Transcriptomic insights into the allelopathic effects of the garlic allelochemical diallyl disulfide on tomato roots.

Fang Cheng,Huan-Wen Meng,Zhi-Hui Cheng

doi:10.1038/srep38902

Abstract

Garlic is an allelopathic crop that can alleviate the obstacles to continuous cropping of vegetable crops. Diallyl disulfide (DADS), one of the most important allelochemicals in garlic, promotes tomato root growth. Therefore, the global transcriptome profiles of DADS-treated tomato roots over time were investigated to reveal the potential growth-promoting mechanisms. We detected 1828, 1296 and 1190 differentially expressed genes (DEGs) in the 4, 24 and 48 h samples, respectively. Most DEGs involved in assimilatory sulfate reduction and glutathione metabolism were up-regulated after short-term (4 h) DADS treatment. In addition, increased activity of defensive enzymes and up-regulation of six peroxidase genes were observed, suggesting that DADS could induce tomato resistance. In plant-pathogen interactions, DEGs related to calcium signaling were primarily inhibited, while those encoding pathogenesis-related proteins were primarily up-regulated. Although plant hormone synthesis and signal transduction were both significantly affected by DADS, the expression trends of the genes in these two pathways were conflicting. This research provides comprehensive information concerning the changes in the tomato root transcriptome affected by DADS and may help direct further studies on DADS-responsive genes to enhance the current understanding of the mechanisms by which DADS alleviates the obstacles to continuous cropping.

Highlights

Garlic is an allelopathic crop that can alleviate the obstacles to continuous cropping of vegetable crops
12 differentially expressed gene (DEG) libraries were constructed from tomato roots treated with Diallyl disulfide (DADS) for 0, 4, 24 and 48 h to identify differentially expressed genes (DEGs) in response to DADS
The expression of three CNGCs and most of the genes related to calcium sensor proteins, such as calcium-dependent protein kinase (CDPK), CaM and CML, were inhibited. These results indicate that the Ca2+ signaling and signal transduction mediated through calcium sensor proteins were weakened in tomato root after DADS application

Summary

Introduction

Garlic is an allelopathic crop that can alleviate the obstacles to continuous cropping of vegetable crops. This research provides comprehensive information concerning the changes in the tomato root transcriptome affected by DADS and may help direct further studies on DADS-responsive genes to enhance the current understanding of the mechanisms by which DADS alleviates the obstacles to continuous cropping. The anticancer mechanisms of DADS include the activation of enzymes that can detoxify carcinogens; suppression of DNA adduct formation; antioxidation; cell-cycle regulation; induction of apoptosis and differentiation; histone modification; and inhibition of blood vessel formation and invasion[9,10]. Researchers have demonstrated that DADS-affected genes and proteins in cancer cells are involved in signal transduction, cell proliferation and differentiation, apoptosis, cell cycle regulation, DNA replication and transcription, protein degradation, immunity, the cytoskeleton, oxidation-reduction and metabolism[14,15]. We propose that DADS may play an important role in alleviating the obstacles to continuous cropping of vegetables

Results

Discussion

Conclusion