Incorporation of Bacterial Blight Resistance Genes Into Lowland Rice Cultivar Through Marker-Assisted Backcross Breeding

Abstract

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.

Development of Basmati rice genotypes with resistance to both bacterial blight and blast diseases using marker assisted restricted backcross breeding

“…Marker assisted breeding (MAB) has been adopted extensively in rice to introgress genes for resistance to BB both in India as well as abroad (Abenes et al 1993;Yoshimura et al 1995;Zhang et al 1996;Sanchez et al 2000;Singh et al 2001;Gopalakrishnan et al 2008;Basavaraj et al 2010;Singh et al 2013;Pradhan et al 2015). Xa21 and xa13 on chromosome number 11 and 8, respectively confers broad spectrum resistance to the BB due to their synergistic effect in combating BB pathogen (Lee et al 2009, Antony et al 2010Pradhan et al 2016), and therefore, is one of the most widely utilized gene combination for marker assisted introgression of BB resistance in rice.…”

Genetic mapping of physiological traits associated with terminal stage drought tolerance in rice

“…Also the phenotypic correlation analysis and genetic advance among the RILs were performed by INDOSTAT software [69]. Analysis for environmental variance, genotypic coefficient of variance, phenotypic coefficient of variance, heritability, and F values were computed following the previous publications [70][71][72].…”

Deployment of Genetic and Genomic Tools Toward Gaining a Better Understanding of Rice-Xanthomonasoryzae pv. oryzae Interactions for Development of Durable Bacterial Blight Resistant Rice

“…The probability of breakdown in cases of resistance conferred by two or more genes in a single genotype is much lower than that of a single gene controlling resistance (Mundt, 1990). For instance, R-genes in combination (Xa4/xa5 and xa5/Xa21) offer higher level of resistance compared to both parental level and single gene (Sattari et al, 2014;Pradhan et al, 2016). Huang et al (1997) developed four-gene pyramid lines comprising Xa4, xa5, xa13, and Xa21 genes in IR24 cultivar genetic background through MABC, and the gene-pyramid lines showed broad spectrum disease resistance.…”