Introgression of Bacterial Blight Resistance Genes in the Rice Cultivar Ciherang: Response against Xanthomonas oryzae pv. oryzae in the F6 Generation.

Sharmistha Ghosal,Arafat Abdel Hamed Abdel Latef,Gayatri Goswami,Alison M. Laing,Yong-Ming Gao,Ujjal Kumar Nath,Omar M. Ali,Akbar Hossain,Priya Lal Biswas,Md. Shalim Uddin

doi:10.3390/plants10102048

Abstract

Bacterial blight (BB) is caused by Xanthomonas oryzae pv. oryzae and is one of the most important diseases in rice. It results in significantly reduced productivity throughout all rice-growing regions of the world. Four BB resistance genes have been reported; however, introgression of a single gene into rice has not been able to sufficiently protect rice against BB infection. Pyramiding of effective BB resistance genes (i.e., Xa genes) into background varieties is a potential approach to controlling BB infection. In this study, combinations of four BB resistance genes, Xa4, xa5, xa13, and Xa21, were pyramided into populations. The populations were derived from crossing Ciherang (a widespread Indonesian rice variety) with IRBB60 (resistance to BB). Promising recombinants from the F6 generation were identified by scoring the phenotype against three virulent bacterial strains, C5, P6, and V, which cause widespread BB infection in most rice-growing countries. Pyramiding of genes for BB resistance in 265 recombinant introgressed lines (RILs) were confirmed through marker-assisted selection (MAS) of the F5 and F6 generations using gene-specific primers. Of these 265 RILs, 11, 34 and 45 lines had four, three, or two BB resistance genes, respectively. The RILs had pyramiding of two or three resistance genes, with the Xa4 resistance gene showing broad spectrum resistance against Xoo races with higher agronomic performance compared to their donor and recipients parents. The developed BB-resistant RILs have high yield potential to be further developed for cultivation or as sources of BB resistance donor material for varietal improvement in other rice lines.

Highlights

Rice accounts for more than 21% of total food intake; it provides up to two-thirds of the total calories consumed by more than two billion people across Asia, Africa, and Latin America [1,2,3,4]
We examined the potential for marker-assisted selection to identify rice lines with multiple bacterial blight (BB) resistance genes (i.e., Xa genes)
To assess the level of virulence of the isolates, the leaf area progressed with BB and the percentage of resistance in recombinant introgressed lines (RILs) were examined (Figure 1)

Summary

Introduction

Rice accounts for more than 21% of total food intake; it provides up to two-thirds of the total calories consumed by more than two billion people across Asia, Africa, and Latin America [1,2,3,4]. It is estimated that rice production must increase by. Rice yields have plateaued due to biotic and abiotic stresses [6]. Bacterial blight (BB), which is caused by Xanthomonas oryzae pv. Oryzae (Xoo), is one of the most destructive diseases, limiting rice production around the world. BB was first identified in Japan at the beginning of the twentieth century [7]. It can cause damage at any stage of the rice-growing cycle. BB causes yield losses generally ranging between 10 and 30%, but which can be as high as 80%, depending on the location, season, weather, crop growth stage, and cultivar [8,9,10,11]. The development of a BB-resistant rice cultivar through a gene introgression breeding program is critically important [13,14,15]

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