Mapping of genomic regions associated with dwarfing and determinate growth habit in horsegram (Macrotyloma uniflorum)”
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Date
2021-10-26
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Palampur
Abstract
Macrotyloma uniflorum is an important, self pollinated diploid (2n=2x=20) food
legume with probable genome size of 400Mbps. Limited genomic resources and lack of
genetic variation are major constrains in its genetic improvement. Further, horsegram
production is hampered due to twining growth habit, longer days to maturity, photosensitivity
and indeterminate growth habit. The present study was aimed to mining the new
microsatellite markers and construct linkage map of an intraspecific F8 RILs population of
157 individuals derived from HPKM249×HPK4 of horsegram and identification of genomic
regions linked to dwarfing and determinate growth habit related traits. 2395 molecular
markers were screened for parental polymorphism and 600 (25.05 %) were found to be
polymorphic among the parents. Of these, 287 were mapped on ten linkage groups at LOD
3.5 spanning 796.76 cM with an average marker density of 2.78 cM.
Analysis of variance of 157 RILs revealed significant differences for all the measured
traits. Phenotypic data from the RILs were used to identify QTLs for plant height and growth
habit related traits by composite interval mapping (CIM). A total of 4 QTLs (LOD ≥ 2.5)
were detected across the ten linkage groups for 4 traits. All these QTLs were major QTLs
with PVE greater than ten per cent.
In conclusion, it is envisaged that the present linkage map, fortified with 287 SSR
markers and 4 QTLs for dwarf plant height and determinate growth habit related traits would
provide genomics tools to breeders for further genetic enhancement of this crop species. Thus,
the current study will serve as a strong foundation for further validation and fine mapping of
QTLs for utilization in horsegram breeding programs.