A regulatory module by which ethylene and cytokinin interaction affects rose flower senescence.

Class I BPCs repress FUSCA3 during reproductive and seed development to promote ovule development while coordinating embryo and endosperm growth.

Summary: Drought is a major abiotic stress that affects the development and growth of most plants, and limits crop yield worldwide. Although the response of plants to drought has been well documented, much less is known about how plants respond to the water recovery process, namely rehydration. Here, we describe the spatio‐temporal response of plant reproductive organs to rehydration using rose flowers as an experimental system. We found that rehydration triggered rapid and transient ethylene production in the gynoecia. This ethylene burst serves as a signal to ensure water recovery in flowers, and promotes flower opening by influencing the expression of a set of rehydration‐responsive genes. An in‐gel kinase assay suggested that the rehydration‐induced ethylene burst resulted from transient accumulation of RhACS1/2 proteins in gynoecia. Meanwhile, RhMPK6, a rose homolog of Arabidopsis thaliana MPK6, is rapidly activated by rehydration within 0.5 h. Furthermore, RhMPK6 was able to phosphorylate RhACS1 but not RhACS2 in vitro. Application of the kinase inhibitor K252a suppressed RhACS1 accumulation and rehydration‐induced ethylene production in gynoecia, and the protein phosphatase inhibitor okadaic acid had the opposite effect, confirming that accumulation of RhACS1 was phosphorylation‐dependent. Finally, silencing of RhMPK6 significantly reduced ethylene production in gynoecia when flowers were subjected to rehydration. Taken together, our results suggest that temporal‐ and spatial‐specific activation of an RhMPK6‐RhACS1 cascade is responsible for rehydration‐induced ethylene production in gynoecia, and that the resulting ethylene‐mediated signaling pathway is a key factor in flower rehydration.

Kiwifruit (Actinidia chinensis) is a rich nutritious fruit crop owing to a markedly higher content of vitamin C and minerals. To promote fruit set and to increase the yield of kiwifruit, forchlorfenuron (CPPU) has been widely applied. However, the molecular details regarding CPPU controlling kiwifruit development, especially at the fastest fruit growth stage, remain unknown. In the present study, we measured the effect of CPPU on developmental regulation in red-fleshed kiwifruit (Actinidia chinensis ‘Hongyang’). Additionally, a cytological analysis was performed to clarify the precise changes in the cell structure of the CPPU-treated kiwifruits. Moreover, the concentration of endogenous phytohormones, including indoleacetic acid (IAA), zeatin (ZT), gibberellic acid 3 (GA₃), and abscisic acid (ABA), were measured by Enzyme-linked Immunosorbent Assay (ELISA). Furthermore, RNA-Seq was performed to dissect the complicated molecular mechanisms, with a focus on biosynthesis, metabolism, and signaling compounds, such as endogenous hormones, sugars, and L-ascorbic acid. Our results demonstrated that CPPU treatment not only regulates the size and weight of a single fruit but also improves the quality in ‘Hongyang’ kiwifruit through the accumulation of both soluble sugar and vitamin C. It was also seen that CPPU regulates kiwifruit development by enhancing cell expansion of epidermal cells and parenchyma cells, while, promoting cell division of subepidermal cells. Additionally, CPPU significantly increased the gibberellin and cytokinin biosynthetic pathway and signaling, while repressing auxin and ABA biosynthetic pathway; thus, signaling plays an essential role in CPPU controlling kiwifruit development. Notably, transcriptomic analysis revealed that a total of 2244 genes, including 352 unannotated genes, were differentially expressed in kiwifruits because of CPPU treatment, including 127 transcription factors. These genes are mainly enriched in plant hormone signal transduction, photosynthesis, MAPK signaling pathway, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Overall, our results highlight that CPPU regulation of kiwifruit development is mainly associated with an antagonistic and/or synergistic regulatory role of endogenous phytohormones, and enhancing the energy supply. This provides new insights into the molecular details of CPPU controlling kiwifruit development at the fastest fruit growth stage, which is of agricultural importance for kiwifruit breeding and crop improvement.

Long non-coding RNAs (lncRNAs) are pivotal in plant development, including organ morphogenesis. However, currently, the biological significance of potato lncRNAs is still not fully known. This study delved into the cytological, transcriptomic, and phytohormonal dynamics that lie beneath potato tuberization. Special attention was given to the potential regulatory functions of lncRNAs. Cytological analysis indicated that tuber formation, encompassing non-swollen stolons (Stolon, stage 1), swelling stolons (Swelling, stage 2), tuber initiation (Initiation, stage 3), and small tubers (Tuber, stage 4), is marked by progressive cellular expansion, vascular disruption, and starch granule accumulation. Through RNA-seq analysis, 11,380 long non-coding RNA (lncRNAs) were identified across the four developmental stages, among which 520 were Arabidopsis homologs. Long intergenic non-coding RNAs (lincRNAs) predominated, accounting for 85.58%. The differentially expressed long non-coding RNAs (DELs) were predominantly enriched in processes related to auxin response, transcription factor activity, and signal transduction pathways. Phytohormonal profiles exhibited dynamic fluctuations in auxin (IAA), gibberellins (GAs), abscisic acid (ABA), and cytokinin (CTKs). The integration of phytohormone analysis with transcriptomics unveiled intricate regulatory networks among hormonal dynamics - particularly those involving GAs, ABA, and CTKs - transcription factors, and lncRNA genes. Upstream regulatory lncRNAs of crucial tuberization-related genes, including StSP6A, StPOTH1, StGA20OX1, StBRC1b, StAST1, and StSP5G, were identified. Moreover, both transient dual-LUC and GUS reporter assays were employed to verify the effect of StLNC_031680 on the expression of StHSFA6b. Overall, our findings comprehensively and for the first time globally uncovered the potentially crucial roles of lncRNAs in potato tuberization. These findings offer valuable insights into potato tuber formation and support advanced strategies for crop improvement.