Seed germination is a key link for plants to enter the vegetative growth stage. During the germination of rice (Oryza sativa L.) seeds, the aleurone layers synthesize and secrete a series of acid hydrolases (such as α-amylase, protease) to degrade the storage substances in the endosperm and provide nutrition for the growth of rice seedlings. The degradation of storage proteins is inseparable from the role of proteasome and protease in rice seeds. In order to explore the involvement of 26S proteasome, 20S proteasome and its subunit PBA1 in the regulation of GA on the storage proteins in the aleurone layers of germinated rice seeds, the rice hybrid Teyou 128 was used as the experimental material. The activity of 26S proteasome, 20S proteasome and PBA1, the transcription level of OsPBA1 and the change of total protein content were detected by enzyme-linked immunosorbent assay and real-time fluorescence quantitative PCR. GA significantly promoted the degradation of storage proteins in aleurone cells and accelerated the germination of rice seeds. When GA synthesis was blocked, the degradation process of storage protein in aleurone layer cells was delayed, thus delaying the germination of rice seeds. Under normal culture conditions, the peak values of 26S proteasome activity and 20S proteasome activity in the aleurone layers of rice seeds appeared at 6 d and 7 d, respectively, while the OsPBA1 expression level and PBA1 activity showed peaks at 5 d and 8 d. Further studies showed that GA could induce the activity of PBA1, 20S proteasome and 26S proteasome, thereby accelerating the process of seed germination. The 26S proteasome activity inhibitor MG132 inhibited the growth of germinated rice seeds, but increased the activity of 20S proteasome and PBA1. The above studies preliminarily revealed the role of 26S proteasome in GA regulating the degradation of storage proteins in rice aleurone layers and its effect on the germination of rice seeds.

Phenotypic traits are the basis of breeding, which can reflect the genetic variation of species to a certain extent. Exploring the phenotypic diversity of Hibiscus rosa-sinensis cultivar can provide reference for the utilization of germplasm resources and the breeding of new varieties. In this study, 39 H. rosa-sinensis cultivar resources were selected as the research object. Data of 25 phenotypic traits were collected and measured, including 9 quantitative traits and 16 qualitative traits. Diversity analysis, correlation analysis, cluster analysis, principal component analysis and comprehensive evaluation were carried out. The results of diversity analysis showed that there was abundant variation in the 39 H. rosa-sinensis cultivar resources resources, and the coefficient of variation of 9 quantitative traits ranged from 9.49 to 31.05, among which, the coefficient of variation of pedicel length was the largest, and the coefficient of variation of leaf length/width was the smallest; the index of diversity was 1.7592 to 2.0299, among which the index of style length was the highest, and edicel length diversity index was the lowest. The diversity index of 16 quality traits ranged from 0.3898 to 1.3203, among which the diversity index of flower heart and eye area was the highest, and the diversity index of flower pattern was the lowest. Correlation analysis showed that there were significant positive correlations between flower diameter and petal length, outermost petal morphology and petal secondary color, leaf length and leaf width, petal length and style length, flower diameter and style length, petal length and width, and flower diameter and petal width. There was a significant negative correlation between petal width and pattern, style length and pattern, leaf width and leaf length-width ratio, and petal length and pattern. The cluster analysis showed that the 39 species could be divided into four groups at Euclidean distance of 20. The Ⅰ group contained 33 species resources, which were mainly characterized by the flower diameter between 11 cm and 17 cm, and could be further divided into two subgroups. The Ⅱ group contained two species, which were mainly characterized by double petals and small flower diameter between 10 cm and 11 cm. The Ⅲ group contained three species, which were characterized by single petals and large flower diameter, with the flower diameter between 18 cm and 20 cm. The Ⅳ group contained only one species. Principal component analysis showed that 9 principal components were extracted, the cumulative variance contribution rate of 79.85%. Through the calculation of main component of the 39 specie, the comprehensive score of Huo fenghuang was the highest, followed by Valentine's day, Moorea Hanging Garden and Fei jiangjun, while that of Yueyecaihong and Chocolate Cake was the lowest.

