Mango (Mangifera indica L.) is one of the major cash crops in the tropics and a typical respiratory leap fruit, whose ripening senescence is associated with ethylenee. AP2/ERF transcription factors are widely present in plants, and it is found that the transcription factors are involved in the signal transduction of endogenous ethylene synthesis in fruits, and are key genes in the ethylene signaling pathway, playing an important role in plant growth and development, response to adversity stress and storage and transportation. To investigate the effect of AP2/ERF transcription factor on post-harvest mango ripening and senescence, a MiERF2 gene of 915 bp in length, encoding 305 amino acids, was cloned by PCR using Guifei mango as the target of this study. The molecular formula of MiERF2 protein was C₁₄₄₉H₂₂₅₉N₄₃₃O₄₇₀S_11. The molecular weight was 33 618.16 Da, the total atomic number was 4622. The theoretical isoelectric point was 7.66, with 30 positively charged residues and 29 negatively charged residues. The protein was hydrophilic and structurally unstable. MiERF2 didn’t contain a signal peptide, didn’t contain a transmembrane region, and phosphorylation modification was mainly threonine. MiERF2 contained a conserved structural domain of AP2, the secondary structure was dominated by 66.12% of random curl, also contained 24.67% of α-helix, 1.32% of β-fold, 7.89% of the extended chain. Its three-dimensional structure model contained three β-fold and one α-helix, consistent with the characteristics of the AP2 structural domain. The results of motif analysis and multiple sequence matching indicated that MiERF2 protein belonged to the ERF subfamily. Phylogenetic analysis showed that the closest relative to MiERF2 was the pistachio PvERF109-like, which is also a member of the Lacertidae family. Onion subcellular localization results showed that MiERF2 was localized in the nucleus. Quantitative real-time fluorescence analysis showed that the expression of MiERF2 differed after 400 μg/mL ethephon treatment at different harvest maturity. In 60% maturity mango, the expression of MiERF2 in the treatment group peaked at 9 d and then was significantly lower than that in the control group. In 80% maturity mango, the expression of MiERF2 in the control group was significantly higher than that in the treatment group during storage, except for 18 d. It is suspected that this gene would play a negative regulatory role in ethylene regulation of fruit ripening. This study would provide a theoretical basis for revealing the regulatory role of ERF transcription factors in postharvest ripening and senescence of mango.

In order to clarify the salt tolerance range of Morinda citrifolia seedlings and the effect of salt stress on the growth of M. citrifolia seedlings, the M. citrifolia seedlings cultured in water for 180 days were used as materials, and the basic medium was 1/8 MS liquid medium, in which NaCl with mass fractions of 0, 0.2%, 0.4%, 0.6%, 0.8% and 1.0% were added respectively for stress treatment. The results showed that with the increase of NaCl stress concentration and stress time, the relative water content (RWC) and biomass of M. citrifolia leaves gradually decreased, and the contents of soluble protein (SP), malondialdehyde (MDA) and the activities of superoxide dismutase (SOD), catalase (CAT), ascorbic acid peroxidase (APX) and peroxidase (POD) gradually increased first and then decreased. The protective enzyme activity of M. citrifolia seedlings changes significantly with the increase of NaCl stress concentration and the passage of stress time. In the range of NaCl concentration below 0.8%, M. citrifolia can reduce damage and ensure growth by regulating osmotic substances and antioxidant enzymes. When NaCl concentration is in the range of 0.8% or above, the protective enzyme system and cell membrane are seriously damaged, which affects the growth of M. citrifolia. Therefore, the seedlings of M. citrifolia can be tested in the area with NaCl concentration below 0.8%.

The alkaloid content of different samples in different seasons and different developmental stages of MHLC of two tea varieties, Nongdao Yecha (MHLC) and Yunkang 10 (YK10) was determined by HPLC. Caffeine synthase 1 gene (TCS1) was cloned from the cDNA of tea plant by RT-PCR in different samples, and its expression level was analyzed. The results showed that MHLC was a natural tea germplasm resource with low caffeine and high theobromine. Theobromine content of MHLC in different seasons was greater than 23.00 mg/g, while the caffeine content was less than 4.00 mg/g. In addition, the accumulation of caffeine and theobromine in MHLC shoots was the highest, and the leaves at the same stage had higher caffeine and theobromine than stems, and the caffeine and theobromine in leaves and stems gradually decreased with the increase of maturity. Through gene cloning and quantitative analysis, it was found that MHLC had two TCS1 allelic variants: TCS1b (with only theobromine synthase activity) and TCS1d (with both theobromine and caffeine synthase activities). Among them, the high expression of TCS1b and the extremely low expression of TCS1d are likely to be the key reasons for MHLC high theobromine and low caffeine. This research would provide material for low-caffeine tea breeding and molecular basis for the efficient utilization of MHLC.

