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Aquaporins (AQPs) are essential membrane proteins involved in seed maturation and germination, stomata movement, photosynthesis, and regulation of plant flowering processes. Pitaya flowers are open at night and wither at daybreak, which shows an obvious circadian rhythm. In this study, a comprehensive genome-wide analysis of AQPs in Hylocereus undantus was conducted to screen key genes associated with flowering processes. A total of 33 HuAQP genes were identified from the H. undantus genome. The 33 HuAQPs were grouped into four subfamilies: 10 PIPs, 13 TIPs, 8 NIPs, and 2 SIPs, which were distributed on 9 out of 11 pitaya chromosomes (Chr) (except for Chr7 and Chr10). Results from expression profiles showed that HuNIP6, 1 may be involved in pitaya’s floral opening. HuNIP6, 1 was localized exclusively in the cell membrane. Overexpression of HuNIP6, 1 in Arabidopsis thaliana significantly promoted early flowering through regulating negative flowering regulators of MJM30, COL9, and PRR5, suggesting that HuNIP6, 1 plays key roles in regulating flowering time. The present study provides the first genome-wide analysis of the AQP gene family in pitaya and valuable information for utilization of HuAQPs.

Additional file 17: Table S10. cDNA sequences of 17 target genes.

Additional file 8: Table S1. Statistics of miRNA sequences in pitaya.

Additional file 5: Figure S5. The sequences of 17 target genes from the two pitaya cultivars. ‘-W’, ‘Guanhuabai’ pitaya. ‘-R’, ‘Guanhuahong’ pitaya. Red lines indicate sequence of target genes primers for real-time PCR. Green lines indicate outer specific primers for nested PCR. Blue lines indicate inner specific primers for nested PCR.

Additional file 6: Figure S6. Transient expressions of miRNAs and their target genes (all). A1-A49, bright field; B1-B49, eGFP; C1-C49, merge; A1-C1, 35 s::eGFP; A2-C2, WT; A3-C3, 35 s::Pre-miR164; A4-C4, 35 s::Pre-Hmo-miR6020; A5-C5, 35 s::HmCYP71A8-like::eGFP; A6-C6, 35 s::positive control HmCYP71A8-like::eGFP; A7-C7, 35 s::negative control HmCYP71A8-like::eGFP; A8-C8, 35 s::HmCYP71A8-like::eGFP+ 35 s::Pre-miR164; A9-C9, 35 s::HmCYP71A8-like::eGFP+ 35 s::Pre-Hmo-miR6020; A10-C10, 35 s::positive control HmCYP71A8-like::eGFP+ 35 s::Pre-Hmo-miR6020; A11-C11, 35 s::negative control HmCYP71A8-like::eGFP+ 35 s::Pre-Hmo-miR6020; A12-C12, 35 s::Pre-Hmo-miR858; A13-C13, 35 s::HmMYB12-like::eGFP; A14-C14, 35 s::positive control HmMYB12-like::eGFP; A15-C15, 35 s::negative control HmMYB12-like::eGFP; A16-C16, 35 s::HmMYB12-like::eGFP+ 35 s::Pre-miR164; A17-C17, 35 s::HmMYB12-like::eGFP+ 35 s::Pre-Hmo-miR858; A18-C18, 35 s::positive control HmMYB12-like::eGFP+ 35 s::Pre-Hmo-miR858; A19-C19, 35 s::negative control HmMYB12-like::eGFP+ 35 s::Pre-Hmo-miR858; A20-C20, 35 s::HmMYBC1-like::eGFP; A21-C21, 35 s::HmMYBC1-like::eGFP+ 35 s::Pre-miR164; A22-C22, 35 s::HmMYBC1-like::eGFP+ 35 s::Pre-Hmo-miR858; A23-C23, 35 s::HmMYB2-like::eGFP; A24-C24, 35 s::HmMYB2-like::eGFP+ 35 s::Pre-miR164; A25-C25, 35 s::HmMYB2-like::eGFP+ 35 s::Pre-Hmo-miR858; A26-C26, 35 s::Pre-Hmo-miR160a; A27-C27, 35 s::Hpcyt P450-like2::eGFP; A28-C28, 35 s::positive control Hpcyt P450-like2::eGFP; A29-C29, 35 s::negative control Hpcyt P450-like2::eGFP; A30-C30, 35 s::Hpcyt P450-like2::eGFP+ 35 s::Pre-miR164; A31-C31, 35 s::Hpcyt P450-like2::eGFP+ 35 s::Pre-Hmo-miR160a; A32-C32, 35 s::positive control Hpcyt P450-like2::eGFP+ 35 s::Pre-Hmo-miR160a; A33-C33, 35 s::negative control Hpcyt P450-like2::eGFP+ 35 s::Pre-Hmo-miR160a; A34-C34, 35 s::Pre-Hmo-novel-2; A35-C35, 35 s::HmCYP83B1-like::eGFP; A36-C36, 35 s::positive control HmCYP83B1-like::eGFP; A37-C37, 35 s::negative control HmCYP83B1-like::eGFP; A38-C38, 35 s::HmCYP83B1-like::eGFP+ 35 s::Pre-miR164; A39-C39, 35 s::HmCYP83B1-like::eGFP+35 s::Pre-Hmo-novel-2; A40-C40, 35 s::positive control HmCYP83B1-like::eGFP+ 35 s::Pre-Hmo-novel-2; A41-C41, 35 s::negative control HmCYP83B1-like::eGFP+ 35 s::Pre-Hmo-novel-2; A42-C42, 35 s::Pre-Hmo-novel-15; A43-C43, 35 s::HmTPST-like::eGFP; A44-C44, 35 s::positive control HmTPST-like::eGFP; A45-C45, 35 s::negative control HmTPST-like::eGFP; A46-C46, 35 s::HmTPST-like::eGFP+ 35 s::Pre-miR164; A47-C47, 35 s::HmTPST-like::eGFP+ 35 s::Pre-Hmo-novel-15; A48-C48, 35 s::positive control HmTPST-like::eGFP+ 35 s::Pre-Hmo-novel-15; A49-C49, 35 s::negative control HmTPST-like::eGFP+ 35 s::Pre-Hmo-novel-15.

