Activities Of Protective Enzymes Research Articles

Codonopsis pilosula seedling drought- responsive key genes and pathways revealed by comparative transcriptome

BackgroundCodonopsis pilosula (Campanulaceae) is a traditional herbal plant that is widely used in China, and the drought stress during the seedling stage directly affects the quality, ultimately impacting its yield. However, the molecular mechanisms underlying the drought resistance of C. pilosula seedlings remain unclear.MethodHerein, we conducted extensive comparative transcriptome and physiological studies on two distinct C. pilosula cultivar (G1 and W1) seedlings subjected to a 4-day drought treatment.ResultsOur findings revealed that cultivar G1 exhibited enhanced retention of proline and chlorophyll, alongside a marked elevation in peroxidase activity, coupled with diminished levels of malondialdehyde and reduced leaf relative electrolyte leakage compared with cultivar W1. This suggested that cultivar G1 had relatively higher protective enzyme activity and ROS quenching capacity. We discerned a total of 21,535 expressed genes and identified 4,192 differentially expressed genes (DEGs) by RNA sequencing (RNA-seq). Our analysis revealed that 1,764 DEGs unique to G1 underwent thorough annotation and functional categorization utilizing diverse databases. Under drought conditions, the DEGs in G1 were predominantly linked to starch and sucrose metabolic pathways, plant hormone signaling, and glutathione metabolism. Notably, the drought-responsive genes in G1 were heavily implicated in hormonal modulation, such as ABA receptor3-like gene (PYL9), regulation by transcription factors (KAN4, BHLH80, ERF1B), and orchestration of drought-responsive gene expression. These results suggest that cultivar G1 possesses stronger stress tolerance and can better adapt to drought growing conditions. The congruence between qRT-PCR validation and RNA-seq data for 15 DEGs further substantiated our findings.ConclusionOur research provides novel insights into the physiological adaptations of C. pilosula to arid conditions and lays the groundwork for the development of new, drought-tolerant C. pilosula cultivars.

Effects of Abscisic Acid on the Physiological and Biochemical Responses of Saccharina japonica Under High-Temperature Stress

Saccharina japonica is one of the most productive aquatic plants in the world, widely used in food, feed, medicine, and other industries. Predominantly inhabiting temperate marine environments in mid- to high-latitude regions of the Northern Hemisphere, the growth of S. japonica is significantly limited by high-temperature stress. Abscisic acid (ABA) plays an important role in plant growth and development and stress responses. However, the role of ABA on high-temperature stress tolerance in S. japonica still needs to be further elucidated. Here, we found that exogenous ABA significantly alleviated disease and decay in S. japonica under high-temperature stress while also increasing the relative growth rate, chlorophyll fluorescence parameters, photosynthetic pigment, and osmotic substance content. Meanwhile, exogenous ABA enhanced the activity of protective enzymes and up-regulated the transcript levels of antioxidant-related genes, thereby reducing oxidative damage. Most importantly, we observed a significant increase in ABA content and the transcript levels of key genes involved in ABA synthesis in S. japonica under high-temperature stress, which were further amplified by the addition of exogenous ABA. In conclusion, this study provides evidence that ABA can moderate the detrimental effects of high-temperature stress and provides a theoretical basis for the screening of S. japonica germplasm resources and the cultivation of new stress-resistant varieties.

Screening and identification of Paenibacillus polymyxa GRY-11 and its biological control potential against apple replant disease.

