Manja Božić*, Dragana Ignjatović Micić, Nikola Grčić, Marko Mladenović and Ana Nikolić
Maize Research Institute Zemun Polje
mbozic [at] mrizp.rs
Abstract
Trehalose is an important osmoprotectant associated with tolerance to various types of abiotic stress factors, such as drought and extreme temperatures, particularly low temperatures. Many research works have shown that trehalose synthesis and accumulation were included in the low-temperature (LT) response in maize, but most were not focused on its synthesis in roots. As one of the most promising strategies of avoiding yield loss due to effects of climate change in temperate areas is early sowing, understanding all the mechanisms and pathways responsible for establishing LT tolerance in every part of the maize plant during the early developmental stages becomes a priority.
Herein, plants belonging to two maize genotypes (tolerant – Ltol and susceptible – Lsus to low temperatures) were exposed to LT conditions for 24h (8/10° C) while in the V3 developmental stage (fully developed third leaf). Samples for RNA isolation and cDNA library preparation were taken 6h and 24h after the treatment began, and paired-end transcriptome sequencing was performed (Illumina® Novaseq 6000). The same was done for control plants grown in optimal conditions (25°/20°C). Sequencing was followed by raw-data quality check and filtering, mapping to the reference genome, and read quantification, necessary for the differential expression (DE) analysis.
DE profiling showed that several trehalose-6-phosphate synthase (TPS) and trehalose 6-phosphate phosphatase (TPP) genes, necessary for trehalose synthesis, were differentially expressed between the control and treatment conditions in both genotypes. TPP genes were up-regulated in either of the time-points in both genotypes – ZmTPP3.2, ZmTPP9, and ZmTPP12. On the other hand, several TPS genes were down-regulated in either of the time points in Lsus, but were up-regulated after 24h in Ltol – ZmTPS6.3, ZmTPS9.3, and ZmTPS11.3. The results show that while both genotypes seemed to successfully synthesise the trehalose precursor, trehalose-6-phosphate, only in Ltol is the precursor translated into trehalose.
Keywords: maize, low-temperature stress, RNAseq, trehalose