Mulberry (Morus spp., Moraceae) is an important economic crop plant and is rich in flavonoids and anthocyanidins in ripe fruits. Anthocyanins are glycosides of anthocyanidins. Flavanone 3-hydroxylase (F3H) catalyzes the conversion of naringenin into dihydroflavonols and is responsible for the biosynthesis of flavonols and anthocyanidins. In this study, MazsF3H was cloned and characterized from Morus atropurpurea var. Zhongshen 1. Conserved motif analysis based on alignment and phylogenetic analysis indicated that MazsF3H belonged to 2-oxoglutarate-dependent dioxygenase and MazsF3H clustered with F3Hs from other plants. MazsF3H was located in both nucleus and cytosol. MazsF3H was expressed in stems, leaves, stigmas and ovaries, except buds. F3H expression levels showed a positive and close relationship with anthocyanin content during the anthocyanin-rich fruit ripening process, while it showed a negative correlation with anthocyanin content in LvShenZi, whose fruits are white and would not experience anthocyanin accumulation during fruit ripening. Significantly different F3H expression levels were also found in different mulberry varieties that have quite different anthocyanin contents in ripe fruits. Overexpression MazsF3H in tobacco showed unexpected results, including decreased anthocyanin content. Down-regulation of F3H expression levels resulted in co-expression of the genes involved in anthocyanin biosynthesis and a significant decrease in anthocyanin content, but the change in total flavonoid content was subtle. Our results indicated that F3H may play quite different roles in different varieties that have quite different fruit colors. In addition, possible complex regulation of flavonoid biosynthesis should be further explored in some of the featured plant species.

The objective of this work was to study the contribution of different peanut varieties with regard to their arachin and conarachin fractions, and their respective subunits to protein gel properties. It was found that the proteins of various cultivars could be classified into two groups according to the lack of the 35.5 kDa acidic subunit of the arachin. Two peanut cultivars, Yueyou7 and Qinglan8, had the highest content of arachin (62.3%) and conarachin (53.5%), respectively. Three indexes, namely, hardness, springiness, and cohesiveness, were used to describe the protein gel properties. An efficient approach was developed to characterize the three gel properties into one index. The correlation coefficients between the newly depicted index and the original ones were 0.87, 0.41, and 0.47, which corresponded to hardness, springiness, and cohesiveness, respectively. Principal component analysis, linear discriminant analysis, and cluster analysis were used as classification techniques. About 40 varieties were classified into three groups by principal component analysis and all group members determined by principal component analysis are in the predicted group that 100.0% of original grouped cases correctly classified by linear discriminant analysis. The result of cluster analysis had some similarities with the principal component analysis.

The V-myb myeloblastosis viral oncogene homolog (MYB) family participate in various bioprocesses including development and abiotic stress responses. In the present study, we first report a 1R SHAQKYF-class MYB, MaMYBR30, in mulberry. Subcellular localization and sequence analysis indicated MaMYBR30 is located in the nucleus and belongs to a CCA-like subgroup with a conserved SHAQKYF motif. Expression profile analysis showed that MaMYBR30 is expressed in leaves and can be induced by drought and salt stress. The down-regulation of MaMYBR30 using virus-induced gene silence (VIGS) in mulberry and the overexpression of MaMYBR30 in Arabidopsis were induced to explore the function of MaMYBR30. The functional characterization of MaMYBR30 in vivo indicated that MaMYBR30 can positively regulate the resistance of mulberry to drought while negatively regulating the resistance of mulberry to salt stress. In addition, MaMYBR30 also affects flower development and reproductive growth, especially after exposure to salt stress. Weighted gene co-expression network analysis (WGCNA) primarily revealed the possible genes and signal pathways that are regulated by MaMYBR30. Our results also imply that complex molecular mechanisms mediated by MaMYBR30, including crosstalk of ion toxicity, phytohormone signal transduction, flowering development, and epigenetic modification, need to be further explored in the future.

Background: The V-myb myeloblastosis viral oncogene homolog (MYB) family of proteins is large, containing functionally diverse transcription factors. However, MYBs in Morus are still poorly annotated and a comprehensive functional analysis of these transcription factors is lacking. Results: In the present study, a genome-wide identification of MYBs in Morus alba was performed. In total 166 MaMYBs were identified, including 103 R2R3-MYBs and four 3R-MaMYBs. Comprehensive analyses, including the phylogenetic analysis with putative functional annotation, motif and structure analysis, gene structure organization, promoter analysis, chromosomal localization, and syntenic relationships of R2R3-MaMYBs and 3R-MaMYBs, provided primary characterization for these MaMYBs. R2R3-MaMYBs covered the subgroups reported for R2R3-MYBs in Arabidopsis and Populus, and had two Morus-specific subgroups, indicating the high retention of MYBs in Morus. Motif analysis revealed high conservative residues at the start and end of each helix and residues consisting of the third helix in R2 and R3 repeats. Thirteen intron/exon patterns (a–m) were summarized, and the intron/exon pattern of two introns with phase numbers of 0 and 2 was the prevalent pattern for R2R3-MaMYBs. Various cis-elements in promoter regions were identified, and were mainly related to light response, development, phytohormone response, and abiotic and biotic stress response and secondary metabolite production. Expression patterns of R2R3-MaMYBs in different organs showed that MaMYBs involved in secondary cell wall components and stress responsiveness were preferentially expressed in roots or stems. R2R3-MaMYBs involved in flavonoid biosynthesis and anthocyanin accumulation were identified and characterized based on functional annotation and correlation of their expression levels with anthocyanin contents. Conclusion: Based on a comprehensive analysis, this work provided functional annotation for R2R3-MYBs and an informative reference for further functional dissection of MYBs in Morus.

Physiological and morphological traits have a considerable impact on the biomass production of fast-growing trees. To compare cultivar difference in shoot biomass and investigate its relationships with leaf functional traits in mulberry, agronomic traits and 20 physiological and morphological attributes of 3-year-old mulberry trees from eight cultivars growing in a common garden were analyzed. The cultivars Xiang7920, Yu711, and Yunsang2 had higher shoot fresh biomass (SFB), which was closely associated with their rapid leaf expansion rate, large leaf area, and high stable carbon isotope composition (δ¹³C). Conversely, the cultivars 7307, Husang32, Wupu, Yunguo1, and Liaolu11 were less productive, and this was primarily the result of slower leaf expansion and smaller leaf size. Growth performance was negatively correlated with leaf δ¹³C and positively correlated with the total nitrogen concentration, indicating that a compromise exists in mulberry between water use efficiency (WUE) (low δ¹³C) and high nitrogen consumption for rapid growth. Several morphological traits, including the maximum leaf area (LA_max), leaf width and length, petiole width and length, leaf number per shoot, and final shoot height were correlated with SFB. The physiological traits that were also influential factors of shoot biomass were the leaf δ¹³C, the total nitrogen concentration, and the water content. Among the studied leaf traits, LA_max, leaf δ¹³C, and concentrations of chlorophyll a and b were identified as the most representative predictor variables for SFB, accounting for 73% of the variability in SFB. In conclusion, a combination of LA_max, leaf δ¹³C, and chlorophyll should be considered in selection programs for high-yield mulberry cultivars.