A combined transcriptional, biochemical and histopathological study unravels the complexity of Alternaria resistance and susceptibility in Brassica coenospecies

Fungal Biol. 2020 Jan;124(1):44-53. doi: 10.1016/j.funbio.2019.11.002. Epub 2019 Nov 14.

Abstract

Alternaria blight is one of the most devastating diseases of rapeseed-mustard caused by a necrotrophic fungus Alternaria brassicae. Lack of satisfactory resistance resource in Brassica is still a main obstruction for developing resistance against Alternaria. In this study, we have selected Brassica juncea, Sinapis alba and Camelina sativa to understand and unravel the mechanism of disease resistance against Alternaria. Histopathological studies showed early onset of necrosis in B. juncea (1 dpi) and delayed in S. alba (2 dpi) and C. sativa (3 dpi) respectively. Early and enhanced production of hydrogen peroxide (H2O2) was observed in C. sativa and S. alba (6 hpi) when compared to B. juncea (12 hpi). An increase in catalase activity was observed in both C. sativa (36 % at 6 hpi) and S. alba (15 % at 12 hpi), whereas it significantly decreased in B. juncea at 6 hpi (23 %), 12 hpi (30 %) and 24 hpi (8 %). Gene expression analysis showed induction of PR-3 and PR-12 genes only in C. sativa and S. alba when compared to B. juncea suggesting their vital role for Alternaria resistance. In contrast, SA marker genes were significantly expressed in B. juncea only which provides evidence of hormonal cross talk in B. juncea during Alternaria infection thereby increasing its susceptibility.

Keywords: Alternaria blight; Disease resistance; Histopathology; Necrotrophs; PR-proteins; ROS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternaria / pathogenicity*
  • Brassicaceae / genetics
  • Brassicaceae / metabolism
  • Brassicaceae / microbiology*
  • Catalase / metabolism
  • Disease Resistance
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Hydrogen Peroxide / metabolism
  • Mustard Plant / genetics
  • Mustard Plant / metabolism
  • Mustard Plant / microbiology*
  • Peroxidase / metabolism
  • Plant Diseases / microbiology*
  • Plant Leaves / microbiology
  • Plant Necrosis and Chlorosis
  • Plant Proteins / genetics
  • Sinapis / genetics
  • Sinapis / metabolism
  • Sinapis / microbiology*

Substances

  • Plant Proteins
  • Hydrogen Peroxide
  • Catalase
  • Peroxidase

Supplementary concepts

  • Alternaria brassicae