Indian Society of Genetics & Plant Breeding

Mapping of bacterial blight resistance gene xa8 in rice (Oryza sativa L.)

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Bacterial blight (BB) of rice, caused by Xanthomonas
oryzae pv. oryzae (Xoo), is one of the major diseases
causing yield losses in rice worldwide. Development and
deployment of resistant rice cultivars and pyramiding two
or more resistance genes into elite varieties is the only
strategy available to combat the disease. The BB
resistance gene, xa8 conferred complete resistance to only
one pathotype and partial resistance against two
pathotypes at seedling stage while complete resistance
against five of the seven pathotypes prevalent in Punjab
at adult plant stage.The gene was earlier mapped on rice
chromosome 7 at 19.9 cM genetic distance from SSR
marker, RM214 using a recombinant inbred line (RIL)
population generated from the cross between PR106 and
IRBB8. However, due to the paucity of markers in that
region, the gap could not be narrowed.With the availability
of new SSR markers in that region, the gene was placed
between two consecutive SSR markers, RM21044 and
RM21045 at 7.0 and 9.9 cM respectively. Analysis of the
9.5 kb DNA sequence harboring the xa8 gene revealed
the presence of three intact genes, which codes for
putative expressed proteins viz., Zinc finger A20 and AN1
domain-containing protein (LOC_Os07g07400),
Oxidoreductase, 2OG-Fe oxygenase family protein
(LOC_Os07g07410) and Gibberellin 20 oxidase 1-B protein
(LOC_Os07g07420). All the three genes are involved in
plant response to various stresses and could be the
possible candidate genes for xa8.

Keywords: Bacterial blight, rice, SSR markers, xa8, candidate genes


Year: 2014
Volume: 74
Issue: Supplementry Issue
Article DOI: 10.5958/0975-6906.2014.00895.5
Print ISSN: 0019-5200
Online ISSN: 0975-6906


J. S. Lore info_circle
Kuldeep Singh info_circle

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