To further explore the molecular characteristics and pathogenicity of Sri Lankan cassava mosaic virus (SLCMV) isolates in China. Mosaic cassava leaves were detected, and the domestic SLCMV isolates full-length genomes of DNA-A and DNA-B were obtained by PCR amplification. It`s nucleic acid and amino acid sequence characteristics were analyzed by bioinformatics software. The infectious clones of strong and weak pathogenic isolates (SLCMV-Colombo and SLCMV-DG1922) were constructed. The DNA-A and DNA-B components of the two virulence isolates were recombined, and the pathogenicity differences of the two isolates were compared by tobacco (Nicotiana tabacum) inoculation. The results showed that SLCMV isolates belong to “Old World begomoviruses” encoding 8 open reading frames (ORFs) including the AV2 gene. It has a typical common region (CR), repeat sequence, TATA Box and TAATATT↓AC stem-loop structure of Geminiviruses, and 7-amino-acid are missing at the carboxyl terminal of Rep protein. Domestic SLCMV genome, coding and non-coding region sequences were 97.0%-100.0% similar to the isolates from Cambodia, Thailand and Vietnam, and 86.5%-98.6% similar to the early isolates from India and Sri Lanka. Coding region of DNA-B were 95.0%-97.6% similar to Indian cassava mosaic virus strain (ICMV), were less than 80.0% to the other 9 African cassava mosaic virus strains. Infection clone inoculation showed that the DNA-A (ColA) component of the strong virulent isolate SLCMV-Col played an important role in the typical mosaic symptoms of N. tabacum leaves, while the DNA-B (DG1922-B) of the domestic isolate could cooperate with Col-A to produce strong pathogenicity to tobacco plants. This study analyzed the whole genome structure of SLCMV in China, the infectious clone and its technology provide an important research basis for further pathogenesis research of SLCMV.

Scientific evaluation of sugarcane germplasm resources can provide high quality parental materials for sugarcane cross breeding. In this study, seven phenotypic traits of 141 excellent sugarcane germplasm were evaluated for diversity using methods such as principal component analysis and cluster analysis. The variation coefficients of smut rate, cane yield, millable stalks, stalk weight and sucrose content were all greater than 10%, with the variation coefficients of smut rate being the largest at 67.21%. Correlation analysis showed that the cane yield was highly significantly positively correlated with plant height, stalk diameter, millable stalks and stalk weight, and the stalk diameter was highly significantly negatively correlated with millable stalks, and the sucrose content was highly significantly negatively correlated with smut rate. The results of principal component analysis showed that the cumulative contribution rate of 3 principal component factors was 74.725%, among which the first principal component was related to yield traits, the second principal component was related to stems and quality traits, the third principal component was related to disease traits and quality traits. Based on cluster analysis, the 141 sugarcane germplasm resources could be divided into 3 groups, among which group Ⅰ had the taller plants, highest yield and highest sucrose content, highest disease resistance, strong persisrence, and had excellent performance for all traits. Group Ⅱ had the smaller plants, lowest yield and lowest sucrose content, lowest disease resistance, poor persisrence, and had poor performance for all traits. Group Ⅲ had average performance for all traits. 60 germplasm resources were selected with excellent overall performance by principal compoment analysis results and cluster analysis results, among which ZZ153303, ZZ150505, ZZ165201 and ZZ151106 could be used as high sugar content parents, ZZ15710, ZZ160913, ZZ162026, ZZ112819, ZZ1415219, ZZ1510055, ZZ140802 and ZZ151106 could be used as highly resistant smut parents, ZZ134007, ZZ118607, ZZ167010, ZZ144101 and ZZ156615 could be used as high yield parents.

