Oncidium is an important fresh-cut flower in the market because of its unique flower pattern and brilliant color. The petals of Oncidium are highly susceptible to flower diversity. RNA extraction and transcriptome analysis were performed on the lateral petals of O. flexuosum ‘Honey Angel’ and variants with two lateral petals converted into lips to explore the molecular mechanism regulating the labialization of Oncidium lateral petals. A total of 45 525 415 high-quality reads were obtained from the sequencing results and 52 253 unigenes were identified. The seven databases of NR, Swissprot, PFAM, GO, NT, KO and KOG were used to annotate gene functions and annotated to 31 828, 23 174, 21 369, 21 367, 20 830, 10 523, 6465 unigenes. Upon expression comparison,3120 differential genes were obtained between O. flexuosum ‘Honey Angel’ and the mutant. A total of 1537 differentially expressed genes were annotated into three functional groups: biological processes, cellular components and molecular functions. KEGG functional enrichment analysis enriched 690 differentially expressed genes into different metabolic pathways, with the most genes enriched by metabolic pathway. To date, the study of lip formation in orchids has focused more on the MADS-box gene family, not only five significantly differentially expressed MADS-box genes were screened in this transcriptome data, but also other transcription factor such as NAC, TCP, MYB and WRKY that may be related to the lip formation in Oncidium were also discovered. RT-qPCR was used to verify the expression of key genes, and the quantitative results were consistent with RNA-seq data, most of the genes were highly expressed in the lip-like lateral petals, indicating that the genes may positively regulate the development of the lip of Oncidium. In summary, this study excavated a large number of key transcription factors involved in the variation of labialization in Oncidium, which would provide a certain reference for the study of the molecular mechanism and regulatory network of lip formation of orchid.

Banana classification is a difficult problem, using morphological features to classify is unable to meet the needs. Molecular marker technology has been gradually applied to population identification and classification, genetic relationship analysis and genetic diversity research of banana varieties (lines). In this paper, SRAP molecular marker technology was used to analyze the genetic relationship of 89 banana germplasm resources. Using 10 pairs of positive and negative primers to form 100 pairs of primer combinations, and 13 pairs of SRAP primers with easy identification, clear band type and high polymorphism were screened out. 170 identifiable bands were amplified by the 13 pairs of primers, with an average of 13.08 bands per pair of primers, of which 140 bands showed polymorphism, with a polymorphism ratio of 79.00%. The similarity coefficient of 89 banana germplasm resources varied from 0.241 to 1.000, and the genetic diversity was very rich. The similarity coefficient of the same type of wild banana from the same place or different places was high. When the similarity coefficient was 0.49, the 89 banana resources could be divided into six groups. The first major category were AAA group Xiangyajiao, AA group Gongjiao, AAB group Longyajiao and AA group wild banana (AAA, AA, AAB). The second major category were ABB group Fenjiao, ABB group Fendajiao and BB group wild banana (ABB, BB). The third major category were Dajiao and a banana wild relative Musa itinerans. M coccinea, Musella lasiocarpa, Heliconia belonged respectively to the fourth, fifth and sixth category. The results are basically consistent with the current classical classification conclusion. Only some banana germplasm have different classification status, indicating that it is feasible to use SRAP markers to classify banana germplasm resources. At the same time, the cultivated Xiangya banana, Gongya banana and Longya banana have the same ancestry, and are close to the wild banana of AA genotype, while the wild banana of BB genotype is close to the pink banana, the pink banana and the wild banana of BB genotype, and the banana germplasm resources of different genomes are gathered together, which showing that the origin of banana germplasm resources affects the genetic relationship of offspring, and a single classification method cannot completely distinguish the banana germplasm resources. In addition, the genetic relationship between plantain and plantain is relatively close, but it is impossible to distinguish whether plantain contains A and B genomes, so the genotype and genetic background of plantain need further study.