In order to explore the effects of nitrogen fertilizer application rate and planting density on the source-sink relationship and yield of sweet potato during ridge-sealing period, and to improve the cultivation techniques of sweet potato in Hainan, a field experiment was carried out from 2019 to 2020. The fresh-eating sweet potato variety Gaoxi14 was used as the test material, and three planting densities were set up, namely 47 600 plants/hm² (D₁), 71, 400 plants/hm² (D₂) and 142 900 plants/hm² (D₃). Four nitrogen application rates (0 kg/hm² (N₀), 60 kg/hm² (N₁), 120 kg/hm² (N₂), 180 kg/hm² (N₃) were designed in a double-factor split plot design with planting density as the main plot and nitrogen application rate as the subplot to study the effects of different planting densities and nitrogen application rates on photosynthetic characteristics, the relative chlorophyll content (SPAD), stem and leaf growth, dry matter accumulation and distribution in source and sink, tuber characteristics in ridge-sealing period, yield and its components and commodity in harvest period of Gaoxi14. Under the same planting density, the net photosynthetic rate (P_n), fresh weight of stem and leaf, number of branches, longest vine length, number of tubers per plant and single tuber weight of commercial sweet potato increased first and then decreased with the increase of nitrogen application rate, and reached the maximum at N₁ treatment. The yield of sweet potato increased first and then decreased with the increase of nitrogen application rate, and reached the maximum under N₂ treatment, which was 32.0% higher than that under N₀ treatment, but there was no significant difference between N₂ and N₁ treatments. Under the same nitrogen application rate, the dry matter distribution ratio of sweet potato roots increased first and then decreased with the increase of planting density. The D₂ treatment reached the maximum but there was no significant difference between D₂ and D₃ treatments. The root shoot ratio and yield increased significantly with the increase of planting density, and reached the maximum at D₃ treatment. The yield of D₃ was 30.9% and 24.1% higher than that of D₁ and D₂, respectively. The results of correlation analysis showed that the nitrogen application rate and planting density had significant effects on the dry matter accumulation and distribution of root tubers, while the planting density had a significant positive correlation with the yield of sweet potato at harvest stage, and the correlation coefficient was 0.704. Based on the results of this experiment, when the nitrogen application rate was 60 kg/hm² and the planting density was 142 900 plants/hm² (D₃N₁), the yield of Gaoxi 14 was the highest, reaching 30.1 t/hm², and the corresponding potato commodity rate was 94.3%, which was the best among all treatments.

Aquaporins (AQPs), assembled in tetramers at the biological membrane, constitute a class of integral membrane proteins facilitating the passive transport of water. Natural rubber, which is specifically synthesized in the laticifer located in the secondary phloem of the rubber tree (Hevea brasiliensis) trunk, is expelled out in the form of latex that represents the cytoplasmic content of laticiferous cells upon tapping. Water, accounting for approximately 70% of the latex upon each tapping, plays a crucial role in the latex production by regulating the latex viscosity and laticifer turgor. Previous studies suggested that the water balance of laticifers is governed by plasma membrane intrinsic proteins (PIPs) especially HbPIP2;3, an efficient and abundant water transporter. To uncover the regulation mechanism of HbPIP2;3 in the laticifer water balance, its 861 bp full-length coding sequence (CDS) was isolated using RT-PCR. Sequence analysis revealed that HbPIP2;3 putatively encoded 286 amino acids with the theoretical molecular weight (MW) of 30.58 kDa, the isoelectric point (pI) of 8.50, the instability index (II) of 31.68, and the grand average of hydropathicity (GRAVY) of 0.449, implying its basic, hydrophobic, and stable features. The protein was shown to contain one conserved MIP (major intrinsic protein) domain, which including six typical transmembrane helices (i.e. TM1-6) as well as two half helices (i.e. HB and HE). 3D prediction via homology modeling suggested that HbPIP2;3 could assemble in homotetramer. In accordance with the bioinformatics prediction, transient over-expression of HbPIP2;3 in Nicotiana benthamiana leaves supported the cell membrane localization, which was also confirmed by bimolecular fluorescence complementation (BiFC). Moreover, BiFC revealed that HbPIP2;3 could interact itself, which was further confirmed by yeast two-hybrid. The results showed that HbPIP2;3 may be involved in the laticifer water balance in the form of homotetramer at the plasma membrane, however, whether it could also function in hereotetramer still needs to be addressed.

