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Flagellin of Bacillus amyloliquefaciens works as a resistance inducer against groundnut bud necrosis virus in chilli (Capsicum annuum L.)
Groundnut bud necrosis virus (GBNV), a member of the genus Tospovirus , has an extensive host range and is associated with necrosis disease of chilli ( Capsicum annuum L.), which is a major threat to commercial production. Plant growth promoting rhizobacteria (PGPR) have been investigated for their...
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Published in: | Archives of virology 2020-07, Vol.165 (7), p.1585-1597 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Groundnut bud necrosis virus (GBNV), a member of the genus
Tospovirus
, has an extensive host range and is associated with necrosis disease of chilli (
Capsicum annuum
L.), which is a major threat to commercial production. Plant growth promoting rhizobacteria (PGPR) have been investigated for their antiviral activity in several crops and for their potential use in viral disease management. However, the microbial mechanisms associated with PGPR in triggered immunity against plant viruses have rarely been studied. To understand the innate immune responses activated by
Bacillus
spp. against GBNV, we studied microbe-associated molecular pattern (MAMP) triggered immunity (MTI) in chilli using transient expression of the flagellin gene of
Bacillus amyloliquefaciens
CRN9 from
Agrobacterium
clones, which also induced the expression of
EAS1
gene transcripts coding for epi-aristolochene synthase, which is responsible for the accumulation of capsidiol phytoalexin. In addition, the transcript levels of WRKY33 transcription factor and salicylic acid (SA)-responsive defense genes such as NPR1, PAL, PO and SAR8.2 were increased. Jasmonate (JA)-responsive genes,
viz
., PDF, and LOX genes, were also upregulated in chilli plants challenged with GBNV. Further analysis revealed significant induction of these genes in chilli plants treated with
B. amyloliquefaciens
CRN9 and benzothiadiazole (BTH). The transcript levels of defense response genes and pathogenesis-related proteins were significantly higher in plants treated with
Bacillus
and BTH and remained significantly higher at 72 h post-inoculation and compared to the inoculated control. The plants treated with flagellin using the agrodrench method and exogenous treatment with
B. amyloliquefaciens
and BTH showed resistance to GBNV upon mechanical inoculation and a reduced virus titre which was confirmed by qPCR assays. Thus, transient expression of flagellin, a MAMP molecule from
B. amyloliquefaciens
CRN9, is able to trigger innate immunity and restrain virus growth in chilli via induced systemic resistance (ISR) activated by both the SA and JA/ET signalling pathways. |
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ISSN: | 0304-8608 1432-8798 |
DOI: | 10.1007/s00705-020-04645-z |