Supplemental light is often used in fruit production, but few studies have been conducted on pitaya. In this study, supplemental blue light was applied to pitaya for four hours each night in the field from flowering to fruit ripening to examine changes in peel and pulp physicochemical parameters and metabolites. Blue light treatment significantly increased fruit weight, improved fruit firmness by increasing pectin content and retarding hemicellulose degradation, and enhanced antioxidant enzyme activity. Blue light had minor effects on primary metabolites but more pronounced effects on volatiles. By affecting alanine, aspartate and glutamate metabolism, blue light treatment resulted in significant fruit growth, increased accumulation of bioactive ingredients in the peel, and significantly altered the accumulation of flavor-associated volatile compounds, such as organic acids, esters and terpenes in the pulp. Our results provide an important reference for improving the yield and quality of pitaya production using supplemental light in the field.

Dragon fruit ( Selenicereus spp. ) is a nutritious and economically important tropical and subtropical fruit crop, mainly cultivated in Central America, Southeast Asia and East Asia. However, the molecular basis of flesh color variation remains poorly understood. Traditional germplasm classification mainly relies on phenotypic traits such as fruit skin and flesh color and stem morphology, which often leads to misclassification due to phenotypic similarity and frequent interspecific hybridization, thus hindering efficient breeding and germplasm utilization. In this study, we used SLAF-seq to develop SNP markers and perform genetic characterization on 45 dragon fruit accessions, and obtained 1,206,498 high-quality SNPs after strict filtering. Genetic diversity analysis showed that the diversity levels of the three main taxa were significantly higher than the overall level. Population structure and phylogenetic analyses clearly distinguished three genetic groups and corrected several misclassified accessions. Furthermore, we constructed a hierarchical core SNP marker set, among which the 10-SNP ultra-core panel showed optimal discrimination ability with 100% accuracy in independent germplasm validation. This panel effectively overcame the misleading effect of flesh color phenotype caused by hybrid germplasm. This study clarified the genetic diversity and population structure of cultivated dragon fruit, resolved germplasm classification confusion, and developed a set of efficient and diagnostic SNP markers. Furthermore, through phenotype-driven SNP screening and transcriptomic analysis, we identified four candidate genes (bHLH, CYP450, POD12, and MATE transporter) that show strong co-expression with key betalain biosynthesis genes ( CYP76AD1-1 and DODA1 ), providing molecular insights into flesh color regulation. These results provide a solid foundation for germplasm management, parental selection and molecular-assisted breeding of dragon fruit, and will promote the genetic improvement and sustainable development of this important horticultural crop.

Pitaya, (Selenicereus spp.), a fruit originating from North and Central America and extensively cultivated in China and Vietnam, holds significant economic value. Utilizing PacBio HiFi sequencing and Oxford Nanopore Technologies ultra-long sequencing, aided by Hi-C data, we have assembled a chromosome-level haplotype-resolved genome. The sizes of the two haplotype genomes were determined to be 1.477 Gb (hap1, contig N50 = 133.35 Mb) and 1.442 Gb (hap2, contig N50 = 132.57 Mb), with 96.7% (hap1) and 98.4% (hap2) respectively allocated to 11 pseudochromosomes. Hap1 comprises 58.94% repeat sequences and predicts a total of 29,139 protein-coding gene models and 18,378 non-coding RNAs. Hap2 comprises 58.37% repeat sequences and predicts a total of 28,538 protein-coding gene models and 19,458 non-coding RNAs. Notably, 93.5% and 93.6% of protein-coding genes were annotated for the two haplotypes. The high-quality genome assembly presented in this study provides a valuable resource for future ecological, evolutionary, biological, and breeding research in pitaya.

Pitaya (Selenicereus spp.), recognized for its economic significance and nutritional properties, undergoes rapid quality decline after harvest. This study elucidates the mechanisms driving quality reduction in pitaya during low-temperature storage, utilizing a multi-level approach spanning phenotypic, physiological, metabolic, and transcriptomic assessments. Throughout storage, the pericarp's cell wall degraded, resulting in pericarp thinning, reduced fruit firmness, water loss, and starch content decline. Simultaneously, there is also a reduction in soluble solids, monosaccharides, and malic acid content. Additionally, color changes occur in the fruit flesh. Antioxidant enzyme activity patterns point towards a stress reaction within the fruit. Metabolomic and transcriptomic data implicate genes associated with cell wall integrity and glycolysis in quality diminishment, concurrent with fluctuations in corresponding metabolites. Additionally, we propose that the imbalance of various metabolites, especially monosaccharides, organic acids, lipids, and benzenoids, contributes to the deterioration of pitaya's taste during storage. Thus, emphasizing strategies such as strengthening the cell wall, regulating metabolic rates, and minimizing water loss is crucial to enhance pitaya storage performance.

