Metabolomic and Transcriptomic Analyses of Lycium barbarum L. under Heat Stress

Heat stress has a strong and detrimental effect on plant growth and yield. Goji berry or wolfberry (Lycium barbarum L.) is a dual-purpose medicinal and food plant but an increase in high temperatures has caused a serious decline in wolfberry yield and quality. In this study, we first explored the heat stress responses of Goji berry, and found that heat stress adaptation mechanisms fluctuated over 48 h. Moreover, L. barbarum 1402 was more heat resistant while L. barbarum Ningqi No. 7 (N7) was sensitive to high temperatures, in which amino acids and alkaloids played key roles; expression and accumulation timing was also crucial. That is, 1402 responded to heat stress rapidly starting at 1 h under high temperature, activated related genes, and accumulated metabolites earlier in the amino acid metabolic pathway compared to N7, which responded to heat stress starting at 3 h under high temperature. Thus, 1402 resisted high temperatures much earlier and better compared to N7. Furthermore, joint transcriptome and metabolome analysis results showed that L-phenylalanine, L-tyrosine, N-benzylformamide, N-benzylmethylene isomethylamine, lysoPC 19:1, and N-acetyl-D-glucosamine-1-phosthate, as well as their related genes, were higher in content, or earlier in expression, in 1402 compared to N7 under heat treatment. This study initially elucidates that Goji berry 1402 has a better tolerance to heat stress than N7 for earlier and higher expression or accumulation of amino acids and alkaloids when related to high temperatures.