Marker-assisted elimination of necrosis gene (Ne1) present in wheat varieties HD2967 and HD2733

Abstract

Hybrid necrosis in wheat occurs because of two dominant complementary genes, Ne1 and Ne2, located on chromosomes 5BL and 2BS,
respectively. While transferring rust resistance genes in some Indian wheat varieties, hybrid necrosis was observed with HD2967 and
HD2733, while no necrosis was observed with HD2932 and HD3059. A marker-assisted backcrossing program was initiated to eliminate
the necrosis gene present in HD2967 and HD2733. Markers linked to Ne1 (Xbarc74) and Ne2 (Leq54_LrLC10 and Leq22_LrLC10) genes were
used in marker validation using a set of genotypes. The linked markers showed the presence of the Ne1 gene in wheat varieties HD2967,
HD2733 and positive check of Ne1, C306 and Ne2 gene in Parula as that of positive check Sonalika. The wheat varieties HD2932 and
HD3059 showed the absence of Ne1 and Ne2 genes as negative checks, Agra Local and NI5439. For marker-assisted elimination of Ne1
from HD2967 and HD2733 or substitution of dominant Ne1 allele with recessive ne1 allele, HD2932 was used as a donor parent. Near
isogenic Lines (NILs) of HD2967 (RPG = 96.80%) and HD2733 (RPG = 95.55%) were identified in BC2F3 generations. Plants homozygous
for recessive allele (ne1ne1) and dominant allele (Ne1Ne1) were crossed with Ne2 carrier Sonalika (Ne2Ne2) to test the effectiveness of
marker-assisted selection. While all the F1s of Ne1Ne1 died at the seedling stage, the F1s of ne1ne1 were viable and produced normal
seeds. The present study validated the available molecular markers of Ne1 and Ne2 and used these markers to develop NILs devoid
of necrosis gene Ne1. The superior genotypes (NILs) without any necrosis gene can be used freely in developing superior male sterile
(A) lines for hybrid breeding programmes or in the transfer of genes of economic importance without fear of getting hybrid necrosis.