Two Different Banana NPR1-Like Coding Sequences Confer Similar Protection Against Pathogens in Arabidopsis

Abstract

Differences between the coding sequences of two banana homologues of the Non-expressor of Pathogenesis-Related 1 (NPR1) genes (MNPR1A and MNPR1B) were investigated as a possible cause for the differential activity of the two genes. Each of the MNPR1 coding sequences were expressed under the control of the cauliflower mosaic virus 35S promoter/terminator sequences in the transgenic Arabidopsis npr1-2 mutant. These MNPR1-expressing plants were then exposed to either the biotrophic oomycete Hyaloperonospora arabidopsidis, the necrotrophic fungus Botrytis cinerea, or the hemi-biotrophic bacterial pathogen Pseudomonas syringae. Expression of either MNPR1A or MNPR1B increased 2 Pathogenesis-related 1 (PR-1) transcription in a similar manner in mutant plants and reduced pathogen growth, restoring resistance of the Arabidopsis npr1-2 mutant plants to pathogens.Sequence differences between MNPR1A and MNPR1B coding sequences did not affect MNPR1activity, suggesting a possible role for the involvement of other regulatory sequences in differential MNPR1 gene expression.

A post-gene silencing bioinformatics protocol for plant-defence gene validation and underlying process identification: case study of the Arabidopsis thaliana NPR1

“…2 a ). This is in agreement with previous results which showed a significant difference in spore numbers between the two phenotypes (data not shown) [ 32 ]. In a study of Wt and npr1 mutant plants by Cao et al [ 56 ], it was observed that infection spread event to uninfected parts of the leaf is quite rapid due to its high level of susceptibility.…”

“…Data analyzed in this study was derived from a study conducted at the John Innes Centre (England) in 2010 [ 32 ] and consisted of data from wild type (Wt) and npr1 mutant Arabidopsis thaliana Columbia (Col – 0) plants 48 hours post infection with Pst -DC3000 [ 34 ]. These plants were grown and inoculated under controlled greenhouse conditions (23 ° C, 10 h day/14 h dark regime and a relative humidity of 65±5 % ) in the John Innes Centre in England [ 32 ].…”

“…Data analyzed in this study was derived from a study conducted at the John Innes Centre (England) in 2010 [ 32 ] and consisted of data from wild type (Wt) and npr1 mutant Arabidopsis thaliana Columbia (Col – 0) plants 48 hours post infection with Pst -DC3000 [ 34 ]. These plants were grown and inoculated under controlled greenhouse conditions (23 ° C, 10 h day/14 h dark regime and a relative humidity of 65±5 % ) in the John Innes Centre in England [ 32 ]. Pst -DC3000 bacteria strain was cultured as described in [ 34 ] using King B’s media [ 20 gL −1 proteose peptone (w/v), 1.5 gL −1 di-potassium hydrogen phosphate (w/v), 1.5 gL −1 magnesium sulphate (w/v), 1.5 % glycerol (v/v) and 1.2 % bacterio agar (w/v)] supplemented with 50 mgL −1 kanamycin.…”

“…Bacteria growth was measured as spore counts 48 h post treatment using 8 mm leaf discs excised from the treated plants. Measurements were conducted using a FB12 luminometer with a single photon counter [ 32 , 34 ]. For adequate representation and statistics purposes, the experiment was conducted three times using a total of 60 plants (three infected leaves per plant) per genotype (see raw data in Additional file 1 ).…”

“…In this study, we used NPR1 (or SAI1 for salicylic acid-insensitivity or NIM1 for non-inducible immunity) as a reference due to the available experimental data and its central role in SAR signalling pathway, a broad-spectrum resistance protecting against several pathogenic attacks [ 23 ], which activates antimicrobial genes products in both the model plant Arabidopsis thaliana and a diverse number of food crops [ 4 , 24 – 32 ], including canola, cabbage, broccoli, tobacco, tomato, potato, corn. NPR1 is also involved in the regulation of signalling pathways like abscisic acid (ABA) [ 33 ], which, as JA- and Et-dependent activation of defense responses resulting from ISR [ 17 ], offers resistance to necrotrophic pathogens.…”