Mycorrhizal and non-mycorrhizal Lactuca sativa plants exhibit contrasting responses to exogenous ABA during drought stress and recovery
Paolo Vernieri2 and
Juan Manuel Ruiz-Lozano1,*
1Departamento de Microbiología del Suelo y Sistemas
Simbióticos. Estación Experimental del Zaidín (CSIC). Profesor Albareda
no. 1, E-18008 Granada, Spain
2Dipartimento di Biologia delle Piante Agrarie, Università degli Studi di Pisa, I-56100 Pisa, Italy
An open access article from Journal of Experimental Botany 2008 59(8):2029-2041.
The arbuscular mycorrhizal (AM) symbiosis enhances plant toleranceto water deficit through the alteration of plant physiologyand the expression of plant genes. These changes have been postulatedto be caused (among others) by different contents of abscisicacid (ABA) between AM and non-AM plants. However, there areno studies dealing with the effects of exogenous ABA on theexpression of stress-related genes and on the physiology ofAM plants. The aim of the present study was to evaluate theinfluence of AM symbiosis and exogenous ABA application on plantdevelopment, physiology, and expression of several stress-relatedgenes after both drought and a recovery period. Results showthat the application of exogenous ABA had contrasting effectson AM and non-AM plants. Only AM plants fed with exogenous ABAmaintained shoot biomass production unaltered by drought stress.The addition of exogenous ABA enhanced considerably the ABAcontent in shoots of non-AM plants, concomitantly with the expressionof the stress marker genes Lsp5cs and Lslea and the gene Lsnced.By contrast, the addition of exogenous ABA decreased the contentof ABA in shoots of AM plants and did not produce any furtherenhancement of the expression of these three genes. AM plantsalways exhibited higher values of root hydraulic conductivityand reduced transpiration rate under drought stress. From plantssubjected to drought, only the AM plants recovered their roothydraulic conductivity completely after the 3 d recovery period.As a whole, the results indicate that AM plants regulate theirABA levels better and faster than non-AM plants, allowing amore adequate balance between leaf transpiration and root watermovement during drought and recovery.
ABA, arbuscular mycorrhiza, drought, recovery, stress-related gene