3 research outputs found
Fine Mapping of Shoot Fly Resistance and Stay-Green QTLS on Sorghum Chromosome SBI-10
Sorghum [Sorghum bicolor (L.) Moench, 2n = 2x = 20] is the fifth most
important cereal crop globally, and is grown primarily in arid and semi-arid
conditions. Major biotic and abiotic constraints hampering sorghum production
include shoot fly infestation during early stages of crop development (seedling
establishment and early growth stages; but only present in the eastern
hemisphere) and terminal drought stress during post-flowering growth stages.
These two stresses can devastate the crop. Hence developing sorghum varieties
with resistance for these two stresses is critical. In order to understand the
genetic basis of sensitivity to these two stresses and to genetically dissect host
plant resistance to shoot fly and tolerance to terminal drought stress, the
following objectives were proposed for the present study:
to develop an introgression-line cross-based fine-mapping population for
morphological components of shoot fly resistance and for the stay-green
mechanism of terminal drought tolerance previously mapped to sorghum
chromosome SBI-10L;
to fine-map the target traits by combining genotyping and phenotyping
datasets of a selected recombinant sub-set of the fine-mapping population;
to annotate functionally and characterize candidate genes identified in the
target region; and
to identify recombinant progenies with pyramided traits of interest
Fine mapping of stay-green QTLs on sorghum chromosome SBI-10L ‒ An approach from genome to phenome
Sorghum is the fifth most important C4 cereal crop grown
globally in arid and semi-arid climatic conditions. Drought is
the major cause for loss of productivity worldwide. Delayed
senescence of plants leads to adaptation to drought stress
conditions by staying-green and giving high yields. In order
to identify and dissect the stay-green genomic regions we
have developed a high resolution fine mapping population
from introgression line cross RSG04008-6 (stay-green) ×
J2614-11 (shoot fly resistant). Nearly 1894 F2 genotypes were
screened with 8 SSR in order to identify double recombinants
for both the parents in the sorghum chromosome-10 long arm
(SBI-10L). The selected F2:4 recombinants were GBSed to increase
the marker density between flanking markers Xgap001-
Xtxp141 for stay-green QTLs on SBI-10L and a high resolution
linkage map was developed using GBS SNPs. Out of 182 only
152 recombinants were replicated thrice in field for staygreen
screening for two seasons (Summer 2013 and 2014).
Fine mapping of the per cent Green Leaf Area (%GLA) traits
identified 33 QTLs and 19QTLs were clustered into 7groups
where 8 genes were identified. These were AP2/ERF transcription
factor family (Sb10g025053), Ankyrin-repeat protein
(Sb10g025310), WD40 repeat protein (Sb10g025320), NBSLRR
Protein (Sb10g025283), Calcium dependant protein kinase
(Sb10g030150), LEA2 protein (Sb10g029570), a putative
uncharacterized protein (Sb10g024920) and senescence associated
protein (Sb10g030520). With this study SBI-10L staygreen
genomic regions were delimited from 15Mb to 8 genes
co-localized with GWAS MTAs. Further cloning and expression
level studies of the identified candidate genes will improve the
development of drought tolerant genotypes