Physiological and transcriptomic analyses reveal a response mechanism to cold stress in Santalum album L. leaves

Xinhua Zhang,Jinhui Zhao,Mingzhi Li,Meiyun Niu,Jun Duan,Chunmei He,Guohua Ma,Songjun Zeng,Jaime A Teixeira Da Silva

doi:10.1038/srep42165

Xinhua Zhang, Jinhui Zhao + Show 7 more

Open Access

https://doi.org/10.1038/srep42165

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Abstract

Santalum album L. (Indian sandalwood) is an economically important plant species because of its ability to produce highly valued perfume oils. Little is known about the mechanisms by which S. album adapts to low temperatures. In this study, we obtained 100,445,724 raw reads by paired-end sequencing from S. album leaves. Physiological and transcriptomic changes in sandalwood seedlings exposed to 4 °C for 0–48 h were characterized. Cold stress induced the accumulation of malondialdehyde, proline and soluble carbohydrates, and increased the levels of antioxidants. A total of 4,424 differentially expressed genes were responsive to cold, including 3,075 cold-induced and 1,349 cold-repressed genes. When cold stress was prolonged, there was an increase in the expression of cold-responsive genes coding for transporters, responses to stimuli and stress, regulation of defense response, as well as genes related to signal transduction of all phytohormones. Candidate genes in the terpenoid biosynthetic pathway were identified, eight of which were significantly involved in the cold stress response. Gene expression analyses using qRT-PCR showed a peak in the accumulation of SaCBF2 to 4, 50-fold more than control leaves and roots following 12 h and 24 h of cold stress, respectively. The CBF-dependent pathway may play a crucial role in increasing cold tolerance.

Highlights

Santalum album L. (Indian sandalwood) is an economically important plant species because of its ability to produce highly valued perfume oils
These results strongly suggest that the cold-stressed sandalwood seedlings actively mounted a stress response after they were exposed to 4 °C
The activities of superoxide dismutase (SOD) and peroxidase (POD) showed continuously increasing trends, with approximately two-fold higher levels than the control at 48 h, implying that these reactive oxygen species (ROS)-scavenging enzymes were involved in the detoxification of ROS induced by cold

Summary

Introduction

Santalum album L. (Indian sandalwood) is an economically important plant species because of its ability to produce highly valued perfume oils. Research has shown that cold stress tolerance involves the remodeling of cell structures and reprogramming gene expression by triggering a series of protective mechanisms against cold damage, including an increase in the level of intracellular solutes, the accumulation of cryoprotectants and antioxidants, as well as the induction of antifreeze proteins and cold-regulated (COR) proteins[8,9]. During cold stress, these metabolites and proteins help to protect plant membranes and prevent cell disruption by stabilizing membrane lipids, maintaining ion homeostasis and scavenging reactive oxygen species (ROS)[3]. Signaling molecules such as Ca2+, protein kinase, ROS, and hormones (auxin, abscisic acid (ABA), and gibberellin (GA)) play important roles in cold-induced gene expression[19,20]

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