This study was conducted to explore the cumulative demand of nitrogen, phosphorus and potassium in disease-free sugarcane original seedlings, and provide reference for the nutrient management in the process of field propagation of disease-free sugarcane original seedlings. The growth of the disease-free sugarcane original seedlings of Zhongtang No. 1 in 2020 and 2021 was investigated, and the biomass and contents of nitrogen, phosphorus and potassium in roots, stems and leaves at various growth stages were determined for further analysis of the accumulation, phase absorption and daily absorption rate of nitrogen, phosphorus and potassium. It took 6 to 7 months for disease-free sugarcane original seedlings to reach 15 stem nodes from temporary planting of seedlings to the best harvest of seed canes. From July, August to late September (stem 1 to 2), the growth of sugarcane stems was the fastest. The cumulative increase of dry matter was the fastest in stem 4 (late October to late November), and this is the key stage of biomass accumulation. During the whole growth period of the disease-free sugarcane original seedlings, the content and accumulation of each element from high to low were potassium > nitrogen > phosphorus. Among the organs of roots, stems and leaves, leaves and stems always had higher nitrogen, phosphorus and potassium contents. The accumulation of nitrogen, phosphorus and potassium was mainly stored in the leaves before the stem elongation stage 1, and then mainly stored in the stems. The nutrient uptake rates of nitrogen, phosphorus and potassium at the seedling stage and tillering stage was 24.84%, 26.18% and 27.74%, respectively, and it was 55.54%, 58.61% and 52.30% at the stem 1 to 3 (late July to late October), while 19.62%, 15.20% and 19.96% during stem 4 and 5 (late October to late December). Reasonable fertilization can be carried out according to the phase absorption of each element, thereby improving the quality and economic benefits of disease-free sugarcane seedlings production. The demands of nitrogen, phosphorus and potassium in the breeding process of disease-free sugarcane original seedlings were clarified, which would provide a reference for the scientific and reasonable fertilization in large-scale field propagation of disease-free sugarcane original seedlings in the future, and improving the efficiency of the propagation and nutrient utilization of disease-free original seedlings.

Considering that the serious shortage of available silicon content in typical paddy soil of Hainan Island, it is urgent to make reasonable application of silicon fertilizer. In this study, paddy soils developed from five typical parent materials (basalt, marine sediments, fluvial alluvium, sand shale, and granite) in Hainan Island were selected to investigate the effect of silicon fertilizer application on rice in a field plot experiment. Rice yield, quality and the related physiological, biochemical and agronomic indicators under different silicon fertilizer treatments were analyzed. Results showed that compared with the blank control, the silicon fertilizer application in both T₂ and T₃ treatments significantly increased the rice yield and its related indicators such as the number of stem tillers and effective heads, seed rates, 1000-grain weight, root activity, chlorophyll and crude cellulose content relative to the control. Rice quality such as milled rice, chalkiness and amylose content also reached a good level. It is generally recommended that the optimal amounts of Si fertilizer application are 750-950 kg/hm² (available SiO₂: 187-238 kg/hm²) for basalt-developed paddy soil and 625-935 kg/hm² (available SiO₂: 156-234 kg/hm²) for granite-developed paddy soil, respectively. Meanwhile, compared with the control, the amount of silicon fertilizer application in T₂ and T₃ treatments significantly increased the number of tillers, root activity, chlorophyll and crude cellulose content in paddy soil developed from marine sediments, river alluvial and sand shale. Rice yield reached the highest and rice quality reached a good level in T₂ treatment, but rice yield and its related agronomic indicators did not increase significantly with the increasing of silicon fertilizer application (T₃), and even some indicators exhibited a downward trend. It is recommended that the optimal amounts of Si fertilizer application are 560 kg/hm² (140 kg/hm² of available SiO₂) for paddy soil developed from marine sediments and river alluvial sediments, and 750 kg/hm² of silicon fertilizer (187 kg/hm² of available SiO₂) for paddy soil developed from sandy shale, respectively. Thus, this study revealed the effect of silicon fertilizer application in typical paddy soil of Hainan Island, providing a scientific basis for formulating the standard of silicon fertilizer application as well as demonstrating and popularizing high efficiency silicon application technology and of rice in Hainan province.

The aim of the study is to estimate the effects of different mulching treatments on the photosynthetic characteristics of leaves, soil physical properties and yield of Amorphophallus muelleri intercropped in rubber plantations. Seven treatments (silver film, black film, white film, straw mat, thickened black film, microporous black film and no mulch (CK) were set up in this experiment. Photosynthetic characteristics of A. muelleri leaves at the three stages of head changing, corm and maturity were measured and analyzed. Net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), intercellular CO₂ concentration (C_i), electron transfer rate (ETR), physiological characteristics parameters including soluble protein (SP) content, soluble sugar (SS) content, chlorophyll (Chl) content, chlorophyll a/b (Chl a/b). soil in situ physical properties including soil moisture comtent (SMC), soil conductivity (SC), soil temperature (ST), and underground corm yield of A. muelleri were assayed. The photosynthetic parameters (P_n, G_s, T_r and ETR) of A. muelleri leaves increased by different plastic film mulching treatments at the same period. P_n, G_s and T_r of straw mat treatment at the head changing stage and expansion stage were significantly higher than those of the other treatments (P<0.05), the amplitude of the other treatments fluctuated irregularly and there were significant differences among them. At the mature stage, SP and Chl of A. muelleri leaves under different treatments were significantly higher than those under the control in the same period, and there was no significant difference among all treatments. In the same period, the SS and Chl a/b of A. muelleri leaves under different treatments were slightly different. The SS of each treatment at the maturity stage was significantly higher than that of the control, and the SS of the control at the three stages was the lowest, while the Chl a/b of e plastic film treatment at the maturity stage was not significantly different from that of the control. In the same period, SMC and SC by different plastic films were higher than those of the control. The water retention effect of thickened black film treatment was the best, the SC of microporous black film treatment in the expansion stage and straw mat treatment in the maturity stage were significantly the highest, but there was no significant difference in SMC and SC among other treatments. P_n, G_s, T_r, ETR, SP, and Chl of the same mulch treatment at different stages were all in the following order: head changing stage>expansion stage>maturity stage, while the SS and Chl a/b of each treatment were in the following order: maturity stage>expansion stage>head changing stage. According to the results of correlation analysis between all indexes and yield, except ST and yield were negatively correlated, other indexes were positively correlated with yield. Compared with the control, different plastic film mulches increased the yield of A. muelleri. Black mulching, straw mat and thickened black mulching treatments significantly increased the yield, while white mulching and microporous black mulching treatments did not significantly increased the yield. Therefore, silver plastic film, black plastic film, straw mat and thickened black plastic film are suitable choices for A. muelleri to increase the production and efficiency in practical production.

