Physiological responses of Burkholderia phytofirmans strain PsJN colonized plantlets of grapevine (Vitis vinifera L.) to low non-freezing temperatures

Wed, 10/12/2011 - 19:59 — Andreas THEOCHARIS

Publication Type:

Thesis

Authors:

THEOCHARIS, A.I.

Source:

Laboratoire de Stress, Défenses et Reproduction des Plantes Unité de Recherche Vignes et Vins de Champagne - Stress et Environnement , UNIVERSITE DE REIMS CHAMPAGNE-ARDENNE, , Reims, p.226 (2010)

Abstract:

Burkholderia phytofirmans strain PsJN has been well characterized as a Plant Growth Promoting Rhizobacteria (PGPR) that triggers induced resistance in grapevine against fungal pathogens. Recently, it has been demonstrated that B. phytofirmans may also enhance resistance to stress in low non-freezing temperatures. To better understand the interaction between grapevine and B. phytofirmans strain PsJN, changes in the expression pattern of different defence related genes were investigated in Chardonnay grapevine leaves after root inoculation with PsJN strain. B. phytofirmans induced a systemic spread of a signal from roots to leaves after root inoculation with bacteria, a phenomenon referred to as Induced Systemic Resistance (ISR). The expression pattern of well-characterized grapevine defence genes was also monitored in grapevine plantlets bacterized four weeks earlier, and subjected to low non-freezing temperature. Results report that PsJN induces earlier and/or higher transcript accumulation of defence genes in bacterized plantlets upon low non-freezing temperatures according to the phenomenon of priming. Further investigation of several biochemical parameters reveals that bacterized grapevine plantlets are in a primed physiological state able to increase their sugar, starch and proline levels upon low non-freezing temperatures while the analysis of membrane lipid peroxidation markers indicates a faster degradation of aldehydes, malonaldehyde and hydrogen peroxide beyond one week, addressing the better adaptation of bacterized plantlets than non-bacterized plantlets to low non-freezing temperature. In addition, nine combinations of non-radioactive digoxigenine labelled-PstI and MseI primers were used to generate differentially expressed genes by cDNA-AFLP technology for further investigation of primed physiological state induced by PsJN and isolation of over-expressed genes upon low non-freezing temperatures. In conclusion, it is suggested that PsJN strain is an ISR-inducing PGPR able to stimulate grapevine defence mechanism by priming physiological responses critical to acclimation under low non-freezing temperatures.