Abstract
BackgroundJalmagna is a popular deepwater rice variety with farmers of India because of its good yield under waterlogged condition. However, the variety is highly susceptible to bacterial blight (BB) disease. The development of resistant cultivars has been the most effective and economical strategy to control the disease under deepwater situation. Three resistance genes (xa5 + xa13 + Xa21) were transferred from Swarna BB pyramid line, using a marker-assisted backcrossing (MAB) breeding strategy, into the BB-susceptible elite deepwater cultivar, Jalmagna.ResultsMolecular marker integrated backcross breeding program has been employed to transfer three major BB resistance genes (Xa21, xa13 and xa5) into Jalmagna variety. During backcross generations, markers closely linked to the three genes were used to select plants possessing these resistance genes and markers polymorphic between donor and recurrent parent were used to select plants that have maximum contribution from the recurrent parent genome. A selected BC3F1 plant was selfed to generate homozygous BC3F2 plants with different combinations of BB resistance genes. The three-gene pyramid and two gene pyramid lines exhibited high levels of resistance against the BB pathogen. Under conditions of BB infection, the three-gene pyramided lines exhibited a significant yield advantage over Jalmagna. The selected pyramided lines showed all agro-morphologic traits of Jalmagna without compromising the yield.ConclusionThe three major BB resistance genes pyramided lines exhibited high level of resistance and are expected to provide durable resistance under deep water situation where control through chemicals is less effective. High similarity in agro-morphologic traits and absence of antagonistic effects for yield and other characters were observed in the best pyramided lines.
Highlights
Jalmagna is a popular deepwater rice variety with farmers of India because of its good yield under waterlogged condition
Pyramiding of bacterial blight resistance genes The parent polymorphism was detected for the donor (CRMAS 2232–85) and recurrent parent (Jalmagna) with the markers pTA 248, RG 136 and xa5S, R for the genes Xa 21, xa13 and xa 5 respectively (Table 1)
Foreground selection was practiced from F1 generation till BC3F3 generation at each stage to select the plants having resistance alleles of the three target genes and only progenies having the resistance alleles were advanced for the generation (Figures 1, 2 and 3)
Summary
Jalmagna is a popular deepwater rice variety with farmers of India because of its good yield under waterlogged condition. Three resistance genes (xa5 + xa13 + Xa21) were transferred from Swarna BB pyramid line, using a marker-assisted backcrossing (MAB) breeding strategy, into the BB-susceptible elite deepwater cultivar, Jalmagna. To sustain self-sufficiency and to meet food grain requirement of future, India has to produce 135–140 million tones of rice by 2030. This has to necessarily meet from less land, less water, less labor and fewer chemicals, constant battle against new Pradhan et al Rice (2015) 8:19 of Asia, it can reduce crop yield by up to 50% (Khush et al 1989) or even up to 80% (Singh et al 1977). Few members of cluster II viz., SPJ53-21-77, SPJ53-21-25, SPJ53-21-52 and SPJ53-21-18 were very close to Jalmagna with 97, 95.33, 92.48 and 92.48% respectively
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