Natural rubber latex (NRL) is susceptible to spoilage, and current high ammonia preservation systems have serious contamination problems. In this study, NRL was preserved by thione derivative LS, and the preservation effect on NRL was investigated. The volatile fatty acid value (VFA No.) and viscosity value of LS-preserved fresh latex were relatively low, and the preservation effect of LS at 0.1% was better than that of 0.25% ammonia. LS-ammonia composite preservation was used to prepare low-ammonia concentrated natural rubber latex (CNRL), and CNRL could be preserved stably for 180 days by the dosage at 0.01%~0.05%. The preserved low-ammonia CNRL had low VFA No. and good stability, and all the indexes met the requirements of production. The stability of the preserved low ammonia CNRL was outstanding, and all the indexes met the current production application requirements. The LS-ammonia composite preserved low ammonia CNRL also had excellent physicochemical and film-forming properties, and the tensile strength and tear strength of the vulcanized film were generally better than those of the current high ammonia preserved CNRL vulcanized film. By infrared absorption spectroscopy, the structure of the preservative LS-ammonia composite preserved low ammonia CNRLvulcanized film did not change significantly; thermal analysis showed that the thermal stability of the vulcanized film was basically the same as that of the high ammonia CNRL film. In addition, the safety analysis showed that the LS-ammonia composite preserved low ammonia CNRL dry rubber film did not have potential toxic effects. There was no skin irritation reaction, and the safety was better. The preservative LS has excellent preservation effect on NRL, and the composite preservation preparation of low ammonia CNRL has good performance, which can be used in the production of a variety of pure rubber products, and at the same time, the low cost has a broad application prospect.

The hyperosmotic Ca²⁺ channel protein OSCA is crucial for controlling hyperosmotic stressors in plants. To understand the role of the OSCA gene family in tea plant response to drought stress, this study was conducted to identify the OSCA gene family based on the whole genome data of tea plant and analyze the gene and protein structures and promoter cis-acting element, and analyze the expression patterns of CsOSCAs in different tissues of tea plant, among different drought-resistant varieties and under drought stress. The results showed that the tea plants genome contained 12 members of the OSCA gene family, named CsOSCA1-CsOSCA12. The amino acid sequences encoded by the CsOSCAs were 667-831 bp in length, with protein molecular weight ranging from 76 630.55 kDa to 93 563.99 kDa and isoelectric points ranging from 6.15 to 9.33, containing 9-12 transmembrane structural domains, all containing the characteristic conserved structural domain DUF221, which could be divided into four subfamilies based on phylogenetic relationships. Ten CsOSCAs were localized to seven chromosomes of Camellia sinensis and two CsOSCAs were localized to the contig of unanchored chromosomes. The secondary structure of the CsOSCAs contained 32%-38% transmembrane structure and 60%-68% α-helix. The CsOSCAs were tissue expression specific, and CsOSCA2, CsOSCA3, CsOSCA11, and CsOSCA12 were significantly higher in the drought-sensitive variety CN98 than those in the other two drought-tolerant varieties. Nine genes were responded to PEG stress, among which CsOSCA2, CsOSCA3, CSOSCA5, CsOSCA8, CsOSCA10, and CsOSCA12 were strongly induced by drought stress. Six genes included drought-inducible response elements, and 11 genes contained abscisic acid response elements, according to further examination of the promoter cis-acting elements. It is hypothesized that the OSCA gene family of tea plants play an important role in the response to drought stress, and this study would provide a reference for the functional analysis and stress resistance of OSCA gene in tea plant.