Differences between appressoria formed by germ tubes and appressorium-like structures developed by hyphal tips in Magnaporthe oryzae
Differences between appressoria formed by germ tubes and appressorium-like structures developed by hyphal tips in Magnaporthe oryzae
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DOI：
10.1016/j.fgb.2013.03.006
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发表时间：
2013-07-01
影响因子：
3
通讯作者：
Xu, Jin-Rong
中科院分区：
文献类型：
--
作者：
Kong, Ling-An;Li, Guo-Tian;Xu, Jin-Rong
黑变附着胞是稻瘟病菌芽管形成的高度特化的侵染结构。M.菌丝顶端也形成附着胞样结构。而附着胞形成的分生孢子芽管已得到很好的特点，形成附着胞样结构的菌丝尖端的研究。在以前的研究中，我们发现chs7缺失突变体不能在芽管上形成附着胞，但在人工疏水表面上附着胞样结构的发育是正常的。本研究比较了菌丝顶端形成附着胞和芽管形成附着胞的差异。奥利瓦。在结构上，附着胞和附着胞样结构都具有在孔区域不存在的黑色素层。一般来说，后者的大小是1.4倍大，但有较低的膨压比附着胞，这是一致的，其在植物渗透效率较低。处理CAMP，IBMX，或角质单体有效地诱导附着胞的形成，但没有附着胞样结构的发展。相比之下，用蜡涂覆表面刺激了两种感染结构的形成。对各种信号突变体的研究表明，Osm1和Mps1是互补的，但Pmk1是菌丝顶端附着胞形成和附着胞样结构发育所必需的。有趣的是，cpkA突变体减少了附着胞样结构的分化，但没有附着胞的形成。我们还观察到我们实验室产生的con7突变体不能在菌丝顶端形成附着胞样结构，但仍能通过芽管在疏水表面产生附着胞。Con7是调节CHS7表达的转录因子。这些结果表明，菌丝顶端形成附着胞和芽管形成附着胞是两个不同的分化过程。可能涉及不同的分子机制。(C)2013 Elsevier Inc. All rights reserved.
Melanized appressoria are highly specialized infection structures formed by germ tubes of the rice blast fungus Magnaporthe oryzae for plant infection. M. oryzae also forms appressorium-like structures on hyphal tips. Whereas appressorium formation by conidial germ tubes has been well characterized, formation of appressorium-like structures by hyphal tips is under-investigated. In a previous study, we found that the chs7 deletion mutant failed to form appressoria on germ tubes but were normal in the development of appressorium-like structures on artificial hydrophobic surfaces. In this study, we compared the differences between the formation of appressoria by germ tubes and appressorium-like structures by hyphal tips in M. olyzae. Structurally, both appressoria and appressorium-like structures had a melanin layer that was absent in the pore region. In general, the latters were 1.4-fold larger in size but had lower turgor pressure than appressoria, which is consistent with its lower efficiency in plant penetration. Treatments with CAMP, IBMX, or a cutin monomer efficiently induced appressorium formation but not the development of appressorium-like structures. In contrast, coating surfaces with waxes stimulated the formation of both infection structures. Studies with various signaling mutants indicate that Osm1 and Mps1 are dispensable but Pmk1 is essential for both appressorium formation and development of appressorium-like structures on hyphal tips. Interestingly, the cpkA mutant was reduced in the differentiation of appressorium-like structures but not appressorium formation. We also observed that the con7 mutant generated in our lab failed to form appressorium-like structures on hyphal tips but still produced appressoria by germ tubes on hydrophobic surfaces. Con7 is a transcription factor regulating the expression of CHS7. Overall, these results indicate that the development of appressorium-like structures by hyphal tips and formation of appressoria by germ tubes are not identical differentiation processes in M. olyzae and may involve different molecular mechanisms. (C) 2013 Elsevier Inc. All rights reserved.