Molecular Horticulture最新文献

The transfer of genetic material between stocks and scions of grafted plants has been extensively studied; however, the nature and frequency of the transferred material remain elusive. Here, we report a grafting system involving woody goji as the stock and herbaceous tomato as the scion, which was developed using in vitro and in vivo approaches; the results confirmed horizontal transfer of multiple nuclear DNA fragments from donor goji cells to recipient tomato cells. Tomato tissues containing goji donor DNA fragments at or near the grafting junctions had a perennial-biased anatomical structure, from which roots or shoots were regenerated. Most of the fragments were plasmid-like extrachromosomal circular DNAs (eccDNAs) present in the regenerants derived from the cells and in their asexual offspring. Plants with transferred eccDNAs in regenerated roots or shoots (designated "Go-tomato") were grown perennially and showed excellent agronomic performance. The present study provides new insights into the replication, expression, and potential function of eccDNAs in the pleiotropic traits of Go-tomato. Mobile eccDNAs offer evidence of stock-to-scion horizontal DNA transfer beyond chromosomes and organelles, thereby contributing to the molecular understanding of graft-induced genetic variation, evolution, and breeding.

The plant hormone ethylene is indispensable to the ripening of climacteric fruits. Although extensive studies have been conducted on ethylene signaling, the ethylene response factor (ERF)-mediated transcriptional regulation of ethylene biosynthesis in pear fruits remains to be fully elucidated. We here constructed, sequenced, and analyzed transcriptome libraries in ethephon-treated and 1-MCP-treated Cuiguan pear fruits. In total, 721 fruit ripening-associated differentially expressed genes were identified. Among them, two key genes exhibited positive correlations: the 1-aminocyclopropane-1-carboxylic acid synthase (ACS)-encoding gene PbrACS3 and the ERF-encoding gene named PbrERF114. PbrERF114 overexpression increased ethylene production as well as the PbrACS3 expression level. Conversely, virus-induced gene silencing downregulated PbrERF114, thereby decreasing ethylene production and reducing PbrACS3 expression levels. Notably, PbrERF114 could directly interact with PbrACS3 and PbrERF24 promoters, thus inducing their expression. However, it did not result in an enhancement in luciferase activity, which is regulated by the PbrACS1b or PbrACO1 promoter. PbrERF24 could directly bind to PbrACO1 as well as PbrACS3 to promote ethylene synthesis. In conclusion, PbrERF114 can directly and indirectly mediate ethylene biosynthesis by transcriptionally regulating PbrACS3 and PbrERF24, respectively, thereby triggering a signaling cascade that induces the expression of both PbrACS3 and PbrACO1.

Okra yellow vein mosaic disease (OYVMD) is a major constraint to okra production globally. It is caused by several distinct begomoviruses, including okra yellow vein mosaic virus (OYVMV), that are transmitted by the whitefly. This study synthesizes current knowledge on the complex interactions between whiteflies, begomoviruses, and okra plants that enable viral spread and cause OYVMD. The acquisition and transmission cycle involves specific processes including virion ingestion during phloem-feeding, endocytosis and passage across insect tissues, secretion in saliva, and inoculation into plants. Molecular compatibilities between vector coat proteins, midgut proteins, and plant factors modulate virus replication and movement through barrier tissues. Abiotic stresses and host traits also impact whitefly behavior and virus epidemiology. Begomoviruses such as OYVMV have spread globally wherever whitefly vectors and susceptible okra varieties occur. Integrated management of the tripartite pathosystem that incorporates host resistance, cultural tactics, and biological control is required to mitigate the transmission of begomoviruses and OYVMD impact. Finally, resolving vector-virus interactions and developing interference strategies will help contribute to strengthening okra germplasm resistance which can support sustainable food production.

The D14 protein, an alpha/beta hydrolase, is a key receptor in the strigolactone (SL) signaling pathway. However, the response of VvD14 to SL signals and its role in grapevine root architecture formation remain unclear. This study demonstrated that VvD14c was highly expressed in grapevine tissues and fruit stages than other VvD14 isoforms. Application of GR24, an SL analog, enhanced the elongation and diameter of adventitious roots but inhibited the elongation and density of lateral roots (LRs) and increased VvD14c expression. Additionally, GR24 is nested within the VvD14c pocket and strongly bound to the VvD14c protein, with an affinity of 5.65 × 10^-9 M. Furthermore, VvD14c interacted with grapevine MORE AXILLARY GROWTH 2 (VvMAX2) in a GR24-dependent manner. Overexpression of VvD14c in the d14 mutant and VvMAX2 in the max2 Arabidopsis mutant reversed the increased LR number and density, as well as primary root elongation. Conversely, homologous overexpression of VvD14c and VvMAX2 resulted in reduced LR number and density in grapevines. VvMAX2 directly interacted with LATERAL ORGAN BOUNDARY (VvLOB) and VvLBD19, thereby positively regulating LR density. These findings highlight the role of SLs in regulating grapevine root architecture, potentially via the VvD14c-VvMAX2-VvLOB/VvLBD19 module, providing new insights into the regulation of root growth and development in grapevines.

