Quantitative trait locus mapping of chlorophyll a fluorescence parameters using a recombinant inbred line population in maize

Abstract

Chlorophyll a fluorescence parameters, derived from its induction, known as the OJIP rise, are often used to characterize the structure and function of photosystem II (PSII). Under field conditions, structure and function of photosystems of crops can be affected by various environmental factors. This study was conducted to identify quantitative trait loci (QTLs) associated with chlorophyll fluorescence parameters in field-grown maize. During three growing seasons, a recombinant inbred line population, consisting of 228 lines, was evaluated for five chlorophyll fluorescence parameters, which indirectly measure: absorbed photon flux per cross section of leaf (ABS/CSo), maximum trapped exciton flux per cross section of leaf (TRo/CSo), electron transport flux from QA to QB per cross section of leaf (ETo/CSo), number of active PSII reaction centers (RCs) per cross section of leaf (RC/CSo), and the performance index on a cross section of leaf (PICS). Significant correlations were frequently observed among these chlorophyll fluorescence parameters. Three major genomic regions dispersed across chromosomes 1, 5, and 9 were detected to be associated with chlorophyll fluorescence parameters. The genomic region in chromosome bins 9.06–9.07 contained QTLs that not only showed pleiotropy for multiple chlorophyll fluorescence parameters but also showed stable expression and explained a large proportion of the phenotypic variation. Additionally, a QTL for grain yield was also detected in this important genomic region. The identified QTLs for chlorophyll fluorescence parameters in the present study may help elucidate plants’ responses to environmental cues and assist in developing marker-assisted selection breeding programs in maize.