ABIOTIC STRESS TOLERANCES (MOISTURE, NUTRIENTS) AND PHOTOSYNTHESIS IN ENDOPHYTE-INFECTED TALL FESCUE
ABIOTIC STRESS TOLERANCES (MOISTURE, NUTRIENTS) AND PHOTOSYNTHESIS IN ENDOPHYTE-INFECTED TALL FESCUE
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DOI：
10.1016/0167-8809(93)90042-n
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发表时间：
1993-03-01
影响因子：
6.6
通讯作者：
BACON, CW
中科院分区：
文献类型：
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作者：
BACON, CW
每种高羊茅（Festuca arundinacea Schreb.）基因型及其伴生真菌内生真菌（Acremium coenophialum Morgan-Jones 和 Gams）的关联所产生的生态意义可能是营养相互作用所固有的，以及由此产生的每种基因型的生理和生化需求。真菌对这种草的定殖遵循羊茅种子发芽、幼苗和分蘖生长的自然顺序。受感染的草是天然且广泛的，因此高羊茅应被视为共生植物。这种在群体水平上的关系的本质更恰当地描述为一种专性生物营养型联合互利共生。在人口层面使用该术语描述了总体生态效应；然而，必须考虑到人群中受感染的高羊茅基因型可能不会表现出任何积极的适应策略。后一类的基因型可能被归类为绝对中性共生，可能只是暂时的。早期类别的受感染基因型提供了对环境胁迫的适应能力，并且可以利用这些特征。对研究证据进行审查，表明高羊茅群体中选定的基因型比未受感染的禾本科植物更能耐受环境非生物胁迫。受感染的高羊茅种子比未受感染的种子需要更多的水分才能发芽。内生菌感染的幼苗比未感染的幼苗需要更多的营养。尽管受感染的高羊茅含有较少的可溶性氮，这会鼓励更多的捕食，但由于昆虫威慑剂、毒素及其增效剂的积累，由食草昆虫应激产生的菌株得到了预防。在形态水平上，受感染的草通过老叶的早期脱落和新叶的卷曲表现出对水分胁迫的耐受性。低气孔导度和增强的渗透调节系统的发展进一步证明了对水胁迫的耐受性，该系统产生增加的细胞膨胀压力。高羊茅的一种基因型含有多元醇，其中一些在未感染的克隆中不存在。受感染的高羊茅还表现出对低土壤氮的效率增加，这可能是由于谷氨酰胺合成酶水平增加，这将增强其在低土壤氮下的竞争能力。在几种受感染草的基因型中，内生菌对光合作用和相关过程没有影响。
The ecological significance resulting from the association of each tall fescue (Festuca arundinacea Schreb.) genotype and its companion fungal endophyte (Acremonium coenophialum Morgan-Jones and Gams) is probably inherent in the nutritional interactions, and the resulting physiological and biochemical requirements of each. The colonization of this grass by the fungus follows the natural sequence of fescue seed germination, seedling and tiller growth. Infected grasses are natural and extensive, therefore tall fescue should be considered a symbiotic plant. The nature of this relationship at the population level is more appropriately described as an obligately biotrophic conjunctive mutualism. The use of this terminology at the population level describes the overall ecological effect; however, allowances must be made for infected tall fescue genotypes within the population that may not show any positive adaptive strategies. Genotypes of this later category may be categorized, possibly only transiently, as obligately neutral symbiotic. Infected genotypes of the earlier category offer adaptations to environmental stresses and may be exploited for these characteristics.Evidence from research is reviewed to indicate that selected genotypes within the population of tall fescue are more tolerant of environmental abiotic stresses than uninfected grasses. Infected tall fescue seed require more moisture to germinate than uninfected seed. Endophyte-infected seedlings require more nutrients than uninfected seedlings. Although infected tall fescue contains less soluble nitrogen which would encourage more predation, strains resulting from the stresses of insect herbivory are prevented because of an accumulation of an insect deterrent, toxins and their synergists. At the morphological level infected grasses show tolerance to water stress by early shedding of older leaves and rolling of younger leaves. Tolerance to water stress is further evidenced by low stomatal conductances and by development of an enhanced osmoregulatory system that produces increased cellular turgor pressure. One genotype of tall fescue contains polyols, some of which are absent in the uninfected clone. Infected tall fescue also shows increased efficiency to low soil nitrogen, possibly due to an increased level of glutamine synthetase which would enhance its competitive ability under low soil nitrogen. There is no endophyte effect of consequence on photosynthesis and associated processes in several genotypes of infected grasses.