Effect of short-term high temperature on the accumulation of glucosinolates in Brassica rapa

Glucosinolates, an important class of secondary metabolites in cruciferous vegetables, play a crucial role in protecting plants from stress-related damage. The mechanism of glucosinolate synthesis under short-term high temperature stress has not been sufficiently studied. In this work, we investigated the changes in transcription factors, synthetic genes, and related metabolites involved in glucosinolate synthesis by pakchoi seedlings under short-term high temperature stress (40 degrees C for 8 h). Short-term high temperature stress inhibited the primary sulfur assimilation and the contents of methionine, cysteine and glutathione. The contents of aliphatic and indolic glucosinolates were increased by short-term high temperature stress, whereas the content of 4-methoxy-glucobrassicin increased significantly. During the stress period, the transcript level of glucosinolate related MYB transcription factors had been basically significantly up-regulated, whereas the transcript level of aliphatic and indolic glucosinolate synthetic genes were predominantly up-regulated and down-regulated respectively. In the early recovery period, primary sulfur assimilation up-regulated rapidly, and decreased during the late recovery process. The glucosinolate content and synthesis gene expression act similar to the primary sulfur assimilation, a short up-regulated in early recovery, then all go down at 40 and 48 h after short-term high temperature treatment.

Automated summary

Short-term high temperature stress affects the synthesis of glucosinolates in pakchoi seedlings by altering the levels of primary sulfur assimilation, aliphatic and indolic glucosinolates, and related gene expression. The stress results in an increase in certain glucosinolate contents, such as 4-methoxy-glucobrassicin, and up-regulation of MYB transcription factors for glucosinolates, but with variations in the transcript levels of different synthetic genes. Additionally, the recovery period shows a rapid up-regulation of primary sulfur assimilation before declining, similar to glucosinolate content and gene expression.