Fine mapping of Bacterial Blight resistant gene from Oryza glaberrima Steud. and expression analysis of putative candidate genes in the region
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most
devastating disease of rice leading to huge yield losses in Southeast Asia. A bacterial blight
recessive gene xa-45(t) was identified from the O. glaberrima accession IRGC102600B and a
QTL was mapped to the rice chromosome 8. This QTL limits an 80 kb region on Nipponbare
reference genome IRGSP-1.0 harboring 9 candidate genes. Fine mapping of this region was
carried out using a RIL population developed from the cross of rice cultivar Pusa 44 and an
Introgression line IL274. The F6 and F7 RIL population were phenotypically evaluated by leaf
clipping method against Xoo pathotype-VII. The phenotypic assessment confirms 1:1
segregation ratio of the gene in the mapping population indicating single gene control of BB
resistance by xa-45(t). For narrowing down the 80 kb region, the sequencing of all the nine
candidate genes were performed using the two parents. The presence of 18 SNPs and Indels
were observed between the parents of which 7 were used for the marker’s development. The
analysis of the genotypic data confirms that among the 9 loci, the LOC_Os08g42410 could be
considered as the putative candidate for the bacterial blight resistance gene xa-45(t). Further,
relative expression analysis of the candidate genes at different time intervals of BB infection
showed over expression of LOC_Os08g42410 specific transcripts and thus strongly supports
its candidacy towards the bacterial blight gene xa-45(t).
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Babbar, Ankita (2021). Fine mapping of Bacterial Blight resistant gene from Oryza glaberrima Steud. and expression analysis of putative candidate genes in the region (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.