Fruit Development Research Articles

The Renaissance of Polyamines: New Roles in Crop Yield and Quality Properties in Freshly Fruit

Polyamines (PAs) are low-molecular-weight compounds that contain amino groups. PAs are present in a variety of organisms, including plants, animals and microorganisms. In plants, the main PAs are putrescine (PUT), spermidine (SPD) and spermine (SPM). They play crucial physiological roles in plant development, including flowering, fruit set, growth, ripening and metabolic processes. In addition, PAs are components of the diet and have a role in health and disease. Furthermore, PAs have been demonstrated to help overcome the negative effects of adverse environmental factors of both biotic and abiotic stresses. Thus, the main objective of this review was to examine the recent literature regarding the mentioned effects of PAs apart from the impact of preharvest PAs treatments, applied at different stages of fruit development, on fresh fruit crop yield and fruit quality properties at harvest, and in their maintenance during storage, with a special emphasis on the fruit content in bioactive compounds with antioxidant activity. Moreover, this review addressed the impact of PAs on other physiological processes affecting crop yield such as flowering and fruit set.

The aerial epidermis is a major site of quinolizidine alkaloid biosynthesis in narrow-leafed lupin.

Lupins are promising protein crops that accumulate toxic quinolizidine alkaloids (QAs) in the seeds, complicating their end-use. QAs are synthesized in green organs (leaves, stems, and pods) and a subset of them is transported to the seeds during fruit development. The exact sites of biosynthesis and accumulation remain unknown; however, mesophyll cells have been proposed as sources, and epidermal cells as sinks. We investigated the exact sites of QA biosynthesis and accumulation in biosynthetic organs of narrow-leafed lupin (Lupinus angustifolius) using mass spectrometry-based imaging (MSI), laser-capture microdissection coupled to RNA-Seq, and precursor feeding studies coupled to LC-MS and MSI. We found that the QAs that accumulate in seeds ('core' QAs) were evenly distributed across tissues; however, their esterified versions accumulated primarily in the epidermis. Surprisingly, RNA-Seq revealed strong biosynthetic gene expression in the epidermis, which was confirmed in leaves by quantitative real-time polymerase chain reaction. Finally, feeding studies using a stably labeled precursor showed that the lower leaf epidermis is highly biosynthetic. Our results indicate that the epidermis is a major site of QA biosynthesis in narrow-leafed lupin, challenging the current assumptions. Our work has direct implications for the elucidation of the QA biosynthesis pathway and the long-distance transport network from source to seed.

The ANP method to relate innovative personal competencies in sustainable development in Ecuadorian fruit exporting SMEs

The development of the personal innovative competences in workers is of capital importance for the competitiveness of organizations, where the ability of the employees must respond in an innovative way to diverse situations that arise in specific contexts. Considering this, the question arises: How do innovative employees’ competences affect the sustainable development of Micro, Small and Medium Enterprises (MSMEs)? Therefore, the objective of this work is to present a multi-criteria method based on the Analytic Network Process (ANP), to relate innovative personal competences and the sustainable development of MSMEs. An instrument was applied to groups of experts from 31 Ecuadorian fruit-exporting MSMEs, to develop a multi-criteria decisional network that allowed identifying the innovative personal abilities that have the greatest impact on the sustainable development of these organizations. The results demonstrate the relevance of the elements of innovative personal competencies, with a cumulative participation of 39.15%, Sustainable Export Development with 32.18% and Improvements with 28.66%. It also presents three types of analysis: i) Global to establish the weight of each variable; ii) Influences, to establish solid cause-effect relationships between the variables and iii) Integrated. The most relevant innovative personal competences for sustainable development and improvements for exporting SMEs are teamwork, critical thinking, and creativity within the international context.

