Development of Bottle Gourd Lines Resistant to Zucchini Yellow Mosaic Virus Using Ethyl Methanesulfonate Mutagenesis

Zucchini yellow mosaic virus (ZYMV) causes serious damage to cucurbit crops worldwide and can be spread by aphids, by mechanical injury, and in seeds. With the popularization of cucurbit grafting, the use of susceptible rootstock has increased the risk of ZYMV infection in cucurbit crops. In China, the bottle gourd (Lagenaria siceraria) is a widely used rootstock in grafted watermelon production. However, few resistant bottle gourds are available commercially. This study developed bottle gourd lines resistant to ZYMV using ethyl methanesulfonate (EMS) mutagenesis. A new mutated bottle gourd population (M-1) was generated by treating seeds with EMS. Diverse phenotypes were observed in the seedlings, flowers, and fruit of M-2 plants, some of which are of potential commercial interest, such as dwarfing and different fruit shapes. Based on the M-2 phenotypes, 106 M-3 lines were selected and screened for resistance to ZYMV by mechanical inoculation and agroinfiltration. Nine M-3 lines were resistant to ZYMV during three tests. One inbred M-4 line (177-8) was developed and showed stable resistance and no virus when tested using a doubleantibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and polymerase chain reaction. These resistant lines are promising materials for developing watermelon rootstock and exploring resistance genes as new ZYMV-resistant resources. EMS induction could be a practical strategy for creating resistant cucurbit crops.