蔓割病不同抗性甘薯品种的茎部细胞结构观察

蔓割病是我国南方薯区甘薯主要病害之一,本研究采用直接观察、显微和超微结构观测等方法,对高抗、中感和高感蔓割病的3个甘薯品种(高抗品种:金山57,中感品种:热薯1号,高感品种:新种花)接种蔓割病菌28 d植株充分发病后其茎基部细胞的侵染结构进行了观察。结果表明,在用清水作对照处理时,3个品种茎部组织的细胞形态和结构正常且完整,细胞代谢强。高抗品种金山57无论是接种组还是对照组,均未发现病原菌丝的存在,其茎下部、中部和上部细胞结构相对完整。中感品种热薯1号,蔓割病菌从其茎基部侵入后导致茎基部细胞破损坏死,而中部寄主-病原互作较为活跃和典型,造成养分运输受阻,茎基部接种后病原菌丝会沿着寄主茎部的维管束和其他组织一直向寄主的茎部末端蔓延,遭受侵染后的部位其细胞反应与高感品种新种花类似。高感品种新种花遭受蔓割病原菌侵染后,病原菌菌丝从茎基部新鲜剪口侵入后进入表皮细胞、皮层、维管束并在甘薯茎基部蔓延至中部、上部,直至寄主整株枯死,甘薯茎的木质部导管出现侵填体,质壁分离;与此同时,细胞壁的沉积物及乳突在病原菌的入侵处形成,各种无定型物质或纤丝构成的织网迅速包围入侵菌丝。

Study on the stem cell structure alteration of sweet potato varieties with different resistance to Fusarium wilt

Fusarium wilt is one of the main diseases of sweet potato in south China. In this study, ultrastructure was performed to understand the disease-resistant mechanism of cell structure alternation in sweet potato via Fob (Fusarium oxysporum f. sp. batatas) inoculation treatment. Sweet potato cultivars with different disease-resistance Highly resistant (HR) cultivars: Jinshan57, Moderate susceptibility (MS) cultivars: Reshu NO.1, Higher susceptible (HS) cultivars: Xinzhonghua,] were inoculated by stem base, and any alteration in cell structure of the sample was observed by direct observation combining with microscopy and transmission electron microscope(TEM) technology. The results showed that there were different performances among different cultivars after inoculation. The Fob mycelium growth was not observed in the stem of Jinshan 57 (the HR cultivars ) after inoculation, which cell structural integrity was not violated. With the inoculation of Fob, the cells in stem base of Reshu No.1 (MS cultivar) were violated to apoptosis. While in the middle part of which stem, the plant-pathogen interaction was more active and the transportation of plant nutrition was disrupted. The Fob mycelium spread from the stem base to the top stem through the vascular bundles. After inoculated by Fob, the mycelium spread to the epidermal cells, cortex and vascular bundles of Xinzhonghua (the HS cultivar ) from the injury, then spread to the middle and top part of the stem till the whole plant exsiccation. During this period, the thylose was observed in the vessels, and rupture of cell wall and membranes of cytoplasmic organoids were also observed. At the same time, the sediment of cell wall and tubercles emerged wherever the pathogen invasion, and the Fob hyphae were surrounded by a variety of amorpphis or cellosilk net.