Tetrasomic inheritance pattern of the pentaploid Solanum chacoense (+) S. tuberosum somatic hybrid (resistant to bacterial wilt) revealed by SSR detected alleles

摘要

Protoplast fusion may be used to introgress desirable traits from wild species into cultivated potato which are cross incompatible. However, none of commercial varieties have been developed from hyper-tetraploid somatic hybrids because of the unpredictable heredity associated with irregular chromosome segregation during meiosis. A pentaploid somatic hybrid (SH) from Solanum chacoense + S. tuberosum, 3C28-1, which carries bacterial wilt (BW) resistance from the wild species, was employed in the present research. Gamete genotypes and inheritance pattern of SH 3C28-1 were estimated by counting the chromosome numbers and detecting the parent-specific SSR alleles in a backcross population of SH 3C28-1 x E-Potato 1 (variety) which is BW susceptible. The SSR alleles retained from S. chacoense were analyzed for association with BW resistance and evaluation of wild species genetic background. Our results implied that SH 3C28-1 could produce viable gametes of n = 2x = 24 + a where a aecurrency sign 6, which are compatible with a tetraploid pollen source to yield a high proportion of tetraploids and aneuploids with chromosome numbers between 48 and 54. Sixty-four of 83 SH 3C28-1-specific SSR alleles fit the tetrasomic or disomic/tetrasomic segregation ratio of a tetraploid, suggesting that the pentaploid mainly exhibits tetraploid inheritance pattern. Four (three positive and one negative) alleles were estimated to associate with BW resistance and backcross clones were selected for preserving less wild species genetic background and harboring the resistance. The present research elucidates the inheritance pattern of the pentaploid somatic hybrid to provide a theoretical and applied foundation for use of the pentaploid in potato breeding.