Abstract
Bacterial leaf blight (BLB) is one of the major rice diseases in Malaysia. This disease causes substantial yield loss as high as 70%. Development of rice varieties which inherited BLB resistant traits is a crucial approach to promote and sustain rice industry in Malaysia. Hence, this study aims were to enhance BLB disease resistant characters of high yielding commercial variety MR219 through backcross breeding approach with supporting tool of marker-assisted selection (MAS). Broad spectrum BLB resistance gene, Xa7 from donor parent IRBB7 were introgressed into the susceptible MR219 (recurrent parent) using two flanking markers ID7 and ID15. At BC3F4, we managed to generate 19 introgressed lines with homozygous Xa7 gene and showed resistant characteristics as donor parent when it was challenged with Xanthomonas oryzae pv. oryzae through artificial inoculation. Recurrent parent MR219 and control variety, MR263 were found to be severely infected by the disease. The improved lines exhibited similar morphological and yield performance characters as to the elite variety, MR219. Two lines, PB-2-107 and PB-2-34 were chosen to be potential lines because of their outstanding performances compared to parent, MR219. This study demonstrates a success story of MAS application in development of improved disease resistance lines of rice against BLB disease.
Highlights
Rice (Oryza sativa L.) is always known to be at the frontline to tackle world hunger, as it is the second most widely grown cereal crop in the world (Siwar et al, 2014)
Pathotype Xanthomonas oryzae pv. oryzae (Xoo) isolated from Malaysian Agricultural Research and Development Institute (MARDI) Seberang Perai were used in this pathogenicity screening on parental lines
Lesion length affected by bacterial leaf blight (BLB) has shown that the disease was slowly developed after 5 days of disease inoculation (DAI)
Summary
Rice (Oryza sativa L.) is always known to be at the frontline to tackle world hunger, as it is the second most widely grown cereal crop in the world (Siwar et al, 2014). MR219 is the major contributor to this number since >90% of Malaysia’s granary areas were planted with this popular variety due to its high yielding character with 8319 kg ha−1 heaviest yield has ever reported (Elixon et al, 2017; Shamsudin et al, 2016). This production size is openly threatening to 30-50% losses by means of bacterial leaf blight (BLB) disease infection (Shamsudin et al, 2019). The disease has become devastating to rice for ages since it was first discovered by a Japanese in 1884 (Tagami and Mizukami, 1962)
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