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Moniliophthora perniciosa , the causal agent of witches’ broom disease of cacao, interferes with cytokinin metabolism during infection of Micro‐Tom tomato and promotes symptom development
Author(s) -
Costa Juliana L.,
Paschoal Daniele,
Silva Eder M.,
Silva Jamille S.,
Carmo Rafael M.,
Carrera Esther,
LópezDíaz Isabel,
Rossi Mônica L.,
Freschi Luciano,
Mieczkowski Piotr,
Peres Lazaro E. P.,
Teixeira Paulo J. P. L.,
Figueira Antonio
Publication year - 2021
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.17386
Subject(s) - biology , cytokinin , nicotiana benthamiana , broom , shoot , botany , gene , genetics , auxin , ecology
SummaryMoniliophthora perniciosa causes witches’ broom disease of cacao and inflicts symptoms suggestive of hormonal imbalance. We investigated whether infection of the tomato ( Solanum lycopersicum ) model system Micro‐Tom (MT) by the Solanaceae (S)‐biotype of Moniliophthora perniciosa , which causes stem swelling and hypertrophic growth of axillary shoots, results from changes in host cytokinin metabolism. Inoculation of an MT‐transgenic line that overexpresses the Arabidopsis CYTOKININ OXIDASE‐ 2 gene ( 35S::AtCKX2 ) resulted in a reduction in disease incidence and stem diameter. RNA‐sequencing analysis of infected MT and 35S::AtCKX2 revealed the activation of cytokinin‐responsive marker genes when symptoms were conspicuous. The expression of an Moniliophthora perniciosa tRNA‐ISOPENTENYL‐TRANSFERASE suggests the production of isopentenyladenine (iP), detected in mycelia grown in vitro . Inoculated MT stems showed higher levels of dihydrozeatin and trans ‐zeatin but not iP. The application of benzyladenine induced symptoms similar to infection, whereas applying the cytokinin receptor inhibitors LGR‐991 and PI55 decreased symptoms. Moniliophthora perniciosa produces iP that might contribute to cytokinin synthesis by the host, which results in vascular and cortex enlargement, axillary shoot outgrowth, reduction in root biomass and an increase in fruit locule number. This strategy may be associated with the manipulation of sink establishment to favour infection by the fungus.