Abstract
BackgroundRecent progress in selective breeding of maize (Zea mays L.) towards adaptation to temperate climate has allowed the production of inbred lines withstanding cold springs with temperatures below 8 °C or even close to 0 °C, indicating that despite its tropical origins maize is not inherently cold-sensitive.ResultsHere we studied the acclimatory response of three maize inbred lines of contrasting cold-sensitivity selected basing on multi-year routine field data. The field observations were confirmed in the growth chamber. Under controlled conditions the damage to the photosynthetic apparatus due to severe cold treatment was the least in the cold-tolerant line provided that it had been subjected to prior moderate chilling, i.e., acclimation. The cold-sensitive lines performed equally poorly with or without acclimation. To uncover the molecular basis of the attained cold-acclimatability we performed comparative transcriptome profiling of the response of the lines to the cold during acclimation phase by means of microarrays with a statistical and bioinformatic data analysis.ConclusionsThe analyses indicated three mechanisms likely responsible for the cold-tolerance: acclimation-dependent modification of the photosynthetic apparatus, cell wall properties, and developmental processes. Those conclusions supported the observed acclimation of photosynthesis to severe cold at moderate chilling and were further confirmed by experimentally showing specific modification of cell wall properties and repression of selected miRNA species, general regulators of development, in the cold-tolerant line subjected to cold stress.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2453-4) contains supplementary material, which is available to authorized users.
Highlights
Recent progress in selective breeding of maize (Zea mays L.) towards adaptation to temperate climate has allowed the production of inbred lines withstanding cold springs with temperatures below 8 °C or even close to 0 °C, indicating that despite its tropical origins maize is not inherently cold-sensitive
Several inbred lines were tested for their performance under field conditions in the West Poland region by assessing their early vigor estimated in a 1-9 scale (1 the lowest, 9 the highest) at the stage of the fourth leaf, and the effective temperature sum (ETS) from sowing to 50 % of silking (Additional file 1)
Cell wall properties and quantitation of selected miRNAs To verify the main conclusions emerging from the transcriptomic studies, i.e., the major role of the cell wall in the acclimation of the cold-tolerant S68911 line and possible induction of developmental processes in that line, we studied those aspects of plant functioning directly
Summary
Recent progress in selective breeding of maize (Zea mays L.) towards adaptation to temperate climate has allowed the production of inbred lines withstanding cold springs with temperatures below 8 °C or even close to 0 °C, indicating that despite its tropical origins maize is not inherently cold-sensitive. Maize is a major crop plant cultivated all around the world except for the far northern and southern regions of the Earth. Maize is a model plant of growing popularity [1], the first C4 crop with a sequenced genome [2]. From the botanical point of view, several maize subspecies are known, the most important being Zea mays spp. indentata, Z. mays spp. indurata, Z. mays spp. saccharata and Z. mays spp. everta. More recent example is the ongoing gradual adaptation of maize to the temperate climate with cold springs and short summers
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