Cloning and analysis of DlERF23 gene in flower induction

Irregular flowering is a serious problem in longan production. Identifying the flower induction-related genes and analyzing their regulation mechanism is the key to solve this problem. The APETALA2/ethylene responsive factor (AP2/ERF) superfamily members are transcription factors (TFs) that regulate diverse developmental processes, including flowering time, and stress responses in plants. However, there is still no research about AP2/ERF involved in the regulation of longan flower induction. In the present study, a AP2/ERF TF member DlERF23 was cloned from longan (Dimocarpus longan). It has a typical AP2 domain with the coding sequence (CDS) of DlERF23 is 552 bp in length and encodes 184 amino acids. The molecular weight of DlERF23 protein was 20.41 kda and the theoretical isoelectric point (PI) was 7.69. The amino acid sequence of DlERF23 protein had the highest similarity with CsERF23 (XP_006478313.1) of Citrus sinensis and CcERF23 (XP_006441807.2) of Citrus clementina. The results of qRT-PCR showed that the relative expression level of DlERF23 gene in pericarp was higher, followed by stem, leave, flower and flower bud. Meanwhile, DlERF23 gene significant down-regulated in the early stage of flower induction in ‘Sijimi’ (SJ) longan and up-regulated in the late stage of flower induction in ‘Shixia’ (SX). The results of transient expression of Arabidopsis protoplasts showed that the fluorescence signal was mainly concentrated in the nucleus. Moreover, overexpression of DlERF23 in Arabidopsis promoted early flowering. These results provide useful information for revealing the biological roles of DlERF23 in longan and increase our understanding of the AP2/ERF superfamily members in fruit trees

Cloning and function analysis of DlWRKY9 gene in longan (Dimocarpus longan)

WRKY is one of the largest plant transcription factors (TFs) which is widely involved in plant growth, development, and responses to stresses. In the present study, a WRKY TF DlWRKY9 was cloned from longan (Dimocarpus longan). The coding sequence (CDS) of DlWRKY9 is 762 bp in length and encodes 253 amino acids. It has a typical WRKY domain and zinc finger structure which belongs to type IIa WRKY protein. The molecular weight of DlWRKY9 protein was 30.27kda and the theoretical isoelectric point (PI) was 5.24. It is an unstable hydrophilic protein. The secondary structure of DlWRKY9 protein consists of helical structure (17.39%), extended chain (8.70%) and other structures (turn and random coil) (73.91%). The amino acid sequence of DlWRKY9 protein had the highest similarity with DlWRKY9 (xp_006450293.1) of citrus Clementina. DlWRKY9 gene promoter elements contain light, abscisic acid, gibberellin, jasmonic acid and other response elements. The results of qRT-PCR showed that the relative expression level of DlWRKY9 gene in pericarp was higher, followed by young fruits and floral organs. Meanwhile, DlWRKY9 gene specifically down-regulated in the early stage of flower induction in ‘Sijimi’ (SJ) longan. The results of transient expression of Arabidopsis protoplasts showed that the fluorescence signal was mainly concentrated in the nucleus. Moreover, overexpression of DlWRKY9 in Arabidopsis promoted early flowering. These results provide useful information for revealing the biological roles of DlWRKY9 in longan and increase our understanding of the WRKY family in fruit trees

Avocado Fruit Pulp Transcriptomes in the after-Ripening Process

Avocado is an important tropical fruit whose after-ripening process is still poorly understood. The fatty acid, phenolics, flavonoids, and tannins were analyzed in ‘Lisa’ avocado (Persea americana Mill. ‘Lisa’) fruit pulp during after-ripening. The transcriptome was analyzed to screen for transcripts associated with the aforementioned after-ripening parameters. The results showed that there were no significant differences in the total fatty acid content among the preclimacteric, climacteric, and postclimacteric stages. Nevertheless, the concentrations of C18:3 (α-linolenic acid) were significantly higher in the climacteric and postclimacteric stages than the preclimacteric stage. RNAseq generated 235,082 transcripts and 151,545 unigenes. In addition, 4,324 DEGs were produced among the three stages. KEGG analysis of the DEGs suggested the pathways about “α-linolenic acid metabolism, unsaturated fatty acid biosynthesis”, “fatty acid degradation”, “linoleic acid metabolism and fatty acid biosynthesis”, “linoleic acid metabolism and fatty acid elongation”, and “fatty acid elongation” may all contribute to the C18:3 variations in ‘Lisa’ avocado fruit pulp. Several transcription factors, including the ethylene-related transcription factors, such as NAC, MYB, bHLH, and WRKY, were also identified in the DEGs database. This study generated transcript data and screened the transcription factors involved in the avocado after-ripening process. This information could be used to control after-ripening in avocado and maintain fruit quality during storage

Effects of bagging treatment on fruit quality and pesticide residues of ‘Donghong’ kiwifruit