Microbial communities on plant surfaces are crucial in regulating plant growth and disease control. Exploring the composition of microorganisms on plant surfaces is essential for understanding their potential functions. The restructuring of microbial communities can help reduce postharvest diseases and maintain fruit quality. In this study, the use of Bacillus velezensis LX fermentation broth resulted in a reduction of Diaporthe and Fusarium abundance on the surface of kiwifruit, as well as changed in the fungal and bacterial communities on the kiwifruit surface, as determined by high-throughput sequencing. B.velezensis LX treatment reduces the natural decay incidence of postharvest kiwifruit but does not decrease the quality of kiwifruit. An analysis of the relationship between microbial taxa and fruit decay incidence revealed that several genera, including Plectosphaerella, Vishniacozyma, Cryptococcus, Papiliotrema, Aureobasidium, Filobasidium, Actinomycetospora, and Parasutterella, were enriched in the CK and LX treatment group during storage. This study contributes to a better understanding of how microbial antagonists regulate postharvest diseases in kiwifruit and provides insights for establishing a beneficial microbial synthetic flora to enhance the postharvest safety of kiwifruit.

【Objective】The study was conducted to investigate the development laws of in-season and off-season fruits of pitaya and to set up growth models, which would provide theoretical basis and guidance for high-quality and high-efficient fruit production.【Method】Dahong pitaya, the main domestic cultivar, was selected as test material. The vertical diameter (VD) and horizontal diameter (HD) of in-season and off-season fruits were measured at regular intervals during fruit development. The temperature and day length were recorded from flowering to maturing every day. Logistic growth equations of fruit development were fitted.【Result】The development of in-season fruits completed in 28 days. The VD and HD of in-season fruits grew faster than off-season fruits per day. In-season fruits were oblong and much smaller. The mean values of daily lowest temperature (DLT), daily average temperature (DAT), daily highest temperature (DHT), day length (DL) and daily temperature range (DTR) were higher than those of off-season fruits. The development of off-season fruits completed in 63 days. The fruit was nearly spherical and larger. The accumulations of DTR, DL, DHT and DAT were higher than those of in-season fruits. Growth curves of both fruits were in S shape. Inflexion point of VD curves of both fruits and HD curve of in-season fruits appeared before flower wilting. HD of off-season fruits was still growing faster and faster until the inflexion point appeared in 9-12 days after flowering, And the growth rate decreased more and more after inflexion point. VD and HD of ripened off-season fruits were 1.03 and 1.25 times those of in-season fruits, respectively.【Conclusion】Higher growth rate of in-season fruit may be relevant to higher means of temperature and day length in the course of fruit development. Off-season fruit was larger, which may be relevant to higher accumulations of temperature and day length. The full development of HD of off-season fruit was and one of the direct factors causing differences in fruit shape of the two fruits. Single factor and multi-factor models of fruit development were fitted well, which could be used for analysis and prediction of fruit development.

Hand pollination is a necessary assisting method for pitaya (Selenicereus spp.) production to achieve a high yield. With the cultivated area increasing at an exponential rate in recent years, a comprehensive study of the pollination process was conducted. We developed an ideal medium for pitaya pollen in vitro germination in this study, then tested the activity of pollen collected from or stored for various time periods. We discovered that those collected between 2 h before blooming and 6 h after blooming had the higher germination rates (27.2–65.1%), the highest activity was at 2 h after blooming, and that storing them at 4°C for 24 hours reduces their germination rate from 65.2 percent to 35.5 percent and their production to about 82%. As a result, pollinating plants with pollen that has been held for more than 24 hours is not recommended unless a breakthrough in pollen storage is achieved. We also discovered that stigma receptivity and pollen activity are synchronized, which together determines the rate of fruit setting and the size of the fruit. Pollination within 6 hours after flowering offers the optimum fruit setting percentage and size, while pollination at 6:00 pm, 2 hours before blooming, is also a good alternative; however, pollination at 6:00 am the next morning is expected to result in a 23 % drop in productivity. These findings will be beneficial for reproductive biology research, as well as laying the groundwork for hand pollination to boost pitaya output and breeding efficiency.

