The study was aimed to study the effects of exogenous ATP and rotenone treatment on chilling injury and sugar metabolism in cold-stored guava fruits. Post-harvest ‘Hongxiang’ guava fruits were treated with distilled water, 0.8 mmol/L ATP, and 0.2 mmol/L rotenone, respectively, and stored at (4±1)℃. During storage, the chilling injury index, commercial rate, sugar content, and sugar metabolism-related enzyme activity of the guava fruits were regularly determined. Compared with the control fruit, ATP treatment reduced chilling injury, increased the activities of sucrose monophosphate synthase (SPS), acid invertase (AI), and sucrose synthase synthesis direction (SSs) during the late stage of storage, decreased the activities of neutral invertase (NI) and sucrose synthase decomposition direction (SSc) during late-storage, inhibited the increase in fructose and glucose content during mid-storage, maintained the content of sucrose and total soluble sugar at a high level, and improved the cold resistance and commercial rate of the fruit. Rotenone treatment exacerbated chilling injury by simultaneously inhibiting the increase of SSS activity and SPS activity during the middle stage of storage, the decrease of AI activity, NI activity, and SSc activity during the middle and late stages of storage, accelerating the decomposition of sucrose, increased the content of fructose, reduced the total soluble sugar and reducing sugar, and resulted in a low commercial rate of the fruit. ATP treatment could enhance cold resistance in guava fruits, and the mechanism may be related to changes in sucrose and soluble total sugar content. However, rotenone treatment induced an imbalance in sugar metabolism and exacerbated chilling injury.

ITS molecular identification and mycelial antagonism experiments on 11 strains collected in the early stage, then screened and studied the biological characteristics of suitable strains for cultivation in tropical regions based on germplasm evaluation to promote the rapid development of Phallus rubrovolvatus industry in tropical regions. The strains collected were all P. rubrovolvatus, of which two strains were synonyms, resulting in a total of 10 different P. rubrovolvatus strains. In mycelial evaluation experience, the mycelia of strains 147, 160, H29 and L70 showed good growth and high degradability on brown sugar medium and rubber sawdust medium, and the mycelia were able to recover growth after stress at 10 ℃ and 35 ℃, making them suitable for off-season cultivation in tropical regions. In rubber forests, four strains were able to produce mushrooms, and H29 produced mushrooms neatly, good shape, storage resistance and high yield (750 kg/667 m²), making it suitable for on-site growing indusium. L70 strain produced more mushroom-eggs, short growth period and high yield (800 kg/667 m²), making it suitable for concentrated growing indusium of mushroom-eggs after harvesting. In the single factor experiment, the nutritional requirements of H29 and L70 mycelia were basically the same, the most suitable carbon sources were trehalose and starch, the most suitable nitrogen source was malt extract, the most suitable temperature was 25-28 ℃, and the most suitable pH was 4-5. In the orthogonal experiment, both strains showed the best growth in formula 4 (soluble starch, malt extract, 25 ℃, pH=4), demonstrating the results of the single factor experiment. Especially, in formula 6, the mycelia of both strains were whiter and denser, making it suitable for the preservation of P. rubrovolvatus. SPSS analysis showed that the influence degree of various factors on mycelial growth was as follows: nitrogen source>pH>carbon source>temperature (H29), nitrogen source>pH>temperature>carbon source (L70), with nitrogen source and pH having a greater impact. The study could provide reference for breeding, large-scale cultivation of P. rubrovolvatus, and the development of mushroom industry in tropical regions.

The diversity of orchid labellum, a specialized petal, has great ornamental and biological value, but the formation mechanism has not been solved so far. APETALA3-3 (AP3-3) is a floral organ identity gene, which is related to the formation of orchid labellum, but there is no report on how it regulating the formation mechanism of orchid labellum diversity. In this project, wild type and DoAP3-3 overexpressing floral organs of Dendrobium officinale were used as the research objects to explore the formation mechanism from the perspective of transcription factor DoAP3-3 regulating downstream target genes through DAP-seq and RNA-seq joint analysis. The results showed that a total of 7 key candidate target genes, MADS6, NAC029, NAC054, WOX3, AS2, ERECTA, AG were identified, which may regulate floral organ development and floral morphogenesis development under the action of DoAP3-3 by specific regulation or interaction with other genes. The interaction between transcription factor DoAP3-3 and MADS6 was verified by yeast one-hybrid experiment, which further affecting floral morphogenesis development. This study would lay a foundation for preliminary analysis of the regulatory mechanism between DoAP3-3 and its target genes, and exploring the formation mechanism of highly specialized and diversified flower morphology in Orchidaceae.

