Improvement of Basmati rice varieties for resistance to blast and bacterial blight diseases using marker assisted backcross breeding

Abstract

Marker assisted backcross breeding was employed to incorporate the blast resistance genes, Pi2 and Pi54 and bacterial blight (BB) resistance genes xa13 and Xa21 into the genetic background of Pusa Basmati 1121 (PB1121) and Pusa Basmati 6. Foreground selection for target gene(s) was followed by arduous phenotypic and background selection which fast-tracked the recovery of recurrent parent genome (RPG) to an extent of 95.8% in one of the near-isogenic lines (NILs) namely, Pusa 1728-23-33-31-56, which also showed high degree of resemblance to recurrent parent, PB6 in phenotype. The phenotypic selection prior to background selection provided an additional opportunity for identifying the novel recombinants viz., Pusa 1884-9-12-14 and Pusa 1884-3-9-175, superior to parental lines in terms of early maturity, higher yield and improved quality parameters. There was no significant difference between the RPG recovery estimated based on SSR or SNP markers, however, the panel of SNPs markers was considered as the better choice for background selection as it provided better genome coverage and included SNPs in the genic regions. Multi-location evaluation of NILs depicted their stable and high mean performance in comparison to the respective recurrent parents. The Pi2+Pi54 carrying NILs were effective in combating a pan-India panel of Magnaporthe oryzae isolates with high level of field resistance in northern, eastern and southern parts of India. Alongside, the PB1121-NILs and PB6-NILs carrying BB resistance genes xa13+Xa21 were resistant against Xanthomonas oryzae pv. oryzae races of north-western, southern and eastern parts of the country. Three of NILs developed in this study, have been promoted to final stage of testing during the ​Kharif 2015 in the Indian National Basmati Trial.

Multi-Location Evaluation of Gene Pyramided Lines of Mtu 1010 and JGL 1798 against Bacterial Blight of Rice

“…Pyramiding multiple resistance genes for different biotic stresses provides in-built resistance to the popular and widely adopted cultivars and thereby reduces the yield loss due to biotic stresses. A number of research laboratories are carrying out gene pyramiding program by introgressing multiple BB resistance genes in popular rice varieties to provide in-built resistance against this disease (Sundaram et al, 2008;2009;Salgotra et al, 2012;Hajira et al, 2014;Ellur et al, 2016a;Ellur et al, 2016b). In this study, two broadspectrum BB resistance genes, Xa21 and xa13 were pyramided in two popular rice varieties, MTU 1010 and JGL 1798 to provide in-built BB resistance.…”

“…Basmati rice varieties Pusa Basmati 1121 and Pusa Basmati 6 were improved for blast and BB resistance by incorporating two BB resistance genes (xa13 and Xa21) and two blast resistance genes (Pi2 and Pi54) using marker assisted backcross breeding (Ellur et al, 2016a). Sundaram et al (2008) evaluated four 3-gene pyramided (xa5 + xa13 + Xa21) lines of Samba Mahsuri under AICRIP (All India Coordinated Rice Improvement Project) trials at different hot spot locations and reported a high degree of resistance of the gene pyramided lines indicating broad spectrum resistance conferred by combination of three BB resistance genes.…”

“…Some of the major BB resistance genes which have been widely used in gene-pyramiding programs in India are xa13 and Xa21 . Several studies in India have reported that combination of Xa21 and xa13 provides high level and broad spectrum resistance to Indian Xoo population (Joseph et al, 2004;Mishra et al, 2013;Mondal et al, 2014;Ellur et al, 2016a). Keeping in view the broad spectrum effectiveness of Xa21 and xa13 combination, these two BB resistance genes were selected for pyramiding in these two popular rice cultivars.…”

Markers Assisted Selection for Pyramiding of Gallmidge Resistance Genes in Kavya, a Popular Rice Variety

“…These multi-race or multi-biotype resistant genotypes proved to be more durable than any single-race or single-biotype resistance. Several researchers have reported the successful application of MAS in rice for targeted improvement of varieties and hybrid rice parental lines (Sundaram et al, 2009;Basavaraj et al, 2010;Rajpurohit et al, 2010;Hari et al, 2011;2013;Khanna et al, 2015;Ellur et al, 2015;Pradhan et al, 2015 andBhaskar et al, 2015).…”

Transgenic basmati rice transformed with the Xa21 gene shows resistance against bacterial leaf blight

“…These results indicated that Xa21 conferred resistance in some of the transgenic T 1 plant lines. Recently Ellur et al (2016) reported that basmati rice varieties (Pusa Basmati 1121 and Pusa Basmati 6) carrying two bacterial blight resistance genes, xa13 and Xa21, were resistant to Xoo races of northwestern, southern, and eastern parts of India. These studies indicate that Xa21 is one of the major genes conferring resistance against the BLB pathogen.…”