Harpin-inducible defense signaling components impair infection by the ascomycete Macrophomina phaseolina

Bisho R Lawaju; Kathy S Lawrence; Gary W Lawrence; Vincent P Klink

doi:10.1016/j.plaphy.2018.06.020

Harpin-inducible defense signaling components impair infection by the ascomycete Macrophomina phaseolina

Plant Physiol Biochem. 2018 Aug:129:331-348. doi: 10.1016/j.plaphy.2018.06.020. Epub 2018 Jun 18.

Authors

Bisho R Lawaju¹, Kathy S Lawrence², Gary W Lawrence³, Vincent P Klink⁴

Affiliations

¹ Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, College of Agriculture and Life Sciences, Mississippi State, MS, 39762, USA. Electronic address: lawaju.bishram@gmail.com.
² Department of Entomology and Plant Pathology, Auburn University, 209 Life Science Building, Auburn, AL, 36849, USA. Electronic address: lawrekk@auburn.edu.
³ Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, College of Agriculture and Life Sciences, Mississippi State University, Mississippi State, MS, 39762, USA. Electronic address: GLawrence@entomology.msstate.edu.
⁴ Department of Biological Sciences, College of Arts and Sciences, Mississippi State University, Mississippi State, MS, 39762, USA. Electronic address: vklink@biology.msstate.edu.

PMID: 29936240
DOI: 10.1016/j.plaphy.2018.06.020

Abstract

Soybean (Glycine max) infection by the charcoal rot (CR) ascomycete Macrophomina phaseolina is enhanced by the soybean cyst nematode (SCN) Heterodera glycines. We hypothesized that G. max genetic lines impairing infection by M. phaseolina would also limit H. glycines parasitism, leading to resistance. As a part of this M. phaseolina resistance process, the genetic line would express defense genes already proven to impair nematode parasitism. Using G. max_{[DT97-4290/PI 642055]}, exhibiting partial resistance to M. phaseolina, experiments show the genetic line also impairs H. glycines parasitism. Furthermore, comparative studies show G. max_{[DT97-4290/PI 642055]} exhibits induced expression of the effector triggered immunity (ETI) gene NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1 (NDR1/HIN1) that functions in defense to H. glycines as compared to the H. glycines and M. phaseolina susceptible line G. max_{[Williams 82/PI 518671]}. Other defense genes that are induced in G. max_{[DT97-4290/PI 642055]} include the pathogen associated molecular pattern (PAMP) triggered immunity (PTI) genes ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), NONEXPRESSOR OF PR1 (NPR1) and TGA2. These observations link G. max defense processes that impede H. glycines parasitism to also potentially function toward impairing M. phaseolina pathogenicity. Testing this hypothesis, G. max_{[Williams 82/PI 518671]} genetically engineered to experimentally induce GmNDR1-1, EDS1-2, NPR1-2 and TGA2-1 expression leads to impaired M. phaseolina pathogenicity. In contrast, G. max_{[DT97-4290/PI 642055]} engineered to experimentally suppress the expression of GmNDR1-1, EDS1-2, NPR1-2 and TGA2-1 by RNA interference (RNAi) enhances M. phaseolina pathogenicity. The results show components of PTI and ETI impair both nematode and M. phaseolina pathogenicity.

Keywords: Charcoal rot; ENHANCED DISEASE SUSCEPTIBILITY1; Effector triggered immunity; Fungus; Glycine max; Harpin; Heterodera glycines; Macrophomina phaseolina; NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1; NONEXPRESSOR OF PR1; Pathogen associated molecular pattern triggered immunity; Soybean; TGA2.

MeSH terms

Animals
Ascomycota*
Disease Resistance / genetics*
Gene Expression
Genes, Plant / genetics
Genes, Plant / physiology
Glycine max / genetics
Glycine max / immunology
Glycine max / microbiology*
Glycine max / parasitology
Nematoda
Plant Diseases / immunology
Plant Diseases / microbiology*
Plant Diseases / parasitology
Plant Roots / microbiology
Plant Stems / microbiology
Plants, Genetically Modified
Polymerase Chain Reaction