Self-incompatibility (SI) is a major issue in dragon fruit (Selenicereus spp.) breeding and production. Therefore, a better understanding of the dragon fruit SI mechanism is needed to improve breeding efficiency and ultimate production costs. To reveal the underlying mechanisms of SI in dragon fruit, plant anatomy, de novo RNA sequencing-based transcriptomic analysis, and multiple bioinformatic approaches were used to analyze gene expression in the pistils of the self-pollinated and cross-pollinated dragon fruit flowers at different intervals of time after pollination. Using fluorescence microscopy, we observed that the pollen of 'Hongshuijing', a self-incompatible dragon fruit variety (S. monacanthus), germinated on its own stigma. However, the pollen tube elongation has ceased at 1/2 of the style, confirming that dragon fruit experiences gametophyte self-incompatibility (GSI). We found that the pollen tube elongation in vitro was inhibited by self-style glycoproteins in the SI variety, indicating that glycoproteins were involved in SI. That is to say the female S factor should be homologous of S-RNase or PrsS (P. rhoeas stigma S factor), both of which are glycoproteins and are the female S factors of the two known GSI mechanism respectively. Bioinformatics analyses indicated that among the 43,954 assembled unigenes from pistil, there were six S-RNase genes, while 158 F-box genes were identified from a pollen transcriptomic dataset. There were no P. rhoeas type S genes discovered. Thus, the identified S-RNase and F-box represent the candidate female and male S genes, respectively. Analysis of differentially expressed genes (DEGs) between the self and cross-pollinated pistils at different time intervals led to the identification of 6,353 genes. We then used a weighted gene co-expression network analysis (WGCNA) to find some non-S locus genes in SI responses in dragon fruit. Additionally, 13 transcription factors (TFs) (YABBY4, ANL2, ERF43, ARF2, BLH7, KNAT6, PIF3, two OBF1, two HY5 and two LHY/CCA) were identified to be involved in dragon fruit GSI. Thus, we uncovered candidate S and non-S genes and predicted more SI-related genes for a more detailed investigation of the molecular mechanism of dragon fruit SI. Our findings suggest that dragon fruit possesses a GSI system and involves some unique regulators. This study lays the groundwork for future research into SI mechanisms in dragon fruit and other plant species.

Cross-pollination can improve the percentage of fruit set and fruit weight for most red flesh varieties in pitaya. The technology of pollen storage was very important for successful cross-pollination. However, till present, the technology of pollen storage is unsatisfactory in pitaya production. In this study, pitaya pollen stored at low temperature was taken as the research object, and its physicochemical indexes, metabolomics, and transcriptomics were studied. The results showed that in vitro pollen germination rate decreased significantly with the increase in storage time. Soluble sugar and soluble protein content of pollen peaked on the first day of storage, whereas its relative conductivity, and manlondialdehyde (MDA) and proline contents increased gradually during storage. At the same time, the antioxidant enzyme system of pollen was also affected. Superoxide dismutase (SOD) activity decreased, while the activities of catalase (CAT) and peroxidase (POD) increased and superoxide anion generation rate increased gradually during storage. According to the metabolomics results, amino acid, peptide, nucleotide, plant hormone, terpene, alcohol, phenol, flavonoid, sterol, vitamin, ester, sphingolipid, and ketone contents increased significantly during storage, whereas flavonoid and pigment contents declined gradually. During pollen storage, the gene expressions related to carbohydrate metabolism, protein metabolism, acid and lipid metabolism, sterol metabolism, plant hormone metabolism, and signal transductions were significantly downregulated. With KEGG pathway analysis, isoquinoline alkaloid biosynthesis, tyrosine metabolism, alanine, aspartate, and glutamate metabolism of pollen were affected significantly during low-temperature storage. Correlation analysis showed that the gene expression patterns of HuRP2, HuUPL1, and HuAAT2 had significant effects on pollen germination. D-arabinose 5-phosphate and myricetin were positively correlated with pollen germination rate, which was valuable for studying preservation agents. In this study, the changes in pollen during low-temperature storage were described from the level of metabolites and genes, which could provide theoretical support for the research and development of pollen long-term storage technology in pitaya.

粤红5号是从大红与普通白肉杂交F1代中选育出的火龙果新品种.果实椭圆形,整齐均匀,平均单果质量310.0 g,可食率79.5％;成熟时果皮粉红色,鳞片尖部绿色;果肉白色,肉质清爽、清甜,无青草味,口感极佳,品质上等,可溶性固形物含量(w,后同)为14.14％,可滴定酸含量0.172％.花芽分化能力强,自花坐果率90％以上,丰产稳产;枝蔓刺极少且短,利于田间管理;适应性强,抗火龙果溃疡病.适宜在火龙果产区种植.