Additional file 7: Figure S7. Different fruit developmental stages of ‘Guanhuahong’ (A) and ‘Guanhuabai’ (B) pitayas. A1 and B1, 13 d; A2 and B2, 16 d; A3 and B3, 19 d; A4 and B4, 23 d; A5 and B5, 25 d; A6 and B6, 27 d; A7 and B7, 29 d. Bar = 2.0 cm.

Additional file 9: Table S2. The information of miRNAs in pitaya.

Additional file 4: Figure S4. Number of miRNA family members in pitaya pulp.

Additional file 3: Figure S3. GC content distributions of assembled transcripts and genes. A, GC content distributions of transcripts; B, GC content distributions of genes.

Additional file 2: Figure S2. The length distributions of assembled transcripts and genes. A, The length distributions of transcripts; B, The length distributions of genes.

Late-ripening characteristics of a fruit is a good agronomic trait for extending both the harvest period and marketing time. However, underlying molecular basis of the late-ripening mechanism in fruit is largely unknown. In this study, RNA sequencing (RNA-seq) technology was used to identify differentially expressed genes (DEGs) related to late-ripening characteristics from a late-ripening mutant ‘Huwan Wuzishatangju’ (HWWZSTJ) (Citrus reticulata Blanco) and its original line ‘Wuzishatangju’ (WZSTJ). A total of approximately 17.0 G base and 84.2 M paried-end reads were obtained. DEGs were mainly enriched in processes including photosynthesis, phenylpropanoid biosynthesis, carotenoid biosynthesis, chlorophyll and abscisic acid (ABA) metabolism. Thirteen candidate transcripts related to chlorophyll metabolism, carotenoid biosynthesis and ABA metabolism were analyzed using real-time quantitative PCR (qPCR) at all fruit maturation stages of HWWZSTJ and WZSTJ. Chlorophyllase (CLH) and divinyl reductase (DVR) from chlorophyll metabolism, phytoene synthase (PSY) and capsanthin/capsorubin synthase (CCS) from carotenoid biosynthesis, abscisic acid 8'-hydroxylase (AB) and 9-cis-epoxycarotenoid dioxygenase (NCED1) from ABA metabolism were cloned and analyzed. NCED1 is probably responsible for the formation of late-repining of HWWZSTJ based on sequence and expression analyses. The preliminary study provides new information to better understand the complex process of late-ripening in Citrus at the transcriptional level.

