Phalaenopsis arunachalensis K. Gogoi & Rinya is reported as a little known species from Medog, Tibet Autonomous Region, China. The detailed morphological descriptions and photos are also provided. This species is similar to P. honghenensis F. Y. Liu, P. wilsonii Rolfe and P. taenialis (Lindl.) Christenson & Pradhan. However, this species has a minutely spurred that bends down, the free part of lateral lobes which are less than half length of the mid-lobe, and dagger-like of lateral lobes ends, which can distinguish from other species.

In order to understand the diversity and distribution characteristics of orchids in Gexigou National Nature Reserve in Sichuan province, a systematic survey was conducted using the line transect combined with sample sampling method from 2020 to 2021. A total length of 95 km including 17 lines were set up, covering various function, habitat and elevation of the reserve. 34 species of Orchidaceae in 20 genera were investigated. Among them, 10 were rare and endangered species, five were wild species under second-class national protection; and two (Liparis brunnea and L. rostrate) were new record species in Sichuan province. Most of them were mainly in terrestrial orchid of life type and absolutely dominant in north temperate zone of geographical. A total of 6703 orchids of 34 species were investigated and distributed in 290 sites. Galearis spathulata and Neottia megalochila were the most and least abundant species respectively, and Epipactis helleborine was the most widely-distributed. Among them, the height of Cypripedium guttatum showed a significant negative correlation with elevation, while there was a slightly correlation in other species. Most of Orchidaceae genera were distributed in 3100-3300 m, followed by 2900-3100 m, while the maximum number of individuals were distributed in 3900-4100 m. The number of Cephalanthera longifolia was positively correlated with slope significantly, the number of Galearis spathulata was positively correlated with elevation significantly, the number of Herminium lanceum was positively correlated with vegetation significantly, the number of whole genus of Herminium was positively correlated with elevation moderately. In general, the orchid resources in Gexigou Nature Reserve are relatively rich, and more distribute in the middle elevation. The number of some species is significantly correlated with environmental factors. Compared with the previous investigations in this reserve, the number of orchid species is significantly increased. However, three national protected species of Cypripedium with high ornamental value were not found, and the population of one species of Cypripedium decreased. Therefore, it is urgent to protect, publicize and enforce the law on orchids in the reserve.

Paphiopedilum hirsutissimum (Lindl. ex Hook. f.) Stein is a rare and endangered plant in China with high ornamental value. In order to explore the genetic characteristics of wild P. hirsutissimum resources in Southwest China, and contribute to the protection and utilization of the wild resources, this study used SSR molecular marker to analyze the genetic diversity and population genetic structure of 190 P. hirsutissimum resources which collected from six populations in Guangxi, Yunnan and Guizhou provinces in Southwest China. In this study, the results showed that ten pairs of primers with good amplification effect were selected from 115 pairs of primers, and 50 alleles were detected by 10 pairs of SSR primers of 190 P. hirsutissimum. The average number of alleles (N_a) was five and the average number of effective alleles (N_e) was 2.4835. The average Shannon information index (I) was 0.8592. The average observed heterozygosity (H_o) was 0.4518 and the average expected heterozygosity (H_e) was 0.4387. The average polymorphic information content (PIC) was 0.3996 and the average Nei's expected heterozygosty (h) was 0.4370. In this six wild P. hirsutissimum populations, the number of alleles (N_a) was from 2.8000 to 4.3000. The number of effective alleles (N_e) was from 1.9655 to 2.4060. The observed heterozygosity (H_o) was from 0.3891 to 0.4839. The expected heterozygosity (H_e) was from 0.3795 to 0.4683. The Shannon information index (I) was from 0.6584 to 0.8369, and the Nei's expected heterozygosty (h) was from 0.3648 to 0.4382. In the six wild populations, the genetic diversity of Guangxi Yachang (GYC) and Guizhou Wanfeng Lake (QWF) populations was generally higher (h=0.4382, h=0.4276), while the genetic diversity of Guangxi Mulun (GML) population was relatively low (h=0.3648). Analysis of molecular variance (AMOVA) results showed that genetic variation mainly occurred among individuals within the population (94%), while genetic differentiation within populations was very small (6%). UPGMA cluster analysis based on genetic distance showed that the genetic distance of the six P. hirsutissimum populations was very small, there was no obvious group division and the genetic distance was not completely related to the geographical location. The results of Structure and principal coordinate analysis were consistent with those of UPGMA cluster analysis. Structure and principal coordinate analysis results showed that there was homogenization among the populations, and there was no obvious group division. In summary, the genetic diversity of Paphiopedilum hirsutissimum resources is relatively rich, which can provide a theoretical basis for the protection and utilization of wild P. hirsutissimum resources in Southwest China.

