Bacterial leaf blight (BLB) caused by
Xanthomonas oryzae
pv. oryzae (
Xoo) is highly
destructive to high-yielding susceptible rice cultivars. In severe epidemics, yield losses
up to 75% have been reported. Considerable information on BLB resistant genes is
available; however, genetic overlaps between BLB resistant and yield related traits
largely remain unclear. Using two sets of backcross introgression inbred lines and one
set of recombinant inbred lines, genetic associations between bacterial leaf blight
resistance and yield component traits in three
Xoo races were analyzed using Single
Nucleotide polymorphism (SNP) markers. Fifteen quantitative trait loci conferring BLB
resistant and 112 QTLs for yield and yield related traits were detected. Among 15 QTLs
conferring bacteria leaf blight resistance, 14 QTLs overlapped with 39 QTLs for yield
and yield related traits. The total resistance variation explained by additive QTLs (R
2)
ranged between 5-76% and epistasis QTLs ranged between 1-26%. Quantitative trait loci
(QTLs) with the highest additive effects for BLB resistance were detected at positions
os04-17305294 (on chr.4), os05-07310209 (on chr.5), os09-15240130 (on chr.9), os11-28421947 (on chr.11) and os12-25291547(on chr.12). The BLB resistance QTL at
position os05-07310209 (on chr.5) overlapped with QTLs for 1000-grain weight, grain
number per panicle, days to heading, grain length width ratio and grain yield per plant.
The BLB resistance QTL at position os09-15240130 (on chr.9) overlapped with QTLs
for grain yield per plant, panicle number, grain width and 1000-grain weight. The BLB
resistance QTL at position os12-25291547-(on chr.12) overlapped with QTLs for 1000-grain weight, panicle number, grain yield per plant, filled grain number and grain width.
Eleven percent of the 717 plants in this study were resistant to at least two
Xoo races and
had higher grain yield compared to both recurrent parents. Overlapping regions
especially with already cloned genes and epistasis detected in this study offer opportunity
to develop rice varieties which combine high yield and resistance to bacteria leaf blight.
