Abstract
Aim:
To screen wheat generations derived from cross HD2967 ? Kharchia65 for two Nax
loci imparting salt tolerance and background selection of the plants using
polymorphic SSRs.
Methodology: The study for salt tolerance was carried out on
three generations, i.e., BC1F3, BC2F2
and F4, derived from the cross HD2967 ? Kharchia65 in net house.
Salt stress was provided at germination stage and the plants were grown to
maturity. Data was recorded for various agro-morphological traits which
contributed to yield. DNA isolated from young leaves of morphologically
superior plants were checked for the presence of Nax1 and Nax2 genes
using gene specific primers. Plants having either or both Nax loci
were then subjected to polymorphic SSR markers screening for background
selection of foreground selected plants.
Results:
On the basis of agro-morphological performance and presence of either or both
Nax genes, 68 high yielding plants were selected. Out of total 178 SSR
markers screened covering the whole genome uniformly (A, B and D), 31 markers
were polymorphic for the parents HD2967 and Kharchia65. These polymorphic SSR
markers were used to produce molecular diversity among the selected progeny
plants. Cluster analysis of parents and all the three generations, showed
that all the selected plants were inclined towards recurrent parent.
Interpretation: This study showed that a linked marker
like Nax1 and Nax2 could be a promising tool for breeding wheat
with enhanced tolerance to salinity conditions. However, growth rates and
biomass production provide reliable criteria for assessing the degree of salt
stress and the ability of a plant to withstand it. Therefore, initial
screening of seeds in the presence of salt stress provides additional
advantage in directional selection. Plants selected with Nax loci,
better mean performances, high heritability, and high genetic advance as 5%
of mean for the studied traits could be further backcrossed with the
recurrent parent to develop salt tolerant wheat lines.
Key words: Na+
exclusion, Nax genes, Salinity, Wheat
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