In order to explore the characteristics and molecular regulation mechanism of high temperature albinism of tea variety Yaoqiu (YQ) and its molecular regulation mechanism, the effects of low temperature albinism on the shoot with one bud and two leaves of tea variety YQ in spring (YQC), summer (YQX), autumn albinism (YQQ) and autumn green (YQQL), and Baiye No. 1 (BY1H) in spring albinism (BY1HC), their biochemical components, and transcriptome sequencing were carried out on the new shoots in summer (BY1HX) and autumn (BY1HQ). The results of biochemical analysis showed that the total free amino acid content and tea polyphenols content of YQQ albino fresh leaves were lower than those of YQC green fresh leaves, and the difference of total free amino acid content was significant; while the total free amino acid content of BY1HC albino fresh leaves was significantly higher than that of BY1HQ green fresh leaves, and the tea polyphenols content was significantly lower than that of BY1HQ green fresh leaves. Cluster analysis revealed that the gene expression profiles of YQQ albino fresh leaves formed a distinct cluster. The comparison between YQQ and BY1HQ exhibited the highest number of differentially expressed genes. The new shoot leaves of YQ showed an albino phenotype induced by high-temperature stress in late summer and early autumn. This stress affected the structure of microtubules, cells, and subcellular components, leading to a reduction in the contents of amino acids and polyphenols. The three functional categories exhibiting the most significant gene enrichment were microtubule binding, movement of cellular or subcellular components, and non-membrane-bound organelles. Similarly, the top three pathways with the highest significance in gene enrichment were the flavonoid biosynthesis pathway, the starch and sucrose metabolism pathway, and the amino sugar and nucleotide sugar metabolism pathway. Through gene co-expression network analysis, modules exhibiting high expression levels were identified. Subsequently, the ten genes demonstrating the highest total connectivity (K value) were selected for further analysis and annotation. Notably, the functions of genes TGY042732 and the novel gene designated as novel.276 could not be predicted. These findings would provide a theoretical foundation for understanding the phenomenon of albinism in tea resources under conditions of elevated temperature.

Genetic engineering technology serves as an effective method to shorten crop breeding cycles, specifically cultivate new crop varieties, and identify plant gene functions. Induced promoters are important tools in genetic engineering research, among which thermally inducible promoters being extensively utilized in plant molecular biology owing to the simple vector structure, convenient induction, and low cost. At present, the development of genetic engineering technology in rubber trees lags behind. Functional studies of target genes typically use constitutive promoters, which limits the progress of related work. In this study, rubber tree calli were treated by heat. Through transcriptome sequencing analysis, identified eight genes that were non-expressed or minimally expressed, but exhibited high level expression after heat induction in calli. After heat induced expression changes and specificity evaluation, two candidate genes HbHSP17.6C and HbHSP17.6B that specifically respond to heat treatment were identified. Further through nested PCR, we cloned the 1962 nt sequence upstream of the start codon of the heat shock protein gene HbHSP17.6C. Confirm that it is composed of a core transcription region and multiple cis acting elements, and is named pHbHSP17.6C. It is inferred that this promoter could be used for gene function research in rubber trees and other closely related plants, which is expected to provide new tool options for related research.

