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Graft healing is a complex process affected by environmental factors, with temperature being one of the most important influencing factors. Here, oriental melon grafted onto pumpkin was used to study changes in graft union formation and sugar contents at the graft interface under night temperatures of 18 °C and 28 °C. Histological analysis suggested that callus formation occurred 3 days after grafting with a night temperature of 28 °C, which was one day earlier than with a night temperature of 18 °C. Vascular reconnection with a night temperature of 28 °C was established 2 days earlier than with a night temperature of 18 °C. Additionally, nine sugars were significantly enriched in the graft union, with the contents of sucrose, trehalose, raffinose, D–glucose, D–fructose, D–galactose, and inositol initially increasing but then decreasing. Furthermore, we also found that exogenous glucose and fructose application promotes vascular reconnection. However, exogenous sucrose application did not promote vascular reconnection. Taken together, our results reveal that elevated temperatures improve the process of graft union formation through increasing the contents of sugars. This study provides information to develop strategies for improving grafting efficiency under low temperatures. [ABSTRACT FROM AUTHOR]

The labor-efficient automation of grafting has been recognized as a key factor in the wider adoption of grafting. In growing cucurbits, the root pruned one-cotyledon grafting method is the most commonly used method with grafting machines. The cutting angle, which affects the matching of the rootstock and scion, is key to the survival of the graft seedling. In the production of cucurbit graft seedlings, the cutting parameters are established based on experience, leading to low grafting success. To determine accurate cutting parameters, the watermelon cv. 'Zaojia84-24′ was used as the scion and the pumpkin cv. 'Zhenzhuang' was used as rootstock, and two one-way experiments investigating the cutting angle of the watermelon scion and the rootstock as factors were conducted. The cutting angle of the rootstock and scion had no significant effect on the xylem reconnection rate or the grafting survival rate. A larger cutting angle for the rootstock and scion led to a delay in the reconnection of the phloem. Different cutting angles for the scion significantly affected the growth of the scion after grafting. Compared with a scion graft cutting angle of 10° (SL), graft cutting angles of 14° (SM) and 20° (SS) led to significantly greater scion dry weights, with increases of 16.00% and 18.61%, respectively. Different cutting angles of the rootstock significantly affected the growth of roots after grafting. Compared with a rootstock graft cutting angle of 10° (RL), graft cutting angles of 17° (RM) and 27° (RS) led to significantly greater root dry weights, with increases of 29.33% and 22.54%, respectively. The results of this study can provide a reference for the design of cutting mechanisms for cucurbit grafting robots, improving the cutting precision of grafting robots. [ABSTRACT FROM AUTHOR]

Mitophagy maintains tissue homeostasis by self-eliminating defective mitochondria through autophagy. How mitophagy regulates stem cell activity during hair regeneration remains unclear. Here, we found that mitophagy promotes the proliferation of hair germ (HG) cells by regulating glutathione (GSH) metabolism. First, single-cell RNA sequencing, mitochondrial probe, transmission electron microscopy, and immunofluorescence staining showed stronger mitochondrial activity and increased mitophagy-related gene especially Prohibitin 2 (Phb2) expression at early-anagen HG compared to the telogen HG. Mitochondrial inner membrane receptor protein PHB2 binds to LC3 to initiate mitophagy. Second, molecular docking and functional studies revealed that PHB2-LC3 activates mitophagy to eliminate the damaged mitochondria in HG. RNA-seq, single-cell metabolism, immunofluorescence staining, and functional validation discovered that LC3 promotes GSH metabolism to supply energy for promoting HG proliferation. Third, transcriptomics analysis and immunofluorescence staining indicated that mitophagy was down-regulated in the aged compared to young-mouse HG. Activating mitophagy and GSH pathways through small-molecule administration can reactivate HG cell proliferation followed by hair regeneration in aged hair follicles. Our findings open up a new avenue for exploring autophagy that promotes hair regeneration and emphasizes the role of the self-elimination effect of mitophagy in controlling the proliferation of HG cells by regulating GSH metabolism., Competing Interests: Competing interests: The authors declare that there is no conflict of interest regarding the publication of this article., (Copyright © 2024 Dehuan Wang et al.)

Rationale: Skin cells actively metabolize nutrients to ensure cell proliferation and differentiation. Psoriasis is an immune-disorder-related skin disease with hyperproliferation in epidermal keratinocytes and is increasingly recognized to be associated with metabolic disturbance. However, the metabolic adaptations and underlying mechanisms of epidermal hyperproliferation in psoriatic skin remain largely unknown. Here, we explored the role of metabolic competition in epidermal cell proliferation and differentiation in psoriatic skin. Methods: Bulk- and single-cell RNA-sequencing, spatial transcriptomics, and glucose uptake experiments were used to analyze the metabolic differences in epidermal cells in psoriasis. Functional validation in vivo and in vitro was done using imiquimod-like mouse models and inflammatory organoid models. Results: We observed the highly proliferative basal cells in psoriasis act as the winners of the metabolic competition to uptake glucose from suprabasal cells. Using single-cell metabolic analysis, we found that the "winner cells" promote OXPHOS pathway upregulation by COX7B and lead to increased ROS through glucose metabolism, thereby promoting the hyperproliferation of basal cells in psoriasis. Also, to prevent toxic damage from ROS, basal cells activate the glutathione metabolic pathway to increase their antioxidant capacity to assist in psoriasis progression. We further found that COX7B promotes psoriasis development by modulating the activity of the PPAR signaling pathway by bulk RNA-seq analysis. We also observed glucose starvation and high expression of SLC7A11 that causes suprabasal cell disulfide stress and affects the actin cytoskeleton, leading to immature differentiation of suprabasal cells in psoriatic skin. Conclusion: Our study demonstrates the essential role of cellular metabolic competition for skin tissue homeostasis., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)