SOMACLONAL VARIATION IN RESISTANCE OF PERENNIAL RYEGRASS TO CROWN RUST

Abstract

Resistance of perennial ryegrass plants regenerated from tissue culture (somaclones) to crown rust (Puccinia coronata) was assessed in growth cabinet/glasshouse experiments. Somaclones regenerated from callus cultures initiated from the vegetative tissue of three different somaclonal parent plants were tested for resistance to crown rust collected from Palmerston North and Linwln. Most plants tested were highty resistant and their leaves developed small pale yellow flecks but showed little or no sporulation. However, a few large pustules did develop on leaves of some of the somaclones. Screening experiments with rust cultures initiated from each of three single pustules showed that somaclones varied in their reaction to crown rust. Within each group of somadones derived from a particular parent some were more susceptible. and some more resistant, than the parental genotype. Two of the somaclones obtained from one of the parent plants had very fine leaves similar to those of turf perennial ryegrass plants. Somactoning may provide an efficient technique for plant breeders to improve the crown rust resistance of both pasture and turf perennial ryegrasses. Keyword% Puccinia coronata, Lolium perenne, somaclones. tissue cutture, plant breeding, plant diseases.