The cellular pathway of photosynthate transfer in the developing wheat grain. III. A structural analysis and physiological studies of the pathway from the endosperm cavity to the starchy endosperm
The cellular pathway of photosynthate transfer in the developing wheat grain. III. A structural analysis and physiological studies of the pathway from the endosperm cavity to the starchy endosperm
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DOI：
10.1111/j.1365-3040.1995.tb00374.x
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发表时间：
1995-04
影响因子：
7.3
通讯作者：
H. L. Wang;J. Patrick;C. Offler;X. Wang
中科院分区：
文献类型：
--
作者：
H. L. Wang;J. Patrick;C. Offler;X. Wang
蔗糖从胚乳腔转移到发育中的小麦籽粒（Triticum turgidum）的淀粉质胚乳的细胞途径已被阐明。修饰的糊粉层和亚糊粉层细胞表现出富含线粒体和内质网的致密细胞质。值得注意的是，亚糊粉层细胞的特征是次生壁向内生长。许多胞间连丝将改性糊粉和淀粉胚乳之间的所有细胞互连起来。质子载体羰基氰化物-间氯苯腙（CCCP）减缓了富含改性糊粉层和亚糊粉层细胞的谷物组织切片对[ 14 C]蔗糖的吸收，但对淀粉胚乳的吸收没有影响。荧光弱酸性磺罗丹明 G (SRG) 优先由修饰的糊粉层和亚糊粉层细胞积累，并且这种吸收对 CCCP 敏感。修饰的糊粉层和亚糊粉层细胞的组合质膜表面积似乎足以支持蔗糖转移至淀粉胚乳的体内速率。完整切下的谷物的质壁分解抑制[ 14 C]蔗糖从胚乳腔转移到淀粉胚乳。巯基修饰剂对氯汞苯磺酸（PCMBS）降低了修饰的糊粉层和亚糊粉层细胞对[ 14 C]蔗糖的吸收，但对淀粉胚乳的吸收几乎没有影响。相反，当将 PCMBS 和[ 14 C]蔗糖供应到完整切除谷物的胚乳腔时，PCMBS 同等地减缓了所有组织的积累。发现通过互连胞间连丝的潜在蔗糖通量的估计值在已发表的范围内。结论是，大部分蔗糖是由修饰的糊粉层和亚糊粉层细胞从胚乳腔积累的，随后通过共质体转移到淀粉胚乳。
The cellular pathway of sucrose transfer from the endosperm cavity to the starchy endosperm of developing grains of wheat (Triticum turgidum) has been elucidated. The modified aleurone and sub-aleurone cells exhibit a dense cytoplasm enriched in mitochondria and endoplasmic reticulum. Significantly, the sub-aleurone cells are characterized by secondary wall ingrowths. Numerous plasmodesmata interconnect all cells between the modified aleurone and starchy endosperm. The protonophore carbonylcyanide-m-chlorophenyl hydrazone (CCCP) slowed [ 14 C]sucrose uptake by grain tissue slices enriched in modified aleurone and sub-aleurone cells but had no effect on uptake by the starchy endosperm. The fluorescent weak acid sulphorhodamine G (SRG) was preferentially accumulated by the modified aleurone and sub-aleurone cells, and this uptake was sensitive to CCCP. The combined plasma membrane surface areas of the modified aleurone and sub-aleurone cells appeared to be sufficient to support the in vivo rates of sucrose transfer to the starcby endosperm. Plasmolysis of intact excised grain inhibited [ 14 C]sucrose transfer from the endosperm cavity to the starchy endosperm. The sulphydryl group modifier p-chloromercuribenzene-sulphonic acid (PCMBS) decreased [ 14 C]sucrose uptake by the modified aleurone and sub-aleurone cells but had little effect on uptake by the starchy endosperm. In contrast, when PCMBS and [ 14 C]sucrose were supplied to the endosperm cavity of intact excised grain, PCMBS slowed accumulation by all tissues equally. Estimates of potential sucrose fluxes through the interconnecting plasmodesmata were found to be within the published range. It is concluded that the bulk of sucrose is accumulated from the endosperm cavity by the modified aleurone and sub-aleurone cells and subsequently transferred through the symplast to the starchy endosperm