Long-term nitrogen fertilization alters the partitioning of amino acids between citrus leaves and fruits

IntroductionThe growth of evergreen fruit trees is influenced by the interaction of soil nitrogen (N) and leaf amino acid contents. However, information on free amino acid contents in leaves of fruiting and non-fruiting branches during long-term N fertilizer application remains scarce.MethodsHere, a four-year field experiment (2018-2021) in a citrus orchard revealed consistently lower total N and amino acid contents in leaves of fruiting compared to non-fruiting branches.Results and discussionAppropriate N fertilizer application increased free amino acid and total N contents in leaves of both types of branches and fruits, but excessive amounts led to decreases. Correlation analysis showed that, in the early stage of fruit development, leaves on both types of branches can meet the N requirements of the fruit (R²=0.77 for fruiting, R²=0.82 for non-fruiting). As fruits entered the swelling stage, a significant positive correlation emerged between fruiting branch leaves and fruit total N content (R²=0.68), while the R² for leaves on non-fruiting branches dropped to 0.47, indicating a shift in N supply towards leaves on fruiting branches. Proline and arginine are the most abundant amino acids in these leaves. At fruit maturity, these amino acids account for more than half of the total amino acids in the fruit (29.0% for proline and 22.2% for arginine), highlighting their crucial role in fruit development. Further research is needed to investigate amino acid transport and distribution mechanisms between citrus leaves and fruits.

Transcriptome Analysis and Phytohormone Profile Reveal Core Phytohormone Regulating Parthenocarpy in Fingered Citron

Background: Parthenocarpy, the development of fruit without fertilization, is a significant trait in fingered citron (Citrus medica L. var. sarcodactylis Swingle). This study aims to elucidate the regulatory mechanisms underlying parthenocarpy through comparative transcriptome analysis and phytohormone profiling between fingered citron and its non-parthenocarpic counterpart, citron. Results: A total of 66 differentially expressed hormone-related genes were identified, with the auxin pathway emerging as the most prominent in fingered citron. Protein–protein interaction analysis revealed a potential interaction between auxin and abscisic acid (ABA). Phytohormone content analysis indicated that fingered citron exhibited higher levels of indole-3-acetic acid (IAA) and lower levels of ABA compared to citron. A weighted gene co-expression network analysis (WGCNA) suggested that the interplay between auxin and ABA is crucial for triggering parthenocarpy. Virus-induced gene silencing (VIGS) experiments demonstrated that silencing CmsABI5 led to decreased ABA levels, while auxin levels remained unchanged, resulting in disrupted parthenocarpy and increased ethylene levels, indicating a secondary hormonal response. Additionally, gene expression changes associated with failed parthenocarpy showed down-regulation of SAUR50 and up-regulation of PP2C 56, linking these changes to ABA signaling. Conclusions: Our findings highlight the central regulatory role of auxin in parthenocarpy in fingered citron, with ABA acting as a critical modulator. The suppression of ABA alone disrupts parthenocarpy despite stable auxin levels, emphasizing the necessity of balanced hormone interactions. This research underscores the significant role of auxin, rather than gibberellin (GA), in regulating parthenocarpy in fingered citron, contributing valuable insights to the understanding of fruit development mechanisms.

Transcriptomic analysis reveals the crucial role of YABBY genes family in hormonal induced parthenocarpy in Cucumis sativus L.

BackgroundThe plant-specific YABBY transcription factor family plays several activities, including responding to abiotic stress, establishing dorsoventral polarity, and developing lateral organs. Cucumis sativus L. commonly referred to as cucumber and one of the first vegetable crops with a fully sequenced genome.ResultsIn this work, we examined the application of NAA, CPPU, and GA4 + 7 to inflict parthenocarpy in the cucumber ZK line. The expression pattern of YABBY genes throughout fruit development and performed a genomic census of cucumber (Cucumis sativus L.). Based on peptide classification, we discovered eight CsYABBY genes and divided them into five subfamilies. Similarities in motif composition and exon-intron structure were also observed. The cis-elements and gene ontology (GO) analysis revealed the involvement of CsYABBY genes in vegetative growth and the transition of vegetative to the reproductive phase. The expression analysis revealed the differential expression response to NAA, CPPU, and GA4 + 7. In particular, the CsYABBY1 was induced sharply by NAA and CPPU but not GA4 + 7. The transient expression of CsCRC disclosed that it is localized in the nucleus.ConclusionThese findings point to the possibility that CsYABBY1 and CsCRC may positively affect fruit development and could be utilized to generate parthenocarpic cucumber fruits.

