Precise Genotype Selection in 'PSL2-Xa21' Rice Introgression Lines Using Whole Genome Sequencing

Backcross Breeding Bacterial Blight Genetic Composition Analysis Rice Resistance Gene Xanthomonas oryzae pv. oryzae (Xoo)

Authors

  • Walailak Laothaworn Department of Biology, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0009-0008-1835-6474
  • Natchanon Meesa Department of Biology, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0009-0009-4603-5827
  • Kumrop Ratanasut 2) Department of Agricultural Science, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand. 3) Center of Excellence in Research for Agricultural Biotechnology, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0000-0002-7221-7888
  • Tepsuda Rungrat 2) Department of Agricultural Science, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand. 3) Center of Excellence in Research for Agricultural Biotechnology, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0000-0001-5642-5102
  • Kittisak Buddhachat 1) Department of Biology, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand. 2) Department of Agricultural Science, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand. 4) Center of Excellence for Innovation and Technology for Detection and Advanced Materials, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0000-0003-4746-9861
  • Kawee Sujipuli
    kawees@nu.ac.th
    2) Department of Agricultural Science, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand. 3) Center of Excellence in Research for Agricultural Biotechnology, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0000-0002-8307-4755
  • Phithak Inthima 1) Department of Biology, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand. 2) Department of Agricultural Science, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand. 4) Center of Excellence for Innovation and Technology for Detection and Advanced Materials, Naresuan University, Phitsanulok 65000, Thailand https://orcid.org/0000-0002-5587-6259
Vol. 6 No. 2 (2025): June
Research Articles

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Rice bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), poses a major threat to global rice production. Enhancing BB resistance through gene introgression is a sustainable strategy for disease management, particularly in elite cultivars like ‘Phitsanulok2’ (‘PSL2’), which has high yield potential and insect resistance but is susceptible to BB. This study improved BB resistance in ‘PSL2’ by introgressing the Xa21 gene, a broad-spectrum resistance gene from the donor parent ‘IRBB21’ through backcross breeding combined with whole genome sequencing (WGS)-assisted selection. Three BC5F6 introgression lines were evaluated for agronomic performance and BB resistance under field conditions. These lines exhibited increased plant height and grain yield compared to both parents, with no significant differences in tiller numbers. Lines ‘A’ and ‘B’ showed moderate resistance (MR) to BB, while line ‘C’ demonstrated resistance (R). WGS revealed that seven of the nine BC5F6 lines retained 71.78%–73.31% genomic similarity with the recurrent parent ‘PSL2’. Seventeen Xa21-mediated immune response genes were identified, highlighting their potential contributions to BB resistance. Genomic composition analysis showed substantial recovery of the recurrent parent genome, with notable donor genome segments retained on chromosome 11 and heterozygous regions observed on chromosomes 3, 6, 7, 8, and 9. Subsequent evaluation of BC5F7 lines under greenhouse conditions confirmed significant improvements in plant height, tiller number, and grain yield with moderate BB resistance in seven of the nine lines. Results demonstrated the effectiveness of combining advanced backcross breeding with WGS-assisted selection to develop high-yielding, BB-resistant rice lines. The identification of immune-related genes and their interactions offers valuable insights for optimizing future rice breeding strategies.