Improving the blast resistance of the elite rice variety Kongyu-131 by updating the pi21 locus

Xiaomin Feng,Guoqiang Jiang,Wenqi Zhang,Rongsheng Wang,Xiaohui Zhang,Shaoyang Lin,Chen Wang,Qingbo Yuan,Kangxue Lin,Jianzong Nan

doi:10.1186/s12870-019-1868-x

Abstract

BackgroundAs an elite japonica rice variety, Kongyu-131 has been cultivated for over 20 years in the third accumulated temperature zone of Heilongjiang Province, China. However, the cultivated area of Kongyu-131 has decreased each year due to extensive outbreaks of rice blast. To achieve the goals of improving blast resistance and preserving other desirable traits in Kongyu-131, a genome-updating method similar to repairing a bug in a computer program was adopted in this study. A new allele of the broad-spectrum blast resistance gene pi21 in the upland rice variety GKGH was mined by genetic analysis and introgressed into the genome of Kongyu-131 to upgrade its blast resistance.ResultQTL analysis was performed with an F2 population derived from a cross between Kongyu-131 and GKGH, and a blast resistance QTL was detected near the pi21 locus. Parental Pi21 sequence alignment showed that the pi21 of the donor (GKGH) was a new allele. By 5 InDel or SNP markers designed based on the sequence within and around pi21, the introgressed chromosome segment was shortened to less than 634 kb to minimize linkage drag by screening recombinants in the target region. The RRPG was 99.92%, calculated according to 201 SNP markers evenly distributed on 12 chromosomes. Artificial inoculation at the seedling stage showed that the blast resistance of the new Kongyu-131 was improved significantly. Field experiments also indicated that the improved Kongyu-131 had enhanced field resistance to rice blast and grain-quality traits similar to those of the original Kongyu-131.ConclusionsIt is feasible to improve resistance to rice blast and preserve other desirable traits by precisely improving the Pi21 locus of Kongyu-131. Linkage drag can be eliminated effectively via recombinant selection on both sides of the target gene.

Highlights

As an elite japonica rice variety, Kongyu-131 has been cultivated for over 20 years in the third accumulated temperature zone of Heilongjiang Province, China
Marker-trait association analysis Genetic analysis was performed by using an F2 population derived form Kongyu-131 and GKGH with 141 individuals
The result indicated that the marker tightly linked to pi21 was significantly associated with lesion degree (LD) and explained 16.4% of the phenotypic variation (Table 1)

Summary

Introduction

As an elite japonica rice variety, Kongyu-131 has been cultivated for over 20 years in the third accumulated temperature zone of Heilongjiang Province, China. The cultivated area of Kongyu-131 has decreased each year due to extensive outbreaks of rice blast. A new allele of the broad-spectrum blast resistance gene pi in the upland rice variety GKGH was mined by genetic analysis and introgressed into the genome of Kongyu-131 to upgrade its blast resistance. Discovering and utilizing blast resistance genes are the premises of disease resistance breeding. More than 100 major blast R-genes have been identified. These genes are distributed on all 12 chromosomes of rice, and more than half are concentrated on chromosomes 6, 11 and 12 [2]. Except for bsr-d1 [4], bsr-k1 [5], Pid2 [6], pi21 [7] and Ptr [8], the blast resistance genes all encode NBS-LRR proteins. Pi21 was the first cloned recessive blast resistance QTL, encoding a proline-rich

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Results

Discussion

Conclusion