Phytosulfokine (PSK) is a small peptide hormone unique to higher plants, widely involved in biological processes such as plant growth and development, division and differentiation, biotic and abiotic stress. PSK receptor (PSKR) is a direct receptor for PSK and is crucial for PSK signal transduction. In the present study, HbPSKR2 was cloned from rubber tree by RT-PCR (reverse transcription-polymerase chain reaction), and its bioinformatics, gene expression pattern, interacted proteins screening and identification were also analyzed. Results showed that the open reading frame of reading frame of HbPSKR2 had a total length of 3159 bp and encoded 1052 amino acids with molecular weight 114.84 kDa and theoretical isoelectric point 6.34. Domain analysis showed that HbPSKR2 was a typical trans-membrane protein. The first 640 amino acids were the antenna structures composed of leucine rich repeat (LRR), the 692 to 714 amino acids were transmembrane domains, and the 765 to 1052 amino acids were kinase domains. Multiple comparisons were conducted on the membrane kinase domain of HbPSKR2 and the membrane kinase domain of PSKR homologous proteins in Arabidopsis and rice. The results showed the existence of conserved sites such as ATP binding site, CaM binding site, Activation segment, GC Centre. Expression pattern analysis showed that HbPSKR2 was highly expressed in the cambium region of rubber tree. The expression level of HbPSKR2 was significantly increased at the early stage of coronatine (COR) treatment. Twelve candidate proteins interacted with HbPSKR2 were screened by yeast two hybrid technology, and the interaction between two protein kinases (HbPBL8 and HbPIX13) and HbPSKR2 was further verified by luciferase complementary imaging. The strong fluorescence signal was observed by co-transformation HbPSKR2-nLUC/HbPBL8-cLUC and HbPSKR2-nLUC/HbPIX13-cLUC into tobacco, suggesting the interaction between HbPSKR2-HbPBL8 and HbPSKR2- HbPIX13 in vivo. The cloning of HbPSKR2 and identification of HbPSKR2 interacted protein would provide new insights into the molecular mechanism of laticifer differentiation in rubber tree.

Pepper mild mottle virus (PMMoV) is one of the most serious pathogens worldwide. Currently, five pathogenic types of PMMoV have been reported, including P₀, P₁, P_1,2, P_1,2,3 and P_1,2,3,4. The wide host range and strong pathogenicity of PMMoV seriously affect the yield and quality of pepper, and breeding for disease resistance is the most economical and effective means to control this virus. Our previous study determined that PMMoV infected with Danzhou pepper germplasm nursery in Hainan is the P_1,2 pathogenic type. In order to screen PMMoV-resistant pepper germplasm resources, 110 germplasms were tested for PMMoV resistance using the reported L³-linked molecular markers. 46 pepper germplasms containing molecular markers of resistance were inoculated with PMMoV P_1,2 pathogenic type by inoculation at seeding stage. Local symptoms were investigated 5 d after inoculation, and systemic symptoms were investigated 20 d after inoculation, and disease indices were calculated. The results showed that there were sig-nificant differences in disease resistance among different pepper germplasms, and the disease indexes of various germplasms ranged from 8.86-60.00. The germplasms showing high resistance (HR) to PMMoV P_1,2 pathogenic type were CF19-34m and 19FB6-1. The germplasms showing resistance (R) wasCCJ93-1. The germplasms showing medium-resistance (MR) included 17YB32, 17SCa28m, 15SM39-2, 14SM555×14SM1, 14SM567-2, 14SM526-1, 14SM565-1, 14SM502-1, 14SM519-1, 14SM504m, 14SM503m, 14SM519-3, 14SM518-2, 14SM519-2, CCJ52-1, etc. The presenting susceptible (S) germplasms were 14SM514m, CCJ22-1, CCJ113-2, CCJ135-1, CCJ157-1, L537-1m, L545, CCJ87-2 and CCJ133-1, and the obtained disease-resistant germplasms accounted for 80.43% of the total identified materials. The results of this study would lay the foundation for creating germplasm resources resistant to pepper mild mottle virus and breeding resistant varieties.

