Abstract:
Objective A mutant rice showing signs of early senescence on leaves and susceptibility to rice blast and blight was used for phenotypic and genetic analyses to study the genes associated with the aging mechanism and vulnerability to the diseases of rice plants.
Method Resistance to blast and bacterial blight of the mutant rice w14 with symptoms of early senescence was tested by artificial inoculation. Phenotype classification of the mutant was determined by chlorophyll content measured in vitro under induced darkness. Expressions of the genes related to senescence and pathogenesis in the mutant and wild-type japonica rice variety, Yunyin (YY), were compared.
Result After inducing darkness for 24h, the chlorophyll content in w14 was 5% lower than that in YY, and the difference reached a 1% statistical significance level in 48 h. The expressions of senescence-related genes SGR, Osh36, Osh69, PAO, NYC3, and RCCR1 in w14 were significantly higher than those in the wild-type counterpart. The mutant rice was more susceptible to the artificial inoculations of rice blast and bacterial blight, and the pathogenesis-related genes PR1a, PR4, Cth1, PR1b, PBZ1, and PR3 significantly up-regulated in w14 than in YY.
Conclusion The mutant rice w14 showed the typical senescence phenotypes with a higher susceptibility to rice blast and bacterial blight than the wild-type YY. The expressions of pathogenesis-related genes in the mutants were significantly altered that substantially affected its defense system leading to the early senescence and disease susceptibility as observed in the study.
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