Nuclear behavior of the cowpea rust fungus during the early stages of basidiospore- or urediospore-derived growth in resistant or susceptible cowpea cultivars
Nuclear behavior of the cowpea rust fungus during the early stages of basidiospore- or urediospore-derived growth in resistant or susceptible cowpea cultivars
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DOI：
10.1094/phyto-86-1057
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发表时间：
1996-10-01
期刊：
影响因子：
3.2
通讯作者：
Eilam, T
中科院分区：
文献类型：
--
作者：
Heath, MC;Xu, HX;Eilam, T
通过光学显微镜在活体和固定材料中研究了真菌核状况与豇豆锈菌两个寄生阶段生长之间的关系。豇豆锈菌的单核冬孢子发芽形成原菌丝体，产生四个担子孢子，每个担子孢子含有两个核，这是核迁移到发育中的孢子期间核分裂的结果。易感宿主品种表皮细胞内的担孢子来源的菌丝通过以下方式迅速变成单核细胞：(i)两个担孢子核在迁移到侵入菌丝中并且后者长到约40μm后进行同步有丝分裂； (ii) 随后入侵菌丝被隔膜立即分裂成一个双核细胞和两个单核细胞； (iii) 双核细胞中的一个细胞核消失。然而，在同一宿主品种中，由于核降解和异步核分裂，源自同一真菌双核夏孢子的胞间感染菌丝、次生菌丝和前两个吸器母细胞（HMC）具有不同的核数。然而，到接种后3天，所有随后形成的细胞间菌丝、HMC和吸器都是双核的。在测试的三个抗性品种中，担子孢子来源的细胞内侵入菌丝是否存在核分裂取决于最大真菌生长的程度。生长抑制与两个品种中的植物细胞死亡以及品种安妮女王中的胼胝质包裹有关。在这些相同品种的夏孢子源性感染中，细胞间感染菌丝和 HMC 发育正常，但核迁移到吸器的数量减少，通常在安妮女王的吸器被胼胝质包裹之前。数据表明，在安妮女王中，真菌包裹在抵抗担子孢子衍生的感染阶段中发挥着更大的作用，而不是在抵抗孢子衍生的感染阶段。
The relationship between fungal nuclear condition and growth of the two parasitic stages of the cowpea rust fungus was studied by light microscopy in living and fixed material. Uninucleate teliospores of the cowpea rust fungus germinated to form a promycelium that produced four basidiospores, each containing two nuclei as the result of a nuclear division during nuclear migration into the developing spore. Basidiospore derived hyphae within an epidermal cell of a susceptible host cultivar rapidly became monokaryotic by (i) synchronous mitosis of the two basidiospore nuclei after they had migrated into the invasion hypha and the latter had grown to about 40 mu m; (ii) the subsequent immediate division by septa of the invasion hypha into one binucleate and two uninucleate cells; and (iii) the disappearance of one of the nuclei in the binucleate cell. However, in the same host cultivar, the intercellular infection hyphae, secondary hyphae, and first two haustorial mother cells (HMCs) derived from dikaryotic urediospores of the same fungus had variable nuclear numbers due to nuclear degradation and asynchronous nuclear divisions. Nevertheless, by 3 days after inoculation, all subsequently formed intercellular hyphae, HMCs, and haustoria were binucleate. In the three resistant cultivars tested, the presence or absence of nuclear division in the basidiospore-derived, intracellular invasion hyphae depended on the degree of maximum fungal growth; growth inhibition was related to plant cell death in two of the cultivars and to callose encasement in cultivar Queen Anne. In urediospore-derived infections of these same cultivars, the intercellular infection hyphae and HMCs developed normally, but nuclear migration into the haustorium was reduced, often before callose encasement of the haustorium in Queen Anne. The data suggest that in Queen Anne, fungal encasement plays a greater role in resistance to the basidiospore-derived than to the urediospore-derived stage of infection.