Stay-green QTLs in temperate elite maize

Abstract

The ability to stay-green (SG) in later stages of the crop cycle is a valuable trait for plants cultivated in standard or stressful environments. Few QTLs studies for SG have been conducted in temperate maize, apart from some experiments carried out with Chinese lines. The aim of our study was to identify QTLs related to SG in temperate maize using PHG39, an important SG line in private breeding. We developed two large F2 mapping populations by crossing PHG39 to the no stay-green (NSG) lines B73 (Corn Belt Dent) and EA1070 (European flint). Samples of individuals of the extreme tails (high and low) of the populations for visual score were genotyped. We found an association between markers and SG in three regions at bins 1.04–1.09, 5.02 and 10.04–10.06. The association was strong for some markers in chromosome 1, for example, for bnlg1556 the frequency of the SG allele was 0.75 and 0.34 in the high and the low tail, respectively. Furthermore, for this marker the homozygote’s with the SG allele had 4 times more chlorophyll than the homozygote’s with the NSG allele 2 months after flowering. Some alleles most likely conferred SG because they increased the maximum chlorophyll content at flowering while other alleles did by diminishing the rate of senescence. The SG conferred by some alleles could be functional as some favourable alleles for SG were also favourable for kernel weight. Regardless of the physiological basis of the SG, the significant markers detected could be useful for marker assisted selection.