Roses are the most important cut flower crops and widely used woody ornamental plants in gardens throughout the world, and they are model plants for studying the continuous-flowering trait of woody plants. To analyze the molecular regulation mechanism of continuous flowering, comparative transcriptome data of once- and continuous-flowering roses in our previous study were used to conduct weighted gene co-expression network analysis (WGCNA) to obtain the candidate genes related to flowering transitions. The expression patterns of candidate genes at different developmental stages between Rosa chinensis “Old Blush” (continuous-flowering cultivar) and R. “Huan Die” (once-flowering cultivar) were investigated, and the relationship of the key gene with the endogenous hormone was analyzed. The results showed that the expression trends of VIN3-LIKE 1 (VIL1), FRIGIDA- LIKE 3 (FRI3), APETALA 2- LIKE (AP2-like) and CONSTANS-LIKE 2 (CO-like 2) genes were significantly different between “Old Blush” and “Huan Die”, and the expression trends of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and CO-like 2 were consistent in the flowering transition of “Old Blush” under different environments. The changes in cytokinin and gibberellic acid (GA₃) content were different in the two rose cultivars. The overall change trend of the abscisic acid and GA₃ in the flowering transition of “Old Blush” under different environments was consistent. The promoter sequence of CO-like 2 contained a P-box element associated with gibberellin response, as well as binding sites for transcription factors. In a word, we found CO-like 2 associated with continuous flowering and some factors that may synergistically regulate continuous flowering. The results provided a reference for elucidating the molecular regulatory mechanisms of continuous-flowering traits in roses.

Protected cultivation is a cultivation practice that plays an important role in improving crop quality. Aroma is an important flavour that assesses the quality of yuzu. In this study, C. junos cv. ‘Kitou’ grown in open fields (CJKTF) and plastic greenhouses (CJKTP) were selected as the study material. Significant differences in aroma performance between CJKTF and CJKTP were found by the olfactory senses of the members of this research group and an electronic nose, with CJKTP having a stronger aroma. Regarding VOCs, GC-MS analyses revealed 13 VOCs up-regulated and 28 VOCs down-regulated in CJKTP compared to CJKTF. Transcriptome analysis revealed that 515 genes were up-regulated and 720 genes were down-regulated in CJKTP compared to CJKTF. The differential VOCs nerolidol and γ-cadinene, and the differential genes nerolidol synthase 1 (NES1), nerolidol synthase 1-like (NES1-like), and cadinene synthase (DCS), were in the sesquiterpene synthesis pathway and showed significant correlation. NES1, NES1-like, and DCS encode terpene synthases, which may be involved in the biosynthetic pathway of nerolidol and γ-cadinene. In conclusion, the use of plastic greenhouses for cultivation may improve the quality and aroma intensity of yuzu, as well as alter the expression of related genes, compared to field cultivation. These results suggest that protected cultivation is a suitable cultivation practice to enhance the aroma of yuzu.

Citrus cultivars are propagated asexually through methods such as layering, cutting, and grafting. Grafting plays a critical role in regulating citrus fruit quality by optimizing stock–scion combinations. This study evaluated the grafting compatibility of two interstocks with Cocktail grapefruits (Citrus paradisi Macf. cv. Cocktail) by analyzing physiological and volatile traits of the fruits. We used Changshanhuyou (Citrus paradisi cv. Changshanhuyou) and Ponkan (Citrus reticulata Blanco cv. Ponkan), which are traditional citrus varieties in Quzhou, Zhejiang Province, as interstocks. Our results showed that the grapefruit fruits grafted onto Changshanhuyou exhibited higher total soluble solids (12.3 °Brix) and a brighter, more uniform peel color. The acidity of fruits grafted onto Changshanhuyou was lower than that of fruits grafted onto Ponkan and similar to the fruits from the control group that were grafted directly onto trifoliate orange. In terms of volatile organic compounds (VOCs), 974 and 577 unique VOCs were identified in the peel and pulp, respectively. In the peel, 34 (26 upregulated and 8 downregulated) and 14 (13 upregulated and 1 downregulated) differentially accumulated VOCs were identified when comparing the trifoliate orange group with Changshanhuyou and Ponkan groups, respectively. The pulp exhibited greater VOC diversity, with 272 (24 upregulated and 248 downregulated) and 199 (4 upregulated and 195 downregulated) differentially accumulated VOCs detected for the same comparisons. In conclusion, compared with direct grafting onto trifoliate orange or on Ponkan as an interstock, grafting onto Changshanhuyou resulted in better fruit quality and distinct differences in flesh flavor. These findings suggest that Changshanhuyou is a more suitable interstock for Cocktail grapefruit (Citrus paradisi Macf. cv. Cocktail) cultivation.