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Transcriptomic response of maize primary roots to low temperatures at seedling emergence
Di Fenza, Mauro Hogg, Bridget Grant, Jim Barth, Susanne
Di Fenza, Mauro
Hogg, Bridget
Grant, Jim
Barth, Susanne
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2017-01-05
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Di Fenza M, Hogg B, Grant J, Barth S. 2017. Transcriptomic response of maize primary roots to low temperatures at seedling emergence. PeerJ 5:e2839 https://doi.org/10.7717/peerj.2839
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.