EMS Derived Mutant of Pisum Sativum Resistant to Nodulation

Abstract

A non-nodulated pea plant was obtained by screening M2 progeny from plants arising from EMS-treated seeds. The nodulation resistant character is stable, and has been maintained to the M8 generation. The parent cultivar ‘Sparkle’ and field pea cultivar ‘Trapper’ are well nodulated while the mutant is resistant to nodulation by 27 strains of Rhizobium leguminosarum tested, including 4 which nodulate the nod-resistant pea variety ‘Afghanistan’ (1,2). Occasionally 1–5 effective nodules are formed. Rhizobia isolated from these nodules are not infective when retested on the mutant. Segregation for nodulation in the F1 and F2 progeny of reciprocal crosses between the mutant and ‘Sparkle’ or ‘Trapper’ show that nodulation resistasnce is conditioned by a single pair of recessive alleles. This was confirmed by analysis of test crosses between F1 plants and the mutant line. Test crosses and F2 progeny of crosses between the mutant and ‘Afghanistan’ were scored for nodulation by R. leguminosarum strain TOM, which infects ‘Afghanistan,’ and by R. leguminosarum 128C53 which does not infect ‘Afghanistan.’ Segregation for nodulation indicates that there are at least two different loci controlling nodulation resistance in ‘Afghanistan’ (sym-2,sym-2) and the EMS derived mutant (sym-5,sym-5).