Transcriptome sequencing reveals jasmonate playing a key role in ALA-induced osmotic stress tolerance in strawberry

BackgroundStrawberry (Fragaria × annanasa Duch.) is an important economic fruit worldwide, whose growth and development are often hindered by water deficiency. 5-Aminolevulinic acid (ALA), a natural plant growth regulator, has been suggested to mitigate the osmotic damages by promoting root water absorption, osmotic adjustment, photosynthetic capacity, and antioxidant improvement. However, the regulatory mechanism remains unclear.ResultsIn the current study, the underlying mechanism by determination of various physiological indices, as well as transcriptome sequencing and the weighted gene correlation network analysis (WGCNA) of 10 mg L− 1 ALA treated strawberry leaves and roots stressed by 20% polyethylene glycol 6000 (PEG) treatment. The findings indicated that ALA enhanced osmotic stress tolerance reflected by enhancing relative water content (RWC), root development, gas exchange parameters and antioxidant enzyme activities, and decreasing the leaf H2O2 and malondialdehyde (MDA) content. Transcriptome analysis showed that the differentially expressed genes (DEGs) stimulated by exogenous ALA were mostly associated with the secondary biosynthesis and hormones signaling pathways, especially jasmonates (JAs). The JA derivative (+)-7-iso-jasmonoyl-L-isoleucine (JA-Ile) was found to be elevated in the strawberry leaves and roots treated with ALA under PEG stress. Additionally, exogenous methyl jasmonate (MeJA) alleviated osmotic stress damages similarly to ALA, while its synthesis inhibitor diethyldithiocarbamate (DIECA) led to adverse effects on strawberries, which can be relieved by further additional application of ALA.ConclusionsTheses findings suggest that JAs can act as the necessary signaling molecules involved in ALA-improved osmotic stress tolerance networks. This provides a new insight for further study on how ALA can help plants cope with water stress.

Protein phosphatase PP2C2 dephosphorylates transcription factor ZAT5 and modulates tomato fruit ripening.

Although C2H2 zinc finger transcription factors are important in plant growth, development, and stress resistance, their specific roles in fruit ripening have been less explored. Here, we demonstrate that the C2H2 zinc finger transcription factor 5 (SlZAT5) regulates fruit ripening in tomato (Solanum lycopersicum L.). Overexpression of SlZAT5 delayed ripening, while its knockout accelerated it, confirming its role as a negative regulator. SlZAT5 functions as a transcriptional repressor by directly inhibiting ripening-related genes, including SlACS4, SlPL8, and SlGRAS38, thereby delaying ripening. Furthermore, SlZAT5 interacts with the type 2C protein phosphatase SlPP2C2, which regulates the repressor activity of SlZAT5 by dephosphorylating SlZAT5 at Ser-65. This interaction is crucial in modulating ethylene production, thereby influencing the ripening process. These findings reveal a regulatory function of SlZAT5 in tomato fruit development, offering insights into the SlZAT5-SlPP2C2 module and potential targets for genetic modification to improve fruit quality and extend fruit shelf life.

