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Down Regulation of Putative Defence‐associated Transcripts Correlates with Ripe Rot Symptoms on Kiwifruit ( Actinidia chinensis )
Author(s) -
Wurms Kirstin,
Cui Wei,
AhChee Annette,
ReesGeorge Jonathan,
Bublin Merima,
Breiteneder Heimo
Publication year - 2011
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.2011.01786.x
Subject(s) - biology , chitinase , actinidia chinensis , postharvest , actinidia , gene , inoculation , gene expression , horticulture , plant disease resistance , thaumatin , pathogenesis related protein , actinidia deliciosa , lasiodiplodia theobromae , botany , microbiology and biotechnology , genetics
A real‐time quantitative reverse‐transcriptase polymerase chain reaction (qRT‐PCR) was employed to investigate the transcriptional levels of putative defence genes expressed during postharvest storage of Actinidia chinensis ‘Hort16A’ kiwifruit. Significant decreases (80% reduction) in normalized gene expression over time relative to the basal levels of gene expression at harvest in control fruit were observed for thaumatin‐like protein (TLP), class IV acidic chitinase, chalcone‐flavonone isomerase (CHI) and glucan endo‐1,3‐beta‐glucosidase (β‐1,3‐glucosidase). Reduction in transcript abundance for these genes paralleled the significant increase in postharvest ripe rot disease incidence over time (P = 0.0008). Gene expression levels were approximately the same in control vs. inoculated fruit for all the four genes described above, except for β‐1,3‐glucosidase where expression was significantly greater (P = 0.007) in inoculated than in control fruit. For one of the genes of interest that we had studied by qRT‐PCR, TLP, a small amount of protein was purified and assayed in vitro for activity against Cryptosporiopsis actinidiae and Phomopsis spp., the causal agents of ripe rots of ‘Hort16A’ kiwifruit. TLP from kiwifruit did not appear to be directly toxic to either pathogen . TLP does not prevent ripe rots, but it may be useful as a marker of resistance given the temporal correlation between decreased TLP and increased ripe rots that was demonstrated by qRT‐PCR.