Apple replant disease (ARD) is a significant factor restricting the healthy development of the apple industry. Biological control is an important and sustainable method for mitigating ARD. In this study, a strain of Paenibacillus polymyxa GRY-11 was isolated and screened from the rhizosphere soil of healthy apple trees in old apple orchards in Shandong Province, China, and the effects of strain GRY-11 on soil microbial community and ARD were studied. The result showed that P. polymyxa GRY-11 could effectively inhibit the growth of the main pathogenic fungi that caused ARD, and the inhibition rates of the strain against Fusarium moniliforme, Fusarium proliferatum, Fusarium solani, and Fusarium oxysporum were 80.00%, 71.60%, 75.00%, and 70.00%, respectively. In addition, the fermentation supernatant played an active role in suppressing the growth of pathogenic fungi. The results of the pot experiment showed that the bacterial fertilizer of the GRY-11 promoted the growth of Malus hupehensis seedlings, improved the activity of protective enzymes in plant roots, enhanced the soil enzyme content, and optimized the soil microbial environment. In general, the GRY-11 can be used as an effective microbial preparation to alleviate ARD. Our study offers novel perspectives for the prevention of ARD.

Antifungal mechanism of nanosilver biosynthesized with Trichoderma longibrachiatum and its potential to control muskmelon Fusarium wilt

Fusarium oxysporum (Schl.) f.sp. melonis, which causes muskmelon wilt disease, is a destructive filamentous fungal pathogen, attracting more attention to the search for effective fungicides against this pathogen. In particular, Silver nanoparticles (AgNPs) have strong antimicrobial properties and they are not easy to develop drug resistance, which provides new ideas for the prevention and control of muskmelon Fusarium wilt (MFW). This paper studied the effects of AgNPs on the growth and development of muskmelon, the control efficacy on Fusarium wilt of muskmelon and the antifungal mechanism of AgNPs to F. oxysporum. The results showed that AgNPs could inhibit the growth of F. oxysporum on the PDA and in the PDB medium at 100–200 mg/L and the low concentration of 25 mg/L AgNPs could promote the seed germination and growth of muskmelon seedlings and reduce the incidence of muskmelon Fusarium wilt. Further studies on the antifungal mechanism showed that AgNPs could impair the development, damage cell structure, and interrupt cellular metabolism pathways of this fungus. TEM observation revealed that AgNPs treatment led to damage to the cell wall and membrane and accumulation of vacuoles and vessels, causing the leakage of intracellular contents. AgNPs treatment significantly hampered the growth of mycelia in the PDB medium, even causing a decrease in biomass. Biochemical properties showed that AgNPs treatment stimulated the generation of reactive oxygen species (ROS) in 6 h, subsequently producing malondialdehyde (MDA) and increasing protective enzyme activity. After 6 h, the protective enzyme activity decreased. These results indicated that AgNPs destroy the cell structure and affect the metabolisms, eventually leading to the death of fungus.

Systematic Analysis of the BrHAT Gene Family and Physiological Characteristics of Brassica rapa L. Treated with Histone Acetylase and Deacetylase Inhibitors under Low Temperature.

Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Investigation of Enzyme Immobilization and Clogging Mechanisms in the Enzymatic Synthesis of Amoxicillin.

This study investigated the blocking mechanism of immobilized penicillin G acylase (PGA) during the enzymatic synthesis of amoxicillin. Laboratory observations revealed that the primary cause of clogging was the crystallization of the substrate and product on the enzyme surface. Adjusting key parameters can significantly reduce clogging and improve catalytic efficiency. Methanol can decrease enzyme activity, but isopropyl alcohol cleaners can effectively remove clogs and protect enzyme activity. These findings provide an experimental foundation for optimizing the PGA immobilization process, which is crucial for achieving high efficiency and sustainability in industrial production.

Research on the Isolation of Endophytic Fungi from Papaya and the Prevention of Colletotrichum gloeosporioides.