In this study, the effects of bagging treatment on fruit appearance and internal quality, including fruit shape index, single fruit weight, fruit vitamin C, soluble solids, titratable acid, chlorophyll and carotenoid content, were studied by using ‘Donghong’ kiwifruit as experimental material. Meanwhile, the pesticide residues of bagged and non-bagged (NB) kiwifruit were compared and analyzed. Results showed that the pericarp color of bagged kiwifruit is lighter in green than that of NB group, with uniform color, cleaner appearance and no scabs and spots. Single fruit weight and transverse meridians of bagged kiwifruits were significantly increased. Interestingly, we found single bagging treatment had little effect on the internal quality of ‘Donghong’ kiwifruit. After pesticide treatment, the fruit shape of kiwifruit was rounder, significantly increased the weight, chlorophyll content of fruit, and decreased the content of vitamin C and carotenoids. In addition, bagging + pesticide treatment had additive effect on these characters. After bagging, the residues of pyraclostrobin and β-cypermethrin in ‘Donghong’ kiwifruit were significantly lower than those in the control. However, the residue of difenoconazole residues did not show significant difference. Bagging treatment has the ability to improve the appearance and reduce the residue of some pesticides. Meanwhile, the application of some pesticides can improve the single fruit weight and fruit quality. Therefore, bagging is a scientific and effective cultivation method in the green production of ‘Donghong’ kiwifruit

Cloning and function analysis of DlWRKY9 gene in longan (Dimocarpus longan)

WRKY is one of the largest plant transcription factors (TFs) which is widely involved in plant growth, development, and responses to stresses. In the present study, a WRKY TF DlWRKY9 was cloned from longan (Dimocarpus longan). The coding sequence (CDS) of DlWRKY9 is 762 bp in length and encodes 253 amino acids. It has a typical WRKY domain and zinc finger structure which belongs to type IIa WRKY protein. The molecular weight of DlWRKY9 protein was 30.27kda and the theoretical isoelectric point (PI) was 5.24. It is an unstable hydrophilic protein. The secondary structure of DlWRKY9 protein consists of helical structure (17.39%), extended chain (8.70%) and other structures (turn and random coil) (73.91%). The amino acid sequence of DlWRKY9 protein had the highest similarity with DlWRKY9 (xp_006450293.1) of citrus Clementina. DlWRKY9 gene promoter elements contain light, abscisic acid, gibberellin, jasmonic acid and other response elements. The results of qRT-PCR showed that the relative expression level of DlWRKY9 gene in pericarp was higher, followed by young fruits and floral organs. Meanwhile, DlWRKY9 gene specifically down-regulated in the early stage of flower induction in ‘Sijimi’ (SJ) longan. The results of transient expression of Arabidopsis protoplasts showed that the fluorescence signal was mainly concentrated in the nucleus. Moreover, overexpression of DlWRKY9 in Arabidopsis promoted early flowering. These results provide useful information for revealing the biological roles of DlWRKY9 in longan and increase our understanding of the WRKY family in fruit trees

Sweet-Potato-Vine-Based High-Performance Porous Carbon for Methylene Blue Adsorption

In this study, sweet-potato-vine-based porous carbon (SPVPC) was prepared using zinc chloride as an activating and pore-forming agent. The optimised SPVPC exhibited abundant porous structures with a high specific surface area of 1397.8 m2 g−1. Moreover, SPVPC exhibited excellent adsorption characteristics for removing methylene blue (MB) from aqueous solutions. The maximum adsorption capacity for MB reached 653.6 mg g−1, and the reusability was satisfactory. The adsorption kinetics and isotherm were in good agreement with the pseudo-second-order kinetics and Langmuir models, respectively. The adsorption mechanism was summarised as the synergistic effects of the hierarchically porous structures in SPVPC and various interactions between SPVPC and MB. Considering its low cost and excellent adsorption performance, the prepared porous carbon is a promising adsorbent candidate for dye wastewater treatment

Genome-Wide Identification, Phylogenetic and Expression Analyses of the Ubiquitin-Conjugating Enzyme Gene Family in Maize.

BackgroundUbiquitination is a post-translation modification where ubiquitin is attached to a substrate. Ubiquitin-conjugating enzymes (E2s) play a major role in the ubiquitin transfer pathway, as well as a variety of functions in plant biological processes. To date, no genome-wide characterization of this gene family has been conducted in maize (Zea mays).Methodology/principal findingsIn the present study, a total of 75 putative ZmUBC genes have been identified and located in the maize genome. Phylogenetic analysis revealed that ZmUBC proteins could be divided into 15 subfamilies, which include 13 ubiquitin-conjugating enzymes (ZmE2s) and two independent ubiquitin-conjugating enzyme variant (UEV) groups. The predicted ZmUBC genes were distributed across 10 chromosomes at different densities. In addition, analysis of exon-intron junctions and sequence motifs in each candidate gene has revealed high levels of conservation within and between phylogenetic groups. Tissue expression analysis indicated that most ZmUBC genes were expressed in at least one of the tissues, indicating that these are involved in various physiological and developmental processes in maize. Moreover, expression profile analyses of ZmUBC genes under different stress treatments (4°C, 20% PEG6000, and 200 mM NaCl) and various expression patterns indicated that these may play crucial roles in the response of plants to stress.ConclusionsGenome-wide identification, chromosome organization, gene structure, evolutionary and expression analyses of ZmUBC genes have facilitated in the characterization of this gene family, as well as determined its potential involvement in growth, development, and stress responses. This study provides valuable information for better understanding the classification and putative functions of the UBC-encoding genes of maize

