The R2R3-MYB is a large gene family involved in various plant functions, including carotenoid biosynthesis. However, this gene family lacks a comprehensive analysis in wolfberry (Lycium barbarum L.) and other Solanaceae species. The recent sequencing of the wolfberry genome provides an opportunity for investigating the organization and evolutionary characteristics of R2R3-MYB genes in wolfberry and other Solanaceae species. A total of 610 R2R3-MYB genes were identified in five Solanaceae species, including 137 in wolfberry. The LbaR2R3-MYB genes were grouped into 31 subgroups based on phylogenetic analysis, conserved gene structures, and motif composition. Five groups only of Solanaceae R2R3-MYB genes were functionally divergent during evolution. Dispersed and whole duplication events are critical for expanding the R2R3-MYB gene family. There were 287 orthologous gene pairs between wolfberry and the other four selected Solanaceae species. RNA-seq analysis identified the expression level of LbaR2R3-MYB differential gene expression (DEGs) and carotenoid biosynthesis genes (CBGs) in fruit development stages. The highly expressed LbaR2R3-MYB genes are co-expressed with CBGs during fruit development. A quantitative Real-Time (qRT)-PCR verified seven selected candidate genes. Thus, Lba11g0183 and Lba02g01219 are candidate genes regulating carotenoid biosynthesis in wolfberry. This study elucidates the evolution and function of R2R3-MYB genes in wolfberry and the four Solanaceae species.

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.

Wolfberry (Lycium barbarum L.) is a small Solanaceae shrub with medicinal and edible homology, and widely used as ethnobotanical medicine and nutraceutical food. The wolfberry fruits mainly have red, purple, and yellow phenotypes. Wolfberries are rich in flavonoids, which are natural water-soluble pigments that endow a variety of colors in plants There are very few investigations on mechanism of flavonoids biosynthesis and fruit coloring reported about wolfberry. The widely targeted metabolome and transcriptome analysis were performed to obtain metabolite and gene expression profiles of red, yellow, and purple wolfberries and to explain the underlying molecular mechanism of the color differences in wolfberry. As result, metabolomics analysis revealed that the bluish anthocyanins Malvidin and petunidin trended to accumulate in purple wolf-berry, while red and yellow wolfberries trended to accumulate more yellowish flavonoids. And transcriptome analysis showed that flavonoid synthesis-related genes, such as CHS, F3H, ANS and DFR, and several MYB and bHLH genes were differentially expressed among wolfberries in different colors: most of them were more highly expressed in purple wolfberries than in red and yellow ones. In conclusion, the different flavonoids’ accumulation patterns may result in the different fruit colors of wolfberry, and the MYB or bHLH transcription factors could regulate the expression of flavonoids biosynthesis related genes to change the composition of flavonoids or anthocyanins in wolfberry fruits and result in varied fruit colors. These findings provide new insights into the underlying molecular mechanism of the fruit color differences in wolfberry and provide new ideas for molecular breeding of wolfberry.

Background: Lycium barbarum L. is gaining significant interest as a medicinal and culinary raw material. The quality and aroma are significantly influenced by metabolite accumulation, which differs based on origins and drying methods. Methods: This study utilizes gas chromatography–mass spectrometry (GC-MS) to analyze the metabolic profiles of the ‘Ningqi’ No. 1 variety from three distinct origins employing two drying techniques (natural sun drying, NSD; hot-air drying, HAD). The samples include Zhongping, Ningxia, with HAD (1-1); Zhongning, Ningxia, with NSD (1-2); Wuwei, Gansu, with NSD (1-3); Nuomuhong, Qinghai, with NSD (1-4); and Nuomuhong, Qinghai, with HAD (1-5). Results: The study found that aldehydes, esters, ketones and alcohol are key secondary metabolites generated during NSD and HAD treatments of goji berry from various regions. Flavor analysis revealed the compound Ethanol, 2-phenoxy- (balsamic) was up accumulated in goji berry from Qinghai drying with NSD compared with HAD; goji berry drying with HAD collected from Ningxia compared with Qinghai; goji berry drying with NSD collected from Gansu compared with Ningxia; and goji berry drying with NSD collected from Qinghai compared with Ningxia. The compound 2-Thiophenemethanol (burnt) was up accumulated in goji berry drying with HAD collected from Ningxia compared with Qinghai. Further flavor analysis revealed that the compound Undecanal (floral) was up accumulated in goji berry drying with NSD collected from Qinghai compared with Ningxia and Gansu. 1H-Pyrrole-2-carboxaldehyde (burnt), 1-ethyl- (burnt) was up accumulated in goji berry drying with NSD collected from Qinghai compared with Gansu. KEGG enrichment analysis suggests that ‘Arginine and proline metabolism’ could be the primary metabolic pathway in the goji berry drying process. Conclusions: This study examined how origins and drying methods affected the metabolites and metabolic pathways of goji berries to elucidate the mechanisms impacting their quality and flavor. The findings provide important insights into the use of goji berries in functional foods and pharmaceuticals.