Abstract
Rice (2n=24) is the main agronomic crop in South Asian countries. Development of
new rice line with special characteristics is a challenge at this present era. Anther
culture techniques allow chromosome doubling of the haploid plants within a shorter
period which may provide homozygosity for specific locus. Conventional breeding
technique requires several seasons to develop a rice line where doubled haploid
plants can be obtained within one generation. On the other hand, marker assisted
selection has moved forward to pyramiding multiple yield QTLs (qDTYs) against
drought along with biotic and abiotic stress tolerance genes to combat adverse effects
caused due to drought. The current study was conducted in Zeigler experimental
station of International Rice Research Institute in the dry seasons (December-May)
and wet seasons (June-November) of 2017, 2018 and 2019. The complex cross was
implemented having QTLs and genes of different abiotic (drought grain yield QTLs:
qDTY1.1, qDTY2.1, qDTY3.1, qDTY12.1, submergence: Sub1) and biotic (bacterial blight:
xa5, xa13, Xa21, Blast: Pi9, Pita, Pita2, gall midge: GM4, brown plant hopper: BPHЗ,
BPH17) with an aim to develop fixed line harboring the QTLs. Anther culture was
induced from different panicles of the complex cross. The cross was also allowed to
self for subsequent generations. Marker assisted selection of lines were performed
across seasons to identify the lines with the QTLs/genes mentioned above. Anther
culture is reported to be potential in the indica lines as well like the japonica showing a
good anther culturability in the study. Cold and dark treatment was induced to the
rice panicles to develop DH lines. IR 126952:656-AC 21-1, IR 126952:656-AC 7-1, IR
126952:656-AC 1-1, IR 126953:324-AC 60 is the best anther culture derived doubled
haploid lines in the study. A total of 41 promising pyramided lines were developed
through MAS under the study. Comparing lines developed from anther culture and
MAS, lines containing qDTY21+qDTY3.1+Pita2+Xa4, qDTY1.1+qDTY31+Pita2+Xa4 and
qDTY1.1+ BPH3+Xa4+xa5+Pita2 combination of doubled haploid lines along with
qDTY3.1 +Sub1+ GM4 + Pita2 + xa13 and qDTY3.1 + Sub1 + GM4 + Pita2 + xa5 + xa13
combinations of MAS lines showed consistent high yield over non-stress and drought
conditions. Seven pairs of promising lines with differential yield (high yielding/low
yielding) of same QTL combinations were evaluated across different seasons and
differential stress conditions with successive generation advancement to know the
interaction of QTLs. The QTL-QTL, QTLs-background and background-background
interactions on same/different rice chromosomes affected the grain yield of low
yielding lines under lowland moderate to stress conditions in the three genetic
backgrounds (Samba Mahsuri, IR64-Sub1 and MR219). The promising lines developed
from the study could be evaluated in the targeted drought prone environments of
Bangladesh and could be incorporated in the varietal release pipeline to develop as a
promising climate resilient drought tolerant rice variety.