Mapping Leaf and Stripe Rust Resistance Genes Using Advanced Genetic Tools

Jim Crocker
16th July, 2024

Mapping Leaf and Stripe Rust Resistance Genes Using Advanced Genetic Tools

Image Source: Natural Science News, 2024

Key Findings

  • The study by Punjab Agricultural University focused on wheat diseases leaf rust (LR) and stripe rust (YR) in India
  • Researchers developed a wheat line, ILsp3603, resistant to multiple LR and YR pathotypes
  • They identified and mapped two resistance genes, Lrsp3603 and Yrsp3603, on chromosome 6B
Wheat is a crucial staple food globally, yet it faces significant threats from fungal pathogens, particularly leaf rust (LR) and stripe rust (YR). These diseases can cause substantial yield losses, which is a pressing concern given the need to feed a growing global population. Enhancing the genetic diversity of cultivated wheat is a key strategy to combat these pathogens effectively. A recent study conducted by the Punjab Agricultural University has made significant progress in this area by developing an introgression line, ILsp3603, which carries resistance against several pathotypes of LR and YR[1]. The study aimed to understand the genetic basis of this resistance and map the responsible genes, named Lrsp3603 and Yrsp3603. The researchers used a hexaploid wheat background and crossed the resistant ILsp3603 with a susceptible cultivar, WL711. Through inheritance studies carried out in the F6 and F7 generations, they revealed that each resistance trait follows a monogenic (single gene) inheritance pattern. To map these genes, the study employed bulk segregant analysis combined with 35K Axiom SNP array genotyping. Both genes were successfully mapped as separate entities on the short arm of chromosome 6B. A genetic linkage map was created, consisting of five markers: 1 SNP, 1 PLUG, and three gene-based SSRs, covering a genetic distance of 12.65 cM. Specifically, Lrsp3603 was flanked by markers Tag-SSR14 (located proximally at 2.42 cM) and SNP AX-94542331 (at 3.28 cM), while Yrsp3603 was mapped closest to AX-94542331 at a distance of 6.62 cM. Functional annotation of the Lrsp3603 target region revealed 10 gene IDs associated with disease resistance mechanisms, including three encoding typical R gene domains. This study builds on previous research that has highlighted the importance of developing resistant wheat varieties to minimize yield losses caused by LR and YR[2]. In earlier studies, researchers identified various resistance loci and mapped them using genetic linkage maps. For example, the study by[2] identified new LR and YR resistance loci in a population of recombinant inbred lines (RILs) derived from a synthetic wheat derivative and an adapted common wheat line. These findings are crucial as they provide a foundation for understanding the genetic mechanisms underlying disease resistance in wheat. Additionally, the current study aligns with broader efforts to manage wheat diseases more effectively, as discussed in[3]. Wheat diseases such as rusts, blotches, and head blight contribute to significant yield losses annually. The development of resistant wheat varieties is a key component of disease management strategies. By identifying and mapping resistance genes, researchers can develop wheat varieties that are less susceptible to these diseases, thereby ensuring stable and increased wheat production. Furthermore, the study's focus on genetic diversity and the introduction of new alleles from wild relatives is consistent with historical trends in wheat breeding. As noted in[4], wheat has undergone significant genetic reshuffling due to breeding programs, especially after 1960. The introgression of resistance genes from wild progenitors, like Aegilops speltoides in the current study, is a continuation of this trend and highlights the importance of maintaining and enhancing genetic diversity in wheat breeding programs. In summary, the study conducted by the Punjab Agricultural University has made significant strides in identifying and mapping resistance genes for LR and YR in wheat. By developing an introgression line with enhanced resistance and understanding the genetic basis of this resistance, the research provides valuable tools for future wheat breeding programs. This work not only builds on previous findings but also contributes to the ongoing efforts to ensure food security by mitigating the impact of wheat diseases.

GeneticsBiochemPlant Science

References

Main Study

1) Mapping of Aegilops speltoides derived leaf rust and stripe rust resistance genes using 35K SNP array

Published 15th July, 2024

https://doi.org/10.1186/s12863-024-01247-5

Related Studies

2) Characterization and Mapping of Leaf Rust and Stripe Rust Resistance Loci in Hexaploid Wheat Lines UC1110 and PI610750 under Mexican Environments.

https://doi.org/10.3389/fpls.2017.01450

3) A review of wheat diseases-a field perspective.

https://doi.org/10.1111/mpp.12618

4) Worldwide phylogeography and history of wheat genetic diversity.

https://doi.org/10.1126/sciadv.aav0536


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