Marker-assisted enhancement of bacterial blight (Xanthomonas oryzae pv . oryzae) resistance in a salt-tolerant rice variety for sustaining rice production of tropical islands

Raj Kumar Gautam; Pankaj Kumar Singh; Krishnan Sakthivel; K Venkatesan; Shyam S Rao; M Srikumar; Joshitha Vijayan; B Rakesh; Soham Ray; Jameel Akhtar; Bharat Raj Meena; Sapna Langyan; Sharik Ali; S L Krishnamurthy

doi:10.3389/fpls.2023.1221537

Marker-assisted enhancement of bacterial blight (Xanthomonas oryzae pv . oryzae) resistance in a salt-tolerant rice variety for sustaining rice production of tropical islands

Front Plant Sci. 2023 Sep 25:14:1221537. doi: 10.3389/fpls.2023.1221537. eCollection 2023.

Authors

Raj Kumar Gautam^{1

2}, Pankaj Kumar Singh¹, Krishnan Sakthivel^{1

3}, K Venkatesan^{1

4}, Shyam S Rao¹, M Srikumar¹, Joshitha Vijayan^{1

5}, B Rakesh¹, Soham Ray⁶, Jameel Akhtar², Bharat Raj Meena², Sapna Langyan², Sharik Ali², S L Krishnamurthy⁷

Affiliations

¹ Indian Council of Agricultural Research (ICAR)-Central Island Agricultural Research Institute, Port Blair, India.
² Indian Council of Agricultural Research (ICAR)-National Bureau of Plant Genetic Resources, New Delhi, India.
³ Indian Council of Agricultural Research (ICAR)-Indian Institute of Oilseeds Research, Hyderabad, India.
⁴ Indian Council of Agricultural Research (ICAR)-National Bureau of Plant Genetic Resources (NBPGR), Regional Research Station, Thrissur, Kerala, India.
⁵ Indian Council of Agricultural Research (ICAR)-National Institute for Plant Biotechnology, New Delhi, India.
⁶ Indian Council of Agricultural Research (ICAR)-Indian Agricultural Research Institute, New Delhi, India.
⁷ Indian Council of Agricultural Research (ICAR)-Central Soil Salinity Research Institute, Karnal, India.

Abstract

Introduction: Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae is a major disease of rice, specially in the tropical regions of the world. Developing rice varieties with host resistance against the disease is the most effective and economical solution for managing the disease.

Methods: Pyramiding resistance genes (Xa4, xa5, xa13,and Xa21) in popular rice varieties using marker-assisted backcross breeding (MABB) has been demonstrated as a cost-effective and sustainable approach for establishing durable BB resistance. Here, we report our successful efforts in introgressing four resistance genes (Xa4, xa5, xa13, and Xa21) from IRBB60 to CARI Dhan 5, a popular salt-tolerant variety developed from a somaclonal variant of Pokkali rice, through functional MABB.

Results and discussion: Both BB and coastal salinity are among the major challenges for rice production in tropical island and coastal ecosystems. Plants with four, three, and two gene pyramids were generated, which displayed high levels of resistance to the BB pathogen at the BC3F2 stage. Under controlled salinity microplot environments, the line 131-2-175-1223 identified with the presence of three gene pyramid (Xa21+xa13+xa5) displayed notable resistance across locations and years as well as exhibited a salinity tolerance comparable to the recurrent parent, CARI Dhan 5. Among two BB gene combinations (Xa21+xa13), two lines, 17-1-69-334 and 46-3-95-659, demonstrated resistance across locations and years, as well as salt tolerance and grain production comparable to CARI Dhan 5. Besides salinity tolerance, five lines, 17-1-69-179, 46-3-95-655, 131-2-190-1197, 131-2-175-1209, and 131-2-175-1239, exhibited complete resistance to BB disease. Following multilocation testing, potential lines have been identified that can serve as a prospective candidate for producing varieties for the tropical Andaman and Nicobar Islands and other coastal locations, which are prone to BB and coastal salinity stresses.

Keywords: bacterial blight; marker-assisted backcross breeding; pyramiding; resistance; rice; salinity tolerance; tropical islands.

Grants and funding

The authors acknowledge the funding support from the Department of Biotechnology (DBT), Government of India, for the financial grant (BT/PR6575/AG11/106/892/2012) to the project “Marker assisted introgression of BB resistance in popular rice cultivars of Andaman and Nicobar Islands” under “Application of molecular markers under accelerated crop improvement programme”. We also acknowledge the funding support from the Bill and Melinda Gates Foundation and IRRI, Philippines, for the “Stress tolerant rice for poor farmers in Africa and South Asia” project.