抗裂性不同的荔枝品种果皮发育过程中钙的分布动态研究

A Study of Calcium Accumulation and Distribution in the Pericarp of Litchi Cultivars Differing in Cracking Resistance

研究比较了抗裂荔枝品种'怀枝'和易裂品种'糯米糍'果皮中钙的含量,并用电子探针技术(X-射线电子散射能谱,X-Ray electron dispersive spectrum)分析了两者钙的显微分布动态.研究表明,'怀枝'积累钙的能力明显高于 '糯米糍'.两品种果皮发育早期,海绵组织形成之前(花后10 d),在中果皮内层有大量的富钙区域,随着果皮发育,海绵组织形成,该部位的富钙区消失; 而在果肉快速膨大前(花后52～66 d),内果皮成为钙信号最强的区域,同时,表皮细胞内积累大量的钙,成为富钙细胞层,表明钙可在果皮组织内再分布.果实发育后期(花后66～80 d)表皮之下的厚壁组织钙分布最弱.本文还对两品种钙含量差异与种子发育的关系及各部位钙与果皮力学性能的关系进行了讨论.

Changes in the micro-distribution of calcium in litchi （ Litchi chinensis Sonn. ） pericarp （ fruit skin） were compared using electron probe （X-ray despersive spectrometer） between ‘Huaizhi＇ and ‘Nuomici＇ , which differ significantly in cracking susceptibility. The results showed that cracking-resistant ‘Huaizhi＇ has a stronger ability to accumulate calcium than the susceptible ‘Nuomici＇. Before spongy tissue was visible （ 10 days after anthesis （DAA） ], calcium had accumulated at the site of spongy tissue formation, which formed calcium-rich zones in the inner mesocarp. These calcium-rich zones largely disappeared as the spongy tissue was formed （52 -66 DAA）, with endocarp becoming “calcium rich”, indicating intercellular re-localization of calcium occurred within the pericarp. At later stages of fruit development （ 66 and 80 DAA）, calcium accumulated abundantly in the epidermis cells, which formed a calcium-rich layer in both cultivars. However, the lowest calcium region was localized in the sclerenchyma tissue immediately beneath the epidermis. The paper also discussed the interrelation between difference in calcium accumulation ability within the two cuhivars and their seed development as well as the roles of calcium in various parts in mechanical properties of the pericarp.