SCREENING FOR ROOT-KNOT NEMATODE RESPONSE IN SOMACLONAL VARIANTS OF SOLANUM QUITOENSE LAM.

Abstract

Solanum quitoense, a perennial herbaceous plant native to the tropical regions of Ecuador and Colombia, is susceptible to root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood. The objectives of this study were to develop protocols for screening regenerants of S. quitoense for response to root-knot nematode. Internodal stem segments cultured on MS medium supplemented with BA (4.4 to 44 µ M) were the most regenerative explants. Growth regulators were not required to proliferate, root and reestablish S. quitoense. Sterile cultures of M.incognita were initiated and maintained on S. quitoense root cultures. Root-knot nematode response for the regenerants was evaluated by screening greenhouse- and in vitro-rooted microcuttings. Screening in the greenhouse of 248 regenerants of S. quitoense 'Dulce' inoculated with 1,000 eggs of M. incognita resulted in 21 regenerants having five or fewer galls. Further screening of these 21 regenerants in the greenhouse determined that nine had greater fresh weights and one regenerant produced more eggs per plant when compared to the susceptible control. Reproductive factor (Rf) values and Host Resistance Classification (HRC) percentages suggest that five regenerants had reduced nematode reproduction.