Yinbo Ma, Sushil Satish Chhapekar, Lu Lu, Xiaona Yu, Seungho Kim, Soo Min Lee, Tae Hyoung Gan, Gyung Ja Choi, Yong Pyo Lim & Su Ryun Choi

Theoretical and Applied Genetics December 2021; vol. 134: 3925–3940

Key message

Two major QTL associated with resistance to Fusarium wilt (FW) were identified using whole-genome resequencing. Sequence variations and gene expression level differences suggest that TIR-NBS and LRR-RLK are candidate genes associated with FW-resistance.

Abstract

Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. raphani is an important disease in radish, leading to severe decrease in yield and quality. YR4 as a novel genetic source to resistant to FW was confirmed through screening with five pathogen isolates. We have generated F₂ and F_2:3 populations segregated with FW resistance using YR4 and YR18 inbred lines. The disease symptom was evaluated in F_2:3 population (n = 180) in three independent studies over two years. We identified 4 QTL including the two major QTL (FoRsR7.1^59A and FoRsR9.3^59A). FoRsR7.1^59A and FoRsR9.3^59A were detected in three replicated experiments. FoRsR7.1^59A was delimited to the 2.18-Mb physical interval on chromosome R07, with a high LOD value (5.17–12.84) and explained phenotypic variation (9.34%–27.97%). The FoRsR9.3^59A represented relatively low LOD value (3.38–4.52) and explained phenotypic variation (6.24%–8.82%). On the basis of the re-sequencing data for the parental lines, we identified five putative resistance-related genes and 13 unknown genes with sequence variations at the gene and protein levels. A semi-quantitative RT-PCR analysis revealed that Rs382940 (TIR-NBS) and Rs382200 (RLK) were expressed only in ‘YR4’ from 0 to 6 days after the inoculation. Moreover, Rs382950 (TIR-NBS-LRR) was more highly expressed in ‘YR4’ from 3 to 6 days after the inoculation. These three genes might be important for FW-resistance in radish. We identified several markers based on these potential candidate genes. The marker set should be useful for breeding system to introduce the FW resistance loci from ‘YR4’ to improve tolerance to FW.

See: https://link.springer.com/article/10.1007/s00122-021-03937-5