Ploidy identification is one of the basic tasks for germplasm resources and new variety breeding of tropical flowers. In this study, flow cytometry was used to identify the ploidy level of Cymbidium hybrid seedlings. aiming at the key links such as the type of dissociated liquid, the tissue organ of the test material, evaluation indexes such as the nuclear dissociation, the clear degree of the main peak, the easy degree of sampling, and the coefficient of variation. A technique system was established and the stomatal traits of different ploidy were analyzed. The results showed that CyStain UV Precise P was the best of the three dissociated liquid and young leaves were most suitable. Six triploid and two tetraploid were identified from the offspring of the three hybrid combinations. There were significant differences in stomatal length, width and density between different ploidy (P<0.05). The rank of stomatal length and stomatal width was tetraploid>triploid>diploid, while stomatal density was reversed. This study is valuable for the polyploid selection and use of different ploidy germplasm resources for cross breeding of Cymbidium hybrid.

The study aimed to define the floral colour of Phalaenopsis precisely and establish a classification system of Phalaenopsis based on floral colour phenotypes. In this study, the floral colour phenotypes of 146 Phalaenopsis germplasm resources were determined using colourimeter and RHSCC, and the floral colours of each Phalaenopsis were named by cluster analysis and combined with ISCC-NBS system, and the quantitative classification was studied. The results showed that the colour of Phalaenopsis petals and sepals did not differ much, and the lip petals were darker and more colourful than petals and sepals. The classification results based on cluster analysis of L^*, a^* and b^* of petals could not fully characterize the classification of Phalaenopsis flower colours. The ISCC-NBS system divided Phalaenopsis flower colour into yellow, brown, red, violet, pink, purple and white groups. Each group had a preferable correspondence with L^*, a^* and b^* parameters of the CIE Lab system, which could realize the quantitative description of different Phalaenopsis flower colour and the colour group classification was reasonable. Phalaenopsis were rich and colourful, and there were significant differences between different colour groups of Phalaenopsis, but lacking blue-green colour. Overall the brightness and colouration of Phalaenopsis were negatively correlated, and could be divided into two groups, the first type containing yellow, brown, violet, pink, purple and white groups, the second type containing red colour groups.

In this study, the effects of different concentration and ratio of growth regulators on seed germination, rapid propagation and in vitro flowering of Mengzia foliosa were studied. The results showed that the seeds had strong activity and high germination rate at 105 days after artificial self-pollination, and 1/2MS+0.6 mg/L NAA+1.0 mg/L 6-BA medium was more suitable for seed germination. Meanwhile, 2.0 mL/L 6-BA without NAA was more suitable for cluster bud proliferation; and 1/2MS+1.0 mL/L NAA+30 g/L potato homogenate medium was the best for rooting and hardening-off. In addition, 1.0 mg/L 6-BA+0.5 mg/L NAA+1.0 mg/L PP₃₃₃ medium had the highest flowering rate. Our results not only contribute to the conservation and sustainable use of the species, but also provide important materials and technical support for wild population restoration and reconstruction.

Ca²⁺ is a second messenger in plant cells, and Ca²⁺-ATPase (ACA/ECA), as an important protein in Ca²+transport, plays a crucial role in ensuring the balance of intracellular calcium ions and abiotic stress in plants. To investigate the biological function of Ca²⁺-ATPase (ACA/ECA) in Hevea brasiliensis, 45 ACA/ECA gene family members were identified from the rubber tree genome using the ACA/ECA protein sequence of the model plant Arabidopsis as a probe, including 38 ACA members and 7 ECA members. Expasy and Plant-mPLoc were used to comprehensively analyze the physicochemical properties, gene structure, chromosomal localization, phylogeny, and expression patterns of the 45 members. Physicochemical properties analysis showed that the number of amino acids encoded by each member was 86-1142, the molecular weight of amino acids ranged from 10 048.04 to 125 412.75 Da, and the protein products were mostly localized on the cytoplasmic membrane, with a few members localized on the endoplasmic reticulum, chloroplast, vacuole, and nucleus. In evolutionary, members of the ACA/ECA family were clearly clustered into ACA and ECA two branches, and rubber tree members were always in close proximity to cassava in both branches, indicating that there was a close relative between rubber tree and cassava during phylogeny. Chromosomal localization revealed that the 45 members of the ACA/ECA family were unevenly distributed across 14 chromosomes and one contig in rubber tree, in which, chromosomes 2 and 9 had the largest member distribution of 11 members. Expression analysis showed that there were obvious differences in the expression of some members in different groups, HbACA31 was expressed the most in leaves, HbACA36 was expressed the most in latex, and the expression of HbACA36 was obviously up-regulated in latex after treatment with ethenol. In addition, we also analyzed the influence of tapping on ACA/ECA gene expression, and found that HbACA36 was at a high expression level during tapping of the two rubber tree varieties, PR107 and Reyan 8-79, and significantly up-regulated during tapping of high-yield variety Reyan 8-79, which speculated that HbACA36 was involved in the regulation of rubber biosynthesis and played an important role. The results presented in this study reveal the physicochemical properties and expression patterns of ACA/CA family members for the first time in rubber tree, and would provide a foundation for further investigation of the biological functions of ACA/ECA genes in H. brasiliensis, especially in the regulation of the rubber production.

