Not AvailableOryza brachyantha, the African wild rice
which is resistant to yellow stem borer (YSB), was
exploited as a source for introgression of YSB
resistance trait into cultivated rice (O. sativa), through
development of monosomic alien addition lines
(MAALs). BC2F1 backcross hybrids (O. sativa cv
Savitri/O. brachyantha//O. sativa cv Savitri///
O. sativa cv Savitri) were produced employing
embryo rescue, with a crossability of 0.12 %. Hybrid
embryos that were collected at 10 and 12 days after
pollination showed highest percentage of survival in
culture with a germination percentage of 35.8 %.
Cytological analysis of pollen mother cells (PMCs) of
the BC2F1 hybrids revealed 15 hybrids with
2n ? 1(2n = 25) chromosome number that exhibited
typical trisomic chromosomal configurations. These
aneuploids were putatively designated as MAALs and
characterized morphologically and cytologically.
Based on their morphological similarity to primary
trisomics of the cultivated rice (O. sativa), 8 MAALs
viz., MAALs-4 (Sterile), 5 (Twisted leaf), 7 (Narrow
leaf), 8 (Rolled leaf), 9 (Stout), 10 (Short grain), 11
(Pseudonormal) and 12 (Tall) were isolated, each of
which exhibited several distinct morphological features.
Among the 505 PMCs analysed, 79.80 % had12II, 5.45 % had 11II and 1.78 % PMCs had 1III
configurations. The size of the extra chromosome was
found to be smaller than those of O. sativa chromosomes
and in 97.25 % of PMCs it remained unpaired
and at a distance from the rest of the chromosomes. Of
the 8 MAALs screened for YSB resistance, MAAL 11
was found to be moderately resistant. Undesirable
morphological traits of O. brachyantha were found to
be eliminated in the MAALs.Not Availabl