The Ubiquitin-Conjugating Enzyme Gene Family in Longan (Dimocarpus longan Lour.): Genome-Wide Identification and Gene Expression during Flower Induction and Abiotic Stress Responses

Ubiquitin-conjugating enzymes (E2s or UBC enzymes) play vital roles in plant development and combat various biotic and abiotic stresses. Longan (Dimocarpus longan Lour.) is an important fruit tree in the subtropical region of Southeast Asia and Australia; however the characteristics of the UBC gene family in longan remain unknown. In this study, 40 D. longan UBC genes (DlUBCs), which were classified into 15 groups, were identified in the longan genome. An RNA-seq based analysis showed that DlUBCs showed distinct expression in nine longan tissues. Genome-wide RNA-seq and qRT-PCR based gene expression analysis revealed that 11 DlUBCs were up- or down-regualted in the cultivar “Sijimi” (SJ), suggesting that these genes may be important for flower induction. Finally, qRT-PCR analysis showed that the mRNA levels of 13 DlUBCs under SA (salicylic acid) treatment, seven under methyl jasmonate (MeJA) treatment, 27 under heat treatment, and 16 under cold treatment were up- or down-regulated, respectively. These results indicated that the DlUBCs may play important roles in responses to abiotic stresses. Taken together, our results provide a comprehensive insight into the organization, phylogeny, and expression patterns of the longan UBC genes, and therefore contribute to the greater understanding of their biological roles in longan

Characterization and expression analysis of genes encoding ubiquitin conjugating domain-containing enzymes in Carica papaya.

BACKGROUND:Ripening affects the quality and nutritional contents of fleshy fruits and is a crucial process of fruit development. Although several studies have suggested that ubiquitin-conjugating enzyme (E2s or UBC enzymes) are involved in the regulation of fruit ripening, little is known about the function of E2s in papaya (Carica papaya). METHODOLOGY/PRINCIPAL FINDINGS:In the present study, we searched the papaya genome and identified 34 putative UBC genes, which were clustered into 17 phylogenetic subgroups. We also analyzed the nucleotide sequences of the papaya UBC (CpUBC) genes and found that both exon-intron junctions and sequence motifs were highly conserved among the phylogenetic subgroups. Using real-time PCR analysis, we also found that all the CpUBC genes were expressed in roots, stems, leaves, male and female flowers, and mature fruit, although the expression of some of the genes was increased or decreased in one or several specific organs. We also found that the expression of 13 and two CpUBC genes were incresesd or decreased during one and two ripening stages, respectively. Expression analyses indicates possible E2s playing a more significant role in fruit ripening for further studies. CONCLUSIONS:To the best of our knowledge, this is the first reported genome-wide analysis of the papaya UBC gene family, and the results will facilitate further investigation of the roles of UBC genes in fruit ripening and will aide in the functional validation of UBC genes in papaya

Identification of WRKY Gene Family from Dimocarpus longan and Its Expression Analysis during Flower Induction and Abiotic Stress Responses

Longan is an important fruit tree in the subtropical region of Southeast Asia and Australia. However, its blooming and its yield are susceptible to stresses such as droughts, high salinity, and high and low temperature. To date, the molecular mechanisms of abiotic stress tolerance and flower induction in longan have not been elucidated. WRKY transcription factors (TFs), which have been studied in various plant species, play important regulatory roles in plant growth, development, and responses to stresses. However, there is no report about WRKYs in longan. In this study, we identified 55 WRKY genes with the conserved WRKY domain and zinc finger motif in the longan genome. Based on the structural features of WRKY proteins and topology of the phylogenetic tree, the longan WRKY (DlWRKY) family was classified into three major groups (I–III) and five subgroups (IIa–IIe) in group II. Tissue expression analysis showed that 25 DlWRKYs were highly expressed in almost all organs, suggesting that these genes may be important for plant growth and organ development in longan. Comparative RNA-seq and qRT-PCR-based gene expression analysis revealed that 18 DlWRKY genes showed a specific expression during three stages of flower induction in “Sijimi” (“SJ”), which exhibited the “perpetual flowering” (PF) habit, indicating that these 18 DlWRKY genes may be involved in the flower induction and the genetic control of the perpetual flowering trait in longan. Furthermore, the RT-qPCR analysis illustrated the significant variation of 27, 18, 15, 17, 27, and 23 DlWRKY genes under SA (Salicylic acid), MeJA (Methyl Jasmonate), heat, cold, drought, or high salinity treatment, respectively, implicating that they might be stress- or hormone-responsive genes. In summary, we systematically and comprehensively analyzed the structure, evolution, and expression pattern of the DlWRKY genes. The results presented here increase our understanding of the WRKY family in fruit trees and provide a basis for the further elucidation of the biological function of DlWRKY genes in longan