EXPLORING THE INNATE IMMUNITY OF WHEAT GERMPLASM AGAINST YELLOW RUST OF WHEAT

Abstract

Wheat (Triticum aestivum L.) is a staple food for a significant portion of the world's population including Pakistan. Among all limiting biotic and abiotic factors, wheat rusts pose a substantial danger to production worldwide and can result in yield losses of over 90% in susceptible varieties or during epidemics. Yellow rust (Puccinia striiformis f. sp. tritici), one of several types of wheat rust, is particularly dangerous to wheat production in Pakistan and cause disease on 70% cultivated area of wheat. Keeping in view the devastating nature of yellow rust pathogen, two-year study 2020-2021 and 2021-2022 was conducted in order to screen out wheat breeding lines against yellow rust followed by its relationship with the environmental variables. In this study, one hundred wheat breeding lines were cultivated in the research area of MNS-University of Agriculture Multan and disease was observed in the months of January-April during 2020-21 and 2021-22. Very low level of disease severity (DS) and area under disease progress curve (AUDPC) recorded in all the breeding lines. Epidemiological variables play an important role in the disease progression. Hence, out of hundred breeding lines screened in 2020-2021, 88 breeding lines were supposed to be immune to all naturally occurring race(s) of yellow rust and 12 lines were categorized as moderately resistant to moderately susceptible. Similarly, 92 breeding lines were found immune and 8 showed moderately resistant to moderately susceptible response out of 100 breeding lines during 2021-2022. The findings showed that a high proportion of wheat breeding lines showed no response towards the disease and supposed to be immune. The results from the correlation and regression analysis showed that there was a positive correlation between the maximum, minimum temperature with yellow rust severity (%). While, there was a negative correlation of humidity during 2020-2021 and positive during 2021-2022. Sunshine hours showed the positive relationship with the yellow rust severity (%) during 2020-2021 and negative during 2021-2022. Current study revealed that breeding lines and pathogen were present, which was responsible for the disease in few breeding lines, while epidemiological factors were non-favorable for the disease to develop and progress at large scale. The findings of the current research clearly showed the importance of epidemiological factor which leads toward less disease development. The analysis of natural conditions with yellow rust helps to predict yellow rust outbreak and appropriate management strategies.