Development of Pokkali Rice-Based Fruit Blended Probiotic Drink and Evaluation of Its Sensory Parameters and Nutritional Content

Development of Pokkali Rice-Based Fruit Blended Probiotic Drink and Evaluation of Its Sensory Parameters and Nutritional Content

Recent changes in thermal indices in Mango cv Dashehari under subtropical climate

Systematic recording of changes in thermal indices at tree phenological stages is prerequisite to understand the impact of environmental factors on mango. Keeping this in view, latest information on growing degree day units, heliothermal and photothermal units were cumulated at flowering, fruit set, fruit development and maturity stages in mango cv Dashehari during growing season of 2021 and 2022. Recent data showed variability in environmental indicators during critical reproductive stages. Highest weekly mean maximum temperature of 39.50 and 44.21°C were recorded in 2021 and 2022 fruiting cycles while minimum temperature showed 1.29°C during 2022 and 3.79°C in 2021. During 2022, bright sunshine hours had maximum value of 15.59h whereas in 2021, 10.7 h. During reproductive stage, weekly mean pan evaporation of 4.46 to 10.01 mm/day was recorded in 2021 fruiting cycle; in contrast, in the next season, 4.77 to 10.06 h was observed. Weekly average growing degree day from January to June varied between 860.51 to 2347.91°Cd and 917.16 to 2597.30°Cd respectively in 2021 and 2022 growth cycles. The heliothermal units had 3094.05 to 17727.54 and 3534.42 to 23219.79°Cdh with photothermal of 8932.92 to 32084.15 and 9517.23 to 35498.52 °Cdh respectively in 2021 and 2022 fruiting seasons. The flowering stages experienced lower heat accumulation in 2021 as compared to 2022 fruiting seasons. It was observed that peanut and marble phase had around 884.48 to 1606.44°Cd GDD across fruiting season. Maturity period had 1655.41 to 2597.3°Cd GDD across seasons. Histographic distribution of these thermal indices at vegetative, flowering, fruit setting to maturity had indicated widespread distribution pattern of GDD, HTU and PTU across seasons. It was found that a 1500 to 1600°Cd GDD at frequency level of <5 per cent in 2021 marble stage while the same GDD at 6 per cent frequency level with higher 1600 to 1700°Cd class intervals at <2 per cent was noted in the next season fruiting. Such widespread distribution indicated the affect of climatic factors at each stage and season. Lower fruit production of 6 to 8 t ha-1 was accorded due to severe atmospheric aberration during the 2022 cropping cycle. Results suggested the impact of environmental factors on tree performances and thus resource conservation practices needs to be followed rigorously to attain optimum yield of mango at subtropics.

Identification and functional characterization of the C2H2 ZFP transcription factor CmSUP7 in regulating melon plant growth and fruit development

Identification and functional characterization of the C2H2 ZFP transcription factor CmSUP7 in regulating melon plant growth and fruit development

Gibberellin-Dependent Pulp Pigmentation in CPPU-Induced Parthenocarpic Melon Fruit: Insights from Metabolome and Transcriptome Analysis

The plant growth regulator N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) is applied to induce parthenocarpic fruit setting in melon (Cucumis melo L.) production. However, CPPU-induced fruits frequently exhibit a decline in quality attributes, such as sucrose, aroma, and pigmentation, the mechanisms underlying these changes remain largely unclear. This research assessed the effects of CPPU application on carotenoid biosynthesis in the pulp during melon fruit development, aiming to elucidate the underlying mechanisms. Transcriptome and metabolome analyses were employed to examine changes in pigment and hormone levels in melon fruit at various developmental stages following CPPU treatment. The results indicated that CPPU application for fruit setting significantly reduced β-carotene content in the fruit pulp compared to fruits resulting from artificial pollination. Transcriptome analysis revealed a decrease in the expression of carotenoid biosynthesis genes (e.g., PSY1/2, Z-ISO, and LYCB), while the expression of catabolic enzyme genes (e.g., NCED5/6, NXS, and CCD4) were up-regulated following CPPU application. Metabolome analysis showed a decrease in gibberellin production during the development of CPPU-induced fruits compared to pollinated samples. Furthermore, exogenous gibberellin application recovered the pigment defects in the CPPU-induced parthenocarpic fruits. This study provides novel insights into how CPPU-induced parthenocarpy affects melon pulp pigmentation during development, offering valuable theoretical foundations for improving fruit set management in melon cultivation.

