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首页> 外文学位 >Patterns of root colonization by the arbuscular mycorrhizal fungus Glomus intraradices and host plant responses.
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Patterns of root colonization by the arbuscular mycorrhizal fungus Glomus intraradices and host plant responses.

机译：丛枝菌根真菌Glomus的内根和寄主植物的根定植模式。

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Mycorrhizal hyphae were directed in their growth pattern in roots. Arbuscules produced by a single isolate of Glomus intraradices Schenck & Smith in roots of corn, wheat, carrot, clover, mung bean, and bean (Phaseolus vulgaris L.) were consistently limited to cortical cells immediately adjacent to the endodermis. Two hypotheses for controlled growth of arbuscular mycorrhizal fungi in plants were examined: (1) activation of plant defenses by the fungus, and (2) availability of host-derived carbon to the fungus. Accumulations of mRNAs for the defense-related genes phenylalanine ammonia-lyase (PAL), chalcone synthase, chitinase (CHT), glucanase, and hydroxyproline-rich glycoprotein were examined in the roots of P. vulgaris colonized by G. intraradices. In situ hybridizations of colonized roots using probes for PAL and CHT showed accumulations of both transcripts changed only in arbusculated cells. Both young, finely branched arbuscules and older, clumped arbuscules displayed PAL and CHT message accumulations. PAL and CHT mRNA accumulations were greater in cortical cells containing young arbuscules than in cells containing clumped arbuscules. Intercellular hyphae and vesicles elicited no defense response.; Because arbuscules in cells surrounding the endodermis are uniquely positioned to intercept the lateral movement of photosynthate out of the vascular cylinder, transcript levels for sucrose-metabolizing enzymes were examined in arbusculated cells. A cDNA was cloned from roots of P. vulgaris encoding a soluble acid invertase with potential vacuolar targeting. This clone and cDNAs for a Rhizobium-responsive sucrose synthase of soybean and a cell wall acid invertase of carrot were used as nucleic acid probes in in situ hybridizations of mycorrhizal roots. Transcript levels for cell wall acid invertase in arbusculated cells of carrot remained unchanged. Sucrose synthase mRNA levels were high in phloem tissues of the vascular cylinder of nonmycorrhizal and mycorrhizal roots of P. vulgaris. Strong endodermal cell-specific expression of the soluble acid invertase cDNA was observed in noncolonized and arbuscular mycorrhizal P. vulgaris roots. In addition, mycorrhizal roots of P. vulgaris showed increased transcript accumulation for the sucrose synthase and soluble acid invertase cDNAs that was limited to arbusculated cells.
机译：菌根菌丝针对其根部生长方式。由单一的Glomus intraradices Schenck＆Smith分离株在玉米，小麦，胡萝卜，三叶草，绿豆和豆类（菜豆）中产生的丛生植物始终局限于紧邻内胚层的皮质细胞。研究了两种控制植物中丛枝菌根真菌生长的假说：（1）真菌激活植物防御，以及（2）宿主来源的碳可被真菌利用。在由内生根瘤菌（G.intraradices）定居的寻常型根腐病菌（P. vulgaris）的根中检查了与防御相关基因苯丙氨酸解氨酶（PAL），查尔酮合酶，几丁质酶（CHT），葡聚糖酶和富含羟脯氨酸的糖蛋白的mRNA积累。使用PAL和CHT探针对定植根的原位杂交表明，两种转录本的积累仅在已接种细胞中发生了变化。年轻的细枝状丛生丛和较旧的丛生丛生丛丛均显示PAL和CHT消息积累。 PAL和CHT mRNA的积累在含有幼小丛状的皮质细胞中比在含有丛状丛状的细胞中更大。细胞间的菌丝和囊泡未引起防御反应。由于内胚层周围细胞中的丛枝被独特地定位以拦截光合产物从维管束向外的横向运动，因此在丛枝化细胞中检查了蔗糖代谢酶的转录水平。从寻常假单胞菌的根克隆cDNA，其编码具有潜在液泡靶向性的可溶性酸转化酶。该菌根和大豆的根瘤菌反应性蔗糖合酶和胡萝卜的细胞壁酸性转化酶的cDNA和cDNA用作菌根根原位杂交的核酸探针。胡萝卜精巢细胞中细胞壁酸性转化酶的转录水平保持不变。在寻常性假单胞菌的非菌根和菌根根的维管组织的韧皮部组织中，蔗糖合酶的mRNA水平较高。在非定殖和丛枝菌根寻常性假单胞菌根中观察到可溶性酸性转化酶cDNA的强烈内胚层细胞特异性表达。此外，寻常型假单胞菌的菌根根显示出蔗糖合酶和可溶性酸性转化酶cDNA的转录物积累增加，而这种现象仅限于被接种的细胞。

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