Background: High soil salinity often adversely affects plant physiology and agricultural productivity of almost all crops worldwide, such as the crude drug known as wolfberry. However, the mechanism of this action in wolfberry is not fully understood yet. Results: Here in this study, we studied different mechanisms potentially in Chinese wolfberry (Lycium chinese, LC) and black wolfberry (L. ruthenicum, LR) under salinity stress, by analyzing their transcriptome, metabolome, and hormone changes. The hormone detection analysis revealed that the ABA content was significantly lower in LR than LC under normal condition, and increased sharply under salinity stress in LR but not in LC. The transcriptome analysis showed that the salinity-responsive genes in wolfberry were mainly enriched in MAPK signaling, amino sugar and nucleotide sugar metabolism, carbon metabolism, and plant hormone signal transduction pathways in LC, while mainly related to carbon metabolism and protein processing in endoplasmic reticulum in LR. Metabolome results indicated that LR harbored higher flavone and flavonoid contents than LC under normal condition. However, the flavone and flavonoid contents were hardly changed in LR, but increased substantially in LC when exposed to salinity stress. Conclusions: Our results adds ABA and flavone to mechanism understanding of salinity tolerance in wolfberry. In addition, flavone plays a positive role in resistance to salinity stress in wolfberry.

The B-box proteins (BBXs) are a family of zinc-finger transcription factors with one/two B-Box domain(s) and play important roles in plant growth and development as well as stress responses. Wolfberry (Lycium barbarum L.) is an important traditional medicinal and food supplement in China, and its genome has recently been released. However, comprehensive studies of BBX genes in Lycium species are lacking. In this study, 28 LbaBBX genes were identified and classified into five clades by a phylogeny analysis with BBX proteins from Arabidopsis thaliana and the LbaBBXs have similar protein motifs and gene structures. Promoter cis-regulatory element prediction revealed that LbaBBXs might be highly responsive to light, phytohormone, and stress conditions. A synteny analysis indicated that 23, 20, 8, and 5 LbaBBX genes were orthologous to Solanum lycopersicum, Solanum melongena, Capsicum annuum, and Arabidopsis thaliana, respectively. The gene pairs encoding LbaBBX proteins evolved under strong purifying selection. In addition, the carotenoid content and expression patterns of selected LbaBBX genes were analyzed. LbaBBX2 and LbaBBX4 might play key roles in the regulation of zeaxanthin and antheraxanthin biosynthesis. Overall, this study improves our understanding of LbaBBX gene family characteristics and identifies genes involved in the regulation of carotenoid biosynthesis in wolfberry.

Plant–water relations mediated by aquaporins (AQPs) play vital roles in both key plant growth processes and responses to environmental challenges. As a well-known medicinal and edible plant, the harsh natural growth habitat endows Lycium plants with ideal materials for stress biology research. However, the details of their molecular switch for water transport remain unclear. In the present work, we first identified and characterized AQP family genes from Lycium (L.) barbarum at the genome scale and conducted systemic bioinformatics and expression analyses. The results showed that there were 38 Lycium barbarum AQPs (LbAQPs) in L. barbarum, which were classified into four subfamilies, including 17 LbPIP, 9 LbTIP, 10 LbNIP, and 2 LbXIP. Their encoded genes were unevenly distributed on all 12 chromosomes, except chromosome 10. Three of these genes encoded truncated proteins and three genes underwent clear gene duplication events. Cis-acting element analysis indicated that the expression of LbAQPs may be mainly regulated by biotic/abiotic stress, phytohormones and light. The qRT-PCR assay indicated that this family of genes presented a clear tissue-specific expression pattern, in which most of the genes had maximal transcript levels in roots, stems, and leaves, while there were relatively lower levels in flowers and fruits. Most of the LbAQP genes were downregulated during L. barbarum fruit ripening and presented a negative correlation with the fruit relative water content (RWC). Most of their transcripts presented a quick and sharp upregulation response to heat stress following exposure of the 2-month-old seedlings to a 42 °C temperature for 0, 1, 3, 12, or 24 h. Our results proposed that LbAQPs were involved in L. barbarum key development events and abiotic stress responses, which may lay a foundation for further studying the molecular mechanism of the water relationship of Lycium plants, especially in harsh environments.

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.

The characterization of the PYL/RCAR ABA receptors in a great deal of plant species has dramatically advanced the study of ABA functions involved in key physiological processes. However, the genes in this family are still unclear in Lycium (Goji) plants, one of the well–known economically, medicinally, and ecologically valuable fruit crops. In the present work, 12 homologs of Arabidopsis PYL/RCAR ABA receptors were first identified and characterized from Lycium (L.) barbarum (LbPYLs). The quantitative real–time PCR (qRT–PCR) analysis showed that these genes had clear tissue–specific expression patterns, and most of them were transcribed in the root with the largest amount. Among the three subfamilies, while the Group I and Group III members were down–regulated by extraneous ABA, the Group II members were up–regulated. At 42 °C, most transcripts showed a rapid and violent up–regulation response to higher temperature, especially members of Group II. One of the genes in the Group II members, LbPYL10, was further functionally validated by virus–induced gene silencing (VIGS) technology. LbPYL10 positively regulates heat stress tolerance in L. barbarum by alleviating chlorophyll degradation, thus maintaining chlorophyll stability. Integrating the endogenous ABA level increase following heat stress, it may be concluded that LbPYL–mediated ABA signaling plays a vital role in the thermotolerance of L. barbarum plants. Our results highlight the strong potential of LbPYL genes in breeding genetically modified L. barbarum crops that acclimate to climate change.

Wolfberry (Lycium barbarum L.) is a valued traditional medicinal plant and dietary supplement in China. The basic leucine zipper (bZIP) transcription factor (TF) family is a multifunctional group of regulatory proteins critical to plant biology, orchestrating processes such as growth and development, secondary metabolite biosynthesis, and stress responses to abiotic conditions. Despite its significance, limited information about this gene family in wolfberry is available. In this study, a total of 66 LbabZIP genes were identified, exhibiting a non-uniform distribution across all 12 chromosomes. Phylogenetic analysis divided these genes into 13 subgroups based on comparison with Arabidopsis bZIP proteins. Analysis of gene structures and conserved motifs revealed high similarities within individual subgroups. Gene duplication analysis indicated that dispersed duplication (DSD) and whole-genome duplication (WGD) events were the primary drivers of LbabZIP gene family expansion, with all duplicated genes subject to purifying selection. Cis-regulatory element (CRE) analysis of LbabZIP promoter regions identified numerous elements associated with plant growth and development, hormone signaling, and abiotic stress responses. Gene Ontology (GO) annotation further indicated that the LbabZIP genes are involved in transcriptional regulation, metabolism, and other biological processes. Transcriptome data and quantitative real-time PCR (qRT-PCR) analysis demonstrated tissue-specific expression patterns for several LbabZIP genes. Notably, LbaZIP21/40/49/65 showed significant involvement in wolfberry fruit development. Subcellular localization assays confirmed that these four proteins are nucleus-localized. This comprehensive analysis provides a theoretical foundation for future studies investigating the biological functions of LbabZIP genes, especially their role in wolfberry fruit development.