NAC transcription factors are a large gene family in plants which play important roles in regulating plant growth and development, signal transduction, stress response, etc. In the previous study, the NAC gene, named MiNAC7, was isolated by the yeast two-hybrid system. In this study, the bioinformatics, expression patterns and gene functions of genes were studied. Bioinformatics analysis showed that the MiNAC7 gene was located on chromosome 10, with 4 introns and 5 exons. The length of the coding region of the MiNAC7 gene was 1137 bp, encoding 379 amino acids, the theoretical isoelectric point was 4.88, the molecular weight of the protein was 93.41 kDa, and the amino acid sequence contained a conserved NAM domain. Phylogenetic tree analysis showed that mango MiNAC7 and pistachio PvNAC26 had the closest genetic relationship and the highest homology, and the amino acid sequence similarity was 69.64%. Promoter sequence analysis showed that the promoter region of the MiNAC7 gene contained light response elements, gibberellin response elements and auxin response elements. Expression analysis showed that the expression level of the MiNAC7 gene was high in the stems and buds of juvenile tissues, low in flowers, high in the stems of adult tissues, and low in flowers and leaves. At the same time, it was found that the MiNAC7 gene maintained a high expression level in the leaves at the vegetative growth stage and a low expression level in the leaves at the flowering transformation stage and flower development stage. Overexpression of the MiNAC7 gene led to a late-flowering phenotype in transgenic Arabidopsis. The overexpression of the MiNAC7 gene in Arabidopsis significantly reduced the expression level of the floral-promoting genes AtFT and AtAP1, while the expression level of the late-flowering gene AtFLC was significantly increased. Stress treatment showed that Arabidopsis with excessive expression of the MiNAC7 gene improved its resistance to drought and salt and improved its resistance to GA₃ but was more sensitive to ABA. This study shows that the mango MiNAC7 gene not only affects flowering but also participates in the response to abiotic stress, which would lay a foundation for further research on the gene regulatory network of the MiNAC7 gene involved in regulating mango flowering and stress response.

Six nuclear extracts and three leaves of different development stage were screened to establish the flow cytometry (FCM) method for determining the genomic size of Piper L. and Cucumis sativus L. was used as the DNA reference standard. Result showed that the modified nuclear extract and inverted leaf were suitable for the flow cytometry of Piper L. The genome size of cultivated varieties, including Kuching, Aman and EMAS, ranged from 667.94 to 719.32 Mb, and Reyin1, microphylla variety from Cambodia, Panniyur-1 and 73F5 ranged from 759.69 to 785.38 Mb. Therefore, the genome size was significantly different among cultivated varieties. Furthermore, it is speculated that the chromosome numbers of P. wallichii and P. hancei, with genome size larger than 900 Mb, should be larger than 52 with a multiple of 13, and the number of chromosomes of germplasm, with genome size ranged from 600 to 800 Mb, may be 52. The hybrid not only had similar phenotypes to cultivated varieties and P. flaviflorum, but also had an average genome size of cultivated varieties and P. flaviflorum. Therefore, it is speculated that the hybrid may be the hybrid offspring of cultivated varieties and P. flaviflorum. This study would provide a method for the determination of the genome size of Piper L. germplasm, and provide a technical basis for the study of Piper L. germplasm evaluation and distant hybridization.

The flavonoid quercetin is one of the main active ingredients in Chinese medicinal herb, Euphorbia maculata. At present, there are few reports on quercetin biosynthesis gene, and real-time quantitative PCR (RT-qPCR) is one of the common methods in gene research. But it is a prerequisite for relative quantitative RT-qPCR to have suitable reference genes. In order to obtain a suitable reference gene, this experiment was based on the results of transcriptome sequencing, EmSE, EmUBC, EmGDI1, EmLSM12, EmGBP, EmSYP22, EmTRI1, EmRSZ21, EmRPL7 and EmUBQ obtained by our research group in the early stage were selected as candidate reference genes. RT-qPCR was used to detect the expression of the candidate reference genes in roots, stems, leaves and fruits of E. maculata during vegetative and reproduction stages. The expression stability of the candidate genes was analyzed using geNorm, NormFinder and BestKeeper software. The results of different software were integrated and ranked by the geometric mean method. The ranking was in the order EmGDI1>EmUBQ>EmSE>EmUBC>EmLSM12=EmGBP>EmTRI1>EmSYP22>EmRSZ21=EmRPL7. EmC4H, a key enzyme gene in quercetin biosynthesis, was analyzed using EmGDI1 as the reference gene. The difference of EmC4H expression in different tissues at different stages was consistent with the trend of transcriptome sequencing. The reference gene EmGDI1 developed in this study could be used as a suitable reference gene for tissue-specific expression studies of different stages of E. maculata.