Melatonin alleviated chilling injury of cold-stored passion fruit by modulating cell membrane structure via acting on antioxidant ability and membrane lipid metabolism.

Fresh passion fruit is sensitive to chilling injury (CI) during storage at improper low temperature of 5°C, which lowers the fruit quality and limits its shelf life. The present study aimed to determine the impacts of melatonin on CI development of passion fruit in relation to antioxidant ability and membrane lipid metabolism during refrigeration. In present study, passion fruit was treated with 0.50mmolL-1 melatonin and distilled water (control) for 20min, hereafter stockpiled at 5°C. The results indicated that, in storage, melatonin-treated passion fruit showed the lower CI index and cell membrane permeability, lower superoxide anion production rate and malondialdehyde level, greater activities of catalase, superoxide dismutase and ascorbate peroxidase, higher levels of ascorbic acid and glutathione, and higher 1, 1-diphenyl-2-picrylhydrazyl radical scavenging capacity than control passion fruit. Besides, lower membrane lipid-degrading enzyme activities, lower contents of phosphatidic acid and saturated fatty acids (SFAs), higher levels of phosphatidylcholine, phosphatidylinositol and unsaturated fatty acids (USFAs), and greater ratio of USFAs to SFAs and index of USFAs were revealed in melatonin-treated passions than control passions. Thus, these results indicated that melatonin retained cell membrane structure via boosting antioxidant capacity and restricting membrane lipid degradation, accordingly increased the chilling resistance and delayed the CI development in fresh passion fruit.

Further insights into the molecular mechanisms underlying tobacco straw cultivation of Pleurotus ostreatus by comparative transcriptome analyses.

Cultivation of edible mushrooms on straw can significantly reduce production costs, provide notable environmental and ecological benefits. However, the molecular mechanisms via which mushrooms utilize straw are not well understood. We conducted a comparative transcriptomic analysis of oyster mushrooms cultivated on two different biomass substrates, namely, corncob and tobacco straw at various developmental stages. The results revealed that the biomass substrates induced distinct transcriptomic changes during mycelium and fruiting body development. Straw affected the metabolism of pyruvate and acetyl-CoA, with significant downregulation of pyruvate decarboxylase expression, and upregulation of acetyl-CoA hydrolase during mycelial growth. Genes associated with cell wall and carbohydrate metabolism were significantly upregulated, and the PLD-PA-mTOR pathway was activated during the fruiting body development stage in mushrooms grown on straw. These findings reveal the transcriptomic adaptations of oyster mushrooms to tobacco straw, and enhance our understanding of the molecular mechanisms underlying biomass conversion by edible fungi using straw.

Consequences of “zombie-making” and generalist fungal pathogens on carpenter ant microbiota

The bacterial microbiome of the ant Camponotus floridanus has been well characterized across body regions and maturation levels. However, potential effects of entomopathogens on the gut microbiome, and the fungal communities therein, are yet to be assessed. Additionally, the mycobiome remains often overlooked despite playing a vital role in gut ecology with potential implications for health and infection outcomes. We characterized the effects of two entomopathogens with different infection strategies on the gut micro- and mycobiota of C. floridanus over time; Ophiocordyceps camponoti-floridani and Beauveria bassiana. Specialist, ‘zombie-making’ O. camponoti-floridani fungi hijack the behavior of C. floridanus ants over three weeks, leading them to find an elevated position and fix themselves in place with their mandibles. This summiting behavior is adaptive to Ophiocordyceps as the ant transports the fungus to conditions that favor fruiting body development, spore production, dispersal, and transmission. In contrast, the generalist entomopathogen B. bassiana infects and kills the ant within a few days, without the induction of obvious fungus-adaptive behaviors. By comparing healthy ants with Beauveria- and Ophiocordyceps-infected ants we aimed to 1) describe the dynamics of the micro- and mycobiome of C. floridanus during infection, and 2) determine if the effects on gut microbiota are distinctive between fungi that have different infection strategies. While Beauveria did not measurably affect the ant host micro-and mycobiome, Ophiocordyceps did, especially for the mycobiome. Moreover, ants that were sampled during Ophiocordyceps-adaptive summiting behavior had a significantly different micro- and mycobiome composition compared to healthy controls and those sampled before and after manipulation took place. This suggests that the host microbiome might have a role to play in the manipulation strategy of Ophiocordyceps.

