Synthesis and Characterization of an Autoallopolyploid Between Allotetraploid and Autotetraploid in Cucumis

Autotetraploid cucumber (CCCC, 2n=28) originated from unpollinated ovary culture along with chromosome doubling by colchicines treatment, while allotetraploid cucumber (HHCC, 2n=38) was created from an interspecific embryo rescue (C. sativus L. × C. hystrix Chakr.) and followed by somaclonal variation. An autoallopolyploid (CCCH) was derived from a cross between autotetraploid (female parent) and allotetraploid (male parent). Morphological, molecular and cytological tests were conducted to identify this new hybrid. The new synthetic plant showed morphological characteristics, such as leaf shape and color, flower size and color, fruit shape, was different from both parents. Simple sequence repeat analysis showed that the unique DNA bands from the wild cucumber C. hystrix could be detected in the autoallopolyploid. Genomic and fluorescent in situ hybridization investigation were also performed on the chromosomes. The result confirmed clearly that the autoallopolyploid has 33 chromosomes including 21 chromosomes of cucumber (CC) and 12 of C. hystrix (HH). This autoallopolyploid could be a new resource as bridge material to transfer alien elite traits for the improvement of cucumber cultivar.