Suk-Man Kim, Jung-Pil Suh, Yang Qin, Tae-Hwan Noh, Russell F. Reinke, Kshirod K. Jena

Theoretical and Applied Genetics; October 2015, Volume 128, Issue 10, pp 1933-1943

http://link.springer.com/article/10.1007/s00122-015-2557-2

Key message

A new bacterial blight resistance gene has been identified through fine-mapping, which confers high levels of resistance to all Korean Xanthomonas oryzae pv. oryzae ( Xoo ) races, including the new Xoo race K3a.

Abstract

Rice bacterial leaf blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is a serious constraint to rice production in Asia and Africa. The japonica advanced backcross breeding lines derived from the indica line IR65482-7-216-1-2 in the background of cultivar Junam are resistant to all Korean BB races, including K3a. To identify the gene(s) involved in resistance to Korean Xoo races, the association of genotypic and phenotypic variations was examined in two F₂ populations derived from the crosses between 11325 (IR83261-3-7-23-6-2-1-1-2-1-2)/Anmi and 11325/Ilpum. The segregation ratios of F₂ individuals from the crosses of 11325/Anmi and 11325/Ilpum were 578 resistant:209 susceptible and 555 resistant:241 susceptible, respectively, which is consistent with the expected allelic frequency of a 3:1 ratio. Genetic analysis using graphical mapping indicated that resistance (R) was controlled by a new resistance gene linked with the flanking markers RM27320 and ID55.WA18-5 within an approximately 80-kb region between 28.14 and 28.22 Mbp on chromosome 11. The eight candidate genes functionally predicted were included in the target region. Examination of the candidate genes by RT-PCR analysis only corroborated with the significant difference in transcript levels of the WAK3 gene in the presence or absence of pathogen infection. Allelism tests performed with other known BB R-genes revealed that the allele was distinct from others having a similar chromosomal location.

See TAG http://link.springer.com/article/10.1007/s00122-015-2557-2

Fig. 1  Background selection of two tested lines in Anmi genetic background. Ais Anmi, D1 and D2 are advanced backcross lines 11325 and 11327, respectively. Blue barsindicating introgressed DNA fragment from the R-donor plant show the polymorphic region between Anmi and the sister line (color figure online)