Highly efficient CRISPR/Cas9-RNP mediated CaPAD1 editing in protoplasts of three pepper (Capsicum annuum L.) cultivars

ABSTRACT Parthenocarpy, characterized by seedless fruit development without pollination or fertilization, offers the advantage of consistent fruit formation, even under challenging conditions such as high temperatures. It can be induced by regulating auxin homeostasis; PAD1 (PARENTAL ADVICE-1) is an inducer of parthenocarpy in Solanaceae plants. However, precise editing of PAD1 is not well studied in peppers. Here, we report a highly efficient clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) ribonucleoprotein (RNP) for CaPAD1 editing in three valuable cultivars of pepper (Capsicum annuum L.): Dempsey, a gene-editable bell pepper; C15, a transformable commercial inbred line; and Younggo 4, a Korean landrace. To achieve the seedless pepper trait under high temperatures caused by unstable climate change, we designed five single guide RNAs (sgRNAs) targeting the CaPAD1 gene. We evaluated the in vitro on-target activity of the RNP complexes in three cultivars. Subsequently, we introduced five CRISPR/Cas9-RNP complexes into protoplasts isolated from three pepper leaves and compared indel frequencies and patterns through targeted deep sequencing analyses. We selected two sgRNAs, sgRNA2 and sgRNA5, which had high in vivo target efficiencies for the CaPAD1 gene across the three cultivars and were validated as potential off-targets in their genomes. These findings are expected to be valuable tools for developing new seedless pepper cultivars through precise molecular breeding of recalcitrant crops in response to climate change.

Effects of different water and fertilizer concentration on leaf area and yield of jujube (ziziphus jujuba mill.)

Effects of different water and fertilizer concentrations on the leaf area index, fruit development and yield of jujube trees under bubbled-root irrigation during the growth period were analyzed. The leaf area index of different water and fertilizer treatments reached a peak at the fruit enlargement stage of the jujube tree. The leaf area index reached maximum with high water and medium fertilizer treatment (W1N2). The highest number of fruits per unit branch length appeared in medium water and medium fertilizer treatment (W2N2), while the lowest appeared in low water treatment (W3N0). The highest yield of all treatments was with medium water and medium fertilizer treatment (W2N2) having a yield of more than 30 000 kg/hm2, while the lowest was with low water and high fertilizer treatment (W3N1) having a yield of less than 15 000 kg/hm2. Therefore, medium water and medium fertilizer treatment can be selected to obtain the highest yield of jujube trees. Bangladesh J. Bot. 53(4): 881-887, 2024 (December)

Comparative transcriptome analysis and heterologous overexpression indicate that the ZjZOG gene may positively regulate the size of jujube fruit

