Molecular Horticulture最新文献

Nitrogen (N) is essential for the physiological metabolism, growth, and development of plants. Plants have evolved a complex regulatory network for the efficient regulation of N uptake and utilization to adapt to fluctuations in environmental N levels. However, the mechanisms underlying the regulation of N absorption and utilization in apple remain unclear. Here, we identified MdILR3 (IAA-LEUCINE RESISTANT3) as an upstream regulator of MdNRT2.4 through yeast one-hybrid (Y1H) screening. MdILR3 overexpression significantly up-regulated the expression of MdNRT2.3/2.4 and MdNIA1, resulting in an increase in nitrate content and nitrate reductase activity. Y1H and EMSA assays revealed that MdILR3 directly interacted with the promoters of MdNRT2.3/2.4 and MdNIA1. Furthermore, MdILR3 can directly bind to the promoter of MdSWEET12 and activate its expression, thereby regulating sucrose transport to provide energy for N uptake in roots. In summary, we provide physiological and molecular evidence suggesting that MdILR3 may positively regulate nitrate response by activating the expression of genes related to N uptake and sugar transport. Our findings suggest that genetic improvements in apple could enhance its ability to absorb and utilize N.

Seedless watermelons are increasingly dominating the consumer market due to their convenience and high quality. However, traditional triploid watermelon breeding faces challenges such as long breeding cycles and low survival rates of triploid F₁ progeny, severely hindering both breeding and production. In this study, we identified the ClPS1 gene as being associated with the formation of 2n gametes in watermelon. Expression analysis revealed that ClPS1 is highly expressed during meiosis and microsporogenesis. Using CRISPR/Cas9, we generated ClPS1-targeted mutants, which disrupted chromosome segregation at metaphase II. This led to the production of diploid male spores and abnormal division of male spores, ultimately generating diploid pollen grains, while female meiosis remained unaffected. Moreover, self-fertilization or crosses using these mutants as paternal parents yielded triploid and aneuploid watermelons. Our findings demonstrate, for the first time, the molecular manipulation of 2n gametes to create triploid seedless watermelons, offering new insights into polyploid breeding and evolutionary studies in the Cucurbitaceae family and other species.

Apyrases are a kind of nucleoside triphosphate diphosphohydrolases that catalyze the removal of the terminal phosphate group from nucleoside triphosphate (NTP) or nucleoside diphosphate (NDP). They also function either intracellularly or extracellularly in mediating the NTP/NDP homeostasis critical for plant growth, development, senescence, stress response and adaptation. Initial studies elucidated the biochemistry, structure and function of plant apyrases, while the recent progresses include the crystallography, newly discovered interaction partners and downstream targets for diverse apyrases. Furthermore, these apyrases play diverse roles in horticultural crops with the new recognition of extracellular ATP (eATP) receptors. This review summarized the types, structures, biochemical and physiological functions of plant apyrases and highlighted their roles in plant growth, development, biotic/abiotic stress responses and adaptation. The physiological activities among the apyrases, eATP with its receptor and eATP/iATP homeostasis, were reviewed. In particular, the quality formation / deterioration of postharvest horticultural crops caused by apyrases was emphasized. This paper reviewed the recent advances in the multiple roles of apyrases in horticultural crops and provided insights into the regulation of physiological activities by the enzyme from molecular network perspectives.

Trichomes, hair-like specialized epidermal structures on the surface of most plant organs, play key roles in plant defense against herbivores, reducing water loss, and shielding plants from UV radiation, among other functions. Controlling trichome development and the biosynthesis of trichome-derived specialized metabolites is a common defensive strategy adopted by plants to protect themselves from environmental stresses. However, trichomes exhibit distinctive functions in different plant tissues. Fruits, being the most economically valuable organs of many horticultural plants, often have trichomes on their surface. Nevertheless, there is a notable lack of research on the regulation and function of fruit trichomes, in comparison to the extensive studies conducted on trichomes in other plant tissues. Further investigation is needed to elucidate the specific functions of fruit trichomes. The regulation of plant trichome development and the multiple roles of trichomes represent a dynamic area of plant biology with significant implications for agriculture and biotechnology. This review aims to enhance the understanding of the functions, regulatory mechanisms, and applications of fruit trichomes, emphasizing their importance in advancing agricultural sustainability and productivity.

Intercropping tea plants with Acacia confusa Merr. offers an environmentally sustainable approach to insect population control in tea plantations. However, the primary compounds in A. confusa responsible for this effect and their biosynthetic mechanisms remain undetermined. This study identified (Z)-3-hexenyl acetate, (Z)-3-hexenol, and 1-hexanol as the major volatiles in A. confusa. Field experiments demonstrated that all three compounds affected the tea leafhopper, a significant pest. (Z)-3-Hexenyl acetate repelled leafhoppers, while the other two compounds attracted them. Leafhopper feeding on tea leaves significantly decreased after fumigation with (Z)-3-hexenyl acetate, potentially altering the metabolism of defensive substances in tea leaves. These findings suggest (Z)-3-hexenyl acetate as a crucial component for pest control in tea plantations intercropped with A. confusa. Furthermore, the study identified the nucleus- and cytoplasm-localized AcAAT4 in A. confusa as responsible for (Z)-3-hexenyl acetate biosynthesis. Notably, AcAAT4 expression and the production of the upstream transcription factor AcMYC2b corresponded to the (Z)-3-hexenyl acetate emission pattern. The research also elucidated the positive regulatory effects of nucleus-localized AcMYC2b on AcAAT4 expression. These findings elucidate the molecular basis of (Z)-3-hexenyl acetate emission from A. confusa and provide a theoretical foundation for enhancing intercropping practices in tea plantations.

