GENOTYPE-BASED VARIATION IN INDUCED SYSTEMIC RESISTANCE ACTIVATED BY THE VOLATILE ORGANIC COMPOUND, (2R,3R)-BUTANEDIOL, IN AGROSTIS SPECIES

摘要

Cultivars of Agrostis stolonifera L.and A.capillaris L.were screened for their level of responsiveness to the induced systemic resistance (ISR) activator,2R,3R-butanediol (BD),by measuring the reduction in disease symptoms caused by the fungal pathogen Waitea circinata Warcup & Talbot var.circinata compared to a water control.Induced resistance in cultivars 'SR7100' and 'SRP1GMC',as measured by reduced yellowing and mycelial coverage,was strongly responsive to BD.In contrast induced resistance of cultivars 'Penn A4' and 'Providence' was weakly responsive,and BD treatment even led to increased yellowing and mycelial coverage.Following BD treatment,expression of the ISR marker genes,AsGNS-5,AsOPR-4 and AsAOS-1,was determined by RT-PCR before inoculation to measure gene induction,and after inoculation to measure gene priming.Expression of both AsOPR-4 and AsAOS-1 was induced by BD only in 'SR7100',and expression of AsGNS-5 was induced only in 'SRP1GMC'.The two weakly responsive cultivars did not show significant induction of the marker genes.None of the genes showed significant priming of expression in the tested cultivars,and the two weakly responsive cultivars showed significant suppression of marker gene expression after inoculation.Variation among cultivars in their responsiveness to ISR activation by BD clearly indicates that this is a trait that could be used in plant breeding programs,and future work is needed to determine if the induced expression segregates with strong BD responsiveness.