Bread wheat cultivar PBW 343 carries residual additive resistance against virulent stripe rust pathotype

ABSTRACT

With continuous outbreaks of stripe rust (Puccinia striiformis f. sp. tritici) epidemics and rapid breakdown of deployed resistance in bread wheat (Triticum aestivum L.) cultivars in North West Plains Zone (NWPZ) in India warrant knowledge and deployment of new and durable sources of resistance to stripe rust. Bread wheat cultivar PBW 343, until recently the most widely cultivated wheat variety in India, is now highly susceptible to stripe rust (score 9 on a 1–9 scale), whereas PBW 621 (score 5.05–5.65) and HD 2967 (score 5.40–6.20) show low levels of resistance. We conducted an experiment, spanning three crop seasons (2013–2014 to 2015–2016), in which parental lines, F₁ and F₂ populations, F₃ and F₄ families from two bread wheat crosses, PBW 621/PBW 343 and HD 2967/PBW 343 were generated and evaluated for stripe rust resistance against a virulent pathotype. While the F₁ revealed partial dominance, the segregation pattern for stripe rust resistance in F₂ and F₃ showed transgressive segregation for resistance in both crosses. Chi-square analysis indicated that resistant segregants possessed two genes, one contributed by PBW 621 or HD 2967 (depending on the cross) and the other, unexpectedly but obviously, came from the most susceptible cultivar, PBW 343. Possible genetic mechanisms for this residual resistance and implications for breeding programs are discussed.

KEYWORDS:

• Adult plant resistance
• disease resistance
• genetic analysis
• Puccinia striiformis f. sp. tritici and Triticum aestivum

Conflict of Interest

The authors declare that they have no conflict of interest.

Funding

The senior author acknowledges the grant received from the Department of Science and Technology, Govt. of India, New Delhi, through INSPIRE Ph.D. FELLOWSHIP PROGRAMME to pursue the research project.

Additional information

Funding

The senior author acknowledges the grant received from the Department of Science and Technology, Govt. of India, New Delhi, through INSPIRE Ph.D. FELLOWSHIP PROGRAMME to pursue the research project.

Notes on contributors

Rupinder Pal Singh

Rupinder Pal Singh: He has conducted the entire study during the period of his PhD research curriculum and has himself done all the work listed in this article and has written the manuscript as submitted to your esteemed journal. Puja Srivastava: She, being an integral team member has contributed towards guidance in genetic analysis and writing the manuscript. Achla Sharma: Being a geneticist, she has played a key and instrumental role in rust epidemiology characterization and field inoculations and genetic analysis of the reactions so obtained during the whole research program. N. S. Bains: Being the major guide in the research, right from the gestation of the concept and throughout conduct of the research, he has played a pivotal role in directing the entire study towards its goal and also has been instrumental in giving valuable inputs for manuscript writing.