Mapping QTL for chlorophyll fluorescence kinetics parameters at seedling stage as indicators of heat tolerance in wheat

High temperature or heat stress is one of the most important abiotic stresses that affect wheat production in almost every part of the world. Parameters of chlorophyll fluorescence kinetics (PCFKs) are the most powerful and reliable characters available to understand the impact of various abiotic stresses on plant physiological processes and heat tolerance. The present research was aimed to identify genomic regions controlling PCFKs at early growth stages of wheat through quantitative trait loci analysis by applying heat stress for different duration of time. A doubled haploid population derived from the cross of two Chinese wheat cultivars Hanxuan 10 and Lumai 14 was exposed to 38 A degrees C for 2, 4, 6 and 8 h of heat stress and PCFKs (initial fluorescence, maximum fluorescence, variable fluorescence and maximum quantum efficiency of photosystem II) were measured. A total of 37 QTLs were identified for the target traits, among which 13 were detected under normal temperature of 25 A degrees C and the remaining 24 under the stressful temperature of 38 A degrees C. Stable or consistently expressed QTLs for initial, maximum and variable fluorescence were detected on chromosomes 1A, 1B, 2B, 4A and 7D. In addition, 24 QTLs were clustered in 9 clusters on chromosomes 1A, 1B, 2B, 3B, 3D, 4A, 5A and 7D. These QTL hot spot regions along with stable QTLs should be targeted for better understanding the genetic basis of chlorophyll fluorescence kinetics parameters in future mapping studies.