Endophytic fungi can be used as a source of herbal antioxidants to overcome the limitations of low yield and lengthy growth cycles associated with using plants as raw materials for antioxidant production. Papaya fruit is often susceptible to infection by Colletotrichum gloeosporioides after harvest, leading to postharvest rot. Endophytic fungi were extracted with ethyl acetate, and the initial screening concentration was 100 mg/L. Seven strains were identified, with scavenging rates exceeding 50% and strong antioxidant activity. The IC50 values in DPPH and ABTS free radical scavenging assays ranged from 19.72 to 84.06 mg/L and from 14.34 to 64.63 mg/L, respectively. Strain Y17 exhibited robust antioxidant activity (IC50 < 20 mg/L) and was identified as Penicillium rolfsii (MT729953) through ITS sequencing. Treatment of papaya fruit wounds with a fermentation broth of strain Y17 significantly inhibited the infection and colonization of anthracnose pathogens, resulting in a slowed disease incidence rate. This promoted the activity of protective enzymes, such as CAT, POD, and SOD, in the papaya fruit and slowed down the rate of MDA accumulation. This strain, which was found to have antioxidant activity in this study, has the potential to control anthracnose in papaya and has value in terms of further development and utilization.

Effects of CO2 elevation on life-history traits of two insecticide-resistant strains of planthopper Nilaparvata lugens on rice.

We made separate experiments to examine life-history traits and activities of protective enzymes as affected by carbon dioxide (CO2) elevation to 780 μL/L as compared to 390 μL/L in imidacloprid- or buprofezin-resistant strains of the brown planthopper (BPH) Nilaparvata lugens. We found an interaction effect between resistance and the CO2 level on the nymphal survival and duration in both resistant strains. Nymphal durations in both resistant strains were much shorter in the resistant than susceptible BPH at 780 μL/L but similar between them or slightly shorter in the resistant than susceptible BPH at 390 μL/L. Nymphal survival was lower for imidacloprid-resistant than its susceptible BPH at 390 μL/L but higher at 780 μL/L; it stayed unaffected by the CO2 elevation in buprofezin-resistant BPH. We did not observe an interaction effect between resistance and the CO2 level on major reproductive parameters in both resistant strains. But the 2 strains were not consistent across CO2 levels in all parameters. Our measurements of protective enzyme activities of superoxide dismutase, catalase, and peroxidase showed an interaction between resistance and the CO2 level. Overall, these enzymes became similar in activity between resistant and susceptible BPH at 780 μL/L compared to 390 μL/L and the change was more distinct in the imidacloprid- than buprofezin-resistant BPH strains. Our findings suggest that CO2 elevation can affect life-history traits of insecticide-resistant BPH, while the effect may vary depending on the kind of insecticides it is resistant to.

Response of growth and physiological enzyme activities in Eriogyna pyretorum to various host plants.

Morphological attributes and chemical composition of host plants shape growth and development of phytophagous insects via influences on their behavior and physiological processes. This research delves into the relationship between Eriogyna pyretorum and various host plants through studuying how feeding on different host tree species affect growth, development, and physiological enzyme activities. We examined E. pyretorum response to three distinct host plants: Camphora officinarum, Liquidambar formosana and Pterocarya stenoptera. Notably, larvae feeding on C. officinarum and L. formosana displayed accelerated development, increased pupal length, and higher survival rates compared to those on P. stenoptera. This underlines the pivotal role of host plant selection in shaping the E. pyretorum's life cycle. The activities of a-amylase, lipase and protective enzymes were the highest in larvae fed on the most suitable host L.formosana which indicated that the increase of these enzyme activities was closely related to growth and development. Furthermore, our investigation revealed a relationship between enzymatic activities and host plants. Digestive enzymes, protective enzymes, and detoxifying enzymes exhibited substantial variations contingent upon the ingested host plant. Moreover, the total phenolics content in the host plant leaves manifested a noteworthy positive correlation with catalase and lipase activities. In contrast, a marked negative correlation emerged with glutathione S-transferase and α-amylase activities. The total developmental duration of larvae exhibited a significant positive correlation with the activities of GST and CarE. The survival rate of larvae showed a significant positive correlation with CYP450. These observations underscore the insect's remarkable adaptability in orchestrating metabolic processes in accordance with available nutritional resources. This study highlights the interplay between E.pyretorum and its host plants, offering novel insights into how different vegetation types influence growth, development, and physiological responses. These findings contribute to a deeper comprehension of insect-plant interactions, with potential applications in pest management and ecological conservation.