Cassava (Manihot esculenta Crantz) is the third largest food crop in the tropics and is the food ration of nearly 600 million people in the world. Cassava is mainly cultivated in tropical regions, where often damaged by waterlogging in rainy season, which leads to serious decline in yield and quality. Therefore, it is important for selecting cassava germplasm resources with high waterlogging-resistance. In this study, a pot experiment was carried out, and plant height increment, relative chlorophyll content (SPAD), relative conductivity, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) of 28 cassava germplasm resources were measured under waterlogging stress treatment after 6 days. Variance, correlation analysis, principal component analysis and subordinate function analysis were used to evaluate waterlogging resistance and screen the waterlogging tolerant germplasms at the seedlings stage. The waterlogging tolerance of 28 cassava germplasms had great difference and the response mechanism of different cassava germplasms to waterlogging stress showed huge difference among the 28 germplasm resources. There were significant positive correlation between plant height increment and relative chlorophyll content (P<0.01), and the correlation coefficient was 0.253. There were negative correlation coefficient between the relative chlorophyll content with relative conductivity of 0.266 (P<0.01). Principal component analysis using 6 indexes indicated that the 4 principal components accounted for 82.85% of accumulative contribution rates among the germplasms. The main factors were CAT, plant height increment, SOD, and relative chlorophyll content, respectively. According to subordinate function analysis, waterlogging tolerance of the germplasms from high to low was Qiongzhong 1, SC6068, SC201, ME191, M-F532, GR891, C222, GR3, F2000, Luoyong 80, 46-12, GR5, KU58, H660, SC5, F03P, M-GR911, CH20, M-F671, COL713, Boss 2, JG1301, GR911, E407, F274, SC8, M-SC5, Thailand. The results of this study would provide basic materials for the breeding of new varieties of cassava with high waterlogging-tolerance and for the future research of cassava waterlogging tolerance mechanism.

Wampee [Clausena lansium (Lour.) Skeels] is a species of Rutaceae family and native to Southern China, which contains a large number of bioactive compounds that are beneficial to human health. However, because of the thin pericarp and soft pulp, wampee fruit is susceptible to the mechanical damage and the quality deterioration symptoms of fruit rot, pericarp browning and storage characteristic loss, and thus reducing the commercial value and edible value of harvested wampee fruit. Therefore, it is necessary to develop a safe and environmentally friendly postharvest storage technology for enhancing the storage behavior and quality, and prolonging storage time of harvested wampee fruit. Oxyresveratrol (OXY) is a naturally active product, with the efficacies of anti-browning, anti-oxidation, antibacterial, anti-inflammatory and antiviral. OXY has been studied more in the field of medicinal health care, but less in the field of food preservation. However, there are no reports on increasing the storage behavior and postharvest quality of wampee fruit by the usage of exogenous OXY. The study was aimed to study the effects of exogenous OXY treatment on the preservation of harvested wampee fruit. The fruit of wampee cv. Jixin was used as the experiment material, and the wampee fruit was treated by OXY solution with concentration of 0.2 g/L and distilled water (CK) for 30 min, separately. Then, the fruit was air-dried and packaged (50 fruits per bag), and stored at relative humidity 85% and temperature (25±1)℃ for 10 days. The changes of related indices of the storage behavior and postharvest quality in wampee fruit were observed and measured every two days. Compared to CK, OXY treatment could delay the increments of pericarp cell membrane permeability, browning degree and browning index, and maintain a higher commercially acceptable fruit rate but a lower weight loss percentage of harvested wampee fruit. Furthermore, OXY treatment might keep the higher values of L^* and hue angle, a higher total phenolics content, but the lower activities of phenolases such as peroxidase and polyphenol oxidase in pericarp of harvested wampee fruit. Moreover, OXY treatment could retain the higher contents of total soluble solids, vitamin C, titratable acidity, sucrose and total soluble sugar in pulp of harvested wampee fruit. Therefore, the treatment of exogenous OXY could effectively enhance the storage behavior, and retain the pericarp appearance quality and pulp nutritional quality, and thus prolong the storage time in harvested wampee fruit.

