SYM 18 - A NOVEL GENE CONDITIONING ALTERED STRAIN SPECIFICITY IN PISUM SATIVUM CV. SPARKLE

摘要

An induced mutant of pea Pisum sativum cv. 'Sparkle' forms few nodules with R. leguminosarum bv. viciea from temperate regions, exemplified by strain PRE, but nodulates normally with some rhizobia from Middle East soils, exemplified by strain TOM. The mutant gene is not an allele of sym2, found in the primitive cultivar 'Afghanistan'. Mutant line E54 has a specificity similar to 'Afghanistan' but forms more nodules with temperate strains, especially PF2 which nodulates 'Afghanistan' only poorly. The new phenotype is conditioned by gene sym18, which can act as recessive or semi-dominant depending on the rhizobial strain. Also sym18 is distinguished from sym 2 by its location on a different linkage group. Sym 18 was mapped 9cM from k on linkage group II.