ZmD11 Gene Regulates Tobacco Plant Floral Development under Drought Stress

Maize is most sensitive to drought stress at the floral stage by reducing tassel and silk quality, and thus improving drought tolerance at this stage may help preserve yield. It has been reported that BRs (brassinosteroids) promote floral development under drought stress. However, the function of the brassinosteroid biosynthesis gene ZmDWARF11 (ZmD11) on floral growth under drought stress has not been elucidated. This study found that under normal growth conditions, the heterologous over-expression of ZmD11 significantly enhanced both the vegetative growth and floral development of tobacco. Under drought stress, overexpressing ZmD11 reduced stress-induced tobacco flower size reduction, while it did not affect vegetative growth. After drought treatment, the activities of protective enzymes, including CAT (Catalase), SOD (Superoxide Dismutase), and POD (Peroxidase), were higher, while the content of MDA (Malondialdehyde) was lower in ZmD11 over-expression tobacco lines than that in the wild type control. The relative expression of dehydrin-related genes NtLeat5 and NtERD10 was increased in ZmD11 over-expression tobacco lines compared to that in the control. In summary, we reported that ZmD11 plays a role in tobacco floral development under drought stress. Our data are valuable in understanding the functions of BRs in regulating plant floral development under drought stress.

Selenium Nanoparticles Boost the Drought Stress Response of Soybean by Enhancing Pigment Accumulation, Oxidative Stress Management and Ultrastructural Integrity

Drought is a persistent and devastating obstacle to crop production, affecting both humanity and livestock. The application of selenium (Se) effectively mitigates various types of abiotic stresses and enhances crop yield under unfavorable conditions. However, our understanding of how nano-Se (nSe) alleviates drought stress (DS) in soybeans is still limited. To address this gap, our study focused on assessing the effectiveness of foliar nSe application during the reproductive stage of soybeans. Three concentrations of nSe were applied to plants grown in pots filled with clay loam soil, simulating DS conditions. Our findings reveal that nSe spraying significantly promoted the accumulation of above-ground dry biomass and enhanced relative water content (RWC) and photosynthetic pigment over alone-DS treatment. Furthermore, nSe application boosted the activity and contents of protective enzymes and osmolytes, resulting in a dose-dependent reduction in electrolyte leakage (EL), reactive oxygen species (ROS) accumulation, and malondialdehyde (MDA) content. Additionally, nSe improved stomatal characteristics and mesophyll cell ultrastructure, further mitigating the adverse effects of drought stress. These findings suggest the potential of nSe as an effective strategy to enhance soybean tolerance and potentially improve crop yields under drought conditions.

Exogenous Calcium Alleviates the Photosynthetic Inhibition and Oxidative Damage of the Tea Plant under Cold Stress

Calcium (Ca2+), a second messenger, plays a crucial role in plant growth and development as well as in responding to biotic and abiotic stresses. In this work, we explored the role of exogenous calcium in alleviating cold stress and examined the relationship between calcium chloride (CaCl2) and calcium channel blockers, lanthanum chloride (LaCl3), in tea plants under cold stress at the physiological and transcriptional levels. Exogenous Ca2+ partially offsets the negative impacts of cold stress which increased the tolerance of tea plants by significantly raising the photochemical efficiency of PSII, protective enzyme activities, and the ABA content, which reduced the relative electrical conductivity (REC) level and the malondialdehyde (MDA) concentration. At the transcriptome level, exogenous Ca2+ significantly enhanced the expression of key genes involved in cold response pathways. Nevertheless, LaCl3 treatment not only significantly inhibited the activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), but also increased cold damage. This study aims to provide essential insight into the role of exogenous Ca2+ in tea plants responding to cold stress, and to better understand the molecular mechanisms that facilitate Ca-mediated cold tolerance.

