Transcriptomic response of maize primary roots to low temperatures at seedling emergence

Mauro Di Fenza; Bridget Hogg; Jim Grant; Susanne Barth

doi:10.7717/peerj.2839

Transcriptomic response of maize primary roots to low temperatures at seedling emergence

PeerJ. 2017 Jan 5:5:e2839. doi: 10.7717/peerj.2839. eCollection 2017.

Authors

Mauro Di Fenza¹, Bridget Hogg², Jim Grant³, Susanne Barth⁴

Affiliations

¹ College of Life Sciences, School of Biology and Environmental Sciences, University College Dublin, Dublin, Ireland; Crops, Environment & Land Use Programme, Crops Research Centre Oak Park, Teagasc, Carlow, Ireland.
² College of Life Sciences, School of Biology and Environmental Sciences, University College Dublin , Dublin , Ireland.
³ Research Operations Group, Statistics and Applied Physics Department, Teagasc , Dublin , Ireland.
⁴ Crops, Environment & Land Use Programme, Crops Research Centre Oak Park, Teagasc , Carlow , Ireland.

Abstract

Background: Maize (Zea mays) is a C₄ tropical cereal and its adaptation to temperate climates can be problematic due to low soil temperatures at early stages of establishment.

Methods: In the current study we have firstly investigated the physiological response of twelve maize varieties, from a chilling condition adapted gene pool, to sub-optimal growth temperature during seedling emergence. To identify transcriptomic markers of cold tolerance in already adapted maize genotypes, temperature conditions were set below the optimal growth range in both control and low temperature groups. The conditions were as follows; control (18 °C for 16 h and 12 °C for 8 h) and low temperature (12 °C for 16 h and 6 °C for 8 h). Four genotypes were identified from the condition adapted gene pool with significant contrasting chilling tolerance.

Results: Picker and PR39B29 were the more cold-tolerant lines and Fergus and Codisco were the less cold-tolerant lines. These four varieties were subjected to microarray analysis to identify differentially expressed genes under chilling conditions. Exposure to low temperature during establishment in the maize varieties Picker, PR39B29, Fergus and Codisco, was reflected at the transcriptomic level in the varieties Picker and PR39B29. No significant changes in expression were observed in Fergus and Codisco following chilling stress. A total number of 64 genes were differentially expressed in the two chilling tolerant varieties. These two varieties exhibited contrasting transcriptomic profiles, in which only four genes overlapped.

Discussion: We observed that maize varieties possessing an enhanced root growth ratio under low temperature were more tolerant, which could be an early and inexpensive measure for germplasm screening under controlled conditions. We have identified novel cold inducible genes in an already adapted maize breeding gene pool. This illustrates that further varietal selection for enhanced chilling tolerance is possible in an already preselected gene pool.

Keywords: Chilling tolerance; Cold stress; Low temperature; Maize; Roots; Transcriptome.

Grants and funding

This research was supported by the Irish Department of Agriculture, Food and the Marine (DAFM) Stimulus Research grant RSF 07 501. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.