以肇实为材料,研究其种子萌发和植株生长特性,结果表明,水生植物肇实的种子萌发特性不同于一般的旱生植物,种子需要度过一段低温的休眠期才能发芽;萌发时子叶轴向伸长,胚根、胚芽挤出种孔;在子叶基部的外侧伸出白色乳头状突起,随后上胚轴伸长,胚芽从子叶的叶柄间伸出。肇实在生长发育过程中,叶片形态多变,不断增厚变粗,但叶面的通气组织发达。研究结果表明,肇实在不同生长时期,叶片中可溶性蛋白含量不断变化,表现为生长后期蛋白含量显著高于生长早期,SDS-PAGE电泳结果显示,3个不同生长时期叶片蛋白在45 k D处均有1条明显清晰的谱带,但生长后期蛋白谱带着色比早期更深。此外,肇实种仁中可溶性蛋白含量显著低于种衣中的,但SDS-PAGE电泳结果显示,种仁含有5条染色较深的清晰谱带,其中31 k D处蛋白含量丰富,而种衣中的蛋白谱带明显不同,数量更为丰富,分布也更加均匀。
以4个不同产地的芡实（Euryale ferox Salisb.）为试验材料,对其种仁中主要营养成分如蛋白质、淀粉组分进行了分析测定。结果表明,芡实种仁蛋白质主要由清蛋白、球蛋白、醇溶蛋白和谷蛋白构成;不同产地芡实的总蛋白质含量无显著差异,但4种不同蛋白的含量存在显著差异,其中3号芡实的清蛋白和球蛋白含量最高、醇溶蛋白和谷蛋白含量最低,1号芡实的醇溶蛋白和谷蛋白含量最高、清蛋白和球蛋白含量最低。SDS-PAGE图谱分析表明,4种不同产地的芡实均在45.0-66.2 k D处均含有一条明显的蛋白谱带,而3号芡实在20-45 k D范围内含3条明显蛋白谱带,表明3号芡实含有更多类型的蛋白组分或同工酶成分。此外,不同产地芡实种仁的直链淀粉和支链淀粉含量比值差异显著,其中2号芡实的支链淀粉含量最高,3号芡实支链淀粉含量最低。
Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid(Asc) is a major plant antioxidant that performs many functions in plants. L-Galactono-1,4-lactone dehydrogenase(L-Gal LDH, EC1.3.2.3) is an enzyme that catalyzes the final step of Asc biosynthesis in plants. Here we show that the L-Gal LDH-overexpressing transgenic rice, GO-2,which has constitutively higher leaf Asc content than wild-type(WT) plants, exhibits significantly reduced grain chalkiness. Higher foliar ascorbate/dehydroascorbate(Asc/DHA)ratios at 40, 60, 80, and 100 days of plant age were observed in GO-2. Further investigation showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate(Ru BP) carboxylase/oxygenase(Rubisco) protein level in GO-2 at 80 days. In addition, levels of abscisic acid(ABA) and jasmonic acid(JA) were lower in GO-2 at 60, 80, and100 days. The results we present here indicate that the enhanced level of Asc is likely responsible for changing redox homeostasis in key developmental stages associated with grain filling and alters grain chalkiness in the L-Gal LDH-overexpressing transgenic by maintaining photosynthetic function and affecting phytohormones associated with grain filling.
Le YuYonghai LiuJianhua TongJunhui DingRuozhong WangChanglian PengLangtao Xiao
