PLASMODESMATAL DISTRIBUTION, STRUCTURE AND FREQUENCY IN RELATION TO ASSIMILATION IN C3 AND C4 GRASSES IN SOUTHERN AFRICA
PLASMODESMATAL DISTRIBUTION, STRUCTURE AND FREQUENCY IN RELATION TO ASSIMILATION IN C3 AND C4 GRASSES IN SOUTHERN AFRICA
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DOI：
10.1007/bf00195658
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发表时间：
1992-06-01
期刊：
影响因子：
4.3
通讯作者：
BOTHA, CEJ
中科院分区：
文献类型：
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作者：
BOTHA, CEJ
本文讨论了四个南部非洲草的叶片束中的胞间连丝的分布和频率-一个C3，和一个每个的NAPD-苹果酸酶（ME），NAD-ME和磷酸烯醇式丙酮酸羧激酶（PCK）C4光合亚型，此外，涉及到计算的胞间连丝频率的光合固碳率。在所有情况下，胞间连丝在Kranz叶鞘-维管束鞘（KMS-BS）、叶鞘-维管薄壁组织（BS-VP）或叶鞘-维管束鞘-叶鞘界面（BSMS）处穿过木栓质层时收缩。频率研究清楚地表明，胞间连丝在KMS-BS、BS-MS和BS-VP界面处数量最多（占总数的31.9- 76.8%），并且它们的数量随着与薄壁和厚壁筛管的接近而迅速减少。在Themeda triandra var. imberbis（Retz.）A. Camus和Bromus unioloides H.B.K.厚壁筛管与维管薄壁细胞的连接很少，并且实际上几乎完全与维管组织的其余部分隔离，这表明这些筛管的装载途径主要是质外体。虽然降低胞间连丝频率表明，加载同化物可能会变得越来越接近筛管，共质体的薄壁筛管的路线，不能被排除。净同化率的研究表明，光合速率与光合类型（C3，C4 NADP-ME，C4 PCK，和C4 NAD-ME）有很好的相关性;此外，最低的胞间连丝频率与C3，C4 NAD-ME类型最高。
This paper addresses plasmodesmatal distribution and frequency in the leaf-blade bundles of four southern African grasses - one C3, and one each of the NAPD-malic-enzyme (ME), NAD-ME and phosphoenolpyruvate carboxykinase (PCK) C4 photosynthetic subtypes and, additionally, relates the calculated plasmodesmatal frequencies to the photosynthetic carbon-fixation rate. Plasmodesmata are, in all instances, constricted where they traverse suberin lamellae at the Kranz mesophyll-bundle sheath (KMS-BS), the bundle-sheath-vascular parenchyma (BS-VP), or the bundle-sheath-mestome-sheath interfaces (BS MS). Frequency studies clearly show that plasmodesmata are most numerous at the KMS-BS, BS-MS and BS-VP interfaces, (31.9-76.8 % of the total) and that their numbers decrease rapidly with increasing proximity to both thin- and thick-walled sieve tubes. In Themeda triandra var. imberbis (Retz.) A. Camus and Bromus unioloides H.B.K. thick-walled sieve tubes have few connections with vascular parenchyma cells and are, to all intents and purposes, almost totally isolated from the rest of the vascular tissue, indicating that the loading pathways for these sieve tubes are predominantly apoplastic. Although decreasing plasmodesmatal frequencies indicate that loading of assimilate may become progressively more apoplastic with increasing proximity to the sieve tubes, a symplastic route to the thin-walled sieve tubes cannot be ruled out. Studies of net assimilation rate indicate a good correlation of photosynthetic rate with the photosynthetic type (C3, C4 NADP-ME, C4 PCK, and C4 NAD-ME); furthermore, the lowest plasmodesmatal frequencies were associated with C3, and the highest with C4 NAD-ME types.