency as well as to solve the problem of rice zinc shortage. The Zn efficient rice cultivars IR8192 and IR36, Zn inefficient rice cultivars Ce 64 and IR26, and their F1 hybrids of the crosses IR36×IR8192, IR36×IR26, and Ce 64×IR26 were grown in chelator buffered nutrient solution at both low zinc level (pZn2+110) and normal zinc level (pZn2+9.7), respectively. The relative values of both parents and F1 rice seedlings under pZn2+110 to the ones under pZn2+9.7 in plant height, sheath height, shoot and root dry weights and zinc contents, chlorophyll content in leaves, and activities of SOD, CAT, POD, and MDA could be used as the screening index of Zn efficient rice. At low zinc level, the four cultivars and their F1 hybrids showed similar trends in all the indices. However, IR8192, IR36, IR36×IR8192 had smaller decreases in chlorophyll content and activity of SOD, greater increases in activities of POD, CAT and APX, and a smaller increase in MDA content, suggesting that these rice genotypes had a stronger ability to resist low zinc stress. Under the low zinc stress, POD, CAT and APX were the main active oxygen scavenging system, while SOD protective enzyme system was firstly weakened. In the low zinc stress, except root length and APX activity, the relative values of the traits in IR36×IR8192 and IR36×IR26 showed over parent heterosis whereas Ce 64×IR26 were close to mid parent values, which indicates that low zinc tolerance was controlled by dominant effect and there existed duplicate effect of gene. Therefore, rice cultivars with stronger ability to resist low zinc stress could be obtained by hybridization of Zn efficient parental rice.