GROWTH, DEVELOPMENT, AND RESPONSE OF PEACH SOMACLONES TO THE ROOT-KNOT NEMATODE, MELOIDOGYNE-INCOGNITA

Somaclonal variation has been reported in many plant species, and seve ral phenotypic and genetic changes, including pathogen and pest resist ance, have been described. This study was designed to evaluate somaclo nal variation in peach [Prunus persica (L.) Batsch] regenerants in res ponse to the root-knot nematode, Meloidogyne incognita (Kofoid & White ) Chitwood, Regenerants SH-156-1, SH-156-7, SH-156-11, and SH-156-12, derived from 'Sunhigh' (susceptible) embryo no. 156, and regenerants R H-30-1, RH-30-2, RH-30-4, RH-30-6, RH-30-7, and RH-30-8, derived from 'Redhaven' (moderately resistant) embryo no, 30, were screened in vitr o for resistance to the root-knot nematode, Under in vitro conditions, fewest nematodes developed on regenerants SH-156-1 and SH-156-11, 'Re dhaven', and all 'Redhaven' embryo no. 30 regenerants. The most nemato des developed on 'Sunhigh','Sunhigh' seedlings (SHS), and regenerant S H-156-7. Nematodes did not develop on 'Nemaguard', In greenhouse tests , fewer nematodes developed and reproduced on the no, 156-series regen erants than on 'Sunhigh', Under in vitro conditions, significant diffe rences among uninfected (control) regenerants, cultivars, and rootstoc k 'Nemaguard' were observed for shoot height and fresh root weights, S ignificant differences were also observed among infected regenerants, cultivars, and 'Nemaguard' for these characteristics, but differences were not observed between control and infected regenerants, Different concentrations of alpha-naphthaleneacetic acid in half-strength Murash ige and Skoog salt medium induced rooting of two peach cultivars, one rootstock, and four regenerants.