Appropriate flowering time is one of the most important traits for oilseed production and crop yield in tea oil camellia (Camellia oleifera Abel.). It secures the availability of pollinators and balances the growth period after flowering with respect to cold winter temperatures and rainfall. However, the effective regulator of flowering time and its mechanisms in C. oleifera are not clearly understood. This study demonstrates that hydrogen cyanamide (HC), rather than gibberellin A3, gibberellin A4+7, thidiazuron, or 6-benzylaminopurine, acts as a potentially effective agent to promote flowering time by ~12 days. Accumulation of indole acetic acid, ethylene, salicylic acid, and reactive oxygen species (ROS) in floral buds of C. oleifera was significantly increased by HC treatment. Transcriptome analysis suggested that exogenous HC application promoted flowering via regulating genes involved in auxin metabolism, ethylene-MAPK (mitogen-activated protein kinase) signaling, and ROS metabolism. These results demonstrate that HC can advance flowering by enhancing cell expansion, cell cycle progression, and flower development in floral buds. These findings help understand the role of HC in flowering regulation in autumn/winter-flowering perennials and provide new insights into the potential utilization of HC as a flower inducer in C. oleifera cultivation.

[目的]探究火龙果嫁接技术中砧木与接穗选择的具体参数,以提高嫁接成活率和出芽速度,完善火龙果嫁接技术.[方法]以红水晶6号火龙果为试材,砧木取自不同长度的老熟或绿熟茎蔓,选取砧木在茎蔓中相对位置(砧位)、嫁接方法、接穗芽数、接穗成熟度等因素,采用混合正交或正交设计进行嫁接试验;根据接穗是否萌芽、出芽时间等分别对砧木长度、质量、砧木质量/长度比、砧木周长、接穗长度等砧穗参数进行多元方差分析.[结果]老熟和绿熟的短茎蔓(可切分两根砧木)嫁接成活率较高,分别为75.0％和87.5％;老熟的长茎蔓(可切分3根砧木)不宜选用单芽接穗;绿熟长茎蔓的中段不宜用做砧木;砧木偏长、砧木质量/长度比较低、成熟度偏嫩、接穗偏长有利于嫁接成活,当砧木较短、较粗、较重、砧木质量/长度比较高、成熟度偏老时接穗萌芽较晚甚至不能萌芽.[结论]初步确定红水晶6号砧木嫁接的基本原则,选取1～2年生茎蔓,优先使用绿熟茎蔓,但避免使用绿熟长茎蔓中段为砧木,砧木长度不低于40 cm,选取生长点附近充实成熟的茎段为接穗,从顶部开始截取接穗进行嫁接,接穗含2芽且长度不低于3 cm,使用平接法为主,嫁接成活率达81.2％,生产实用性较好,对火龙果苗木繁育生产具有参考意义.

Banana streak virus (BSV) belongs to the members of the genus Badnavirus, family Caulimoviridae. At present, BSV contains nine species in the International Committee on Taxonomy of Viruses (ICTV) classification report (2018b release). Previous study indicated that the viral particles of Banana streak virus Acuminata Yunnan (BSV-Acum) were purified from banana (Cavendish Musa AAA group) leaves in Yunnan Province, China, and its complete genome was obtained. To further determine whether this sample infecting with Banana streak GF virus (BSGFV), the polymerase chain reaction (PCR) cloning and complete genome analysis of the Banana streak GF virus Yunnan isolate (BSGFV-YN) isolate were carried out in this study. The result showed that BSGFV-YN infecting Cavendish Musa AAA group was co-infecting this sample. Its genome contains a total of 7,325 bp in length with 42% GC content. This complete genome sequence was deposited in GenBank under accession number MN296502. Sequence analysis showed that the complete genome of BSGFV-YN was 98.14% sequence similarity to BSGFV Goldfinger, while it was 49.10-57.09% to other BSV species. Two phylogenetic trees based on the complete genome and ORFIII polyprotein indicated that BSGFV-YN and other BSV species clustered into a group, while it was the highest homology with BSGFV Goldfinger. Although BSGFV-YN and BSGFV Goldfinger were highly homologous, their cultivating bananas are different. The former cultivating banana was from Cavendish Musa AAA group, while the latter cultivating banana was from Goldfinger Musa AAAB group. Compared with BSGFV Goldfinger, the genome of BSGFV-YN has an extra multiple repetitive sequences in the intergenetic region between ORFIII and ORFI, suggesting that this region might be related to host selection. In summary, a BSGFV-YN distant from BSV-Acum was identified from the same sample, and its complete genome sequence was determined and analyzed. The study extends the polymorphism of BSVs in China and provides scientific clue for the evolutionary relationship with host selection of badnaviruses.

