Regulation of carbohydrate partitioning during the interaction of potato virus Y with tobacco
Regulation of carbohydrate partitioning during the interaction of potato virus Y with tobacco
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DOI：
10.1046/j.1364-3703.2000.00007.x
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发表时间：
2000-01-01
影响因子：
4.9
通讯作者：
Sonnewald, U.
中科院分区：
文献类型：
--
作者：
Herbers, K.;Takahata, Y.;Sonnewald, U.
为了测试碳水化合物是否在植物发病过程中发挥信号传导功能，我们研究了烟草和马铃薯Y病毒（PVY（N））之间的相互作用。PVY（N）侵染后第4天，叶片开始积累可溶性糖，光合作用下降。可溶性糖的积累伴随着细胞壁转化酶的诱导和蔗糖-己糖比的逐渐降低。在平行的碳水化合物代谢和光合作用的变化，转录编码PR蛋白积累。基于这种巧合，有人推测，己糖水平的升高可能会增强防御相关功能的表达，并可能解释植物的高糖抗性现象。这一观点得到了以下事实的支持：发现表达细胞壁转化酶的转基因烟草植物对PVY（N）具有抗性（Herbers等人，1996年b）。为了排除在表达转化酶的植物中积累的水杨酸盐可能导致观察到的抗性的可能性，将这些转基因植物与表达水杨酸羟化酶的植物（nahG）杂交。后代选择高水平的糖和低水平的水杨酸盐。坏死性病变也发展，通常形成在表达转化酶的植物的叶子上，并且在不存在水杨酸盐的情况下编码PR-Q的转录物积累。另一方面，PR-1b转录物的积累减少，表明糖不足以诱导PR-1b。利用这些植物作为寄主的侵染试验表明，它们对PVY（N）具有抗性。因此，质外体转化酶诱导的病毒抗性的机制是水杨酸独立的，最有可能是糖介导的。
To test whether carbohydrates may play a signalling function during plant pathogenesis, we investigated the interaction between tobacco and potato virus Y (PVY(N)). Four days after PVY(N) infection, leaves started to accumulate soluble sugars and leaf photosynthesis decreased. The accumulation of soluble sugars was accompanied by an induction of cell wall invertase and a gradual decrease in the sucrose-to-hexose ratio. In parallel to changes in carbohydrate metabolism and photosynthesis, transcripts encoding PR-proteins accumulated. Based on this coincidence, it was hypothesized that elevated hexose levels may enhance the expression of defence-related functions and might possibly explain the phenomenon of high sugar resistance in plants. This notion has been supported by the fact that cell wall invertase-expressing transgenic tobacco plants were found to be resistant against PVY(N) (Herbers et al., 1996b). To exclude the possibility that salicylate, which accumulates in plants expressing invertase, may be responsible for the observed resistance, these transgenic plants were crossed with salicylate hydroxylase-expressing plants (nahG). The progeny were selected for high levels of sugar and low levels of salicylate. Necrotic lesions also developed, typically formed on the leaves of plants expressing invertase, and transcripts encoding PR-Q accumulated in the absence of salicylate. On the other hand, accumulation of PR-1b transcripts decreased, indicating that sugars are not sufficient for PR-1b induction. Infection experiments using these plants as hosts revealed resistance towards PVY(N). Thus, the mechanism of apoplastic invertase induced virus resistance is salicylate independent and most likely sugar mediated.