Dendrobium kingianum belongs to Orchidaceae family, which is widely grown as an ornamental plant in China. In recent years, a blight disease in D. kingianum is observed in Guangdong province, China. This disease infects the stems and leaves of D. kingianum, causing brown rot and plant death. It has a serious impact on production. A fungus was isolated from the diseased plants of D. kingianum. The pathogenicity test showed that this fungus could infect healthy potted plants and cause the disease. The symptoms on inoculated plants were similar to field symptoms. Morphological characteristics of the fungus from the inoculated plants were consistent with that of the original fungus from field samples. The pathogen was identified by both morphological characteristics and β-tubulin (tub) gene sequence analysis. The morphological characteristics of the isolates were similar to Phytophthora palmivora. BLAST results showed both the sequences of two isolates in this study were 99% identical to the sequence of P. palmivora. In the maximum likelihood (ML) tree based on tub gene sequences, the strains in this study clustered with P. palmivora with 100% support. Therefore, P. palmivora was identified as the pathogen of Phytophthora blight on D. kingianum based on morphological characteristics and phylogenetic analysis. This is the first report of P. palmivora causing Phytophthora blight on D. kingianum in China and worldwide. The inhibitory effect of 10 fungicides on P. palmivora was determined using the mycelial growth rate method. The results showed that four fungicides, namely diacetylomyamide, dimethomorph, metalazepine and metalazepine · mancozeb, were the top four toxic to P. palmivora, and the EC₅₀ value was 0.000 03 μg/mL, 0.0628 μg/mL, 0.2381 μg/mL and 0.5457 μg/mL, respectively. It was followed by chlorothalonil, pyrimethole and mancozeb, the EC₅₀ was less than 10 μg/mL. However, the effect of downy mildew hydrochloride and triethylphosphonate was poor, and the EC₅₀ was more than 100 μg/mL. Carbendazim showed no inhibitory effect, the EC₅₀ was more than 1000 μg/mL. The result would provide a theoretical basis for the prevention and control of Phytophthora blight in Dendrobium.

Phosphatidyl ethanolamine-binding protein (PEBP) widely exist in plants and play important roles in regulating flowering, seed dormancy and the formation of underground storage organs (e.g. potato tubers and onion bulbs). However, up to now, there is few studies conducted on PEBP genes in sweet potato (Ipomoea batatas), and there is also no research published to reveal the key members of PEBP gene family that regulate the development of storage root of sweet potato. Our study first identified the number and types of the PEBP gene family in sweet potato through bioinformatics analysis. Then, to screen the candidate members of the PEBP gene family that regulate the development of storage root of sweet potato, the tissue specificity of PEBP gene expression and the dynamic changes of PEBP gene expression level in storage roots at different development stages were analyzed. To explore possible regulatory mechanism, the correlation between PEBP gene expression level and SWEET gene expression level in storage roots were also examined. The results are as follows: (1) A total of 15 putative PEBP genes were identified from the sweet potato genome, which were classified into 4 subfamilies: 5 of FT-like genes (IbFT1-5), 6 of TFL1-like genes (IbTFL1-6), 2 of MFT-like genes (IbMFT1-2), and 2 of PEBP-like genes (IbPEBP1-2). (2) Clustering analysis revealed that IbFT5 may promote the development of storage root of sweet potato, while IbTFL3 may inhibit the development. (3) The tissue specificity analysis of sweet potato PEBP gene expression showed that IbFT5, IbTFL4 and IbTFL6 not only showed higher expression levels in the diverse root tissues than in other tissues, but also had higher expression levels in roots than other PEBP genes. Therefore, it is speculated that the three PEBP genes may promote root enlargement. (4) The expression levels of the four candidate PEBP genes (IbFT5, IbTFL3, IbTFL4 and IbTFL6) obtained from the above two methods were determined in storage roots at different developmental stages (30, 60, 90 and 120 days after planting). It was found that the expression levels of IbFT5, IbTFL4 and IbTFL6 significantly increased with the development of root tubers, especially during the rapid expansion period (60-90 days), while the expression level of IbTFL3 rapidly de-creased during the rapid expansion period (60-90 days). Therefore, all the above measurement results indicate that IbFT5, IbTFL4 and IbTFL6 may promote root development, while IbTFL3 may inhibit root development. (5) With the increase of expression levels of IbFT5, IbTFL4 and IbTFL6, the expression levels of four out of the five highly ex-pressed SWEET genes (IbSWEET4, IbSWEET11, IbSWEET16 and IbSWEET19) in storage roots showed a continuous decreasing trend. This result is similar to the findings in potatoes, indicating that the PEBP gene of sweet potato may also inhibit SWEET activity and thus promotes the transportation of sugar to the storage roots through more efficient symplasmic pathway, which ultimately promotes the development of storage roots. In conclusion, this study not only determined the number and types of members of the PEBP gene family in the sweet potato genome, but also systematically identified four candidate PEBP genes affecting the development of sweet potato storage roots, which can provide a theoretical basis for further improvement of sweet potato yield in China.

