Role of Fungal Factors in Mycorrhizal Formation

VAM真菌在根皮质细胞内的复杂生长引发了关于允许共生的关键事件的分子性质的问题。拟议的研究将测试真菌产品在调节植物机制方面的作用，这些机制可以控制菌丝发育。这些假说调用VAM真菌产物来影响质膜功能和宿主细胞的防御能力。研究将探索真菌产品是否会改变关键的质膜酶活性，如ATPase和NAD(P)H氧化酶，这些酶可以调节生物之间的离子和营养流动。对防御机制的影响将通过筛选在植物抗性中可能起作用的化合物和酶的水平变化来研究。分子生物学技术将被用来确定由VAM真菌成分触发的植物基因表达变化的程度。%植物的健康发展可能需要在植物根和某些形成菌根的有益真菌之间建立共生关系。大约90%的高等植物形成泡状丛枝菌根。VA菌根是由真菌菌丝侵染植物细根的皮层细胞而产生的。菌丝延伸到土壤中，并创造了一个增强的摄食区，从那里可以获得养分由植物提取和利用。菌根植物通常表现出对磷、微量金属和其他难于溶解的营养物质的吸收增加。据报道，菌根植物对干旱的耐受性更强，对某些根部疾病的抵抗力也有所提高。因此，菌根植物通常表现出比非菌根植物更高的生长产量和存活率，特别是在肥力较低的土壤上。VAM形成的这些有利影响在农业、林业、复垦和园艺业中具有相当大的潜力来提高植物产量。这些改进将通过减少化肥和水的需求直接降低与能源有关的成本，并间接通过生产更健壮的植物。*/

The intricate growth of the VAM fungus within the root cortical cells raises questions as to the molecular nature of key events which permit the symbiosis. The proposed studies will test the role of fungal products in regulating plant mechanisms which could control hyphal development. The hypotheses invoke VAM fungal products to effect plasmalemma function and the defense potential of the host cell. Studies will probe whether fungal products alter key plasmalemma enzyme activities such as ATPase and NAD(P)H oxidase which could regulate ion and nutrient flux between organisms. Effects on defense mechanisms will be studied by screening for altered levels of compounds and enzymes which have putative roles in plant resistance. Molecular biology techniques will be used to determine the extent of changes in plant gene expression which are triggered by VAM fungal components.%%% Healthy plant development may require symbiosis to be established between the plant root and certain beneficial fungi which form mycorrhizae. Approximately 90% of all higher plants form vesicular-arbuscular (VA) mycorrhizae. VA mycorrhizae are produced by the colonization of the cortical cells of fine feeder roots of plants by fungal hyphae. The hyphae extend out into the soil and create an enhanced feeding area from which nutrients can be extracted and utilized by the plant. Mycorrhizal plants often demonstrate increased uptake of phosphorus, trace metals and other sparingly soluble nutrients. Greater tolerance to drought and improved resistance to some root diseases have been reported for mycorrhizal plants. Consequently mycorrhizal plants frequently exhibit increased growth yield and survival over non-mycorrhizal plants especially on less fertile soil. These beneficial effects of VAM formation hold considerable potential for improving plant production in agriculture, forestry, reclamation, and horticulture. These improvements will reduce energy-related costs directly through reduction in fertilizer and water requirements and indirectly by the production of more robust plants.***//