© 2024 Anil Kumar, et al. This is an open access article distributed under the terms of the Creative Commons Attribution License -NonCommercial-ShareAlike Unported License (http://creativecommons.org/licenses/by-nc-sa/3.0/). Screening and identification of heat tolerance in Indian wheat genotypes using generalized regression neural network (GRNN) model Anil Kumar 1 , Sadaf Fatima 1 , Iffat Azim 2 , Anshika Negi 1 , Shalini Bhadola 1 , Pooja Jha 2 , Suboot Hairat 3 * 1 Dr Akhilesh Das Gupta Institute of Professional Studies (Formerly ADGITM), Delhi, India. 2 Department of Biotechnology, SR Group of Institution, Lucknow, India. 3 Safa Biolabs, Daryaganj, P.O. Box 110002, Delhi, India. ABSTRACT The present study using a generalized regression neural network (GRNN) model was carried out to check the effect of high temperature on five Indian bread wheat genotypes, namely, C306, K7903, CBW12, HD2329, and HD2428, and to develop an algorithm for the screening and identification of heat tolerance in wheat. A highly significant differential survivability in response to the temperature induction response technique with germinating seeds was observed for the five wheat genotypes. Maximum survivability was observed for C306 and K7903, whereas HD2329 and HD2428 showed minimum survival in response to lethal temperature stress. Similarly, at the mature plant stage, in response to heat treatment of 34°C/26°C (day/night), all five wheat genotypes showed a significant difference in chlorophyll a fluorescence, total chlorophyll content, and the reduction of 1,1- diphenyl-2-picryl-hydrazyl (DPPH) in response to heat treatment. The genotypes, C306, K7903, and CBW12 showed better performance for all the chlorophyll a fluorescence parameters under study including Fo, Fv/Fm, qL, qP, NPQ, θPSII, ETR, along with the total chlorophyll content and DPPH reduction, in contrast, the genotypes, HD2329 and HD2428 performed poorly for all parameters including chlorophyll a fluorescence parameters, total chlorophyll, and DPPH reduction. Higher inflection temperature and peak temperature were observed in C306 and K7903, in contrast, HD2329 and HD2428 showed significantly lower inflection temperature and peak temperature. Higher expression of the selected genes involved in photosynthesis and ROS scavenging was observed in C306 and K7903 relative to HD2329 and HD2428. On the basis of the different chlorophyll a fluorescence parameters, the algorithm was developed for the calculation of the heat susceptibility index. The algorithm was independently checked for the identification and segregation of all the five wheat genotypes taken in this study as tolerant, moderate, and susceptible. For all the genotypes, the algorithm was able to predict the heat susceptibility of the genotypes with high accuracy. Hence, the algorithm in combination with chlorophyll a fluorescence can be used for the screening of wheat and other plant species in response to abiotic stress, especially heat stress. 1. INTRODUCTION All recent evidence suggests that global warming-induced increase in temperature in the coming decades along with frequent droughts thus imposing adverse effect on living organisms including species ecology, geographic distribution, and phenology [1,2]. The major factors associated with climate change in the near future are an increase in the average atmospheric temperature and a change in rainfall pattern [3]. The plants have evolved to cope with high temperature stress, along with drought depending on their geographic location and the prevailing climate. Over centuries, the domestication of all major crop plants has *Corresponding Author: Suboot Hairat, Safa Biolabs, Delhi, India. E-mail: hsuboot@yahoo.com resulted in the erosion of genetic diversity for high-temperature stress thus threatening food security. Nevertheless, thermo-tolerant plants show acquired temperature stress tolerance mainly attributed to the changes in the plant transcriptome [2,4,5]. One of the important crop plants, wheat is very sensitive to high- temperature stress. In general, wheat is a cool climate crop requiring an optimal growth temperature of 20–30°C and 15°C for reproductive growth [6-9]. With every degree of rise in temperature, a 6% decrease in wheat production is predicted [8]. Earlier reports have attributed the photosynthesis susceptibility to high temperature mainly due to the damage to thylakoid membranes, along with a decrease in the expression of genes involved in photosynthesis [5,10,11]. A major limitation for the timely approval of heat-tolerant wheat genotype for cultivation by farmers is the identification and characterization of the heat-tolerant genotypes. Until date, field-based characterization of the wheat Available online at http://www.jabonline.in ARTICLE INFO Article history: Received on: August 26, 2023 Accepted on: January 05, 2024 Available online: *** Key words: Chlorophyll a fluorescence; heat susceptibility index; GRNN model, Temperature Induction Response, wheat. Journal of Applied Biology & Biotechnology Vol. X(XX), pp. 1-9, 2024 DOI: 10.7324/JABB.2024.167028