Insects use floral volatiles as the olfactory cues to locate flowers. Numerous studies have shown that the selection behavior of insects can be impacted by variations in the volatile component concentration of floral varieties. The flower of mango (Mangifera indica L.) rely on insect pollination and susceptible to florivorous pests. However, volatiles in different varieties of mango flowers are relatively insufficient, which is unfavourable to the development of attractants and repellents. Therefore, the volatile floral chemical components in seven mango varieties (M. indica var. Sijimi, M. indica var. Tainong 1, M. indica var. Guire 82, M. indica var. Kaite, M. indica var. Hongmang 6, M. indica var. Hongxiangya, and M. indica var. Jinhuang) were collected using the dynamic headspace adsorption technique. The volatile components were identified and analyzed using gas chromatography-mass spectrometry-mass spectrometry (GC-MS) to compare the composition differences and similarities of the components. The findings indicated that a total of 115 volatile components, comprising 44 terpenes, 30 alkanes, 16 esters, 16 alcohols, five ketones, three aldehydes, and one phenol, were found in the volatiles of the seven species of mango flowers. 82 distinct types of volatile substances were discovered in M. indica var. Sijimi, 49 distinct types of M. indica var. Tainong 1, 46 distinct types of M. indica var. Guire 82, 49 distinct types of M. indica var. Kaite, 60 distinct types of M. indica var. Hongmang 6, 49 distinctive types of M. indica var. Hongxiangya, and 59 distinct types of M. indica var. Jinhuang. Seven species of mango blossoms contained 14 common volatile components: α-pinene, camphene, β-pinene, β-myrcene, 3-carene, α-terpinene, D-limonene, β-ocimene, terpinolene, 1-caryophyllene, germacrene D, o-cymene, benzoic acid, ethyl ester and 2-propyl-1-pentanol; 33 different types of specific components existed, including 24 different types of M. indica var. Sijimi, four different types of M. indica var. Tainong 1, two different types of M. indica var. Jinhuang, one type of M. indica var. Guire 82, M. indica var. Hongmang 6, and M. indica var. Kaite. The volatile compounds of mango flowers had higher relative concentrations of terpenes (46.15%–89.41%), alcohols (2.01%–23.58%), esters (3.34%–14.67%), and alkanes (2.27%–13.75%). The most abundant terpenes were α-pinene, 3-carene and terpinolene, the most abundant alcohols was linalool. The most abundant esters were benzoic acid, ethyl ester, and the most abundant alkanes were cyclohexasiloxane, dodecamethyl. The flower volatilesof M. indica var. Sijimi and M. indica var. Jinhuang had highest similarity of 0.862 among seven mango species; and that of M. indica var. Sijimi and M. indica var. Hongxiangya had the lowest similarity of 0.255. The findings would provide a reference for flower-volatile-mediated behavior preference researches in pollination insects and florivorous pests to various mango varieties.

The heat shock transcription factor MeHsfB3b is important in regulating the resistance to cassava bacterial blight. In the previous study, the candidate interaction protein MeFKBP20 of MeHsfB3b was obtained by the yeast two-hybrid technology, which belongs to the FKBP-type peptide prolyl cis-trans isomerase gene family. In this study, the full-length MeFKBP20 gene was cloned to be 561 bp, encoding 186 amino acids, with a molecular weight of 19.99 kDa and a FKPB_C domain. The expression pattern analysis showed that MeFKBP20 was highly expressed in mature leaves and roots of cassava, and the expression level of young leaves and petioles was low. It could quickly respond to the in-duction of pathogen XpmCHN11 and maintain a high expression abundance, suggesting that it is involved in response to pathogen infection. The interaction between MeHsfB3b protein and MeFKBP20 protein through 201-241 aa region was proved by the yeast two-hybrid point-to-point and bimolecular fluorescence complementation experiments. The results of this study are helpful to further analyze the mechanism of MeHsfB3b gene regulating cassava resistance to cassava bacterial blight.