Hand pollination is a necessary aiding method for pitaya ( Hylocereus undatus ) production to achieve a high yield. With the cultivated area of pitaya going up exponentially in the recent years, a systematic study was carried out to understand the mechanism behind the high yield. In this study, we first developed an optimal medium for the in vitro germination of pitaya pollen. Upon testing the activity of the pollen collected from or stored for different time, we observed that the relative high pollen germination rates (27.2–65.1%) were those collected at between 2 h before blooming and 6 h after blooming, the highest activity was at 2 h after blooming, and that storing them for 24 h at 4°C reduces their germination rate from 65.2% to 35.5% and their production to about 82%. Therefore, it is not appropriate to pollinate plants with pollen that have been stored for more than 24 h, without bringing a breakthrough in pollen storage. We also observed that stigma receptivity and pollen activity are synchronous, which together determine fruit setting rate and fruit size. Pollination within 6 h after blooming provides the best fruit setting percentage and fruit size, the other favorable option being pollination at 6:00 pm, that is, 2 h before blooming; however, pollination at 6:00 am the next morning is expected to lead to 23% reduction in the production. These results will be useful for reproductive biology studies in this species. Moreover, this work set an important foundation for collecting pollen and selecting the right time of hand pollination to improve the yield and breeding efficiency in pitaya.

[目的]探明杆状DNA病毒属病毒的ORFⅠ基因功能.[方法]本研究从香蕉条斑病毒云南分离株(BSV-YN)中克隆了BSV ORFⅠ基因,通过核苷酸和氨基酸序列分析和同源关系分析,确定了BSV-YN的分类地位;对其编码蛋白及同源物的理化性质、氨基酸序列组成、亲疏水性、跨膜区域、信号肽、亚细胞定位、磷酸化位点、同源结构域、蛋白二级和三级结构等进行预测和分析.[结果]BSV ORFⅠ基因片段大小为528 bp,编码175个氨基酸,通过核苷酸和氨基酸序列分析和同源关系分析,确定了BSV-YN属于BSGFV种.生物信息学分析表明,BSV-YN ORFⅠ及同源蛋白都是不稳定的、亲水性蛋白,以丝氨酸和苏氨酸磷酸化为主.这些蛋白二级结构主要由α-螺旋和无规则卷曲组成,无信号肽或跨膜区域.亚细胞定位预测表明,BSV-YN ORFⅠ及同源蛋白主要在细胞核分布,推测它们在病毒感染的宿主细胞核中发挥重要作用.[结论]推测BSV-YN ORFⅠ在病毒感染的宿主细胞核中参与病毒复制、转录等相关过程.本研究为进一步开展该蛋白的功能研究提供科学线索.

MAIN CONCLUSION:Moringa oleifera TPSs were genome-wide identified for the first time, and a phylogenetic analysis was performed to investigate evolutionary divergence. The qRT-PCR data show that MoTPS genes response to different stress treatments. The trehalose-6-phosphate synthase (TPS) family is involved in a wide range of stress-resistance processes in plants. Its direct product, trehalose-6-phosphate, acts as a specific signal of sucrose status and a regulator to modulate carbon metabolism within the plant. In this study, eight TPS genes were identified and cloned based on the M. oleifera genome; only MoTPS1 exhibited TPS activity among Group I proteins. The characteristics of the MoTPS gene family were determined by analyzing phylogenetic relationships, gene structures, conserved motifs, selective forces, and expression patterns. The Group II MoTPS genes were under relaxed purifying selection or positive selection. The glycosyltransferase family 20 domains generally had lower Ka/Ks ratios and nonsynonymous (Ka) changes compared with those of trehalose-phosphatase domains, which is consistent with stronger purifying selection due to functional constraints in performing TPS enzyme activity. Phylogenetic analyses of TPS proteins from M. oleifera and 17 other plant species indicated that TPS were present before the monocot-dicot split, whereas Group II TPSs were duplicated after the separation of dicots and monocots. Quantitative real-time PCR analysis showed that the expression patterns of TPSs displayed group specificities in M. oleifera. Particularly, Group I MoTPS genes closely relate to reproductive development and Group II MoTPS genes closely relate to high temperature resistance in leaves, stem, stem tip and roots. This work provides a scientific classification of plant TPSs, dissects the internal relationships between their evolution and expressions, and promotes functional researches.