Molecular screening of rice (Oryza sativa L.) germplasm for Xa4, xa5 and Xa21 bacterial leaf blight (BLB) resistant genes using linked marker approach

Abstract

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) has now become one of major rice diseases. During recent years, its occurrence has increased in Pakistan, particularly in 'Kallar tract' which is well-known for quality rice cultivation. Development of new resistant varieties by utilizing the available resistant gene-pool is most reliable breeding technique for the plant breeders. The present study was conducted to explore the genetic resources regarding presence and absence of BLB resistance genes Xa4, xa5 and Xa21 through DNA marker technology. Effectiveness of Xa21 followed by xa5 and Xa7 genes has been reported to confer more resistance level for BLB in traditional rice belt of Pakistan. For this purpose, eighty (80) rice genotypes comprising of diverse origin including three isogenic lines viz., IRBB4 (carrying Xa4), IRBB5 (carrying xa5) and IRBB21 (carrying Xa21) as positive resistant gene checks and IR24 (carrying none of these) as negative gene check were genotyped. DNA fingerprinting results indicated the presence of Xa4 gene in 41 entries, while 14 lines were positive for xa5 gene. Only one local line was carrying Xa21 gene along with Xa4. Thus, the present study will not only be helpful for rice breeders to develop new rice varieties carrying disease resistant genes, but will also provide the donors to incorporate / pyramid disease resistant genes in popular rice varieties like Super Basmati and Basmati 515 which are susceptible to BLB disease.

Exploring of bacterial blight resistance in landraces, mining of resistant gene(s) and genetic divergence of resistant germplasm through molecular markers and quantitative traits

“…However, in our study, around 20.27% germplasm (15 out of 74) showed to have recessive xa5 gene. Similar to our finding, 34.29% germplasm were found to carry xa5 gene in India [14], 17.5% in Pakistan [53] and 29.62% in Nepal [16]. Alternatively, [15,17] Xoo [60].…”

“…However, Xa21 had been identified as an effective and durable R gene against Xoo strains in Bangladesh [21,66], India [67,68], Vietnam [69], as well as in Korea [70]. Despite of its high effectiveness, Xa21 appeared to be a rare gene in terms of presence in the germplasm [12,14,16,17,53]. In our study we found only one germplasm carrying Xa21 gene.…”

“…In the current study, we identified around 55.41% germplasm (41 out of 74) harboring Xa4 gene. Similarly, high presence rate of Xa4 gene among the germplasm were also reported by [12,15,52,53]. Subsequently, among the two recessive R genes ( xa5 and xa13 ) under the current query, xa5 was first identified by [48] and typically found in the Aus-Boro varieties of Bangladesh [11].…”

Quantitative Trait Locus Analysis of Microscopic Phenotypic Characteristic Data Obtained Using Optical Coherence Tomography Imaging of Rice Bacterial Leaf Blight Infection in the Field

“…The most effective method for BLB control currently reported is to cultivate resistant varieties. However, since the causative bacteria inducing BLB have a very fast appearance of races, it is essential to develop resistant varieties using new resistance genetic resources to match their speed [25,26]. Therefore, it is essential to analyze the characteristics of the rice BLB progenitor and to analyze the various phenotypic changes of the plant in response to the pathogen inoculation to explore the resistance gene [25].…”

Molecular profiling of bacterial blight resistance in Malaysian rice cultivars

“…However, this method is not durable for long term breeding programs (Suh et al, 2009). Rice cultivars containing multiple resistance genes have been shown to deliver durable resistance against bacterial blight (Muhammad et al, 2016;Pradhan et al, 2015, Rajpurohit et al, 2011.…”