Insect-resistant plants with improved horticultural traits from interspecific potato hybrids grown in vitro

Abstract

Plants were regenerated from petiole calli of interspecific hybrids of Solanum tuberosum x S. berthaultii, an insect-resistant wild species. Callus culture was used to generate genetic changes to overcome the restricted recombination between the two genomes. Two plants out of 58 (3.5%) from calli of hybrid J114-1 showed stable and heritable differences from the hybrid over two cycles of evaluations in the field. Replicated trials were conducted in 1987 and 1988, using two populations of plants propagated by nodal cuttings from the original regenerates maintained in vitro. One regenerate showed insect resistance and increased marketable yield (approximately two fold) in the field. The other had higher levels of phenolic exudate in one of the two types of foliar trichomes associated with the insect resistance mechanism. Some desirable changes were discernible only in sexual progeny of regenerates, not in the regenerates themselves. In a backcross to S. tuberosum, 7 of 14 (50%) regenerates from hybrid F743-4 showed more progeny (up to 15-fold) with improved trichome traits and horticultural characteristics than the original hybrid. The variations were not associated with changes in ploidy. Fifteen plants obtained from these crosses are currently being incorporated into breeding lines. These results suggest that a period of callus culture followed by plant regeneration may aid in the introgression of desirable traits from wild species into crop plants.

Natural Genes and Mechanisms for Resistance to Viruses in Cultivated and Wild Potato Species (Solanum spp.)

“…S. berthauttii Hawkes, have two types of glandular hair on their leaves capable of repelling aphids with the alarm pheromones they produce or trapping insects (GIBSON and PiGKETT 1983). The trait is inherited in S. berthaultii in a monogenic dominant fashion (GIB-SON 1979) and it has been transferred to the 5. tuberosum gene pool (MEHLENBACHER et al 1983;LENTINI et al 1990, KALAZICH and PLALSTEI) 1991). Transmission of PLRV and PVY by aphids is reduced in the field and glasshouse, respectively, on S. berthauttii having the two types of glandular hair (GUNENC and GIBSON 1980).…”

Efficient, one step and cultivar independent shoot organogenesis of potato

“…Shoot organogenesis is an effective mode of in vitro regeneration, besides its utility for undertaking trait specific improvement programme. After the first report of shoot organogenesis from potato tuber discs (Lam 1975), many workers reported shoot organogenesis using different explants (Lentini et al 1990;Ooms et al 1987;Webb et al 1983;Yee et al 2001) and protoplasts (Haberlach et al 1985). However, most of the reported protocols are cultivar-specific (Al-Hussaini et al 2015;Mani et al 2014;Pal et al 2011) and there is a need to develop a plant regeneration protocol that is effective across the cultivars (Saker et al 2012;Wheeler et al 1985).…”

Genetic mapping and utilization of quantitative trichome-mediated insect resistance in potato

“…One involves selecting within a segregating population independently for tuber type and insect resistance and then crossing the two sets of selections. The second approach is a continuous backcrossing program using somaclones which have the rare ability to pass the 'type B' trichome traits to their backcross progeny (Lentini et al, 1990). This year we have two advanced clones with a high level of resistance to Colorado potato beetle (CPB) conferred by 'type A' trichomes from S. berthaultii, as well as virus immunity and cyst nematode resistance from other sources.…”