Leptosphaeria maculans Effector Protein AvrLm1 Modulates Plant Immunity by Enhancing MAP Kinase 9 Phosphorylation

Lisong Ma; Mohammad Djavaheri; Haiyan Wang; Nicholas J Larkan; Parham Haddadi; Elena Beynon; Gordon Gropp; M Hossein Borhan

doi:10.1016/j.isci.2018.04.015

Leptosphaeria maculans Effector Protein AvrLm1 Modulates Plant Immunity by Enhancing MAP Kinase 9 Phosphorylation

iScience. 2018 May 25:3:177-191. doi: 10.1016/j.isci.2018.04.015. Epub 2018 Apr 22.

Authors

Lisong Ma¹, Mohammad Djavaheri¹, Haiyan Wang², Nicholas J Larkan³, Parham Haddadi¹, Elena Beynon¹, Gordon Gropp¹, M Hossein Borhan⁴

Affiliations

¹ Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
² Center of Plant Disease and Plant Pests of Hebei Province, College of Plant Protection, Hebei Agricultural University, Baoding 071001, China.
³ Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; Armatus Genetics Inc., Saskatoon, SK S7J 4M2, Canada.
⁴ Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada. Electronic address: hossein.borhan@agr.gc.ca.

Abstract

Leptosphaeria maculans, the causal agent of blackleg disease in canola (Brassica napus), secretes an array of effectors into the host to overcome host defense. Here we present evidence that the L. maculans effector protein AvrLm1 functions as a virulence factor by interacting with the B. napus mitogen-activated protein (MAP) kinase 9 (BnMPK9), resulting in increased accumulation and enhanced phosphorylation of the host protein. Transient expression of BnMPK9 in Nicotiana benthamiana induces cell death, and this phenotype is enhanced in the presence of AvrLm1, suggesting that induction of cell death due to enhanced accumulation and phosphorylation of BnMPK9 by AvrLm1 supports the initiation of necrotrophic phase of L. maculans infection. Stable expression of BnMPK9 in B. napus perturbs hormone signaling, notably salicylic acid response genes, to facilitate L. maculans infection. Our findings provide evidence that a MAP kinase is directly targeted by a fungal effector to modulate plant immunity.

Keywords: Interaction of Plants with Organisms; Parasitology; Plant Biology.