Fruit ripening is accompanied by the development of fruit quality traits; however, this process also increases the fruit's susceptibility to various environmental stresses, including pathogen attacks and other stress factors. Therefore, modulating the fruit ripening process and defense responses is crucial for maintaining fruit quality and extending shelf life. Membrane proteins play intricate roles in mediating signal transduction, ion transport, and many other important biological processes, thus attracting extensive research interest. This review mainly focuses on the functions of membrane proteins in regulating fruit ripening and defense responses against biotic and abiotic factors, addresses their potential as targets for improving fruit quality and resistance to environmental challenges, and further highlights some open questions to be addressed.

Fruit color substantially affects consumer preferences, with darker red strawberries being economically more valuable due to their higher anthocyanin content. However, the molecular basis for the dark red coloration remains unclear. Through screening of an ethyl methanesulfonate mutant library, we identified a rg418 mutant, that demonstrated anthocyanin accumulation during early fruit development stages. Furthermore, the ripening fruits of this mutant had higher anthocyanin content than wild-type (WT) fruits. An analysis of flavonoid content in WT and rg418 mutant fruits revealed substantial changes in metabolic fluxes, with the mutant exhibiting increased levels of anthocyanins and flavonols and decreased levels of proanthocyanidins. Bulked sergeant analysis sequencing indicated that the mutant gene was anthocyanidin reductase (ANR), a key gene in the proanthocyanidin synthesis pathway. Furthermore, transcriptome sequencing revealed the increased expression of MYB105 during the early development stage of mutant fruits, which promoted the expression of UFGT (UDP-glucose flavonoid 3-O-glucosyltransferase), a key gene involved in anthocyanin synthesis, thus substantially enhancing the anthocyanin content in the mutant fruits. Additionally, mutating ANR in a white-fruited strawberry variant (myb10 mutant) resulted in appealing pink-colored fruits, suggesting the diverse roles of ANR in fruit color regulation. Our study provides valuable theoretical insights for improving strawberry fruit color.

The cultivated tomato, Solanum lycopersicum, is highly sensitive to cold stress (CS), resulting in significant losses during cultivation and postharvest fruit storage. Previously, we demonstrated the presence of substantial genetic variation in fruit chilling tolerance in a tomato recombinant inbred line (RIL) population derived from a cross between a chilling-sensitive tomato line and a chilling-tolerant accession of the wild species S. pimpinellifolium. Here, we investigated molecular and biochemical components associated with chilling tolerance in fruit and leaves, using contrasting groups of "chilling tolerant" and "chilling sensitive" RI lines. Transcriptomic analyses were conducted on fruit exposed to CS, and gene expressions and biochemical components were measured in fruit and leaves. The analyses revealed core responding genes specific to either the cold-tolerant or cold-sensitive RI lines, which were differentially regulated in similar fashion in both leaves and fruit within each group. These genes may be used as markers to determine tomato germplasm cold tolerance or sensitivity. This study demonstrated that tomato response to CS in different developmental stages, including seedling and postharvest fruit, might be mediated by common biological/genetic factors. Therefore, genetic selection for cold tolerance during early stages of plant development may lead to lines with greater postharvest fruit chilling tolerance.

Plants possess the ability to induce programmed cell death (PCD) in response to abiotic and biotic stresses; nevertheless, the evidence on PCD initiation during pear scald development and the involvement of the scald trigger 6-methyl-5-hepten-2-one (MHO) in this process is rudimentary. Pyrus bretschneideri Rehd. cv. 'Dangshansuli' pear was used to validate such hypothesis. The results showed that superficial scald occurred after 120-d chilling exposure, which accompanied by typical PCD-associated morphological alterations, such as plasmolysis, cell shrinkage, cytosolic and nuclear condensation, vacuolar collapse, tonoplast disruption, subcellular organelle swelling, and DNA fragmentation. These symptoms were aggravated after MHO fumigation but alleviated by diphenylamine (DPA) dipping. Through transcriptome assay, 24 out of 146 PCD-related genes, which were transcribed during cold storage, were identified as the key candidate members responsible for these cellular biological alternations upon scald development. Among these, PbrCNGC1, PbrGnai1, PbrACD6, and PbrSOBIR1 were implicated in the MHO signaling pathway. Additionally, PbrWRKY2, 34 and 39 could bind to the W-box element in the promoter of PbrGnai1 or PbrSOBIR1 and activate their transcription, as confirmed by dual-luciferase, yeast one-hybrid, and transient overexpression assays. Hence, our study confirms the PCD initiation during scald development and explores the critical role of MHO in this process.