INTROGRESSION OF ROOT AND WATER USE EFFICIENCY TRAITS BY MARKER ASSISTED BACKCROSS (MABC) STRATEGY IN RICE (Oryza sativa L.) AND VALIDATION OF PROGENY THROUGH PHYSIOLOGICAL CHARACTERIZATION
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Date
2016-10-11
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
With the rapidly decreasing water resources, devising water saving agronomic
practices rice cultivation is the most crucial need of the hour. Introgression of water
mining and water use efficiency (WUE) traits on to a single elite genetic background is
needed while developing aerobic worthy rice cultivars. In this investigation, a focused
marker assisted backcross breeding approach was adopted to introgress the root and
WUE traits into the elite genetic background of IR-64. In an earlier investigation, a panel
of germplasm was characterized for molecular and phenotypic diversity leading to the
discovery of trait donor genotypes (AC-39020 for roots and CLT, IET-16348 for WUE)
and DNA markers for the traits by Association Mapping. Of the 50 markers associated
with root and WUE traits, 16 markers found to be polymorphic and used as foreground
markers. A set of 120 polymorphic genome wide SSR markers were used for background
selection to reconstitute the recurrent parent genome. Three backcrosses were done and at
DCBC3F1 generation four plants with maximum foreground and background were
selected for further advancement by selfing. At DCBC3F2 generation a set of 1500 lines
were screened under aerobic field conditions and the best lines (250) were advanced to
DCBC3F3. These lines were extensively phenotyped for root, Δ13C and yield under
aerobic conditions and identified 26 promising trait introgressed lines with background
genome recovery of more than 95 percent and 30 per cent more yield than IR-64. These
lines when grown under well-watered and water limited condition maintained higher
growth and spikelet fertility compared to IR-64. This study significantly contributed for
the development of trait introgressed lines that can be used for commercial cultivation
and QTL-NILS that have great potential in academic understanding of QTL interactions.
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