Development of cucumber lines resistant to Cucumber mosaic virus by ovule culture

One-hundred varieties of cucumber from different origins: China, India, Japan, Malaysia, Pakistan, Philippines, Thailand and the USA were screened for resistance to cucumber mosaic virus by mechanical inoculation. Twenty cucumber seedlings were planted in seed trays and kept under greenhouse conditions. Seedlings at the cotyledon stage were inoculated with virulent CMV subgroup I isolates collected from different cucumber plantations. Leaf samples were collected 4 weeks after inoculation and the DAS-ELISA was used for virus determination. The results revealed that the majority of the tested lines showed different symptoms ranging from severe to mild mosaic and some with no symptom which corresponded to the DASELISA reading. Forty two selected lines were used for further selfing and tested in the S1 generation. Five lines showing no symptom were used for double haploid plant production. Five lines of double haploid plants obtained from ovule culture were mechanically inoculated with CMV and evaluated for their level of CMV resistance by DAS-ELISA. The double haploid plants produced were highly resistant to the virus as was suggested by the first screening. All of resistant lines were selfed and seed was harvested.