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International Journal of Genomics
Volume 2018, Article ID 6725728, 8 pages
https://doi.org/10.1155/2018/6725728
Research Article

Comparative Transcriptome Analysis of Temperature-Induced Green Discoloration in Garlic

1Key Laboratory of Food Processing Technology and Quality Control in Shandong Province, College of Food Science and Engineering, Shandong Agricultural University, No. 61, Daizong Road, Tai’an, Shandong Province 271018, China
2State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, No. 61, Daizong Road, Tai’an, Shandong Province 271018, China

Correspondence should be addressed to Xiaozhen Tang; nc.ude.uads@zxt and Xuguang Qiao; nc.ude.uads@oaiqgx

Received 16 April 2018; Revised 17 September 2018; Accepted 16 October 2018; Published 2 December 2018

Academic Editor: Wilfred van IJcken

Copyright © 2018 Ningyang Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Green discoloration is one of the most important problems that cause low quality of product in the processing of garlic, which can be induced by low-temperature stress. But the mechanism of low temperature-induced green discoloration is poorly understood. In the present study, the control garlic and three low temperature-treated garlic samples (stored at 4°C with 10, 15, and 40 days, respectively) were used for genome-wide transcriptome profiling analysis. A total of 49280 garlic unigenes with an average length of 1337 bp were de novo assembled, 20231 of which were achieved for functional annotation. When being suffered from 10, 15, and 40 days of low-temperature treatment, an increased degree of discoloration was observed, and a total of 4757, 4401, and 2034 unigenes showed a differential expression, respectively. Finally, 5923 differentially expressed genes (DEGs) were found to respond to the low-temperature stress, of which 3921 were identified in at least two treatments. Among these stress-responsive unigenes, there were large numbers of enzyme-encoding genes, which significantly enriched the pathway “proteasome,” many genes of which are potentially involved in the garlic discoloration, such as 7 alliinase-encoding genes, 5 γ-glutamyltranspeptidase-encoding genes, and 1 δ-aminolevulinic acid dehydratase-encoding gene. These stress-responsive enzyme-encoding genes are possibly responsible for the low-temperature-induced garlic discoloration. The identification of large numbers of DEGs provides a basis for further elucidating the mechanism of low-temperature-induced green discoloration in garlic.