A study to prevent or brake bud dormancy in 3 to 4 years old Myrica rubra cv. ‘Biji’ plants under controlled green house and field conditions, was conducted using GA3 and WPM nutrient media as fertigation and drainage. Two batches of the plant were shifted in different growth stages “dormant” and “non-dormant”. Plants shifted in the month of October were in the late autumn growth stage (non-dormant), while plants shifted in the month of December were in a complete bud dormancy stage. Plants of the first batch were prevented to enter bud dormancy while in the second batch bud dormancy was broken by providing warm temperature ranging 25±3°C in the green house. Green house plants took 2-4 weeks to initiate the growth flushes as compared to 17 to 18 weeks taken for the field plants. Buds break and leafs shed in the green house were observed earlier in the plants drained with nutrients media followed by fertigation, while spraying of GA3 delayed leaf shed and increased shoot length both in the green house and in the field. GA3 treated plants sprouted few days earlier than that of control. Significant differences were observed in initial sprouts among the treatments of GA3, nutrient fertigation and nutrient drainage as compared to the control plants. Similarity in days to initial sprout was observed in both the nutrient fertigation and drainage methods with a slight variation of one or two day’s differences. Nutrients used as drainage showed outstanding results than fertigation. Key words: Bud dormancy, gibberellic acid, GA3, Myrica rubra, warm temperature.

‘Wuzishatangju’( Citrus reticulata Blanco ) is an excellent cultivar derived from a bud sport of a seedy ‘Shatangju’ cultivar found in Guangdong Province in the 1980s. In this study, six molecular markers including random amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR), simple sequence repeat (SSR), sequence-related amplified polymorphism (SRAP), inter-retrotransposn amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) were used to study the genetic variations between ‘Shatangju’ and ‘Wuzishatangju’. 1196 RAPD, seven SSR, 28 IRAP and 56 REMAP primers were used to detect the genetic variations between ‘Shatangju’ and ‘Wuzishatangju’. However, no difference was observed between the two cultivars. These results indicate that there was a very close genetic relationship between ‘Shatangju’ and ‘Wuzishatangju’ and RAPD, SSR, IRAP and REMAP markers could not distinguish them. Two and 21 specific bands were obtained using 100 ISSR and 153 SRAP primers, respectively. The present research could be a valuable tool for identification of Citrus bud sport clones, which laid the foundations for the further study of the mechanisms of Citrus bud sports. Key words : Citrus reticulata Blanco, random amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR), simple sequence repeat (SSR), sequence-related amplified polymorphism (SRAP), inter-retrotransposon amplified polymorphism (IRAP), retrotransposon-microsatellite amplified polymorphism (REMAP), identification.

Betalains have high nutritional value and bioactivities. Red pulp pitaya (Hylocereus polyrhizus) is the only fruit containing abundant betalains for consumer. However, no information is available about genes involved in betalain biosynthesis in H. polyrhizus. Herein, two cDNA libraries of pitaya pulps with two different coloration stages (white and red pulp stages) of Guanhuahong (H. polyrhizus) were constructed. A total of about 12 Gb raw RNA-Seq data was generated and was de novo assembled into 122,677 transcripts with an average length of 1183 bp and an N50 value of 2008. Approximately 99.99% of all transcripts were annotated based on seven public databases. A total of 8871 transcripts were significantly regulated. Thirty-three candidate transcripts related to betalain biosynthesis were obtained from the transcriptome data. Transcripts encoding enzymes involved in betalain biosynthesis were analyzed using RT-qPCR at the whole pulp coloration stages of H. polyrhizus (7-1) and H. undatus (132-4). Nine key transcripts of betalain biosynthesis were identified. They were assigned to four kinds of genes in betalain biosynthetic pathway, including tyrosinase, 4, 5-DOPA dioxygenase extradiol, cytochrome P450 and glucosyltransferase. Ultimately, a preliminary betalain biosynthetic pathway for pitaya was proposed based on betalain analyses, gene expression profiles and published documents.