PvLOX2 silencing in common bean roots impairs arbuscular mycorrhiza-induced resistance without affecting symbiosis establishment.

Mora-Romero, Guadalupe A.; Gonzalez-Ortiz, Maria A.; Quiroz-Figueroa, Francisco; Calderon-Vazquez, Carlos L.; Medina-Godoy, Sergio; Maldonado-Mendoza, Ignacio; Arroyo-Becerra, Analilia; Perez-Torres, Anahí; Alatorre-Cobos, Fulgencio; Sanchez, Federico; Lopez-Meyer, Melina

The arbuscular mycorrhizal (AM) symbiosis is an intimate association between specific soil-borne fungi and the roots of most land plants. AM colonisation elicits an enhanced defence resistance against pathogens, known as mycorrhizal-induced resistance (MIR). This mechanism locally and systemically sensitises plant tissues to boost their basal defence response. Although a role for oxylipins in MIR has been proposed, it has not yet been experimentally confirmed. In this study, when the common bean (Phaseolus vulgaris L.) lipoxygenase PvLOX2 was silenced in roots of composite plants, leaves of silenced plants lost their capacity to exhibit MIR against the foliar pathogen Sclerotinia sclerotiorum, even though they were colonised normally. PvLOX6, a LOX gene family member, is involved in JA biosynthesis in the common bean. Downregulation of PvLOX2 and PvLOX6 in leaves of PvLOX2 root-silenced plants coincides with the loss of MIR, suggesting that these genes could be involved in the onset and spreading of the mycorrhiza-induced defence response. Arbuscular mycorrhizal colonization elicits mycorrhizal-induced resistance (MIR), an enhanced pathogen defence response. To investigate the role of the oxylipin biosynthetic pathway in this phenomenon, we silenced lipoxygenases in normally AM colonized common bean roots and observed MIR impairment against a foliar pathogen. These findings provide novel insights into the onset of MIR, and will eventually be of great benefit to agriculture.

PLANT gene silencing; EFFECT of fungicides on plants; BEAN genetics; LIPOXYGENASES; GENETIC research; PLANT genetics

Functional Plant Biology, 2015, Vol 42, Issue 1, p18

1445-4408

Academic Journal

10.1071/FP14101