BackgroundFruit size is a crucial economic trait that impacts the quality of jujube (Ziziphus jujuba), however, research in this area remains limited. This study utilized two jujube cultivars with similar genetic backgrounds but differing fruit sizes to investigate the regulatory mechanisms affecting fruit size through cytological observations, transcriptome sequencing, and heterologous overexpression.ResultsThe findings reveal that variations in mesocarp cell numbers during early fruit development significantly influence final fruit size. Comparative transcriptome sequencing identified 16,778 differentially expressed genes across five developmental stages. Co-expression network analysis identified 16 co-expression modules. KEGG enrichment analysis of these modules indicated the significant role of plant hormone-related pathways in fruit development. A detailed analysis of the ‘sky blue’ module revealed candidate genes associated with the regulation of mesocarp cells, leading to the construction of a regulatory network. Heterologous overexpression of the candidate gene ZjZOG in tomato confirmed its positive role in fruit size enhancement. Transcriptomic analysis of these overexpression lines further validated the regulatory network and identified reliable candidate genes for fruit size control.ConclusionThis study provides valuable insights into the regulatory mechanisms of fruit size, which may facilitate the breeding of larger jujube cultivars.

Conservation of the dehiscence zone gene regulatory network in dicots and the role of the SEEDSTICK ortholog of California poppy (Eschscholzia californica) in fruit development

BackgroundFruits, with their diverse shapes, colors, and flavors, represent a fascinating aspect of plant evolution and have played a significant role in human history and nutrition. Understanding the origins and evolutionary pathways of fruits offers valuable insights into plant diversity, ecological relationships, and the development of agricultural systems. Arabidopsis thaliana (Brassicaceae, core eudicot) and Eschscholzia californica (California poppy, Papaveraceae, sister group to core eudicots) both develop dry dehiscent fruits, with two valves separating explosively from the replum-like region upon maturation. This led to the hypothesis, that homologous gene regulatory networks direct fruit development and dehiscence in both species.ResultsTranscriptome analysis of separately collected valve and replum-like tissue of California poppy yielded the SEEDSTICK (STK) ortholog as candidate for dehiscence zone regulation. Expression analysis of STK orthologs from dry dehiscing fruits of legumes (Vicia faba, Glycine max and Pisum sativum) shows their involvement in fruit development. Functional analysis using Virus-Induced Gene Silencing (VIGS) showed premature rupture of fruits and clarified the roles of EscaSTK: an evolutionary conserved role in seed filling and seed coat development, and a novel role in restricting cell divisions in the inner cell layer of the valve.ConclusionOur analysis shows that the gene regulatory network described in Arabidopsis is significantly different in other dicots, even if their fruits form a dehiscence zone at the valve margins. The ortholog of STK, known to be involved in ovule development and seed abscission in Arabidopsis, was recruited to a network regulating fruit wall proliferation in California poppy. There, EscaSTK allows fruit maturation without premature capsule rupture, highlighting the importance of proper endocarp development for successful seed dispersal.

ATP Citrate Lyase ClACLB-1 Facilitates Citrate Cleavage in Lemon

Citric acid is an important organic acid with wide applications and diverse biological functionality. As the predominant organic acid in lemons, citric acid plays a crucial role in determining the flavor of citrus, especially in lemons. ATP citrate lyase (ACL, EC4.1.3.8) is the keg gene in citric acid metabolism. Several research studies on ACL only focused on high-sugar- and low-acid-content citrus varieties; however, the ACL mechanism in lemons with high acid and low sugar levels remains undetermined. In this study, a key candidate gene, ClACLB-1, for citrate cleavage was identified from the genome data of ‘Xiangshui’ lemon [Citrus limon (L.) Burm f.]. The putative protein coded by the gene ClACLB-1 is localized in the nuclear and cell membranes. The ClACLB-1 gene was expressed in all tissues, with the highest expression in male flowers and the lowest expression in mature fruits; the expression decreased during lemon fruit development. The overexpression of ClACLB-1 in transgenic tomatoes significantly increases the activity of citrate lyase, which subsequently reduces citric acid content. This study clarified the function of the ClACLB-1 gene in cleaving citric acid, provided new insights into the citric acid metabolism of citrus, and offered a theoretical reference for reducing acid and increasing sugar in citrus to improve fruit quality. It also helped to enhance the understanding of the metabolism and role of citrate in plants.