In August 2022, we found Phyllanthus urinaria with yellows and witches’-broom symptoms, respectively, in areca yellows disease garden in Wenchang city, Hainan province, which were phytoplasma infection. In order to clarify the taxonomic status of the phytoplasma strain in the yellows leaves and witches’-broom of P. urinaria. In this study, we cloned the 16S rDNA gene and ribosomal protein (rp) gene, and analyzed the gene sequence consistency, phylogenetic tree and virtual RFLP. The results showed that the 16S rDNA fragment 1246 bp and rp gene 1212 bp were cloned of P. urinaria yellows phytoplasma, the 16S rDNA fragment 1827 bp and rp gene 1240 bp were cloned of P. urinaria witches’-broom phytoplasma. The gene sequence consistency showed that the 16S rDNA gene sequence of the P. urinaria yellows phytoplasma and the P. urinaria witches’-broom phytoplasma was more than 98% consistent with the phytoplasma of 16SrⅠ group, and 100% consistent with the 16S rDNA sequence of areca yellows phytoplasma Hainan strain; the consistency of them in rp gene sequences was more than 99% to those of the rpⅠ group. The phylogenetic tree analysis showed that the 16S rDNA genes of P. urinaria yellows phytoplasma and P. urinaria witches’-broom phytoplasma were clustered in a large branch with those of aster yellows phytoplasma group (16SrⅠ), and clustered in the same small branch with those of areca yellows phytoplasma of 16SrⅠ-B subgroup, with the close genetic relationship; in the phylogenetic tree of rp gene, they were clustered in a large branch with the aster yellows phytoplasma group (rp Ⅰ), and clustered in the same small branch with those of aster yellows phytoplasma of rpⅠ-B subgroup, with the close genetic relationship. The virtual RFLP analysis showed that the RFLP map obtained by the 16S rDNA gene of the P. urinaria yellows phytoplasma and P. urinaria witches’-broom phytoplasma was the same as the reference map of the onion yellows phytoplasma of 16SrⅠ-B, and the similarity coefficient was 1.00. In summary, the P. urinaria yellows phytoplasma and the P. urinaria witches’-broom phytoplasma belong to 16SrⅠ-B subgroup in classification. The results of this study could provide a theoretical basis for the prevention and control of areca palm yellow disease by eradicating its intermediate host.

The yield and quality of sweetpotato root tubers can be significantly improved by applying paclobutrazol (PBZ), and sucrose-degrading enzymes play important roles in the development of storage roots of sweetpotato. However, the physiological and biochemical mechanisms underlying PBZ-regulated storage root development is still unclear, and especially it remains to be investigated whether sucrose metabolism is involved in the PBZ-regulated development of storage roots. In this paper, sweetpotato cultivar Kokei 14 was used, a predominant cultivar planting in Hainan. After applying PBZ treatment in the early stage of cultivation (20-30 d after planting, dap), the following phenotypic parameters were investigated at 120 dap including the fresh weight of storage root per plant, fresh weight per storage root and storage root number per plant. To elucidate the physiological and biochemical mechanisms relevant to sucrose metabolism underlying PBZ-regulated storage root development, the following physiological and molecular parameters were also examined in storage roots at different development stages (30, 60, 90 and 120 dap) including the content of starch and soluble sugars (glucose, fructose and sucrose), the activities of sucrose-degrading enzymes and expression levels of the gene families. PBZ increased the yield of sweetpotato by increasing the fresh weight per storage root, but without affecting storage root number per plant. PBZ increased the content of soluble sugar and starch in storage root. However, the effect of PBZ on the yield and quality of storage roots only occurred in the early stage (30-60 d after planting) after treatment, and in the late stage (90-120 d), PBZ treatment had no significant effect on yield and quality. PBZ treatment significantly increased the activities of sucrose synthase (Sus), cell wall invertase (CWIN) and cytoplasmic invertase (CIN). However, PBZ had no significant effects on vacuolar invertase (VIN). As compared to CWIN and CIN, Sus activity was induced by PBZ treatment much earlier and more dramatic. Sus activity was significantly induced at 30 dap, whereas the activity of CWIN and CIN were significantly induced at late stage i.e. 60 dap. In other periods (especially 90-120 d), PBZ treatment had no significant effect on the activities of Sus, CWIN and CIN. The determination of the expression level of Sus, CWIN and CIN genes showed that IbSus2, IbSus5-7 and IbSus9 highly expressed in storage tuber were all significantly induced by PBZ at 30 dap. IbCIN3, IbCIN7 and IbCIN8 expressed in storage roots, and IbCWIN2 and IbCWIN4 expressed in storage roots were significantly induced by PBZ at 60 dap. However, in other periods (especially 90-120 d), PBZ treatment had no significant effect on the expression level of the relevant genes. It is speculated that the increase of Sus expression and activity under PBZ treatment is earlier and more dramatic, which can promote the rapid and biosynthesis and accumulation of starch and the rapid expansion of storage roots, while the subsequent increase of CWIN and CIN expression and activity can increase the content of soluble sugar in root tubers thus improving the quality of storage roots, and can also provide energy supply for starch biosynthesis and storage root expansion. The specific members of Sus, CWIN and CIN genes induced by PBZ had also been identified. Notably, the effects of PBZ on the yield and quality of storage roots, and activities and gene expression levels of sucros-degarding enzymes in storage roots mainly occurred in the short period after PBZ treatment. With the extension of time, the effects of PBZ on the above indicators gradually disappeared. Therefore, in order to improve the yield of sweetpotato in production, it is necessary to conduct PBZ treatment throughout the entire growth period of sweetpotato. The above results can provide a theoretical basis for achieving high-quality and high-yield sweetpotato production by variety breeding or cultivation measures.

