Aroca Ricardo, Del Mar Alguacil Maria, Vernieri Paolo, Ruiz-Lozano Juan Manuel
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda no. 1, 18008 Granada, Spain.
Microb Ecol. 2008 Nov;56(4):704-19. doi: 10.1007/s00248-008-9390-y. Epub 2008 Apr 29.
The aims of the present study are to find out whether the effects of arbuscular mycorrhizal (AM) symbiosis on plant resistance to water deficit are mediated by the endogenous abscisic acid (ABA) content of the host plant and whether the exogenous ABA application modifies such effects. The ABA-deficient tomato mutant sitiens and its near-isogenic wild-type parental line were used. Plant development, physiology, and expression of plant genes expected to be modulated by AM symbiosis, drought, and ABA were studied. Results showed that only wild-type tomato plants responded positively to mycorrhizal inoculation, while AM symbiosis was not observed to have any effect on plant development in sitiens plants grown under well-watered conditions. The application of ABA to sitiens plants enhanced plant growth both under well-watered and drought stress conditions. In respect to sitiens plants subjected to drought stress, the addition of ABA had a cumulative effect in relation to that of inoculation with G. intraradices. Most of the genes analyzed in this study showed different regulation patterns in wild-type and sitiens plants, suggesting that their gene expression is modulated by the plant ABA phenotype. In the same way, the colonization of roots with the AM fungus G. intraradices differently regulated the expression of these genes in wild-type and in sitiens plants, which could explain the distinctive effect of the symbiosis on each plant ABA phenotype. This also suggests that the effects of the AM symbiosis on plant responses and resistance to water deficit are mediated by the plant ABA phenotype.
本研究的目的是确定丛枝菌根（AM）共生对植物抗旱性的影响是否由宿主植物的内源脱落酸（ABA）含量介导，以及外源ABA的施用是否会改变这种影响。使用了ABA缺陷型番茄突变体sitiens及其近等基因野生型亲本系。研究了植物发育、生理学以及预期受AM共生、干旱和ABA调节的植物基因的表达。结果表明，只有野生型番茄植株对菌根接种有积极反应，而在水分充足条件下生长的sitiens植株中，未观察到AM共生对植物发育有任何影响。对sitiens植株施用ABA在水分充足和干旱胁迫条件下均能促进植物生长。对于遭受干旱胁迫的sitiens植株，ABA的添加与接种根内球囊霉具有累积效应。本研究中分析的大多数基因在野生型和sitiens植株中表现出不同的调控模式，表明它们的基因表达受植物ABA表型的调节。同样，根内球囊霉对根的定殖在野生型和sitiens植株中对这些基因的表达有不同的调控，这可以解释共生对每种植物ABA表型的独特影响。这也表明，AM共生对植物反应和抗旱性的影响是由植物ABA表型介导的。
