Can we improve the chilling tolerance of maize photosynthesis through breeding?

Abstract

Chilling tolerance is necessary for crops to thrive in temperate regions where cold snaps and lower baseline temperatures place limits on life processes; this is particularly true for crops of tropical origin such as maize. Photosynthesis is often adversely affected by chilling stress, yet the maintenance of photosynthesis is essential for healthy growth and development, and most crucially for yield. In this review we describe the physiological basis for enhancing chilling tolerance of photosynthesis in maize by examining nine key responses to chilling stress. We synthesise current knowledge of genetic variation for photosynthetic chilling tolerance in maize with respect to each of these traits and summarise the extent to which genetic mapping and candidate genes have been used to understand the genomic regions underpinning chilling tolerance. Finally, we provide perspectives on the future of breeding for photosynthetic chilling tolerance in maize. We advocate for holistic and high-throughput approaches to screen for chilling tolerance of photosynthesis in research and breeding programmes in order to develop resilient crops for the future.

Integrative Proteome and Phosphoproteome Profiling of Early Cold Response in Maize Seedlings

“…Chilling stress damages photosystems in maize [ 17 ]; we provide evidence that photosynthesis proteins drop much earlier than previously reported in maize. Previous studies showed that photosynthetic light-reaction proteins decreased after long durations of cold treatment [ 17 ], such as 12 h of cold treatment at 4 °C [ 54 ].…”

“…Much progress has been made in understanding the physiological response of cold stress in maize [ 1 , 3 , 17 ], but the genetic basis of the cold adaptation in maize remains poorly characterized [ 1 , 3 , 17 , 18 ]. Physiological and genetic studies suggest that chilling temperatures affect distinct metabolic functions at different maize growth stages, each under the control of independent gene sets [ 1 , 17 ]. Temperatures below 10 °C negatively affect gemination rate and slow seedling establishment [ 1 , 19 ].…”

“…Temperatures below 10 °C negatively affect gemination rate and slow seedling establishment [ 1 , 19 ]. During the seedling growth stage, chilling temperatures reduce chlorophyll content, decrease photosynthesis rate including photosystem II efficiency, retard growth, and induce oxygen species that would cause cellular and tissue damages [ 1 , 3 , 17 ]. Genetic mapping and GWAS analyses have identified a large number of quantitative trait loci (QTL) and single nucleotide polymorphisms (SNPs) associated with distinct traits of cold tolerance [ 3 , 17 ], and have uncovered a few underlying candidate genes with mostly minor effects on chilling tolerance [ 1 , 4 , 5 ].…”

“…During the seedling growth stage, chilling temperatures reduce chlorophyll content, decrease photosynthesis rate including photosystem II efficiency, retard growth, and induce oxygen species that would cause cellular and tissue damages [ 1 , 3 , 17 ]. Genetic mapping and GWAS analyses have identified a large number of quantitative trait loci (QTL) and single nucleotide polymorphisms (SNPs) associated with distinct traits of cold tolerance [ 3 , 17 ], and have uncovered a few underlying candidate genes with mostly minor effects on chilling tolerance [ 1 , 4 , 5 ]. Large scale RNA-seq analyses have identified thousands of genes responsive to cold stress in maize [ 3 , 20 , 21 , 22 , 23 ], but functional characterization of cold-responsive genes was limited, and genetic verification of implication of candidate genes in cold tolerance was mostly performed in Arabidopsis and tobacco [ 3 ].…”

Genetic variation in photosynthesis: many variants make light work

“… Posch et al (2022) show that thermal tolerance of PSII in wheat is subject to rapid acclimation in response to short-term supraoptimal temperature conditions, but also varies significantly between a range of genotypes with contrasting high temperature tolerance. Finally, on the suboptimal end of growth season temperature, Burnett and Kromdijk (2022) argue the case for enhancing chilling tolerance of photosynthesis in maize via selective breeding, which may help to better adapt the global number one grain crop to its increasingly temperate surroundings as its cultivation area spreads further north.…”