Tissue-level transcriptome response to local and distal chilling reveals potential chilling survival mechanisms in maize

Chilling is a major stress to plants of subtropical and tropical origins including maize. To reveal molecular mechanisms underlying chilling tolerance and chilling survival, we investigated maize transcriptome responses to chilling stress in differentiated leaves and roots as well as in crowns with meristem activity for survival. Chilling stress on maize shoots and roots is found to each contribute to seedling lethality in maize. Comparison of maize lines with different chilling tolerance capacity reveals that chilling survival in maize is highly associated with upregulation in leaves and crowns of abscisic acid response pathway, transcriptional regulators and cold response as well as downregulation of heat response in crowns. Comparison of chilling treatment on whole and part of the plants reveals that response to distal-chilling is very distinct from, and sometimes opposite to, response to local- or whole-plant chilling in both leaves and roots, suggesting a communication between shoots and roots in environmental perception. In sum, this study details chilling responses in leaves, roots and crowns and reveals potential chilling survival mechanism in maize, which lays ground for further understanding survival and tolerance mechanisms under low but non-freezing temperatures in tropical and subtropical plants. Overall design: Examination of 48 samples in maize B73 on three-leaf stage, including four tissues (leaf, root, top-crown and bottom-crown) under four conditions (normal condition, whole-plant chilling, shoot-only chilling and root-only chilling) with three biological repeats. The four tissues under normal condition were the control group and the others were experimental group.