State transition is a dynamic process to balance the amount of light energy received by photosystem I (PSI) and photosystem II (PSII) so as to maintain an optimal photosynthetic yield and to minimize photo-damage in a fluctuating light environment. Recent studies show that chloroplast acetyltransferase participates in the acetylation of photosynthetic proteins and state transitions. However, the exact molecular mechanisms are poorly understood. In this study, we characterized a chloroplast acetyltransferase in Solanum lycopersicum, SlGNAT2, and found that mutants lacking this enzyme are deficient in state transitions and retarded in growth under fluctuating light. Acetyltransferase activity assays and fluorescence measurements suggest that ⁶Lys of mature SlLhcb2 protein is a target of SlGNAT2 and might be involved in state transitions. In addition, ¹³¹Cys-related redox changes of SlGNAT2 affect its acetylation activity on SlLhcb2 and influence the assembly of the PSI-LHCI-LHCII supercomplex. Therefore, we propose that the chloroplast redox state may regulate the activity of SlGNAT2 which in turn acetylates SlLhcb2 and mediates state transitions in higher plants.

Ultraviolet A (UV-A) radiation possesses great potential for enhancing the bioactive properties of vegetables and also has promising application prospects in controlled-environment agriculture. Lettuce is a widely cultivated model vegetable in controlled-environment agriculture with abundant health-beneficial bioactive compounds. However, the comprehensive regulatory effectiveness and mechanism of UV-A on bioactive compounds in lettuce remain largely unclear. To address this issue, we performed transcriptomic and metabolomic analyses of UV-A-treated lettuce to construct a global map of metabolic features and transcriptional regulatory networks for all major bioactive compounds. Our study revealed that UV-A promotes the accumulation of most phenylpropanoids and vitamins (provitamin A and vitamin E/K₁/B₆) but represses the biosynthesis of sesquiterpenoids. MYB transcription factors (TFs) are key activators of bioactive compound biosynthesis promoted by UV-A, whereas WRKY TFs primarily inhibit the production of sesquiterpenoids. Moreover, light signaling plays a crucial and direct regulatory function in stimulating the biosynthesis of phenylpropanoids and vitamins but not in that of sesquiterpenoids. In comparison, hormone signaling dominates a more decisive regulatory role in repressing sesquiterpenoid biosynthesis through working directly and interacting with WRKY TFs. This study paves the way toward an understanding of the bioactive compound regulation and genetic improvement of lettuce bioactivity value.

Terpenoids, a group of metabolites, are important to plant development and color formation, and serve as valuable nutrients for humans. The enzyme 4-diphosphocytidyl- 2 C-methyl-D-erythritol cytidyltransferase (MCT) plays a pivotal role in the methylerythritol phosphate (MEP) pathway for terpenoid biosynthesis. However, the potential lethality of MCT mutants has hindered further exploration into its functional role in terpenoid metabolite families in plants. Here, we characterized a rare MCT mutant yfm with dwarfism, chlorosis, small leaves, and yellow fruits in tomato. Map-based cloning and sequence analysis revealed that a single nucleotide substitution in the SlMCT gene, which resulted in a point mutation (Leu297Pro) in amino acid in the mutant. Over-expression and complementation of the wild-type SlMCT^T in the yfm mutant restored the fruit color and the other defective phenotypes. This mutation altered the gene expressions and metabolic components in the MEP and other pathways. Consequently, the total contents of carotenoids, chlorophyll, IAA, GAs, and SA were decreased, while the contents of CK, JA, and ABA were increased. Eventually, these alterations led to changes in plant phenotypes and fruit color in yfm. These findings provide novel insights into understanding the roles of MCT on plant development and pigment biosynthesis.

Colletotrichum fructicola is a hemibiotrophic fungal plant pathogen that transitions from biotrophic growth on living host tissue to necrotrophic tissue destruction. During the hemibiotrophic phase, numerous proteins are secreted into the apoplast, mediating host‒pathogen interactions. In this study, we employed apoplastic proteomics and RNA-seq to analyse the proteins secreted during the interaction between C. fructicola and pear. A secreted xylanase, CfXyn11A, was identified as a dual-function effector. In the nonhost Nicotiana benthamiana, it triggered immune responses, including reactive oxygen species production and programmed cell death. However, CfXyn11A evades detection in the host pear, enabling its role in cell wall degradation and nutrient acquisition. Genetic and biochemical assays confirmed that the immune-triggering function of CfXyn11A relies on its apoplastic localization and is independent of enzymatic activity. Additionally, we identified an aspartic protease-like protein, PbXIP1, in the pear apoplast, which binds CfXyn11A to suppress its enzymatic activity and virulence. This study highlights the role of apoplastic proteomics in elucidating the molecular mechanisms underlying plant immunity and pathogen virulence and emphasizes the contrasting outcomes of CfXyn11A in different host contexts. The findings provide new insights into the interplay between extracellular effectors and plant defense proteins during fungal infection.