The fruit quality of different varieties (lines) of cultivated ginseng fruit in Shilin county was tested and evaluated to provide guidance for the development of ginseng fruit industry. Seven fruit quality indexes of soluble sugar, soluble protein, soluble solid, mineral elements, vitamin C, cellulose and amino acid were determined by using eight main ginseng fruit varieties (lines) of Dayuangguo, Yuangguo No. 1, Yuangguo No. 2, Yuangguo No. 3, Shiyou No. 1, Shiyou No. 2, Shiyou No. 3 and Ruiyu cultivated in the field of Shilin county. By multiple comparison of quality indexes of Panax ginseng fruit, it was found that the content of soluble sugar in Yuanguo No. 2 was the highest, while that in Dayuanguo and Yuanguo No. 3 was the lowest; The soluble protein content of Shiyou No. 2 was the highest, and that of Shiyou No. 1 and Ruiyu was the lowest; The content of soluble solids of Yuanguo No. 2 was the highest, while that of big round fruit was the lowest; Shiyou No. 3 has the highest content of vitamin C and Yuanguo No. 3 has the lowest content; The crude fiber content of Yuanguo No. 2 was the highest, and that of Shiyou No. 1 was the lowest; The content of trace elements in Yuanguo No. 2 was the highest, while that in Yuanguo No. 3 was the lowest; The amino acid content of big round fruit was the highest, and that of Shiyou No. 2 was the lowest. There were significant correlations between the quality indicators of different varieties (lines), among which soluble sugar and soluble solids were significantly correlated with each other (P<0.05). The principal component analysis of 6 quality indicators was carried out, and the cumulative contribution of the first three principal components reached 83.955%, which could reflect most of the information of the original quality index. The resulting comprehensive evaluation system was established to evaluate eight different varieties (lines) of ginseng fruit. In conclusion, the above eight ginseng fruit varieties (lines) all contain rich nutritional components, among which Yuanguo No. 2 has the best comprehensive quality, and can be selected as the parent material for the main variety or new germplasm creation.

Anacardium occidentalie Linn is a typical tropical fruit tree, which is mainly planted in Yunnan and Hainan provinces of China. Cashew cultivation has important economic, social and ecological values. It is of great value to realize realize the strategy of rural revitalization in China, increase farmers' production and income, and achieve common prosperity. Cashews are very sensitive to low temperatures, and they will be severely damaged at 8 ℃and the growth will stop. Therefore, lowtemperature stress is an important abiotic stress that restricts cashew growth. CBF transcription factors play important roles in plant response to abiotic stresses such as low temperature, drought and salt. However, the role of CBF gene family in cashews has not been elucidated, and the expression pattern of this family in response to low temperature stress is unknown. In this study, in order to explore the basic characteristics of the CBF gene family in cashew nuts, six AoCBF gene family transcription factors were identified and obtained from the cashew transcriptome by bioinformatics methods, and the physical and chemical properties, protein structure, phylogeny, promoter action elements and expression patterns under low temperature induction were analyzed. The length of the six AoCBF proteins ranged from 189 to 334 aa, and the molecular weight of the proteins ranged from 21.31 to 37.89 kDa. The isoelectric points of the six AoCBF proteins were less than 7, indicating that the proteins were acidic. The proteins all contained an AP2/ERF domain. Motif analysis showed that there were five motifs in AoCBF genes, and the absence of different AoCBF gene motifs implied the absence of related functions. Phylogenetic tree analysis showed that the six AoCBF genes could be divided into two subgroups, A and B, in which group A contained one gene and group B only contained five genes. The analysis of homeotropic elements of promoter showed that AoCBF gene might be involved in the response to hormone and abiotic stress. Fluorescence quantitative expression analysis showed that all the six AoCBF genes responded to low temperature and cold stress to different degrees, indicating that AoCBF played a role in the biological process of cashew nut in response to low temperature stress. The results summarized the basic characteristics of the AoCBF gene family and accumulated basic data for further molecular resistance research and application of cashews AoCBF genes.