Dandan Zhang , Yulong Fan , Xiangyun Ji , Zhihui Xia

Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, 570228, P.R. China
Author    Correspondence author
Rice Genomics and Genetics, 2022, Vol. 13, No. 3   doi: 10.5376/rgg.2022.13.0003
Received: 09 Feb., 2022    Accepted: 18 Feb., 2022    Published: 14 Mar., 2022

This article was first published in Molecular Plant Breeding in Chinese, and here was authorized to translate and publish the paper in English under the terms of Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Zhang D.D., Fan Y.L., Ji X.Y., and Xia Z.H., 2022, Variation and functional markers of Xa23 promoter of rice bacterial blight resistance gene, Rice Genomics and Genetics, 13(3): 1-6 (doi:10.5376/rgg.2022.13.0003)

Xa23 is a dominant gene with broad spectrum and strong resistance to bacterial blight of rice. The functional difference between Xa23 and the allele susceptible gene xa23 lies in the 28 bp core sequence on the promoter that is recognized and activated by the avirulent effector avrXa23 of Xanthomonas oryzae pv. Oryzae (EBEavrXa23) and development of Xa23 functional markers can speed up the process of rice breeding. In this study, the Xa23 promoters of 43 wild rice and 7 representative conventional rice were tested, and the 200 bp sequence upstream of the promoter was analyzed using Vector NTI. The results showed that only 9 common wild rice and 2 conventional rice could amplify about 200 bp sequence upstream of promoter, and the detection rate was only 22.0%, indicating that Xa23 was not widespread in rice. Further sequence analysis showed that there were abundant variations in the sequence of EBE_avrXa23, with at least seven haplotypes in its allele sequence, but EBE_avrXa23 only exists in rice CBB23. Finally, the Xa23 dominant functional marker was developed based on the sequence of EBE_avrXa23. It was verified that the marker could clearly distinguish whether there was Xa23 gene in rice. This study will be helpful to further study the evolution mechanism of Xa23 and molecular mark assisted breeding. 

Bacterial blight; Xa23 promoter; Sequence analysis; EBE_avrXa23; Molecular marker