Hyphal polarized growth in filamentous fungi requires tip-directed secretion of growth-related substances, and previous studies have shown that exocyst complex plays an important role in the processes of fungal secretion and polar growth. However, there are few researches on the hyphal polarized growth and pathogenic mechanism of obligate biotrophic fungi at present. Rubber tree (Hevea brasiliensis) is the most important source of natural rubber. Powdery mildew is one of the most serious diseases of H. brasiliensis, and its pathogen Erysiphe quercicola belongs to obligate parasitic fungi. In this study, EqExo70, a subunit of the exocyst complex, was identified in E. quercicola. The GFP labeled EqExo70 was expressed in the E. quercicola by electrotransformation method, and it was found that the protein showed fluorescence aggregation at the hyphal tip, suggesting that EqExo70 may be related to hyphal polarized growth. In addition, we silenced the EqExo70 by electroporating the reverse complementary sequence of EqExo70 into the E. quercicola, it was found that the pathogenic ability of E. quercicola decreased and the growth of hypha slowed down, suggesting that EqExo70 affects the pathogenicity of E. quercicola. The level of callose deposition and reactive oxygen species burst in H. brasiliensis significantly increased upon infection with the EqExo70-silenced strain, indicating that EqExo70 contributes to suppressing host immune response. The results indicated that EqExo70 is a key factor affecting pathogenicity of E. quercicola, and may be involved in the interaction with H. brasiliensis, as well as the hyphal polarized growth.

Guangxi is the leading sugarcane production area in China. over 85% of the sugarcane is planted on non-irrigated dry land, and varying degrees of drought damage occur every year. Drought is the main limiting factor for sugarcane production in China. Tillering is one of the important traits affecting the yield of sugarcane. It is of great significance to study the effect of drought stress on the development of tillering buds at tillering stage. Guire 2 is a new sugarcane variety bred by our team with good drought resistance and strong tillering ability. In order to investigate the effects of drought stress on physiological indicators of sugarcane tillering seedlings and leaves at tillering stage, Guire 2 was used to conduct drought stress experiments at the early stage of sugarcane tillering. The experiment was set up with control (19%-25% soil absolute water content) and drought stress treatment by stopping irrigation. Samples were taken from the control group and treatment group at early drought stress (14%-15% soil absolute water content), middle drought stress (10%-11% soil absolute water content), late drought stress (6%-7% soil absolute water content) stages. The changes of antioxidant enzyme activity, MDA, osmoregulatory substances and endogenous hormone contents were measured by subordination function method. The correlation of the physiological indicators in sugarcane tiller shoots and leaves was analyzed, and the drought resistance of tiller shoots and leaves was evaluated. The results showed that drought stress increased the activities of peroxidase (POD), and superoxidate dismutase (SOD), and contents of proline (Pro), soluble protein, starch, sucrose and abscisic acid (ABA), especially in tiller shoots, the treatment group and the control group reached a significant difference, while the malondialdehyde (MDA) content remained at a similar level in sugarcane tillering seedlings and leaves during drought stress. Compared with leaves, drought stress significantly increased the activity of SOD and the contents of Pro, soluble protein and sucrose in tiller shoots. Correlation analysis showed that most significant correlations between the physiological indicators in sugarcane tiller shoots and leaves under drought stress were positive, and sucrose content, starch content, Pro content, IAA content and SOD activity were more significantly or extremely significantly correlated with other indicators. According to the comprehensive drought resistance coefficient and the average of subordinate function values of each index, the drought resistance of tiller shoots was stronger than that of leaves in sugarcane.

