Intraspecific somatic and sexual hybridisation between dihaploid lines of Solanum tuberosum L.: evaluation of morphological traits and resistance to late blight Phytophthora infestans (Mont.) de Bary in the foliage

Abstract

Intraspecific tetraploid somatic and sexual hybrid plants have been resynthesised following protoplast fusion and by sexual crosses between two dihaploid potato (Solanum tuberosum) lines each possessing complementary agronomic traits . The dihaploid PDH 40 possesses good tuber shape and yield but has foliage susceptibility to late blight (Phytophthora infestans) . On the other hand, the dihaploid PDH 727 possesses resistance to blight in the foliage but has a low yield of small and irregular shaped tubers . Since it was only possible to use a partial selection strategy based on culture media to facilitate recovery of somatic hybrid plants -further morphological and esterase isozyme based characterisations were performed to identify somatic hybrid plants from amongst the non-hybrid plant material . When the blight resistance of both the intraspecific somatic and sexual hybrid plants was assessed there was no significant difference in the mean resistance value and it was intermediate between those of their parents . However, the range of resistance was much wider among the sexual hybrids than among the plants derived from somatic fusion . An assessment of tuber yield between tetraploid sexual and somatic hybrids showed no significant difference and it was higher than that of either parent value . The implication of these results in the context of potato genetics and breeding is discussed .

Interspecific potato somatic hybrids between Solanum berthaultii and Solanum tuberosum L. showed recombinant plastome and improved tolerance to salinity

“…It has the potential for self-generating biodiversity in the numerous nuclear and cytoplasmic genome combinations along with possible recombination events between parental ones can occur (Kumar and Cocking 1987). Some somatic hybrids can express various traits, including disease resistance against viruses (Thach et al 1993;Pehu et al 1990), bacteria (Austin et al 1988), fungi (Cooper-Bland et al 1996;Mattheij et al 1992) or insect pests (Austin et al 1993;Cooper-Bland et al 1994).…”

Tetraploid somatic hybrids of potato (Solanum tuberosum L.) obtained from diploid breeding lines

“…They also studied the fusion combining ability of dihaploid lines and its relationship to the type of cytoplasm [8] and the different cytoplasmic configurations present in somatic hybrids [9]. Somatic and sexual tetraploid hybrids obtained from two diploid lines were characterised by Cooper-Bland et al [10], who found that late blight resistance in the hybrids was intermediate, while the tuber yield indicated hybrid vigour. Rasmussen et al [4] found the foliage and tuber late blight resistance of hybrids derived from four different fusion combinations to be inherited independently, and the individual hybrids to vary from highly resistant to sensitive.…”