Marker‐assisted introgression of bacterial blight and blast resistance into IR 58025B, an elite maintainer line of rice

Abstract

IR 58025A is a very popular wild-abortive cytoplasmic male sterile (WA-CMS) line of rice and is extensively used for hybrid rice breeding. However, IR 58025A and many hybrids derived from it possess mild aroma (undesirable in some parts of India) and are highly susceptible to bacterial blight (BB) and blast diseases. To improve IR 58025A for BB and blast resistance, we have introgressed a major dominant gene conferring resistance against BB (i.e. Xa21) and blast (i.e. Pi54) into IR 58025B, the maintainer line of IR 58025A. An introgression line of Samba Mahsuri (i.e. SM2154) possessing Xa21 and Pi54 genes in homozygous condition and fine-grain type was used as donor parent, and backcross breeding strategy was adopted for targeted introgression of the resistance genes. PCR-based molecular markers tightly linked to Xa21 and Pi54 were used for selection of BB-and blast-resistant lines, while closely linked markers were used for identification of backcross-derived plants devoid of Rf4 and aroma. At BC 2 F 5 , four backcross-derived lines possessing resistance against BB and blast, devoid of aroma, high yield, short plant stature, long-slender grain type and with recurrent parent genome recovery ranging from 88.8% to 98.6% were selected and advanced for further evaluation. The improved versions of IR 58025B, viz. behaved as perfect maintainers when testcrossed with WA-CMS lines. Agronomically superior lines of improved IR 58025B are being converted to CMS line through backcrossing for developing high-yielding and biotic stress-resistant rice hybrids.

Marker-assisted introgression of bacterial blight and blast resistance into DRR17B, an elite, fine-grain type maintainer line of rice

“…There are many successful Tetep -1 # A total of five plants from each of the backcross-derived lines, the donor and recurrent parents were screened for BB resistance under glass house conditions, and lesion length (cm) was calculated as an average of five leaves per plant * A total of twenty seedlings from each of the backcross-derived lines, the donor and recurrent parents were screened in the Uniform Blast Nursery (UBN), and disease score was calculated as per IRRI-SES (IRRI 1996) instances wherein marker-assisted backcross breeding has been deployed for targeted improvement of elite varieties and parental lines of rice hybrids. Markerassisted selection (MAS) has been successfully applied for improving resistance against biotic stresses like bacterial blight, blast and BPH in rice (Narayanan et al 2002;Joseph et al 2004;Sundaram et al 2008Sundaram et al , 2009Basavaraj et al 2010;Sreewongchai et al 2010;Hari et al 2011Hari et al , 2013Singh et al 2012;Zhan et al 2012;Khanna et al 2015). Breeders can easily transfer beneficial alleles into other genetic backgrounds, whenever DNA markers tightly linked to the resistance genes have been identified.…”

“…oryzae (Xoo) is one of the most important diseases of rice worldwide (Mew 1987) and causes yield loss ranging from 74 to 81 % (Srinivasan and Gnanamanickam 2005). Deployment of host plant resistance is the only effective strategy for management of the disease, and till date more than 38 BB resistance genes have been identified (Cheema et al 2008;Hari et al 2013). Some of the major resistance genes like Xa1, Xa4, xa5, Xa7, xa8, xa13, Xa21 and Xa27 have been tagged and mapped by closely linked molecular markers (Sonti 1998;Rao et al 2002;Sundaram et al 2014).…”

“…Xa21, Xa33 and Xa38). Availability of tightly linked molecular markers in rice has enabled markerassisted breeding (MAB) for bacterial blight resistance, a reality in India and abroad (Abenes et al 1993;Yoshimura et al 1995;Zhang et al 1996;Huang et al 1997;Sanchez et al 2000;Davierwala et al 2001;Singh et al 2001;Joseph et al 2004;Leung et al 2004;Perez et al 2008;Sundaram et al 2008Sundaram et al , 2009Basavaraj et al 2010;Hari et al 2011Hari et al , 2013. The major dominant BB resistance gene Xa21 was originally introgressed from the wild rice, Oryza longistaminata (Ronald et al 1992;Song et al 1995), which conferred broadspectrum of resistance against most of the virulent isolates existing in India.…”

“…Most importantly, a very closely linked PCR-based marker, pTA248 is available for marker-assisted selection of the gene (Ronald et al 1992). Many earlier studies have shown that through marker-assisted breeding, Xa21 can be successfully introgressed into elite rice varieties (Joseph et al 2004;Gopalakrishnan et al 2008;Sundaram et al 2008Sundaram et al , 2009Perumalsamy et al 2010;Pandey et al 2013) and into hybrid rice parental lines (Chen et al 2001;Liyong et al 2003;Basavaraj et al 2010;Hari et al 2011Hari et al , 2013.…”

“…The Pi54 blast resistance gene was mapped on chromosome 11L from the Vietnamese rice genotype, Tetep that conferred the resistance against predominant races of the pathogen in India (Sharma et al 2010). Tightly linked (Sharma et al 2005) and functional markers (Ramkumar et al 2010) are available for marker-assisted selection of the gene, and a few research groups in India have successfully introgressed Pi54 into varieties (Narayanan et al 2002;Joseph et al 2004;Sundaram et al 2008Sundaram et al , 2009 and parental lines (Basavaraj et al 2010;Singh et al 2011;Zhan et al 2012;Hari et al 2011Hari et al , 2013.…”