Using the meteorological data and disaster information of 18 meteorological stations in Hainan Island in winter (from December to February of the next year) of 1971 to 2020, this paper constructed the meteorological index of chilling injury to winter vegetables with biological characteristics which not only considered the influence of overcast rain and few sunlight, but also could quantify the influence of previous cold injury processes. Combining Mann-Kendall trend test method and ArcGIS techniques, the spatiotemporal change law of chilling injury to winter vegetables in Hainan Island was obtained. The areas with high probability of chilling injury to vegetables in December, January and February and the areas with high probability of light, medium and severe chilling injury to vegetables in each month were mainly distributed in the northwest and middle of Hainan Island, while the areas with low probability were mainly distributed in the west-south-east coastal regions. The chilling injury to vegetables in each month was mainly light and moderate grade, accounting for about 88.3%. Among the three months, chilling injury to vegetables occurred most frequently in January (48.6%), and chilling injury of all grades to vegetables also occurred most frequently in January (50.2%, 43.4% and 40.2% respectively). In the recent 50 years, the annual occurrence times of cold injury to vegetables in each month of winter in Hainan Island were not significantly decreasing in most stations (83.3%, 94.4% and 72.2% respectively). Among the different grades of cold injury to vegetables in 3 months, only the annual occurrence times of severe cold injury to vegetables in February showed an increasing trend in many stations (38.9%), the annual occurrence times of other grades of cold injury were also not significantly decreasing in most stations (61.1%-88.9%). The influence scope of different grades of cold injury to vegetables in each month all decreased significantly in the order of light to severe chilling injury. Compared with each other in three months, the influence scope of cold injury to vegetables in Hainan Island were close to each other in December and February and were significantly smaller than that in January, the influence scope of light and moderate cold injury to vegetables also showed similar rules between months, while the influence scope of severe cold injury to vegetables were close to each other in December and January and were significantly larger than that in February. In the recent 50 years, the influence scope of chilling injury to vegetables in Hainan Island in December, January and February and the influence scope of different grades of chilling injury to vegetables in each month were all non-significant shrinking. In general, in the recent 50 years, the annual occurrence times of cold injury to winter vegetables was decreasing and the influence scope was shrinking, which was generally beneficial to the cultivation of winter vegetables in Hainan Island. However, in February, the annual occurrence times of severe cold injury to vegetables in eastern, central and western regions were increasing, which should be paid attention to.

Eight main agronomic traits were statistically analyzed using cassava germplasm resources. The result showed that the data for the eight agronomic traits were normally distributed, with the coefficients of variation ranging from 7.2% to 46.9%. The coefficient of variation for starch yield was 46.9% and the coefficient of variation for the dry matter rate was 7.2%. Correlation analysis showed that there was a degree of significant positive correlation between the different traits, with a highly significant positive correlation between weight of fresh tuberous root per plant and stem diameter. Principal component analysis combined eight traits into three main components. The cumulative contribution rates in each year amounted to 92.55% and 93.67%, respectively. The first principal components were weight of fresh tuberous root per plant, fresh tuberous root yield, starch yield and dry tuberous root yield. The second principal components were starch content and dry matter. Cluster analysis suggested that the resources could be divided into four groups in each year at the Euclidean distance of 6.0. Group Ⅱ had excellent performances in weight of fresh tuberous root per plant, fresh tuberous root yield, starch yield and dry tuberous root yield, which could be preferred as parental materials for new cassava varieties selection and breeding of high yield and good quality.