Partial replacement of chemical fertilizers with organic fertilizers is a key path for achieving zero growth in chemical fertilizers in tea gardens. Biochar, a new agricultural soil amendment, has positive effects in optimizing the soil microecological environment. Further understanding the effects of organic fertilizer substitution and biochar application on the soil aggregate stability and organic carbon accumulation in tea gardens, also the synergistic effects, can provide scientific basis for reducing fertilizer application, increasing efficiency, and carbon sequestration and emission reduction in tea gardens. Wet screening method was used to treat seven different fertilizers, namely no fertilization (CK), conventional fertilization (NPK), fertilizer and biochar application (biochar dosage 10 t/hm², NPK+BC10), 50% fertilizer+50% organic fertilizer (OM50), 50% fertilizer+50% organic fertilizer (OM50) combined with different amounts of biochar. The amount of biochar was 10 t/hm² (OM50+BC10), 20 t/hm² (OM50+BC20) and 40 t/hm² (OM50+BC40) for physical grading of soil aggregates. The distribution, structure and stability and the change of organic carbon content in different treated tea plantations were studied. Under the treatment of OM50+BC10, OM50+BC20 and OM50+BC40, the organic carbon reserves of aggregates increased to different degrees compared with the conventional fertilization control treatment. In contrast to the NPK and CK treatments, the replacement of 50% chemical fertilizer with different doses of biochar could significantly improve the organic carbon content of soil>2 mm and 0.25-2.00 mm granular aggregates. The increase rate was ranged from 23.96%-70.87% and 21.87%-49.27%, OM50+BC20 and OM50+BC40 had the most significant treatment effect. Geometric mean diameter (GWD) and mean mass diameter (MWD) in aggregate were in the order CK<NPK<NPK+BC10<OM50<OM50+BC10<OM50+BC20<OM50+BC40. The aggregate content and organic carbon content were the most significant in OM50+BC40 treatment. 50% organic fertilizer replacing 50% fertilizer, different amount of biomass carbon application could significantly increase tea garden soil aggregate, organic carbon content, promote tea garden soil aggregate stability and structure level. Organic fertilizer and biomass carbon is more conducive to improving the stability of soil aggregate and promoting the sequestration of organic carbon. OM50+BC20 and OM50+BC40 treatment showed significant results in improving the stability of soil organic carbon and soil aggregates in tea plantations. Without considering the cost effect, OM50+BC40 is a suitable fertilization scheme; otherwise, OM50+BC20 can be selected.

The study on the ecological suitability regionalization for jackfruit (Artocarpus heterophyllus Lam.) is of great significance for guiding its cultivation layout and digging its development potential, via utilization of environmental resources efficiently in tropical and subtropical regions. Based on the analytic hierarchy process (AHP) and GIS, this study constructed a suitability analysis model for jackfruit cultivation using four evaluation factors: temperature, precipitation, sunshine hours and soil index. The results of the regionalization are then validated in conjunction with previous research findings and the actual distribution of jackfruit, while further explore the spatial potential for jackfruit cultivation by integrating land use spatial data. The results indicate that the zones able to plant are primarily distributed in tropical and subtropical monsoon climate regions. The suitable zones for planting are mainly found in Hainan, southern Guangxi, southern Guangdong, parts of southern Yunnan and southern Fujian, where there is sufficient heat throughout the year, favorable wintering conditions, and a good combination of light, heat and water. Total plantable area for jackfruit in China is approximately 47.85×10⁴km², of which 22.71×10⁴km² is suitable for cultivating, comprising 8.89×10⁴km² of arable land and 182.05 km² of unused land. In comparison to previous research findings, this study expanded the amount of potentially viable arable land for jackfruit cultivation by about 58 times the existing cultivating area. Considering comprehensive land use, ecological environment, and policy support, jackfruit has a high potential for production in suitable and relatively suitable arable and unused land in China. Priority should be given to developing suitable planting areas in the southern regions of Guangxi and Yunnan. The study findings could provide scientific and analytic references for optimizing the regional layout and development planning of jackfruit cultivation in China.

In order to explore the effect of DNA methylation on drought hardening of different ploidy watermelon, mannitol was used to mimic drought stress in suspension cultured cells of different ploidy watermelon. The cell growth and resistance related physiological indexes were measured after stress, recovery and re-stress treatments. Meanwhile, the DNA methyltransferase inhibitor 5-azacytidine (5-AzaC) was used to explore whether methylation is involved in resistance regulation. The results showed that 5-AzaC could retard the growth, inhibit the extracellular alkalization, increase the content of malondialdehyde, bring down the content proline and the activity of protective enzymes such as SOD in all types of cells. Moreover, it caused the membrane permeability raising in diploid and triploid cells. Above results suggest that 5-AzaC can aggravate the osmotic stress injury and reverse the effects of drought hardening partially. Principal component analysis revealed that malondialdehyde content, proline content, PAL, CAT and APX activity could be used as the main evaluation indexes for evaluation the effect of drought hardening. This study would provide clues for mining the physiological indexes for evaluate the effects of stress hardening and the mechanism of DNA methylation involved in watermelon resistance regulation.