蚕豆籽粒内的~(14)C同化物的运转和卸出动态

通过向蚕豆叶片饲喂~(14)CO_2,应用液闪和显微放射性自显影技术表明标记同化物经叶脉和果荚韧皮部筛管快速运输至蚕豆种皮。种皮吸收营养、生长,后期逐步降解、供养子叶。种皮内的两类维管束系统同时输送营养并卸出到种皮内侧的质外体空间里。种皮里的反向维管束韧皮部卸出以共质体方式为主。并提供养分供种皮生长,而大部分的同化物由正向完整维管束韧皮部的筛分子一传递细胞进行质外体方式卸出。膨大中的子叶在早期即已成为生理上十分活跃的库。它对标记同化物的摄入随时间进程而急剧上升。

Translocation and Unloading of ~(14)C-Assimilates in Broad Bean Seed

By feeding ~(14)CO_2 to broad bean (Vicia faba)leaf and using liquid scintilation and microautoradiograph, it is indicated that labelled assimilates are transported quickly through leaf vein and pod phloem sieve element to seed coat. The coat itself absorbs nutrients and grows, and at late stage disintegrates and contributes its cell contents to the cotyledon. The two types of vascular bundles in seed coat simultaneously continue transporting nutrients and unloading them to apoplastic space inside the seed coat. The phloem of recurrent vascular bundle of seed coat unload mainly symplastically, and also supply nutrients for the growth of seed coat, while the majority of assimilates are unloaded apoplastically through sieve element-transfer cell complex of the phloem of complete chalazal vascular bundle. The cotyledon in the early stage of expanding has become a physiologically active sink, and its uptaking of assimilates increases rapidly in due course.