Ethylene Is Not Essential for R-Gene Mediated Resistance but Negatively Regulates Moderate Resistance to Some Aphids in .

Ethylene is important for plant responses to environmental factors. However, little is known about its role in aphid resistance. Several types of genetic resistance against multiple aphid species, including both moderate and strong resistance mediated by R genes, have been identified in . To investigate the potential role of ethylene, a ethylene- insensitive mutant, , was analysed. The mutant occurs in the accession A17 that has moderate resistance to , and . The mutant resulted in increased antibiosis-mediated resistance against and but had no effect on . When was introduced into a genetic background carrying resistance genes, ( resistance), ( resistance) and ( resistance), it had no effect on the strong aphid resistance mediated by these genes, suggesting that ethylene signaling is not essential for their function. Interestingly, for the moderate aphid resistant accession, the mutant delayed leaf senescence following aphid infestation and reduced the plant biomass losses caused by both and . These results suggest manipulation of the ethylene signaling pathway could provide aphid resistance and enhance plant tolerance against aphid feeding.