Analysis of chitinase gene family in barley and function study of HvChi22 involved in drought tolerance.

Chitinase (Chi) is a pathogenesis-related protein, also reported to play an important role in plant responses to abiotic stress. However, its role in response to abiotic stress in barley is still unclear. In this study, a total of 61 Chi gene family members were identified from the whole genome of wild barley EC_S1. Phylogenetic analysis suggested that these family genes were divided into five groups. Among these genes, four pairs of collinearity genes were discovered. Besides, abundant cis-regulatory elements, including drought response element and abscisic acid response element were identified in the promoter regions of HvChi gene family members. The expression profiles revealed that most HvChi family members were significantly up-regulated under drought stress, which was also validated by RT-qPCR measurements. To further explore the role of Chi under drought stress, HvChi22 was overexpressed in Arabidopsis. Compared to wild-type plants, overexpression of HvChi22 enhanced drought tolerance by increasing the activity of oxidative protective enzymes, which caused less MDA accumulation. Our study improved the understanding of the Chi gene family under drought stress in barley, and provided a theoretical basis for crop improvement strategies to address the challenges posed by changing environmental conditions.

Physiological responses of Bassia dasyphylla to drought during seed germination from different provenances

Bassia dasyphylla is a prevalent herbaceous plant that exhibits enhanced resilience to dryness and elevated temperatures. It is frequently found in dispersed or grouped formation on sandy soil within steppe, semi-desert, and desert regions. Herein, we conducted experiments to examine the growth and physiological traits of B. dasyphylla seeds originated from various regions in response to water scarcity. The study seeks to investigate the ability of these seeds to germinate under drought conditions and offer valuable insights for the development and breeding of high-quality germplasm resources in Inner Mongolia. The results demonstrated that B. dasyphylla originating from desert steppe (DS) exhibited a greater capacity to endure drought conditions in comparison to its counterparts from sandy land (SL). At a water potential of -0.30 MPa, the Seed germination rate from DS was 33.3%, while from SL it was 22.7%. With the increase in drought duration and intensity, germination rate, plumule length, both single-seed weight (SSW) and seed water content (SWC) of B. dasyphylla declined. The protective enzyme activity exhibited an initial increase, followed by a subsequent decline as the duration of the drought increased. Notably, we found that the protective enzyme activity from DS was higher than that from SL. During the initial and intermediate stages of dryness, the soluble sugar and protein of the plant from DS effectively inhibited the peroxidation of membrane lipids, whereas the osmoregulatory properties from SL did not have a significant impact. The findings suggest that the ability of B. dasyphylla to withstand drought conditions in DS can be attributed to its elevated amounts of protective enzymes and osmoregulatory factors, which serve to safeguard the cell membrane during periods of drought.

Insecticidal activity of Ageratina adenophora (Asteraceae) extract against Limax maximus (Mollusca, Limacidae) at different developmental stages and its chemical constituent analysis.

Limax maximus, or great gray slug, is a common agriculture pest. The pest infests crops during their growth phase, creating holes in vegetable leaves, particularly in seedlings and tender leaves. A study was conducted to assess the insecticidal activity of Ageratina adenophora extract against these slugs. Factors such as fecundity, growth, hatching rate, offspring survival rate, protective enzyme activity, and detoxifying enzyme activity were examined in slugs exposed to the extract's sublethal concentration (LC50) for two different durations (24 and 48 h). The phytochemical variability of the extracts was also studied. The LC50 value of the A. adenophora extract against L. maximus was 35.9 mg/mL. This extract significantly reduced the hatching rate of eggs and the survival rate of offspring hatched from exposed eggs compared with the control. The lowest rates were observed in those exposed for 48 h. The survival, growth, protective enzyme, and detoxification activity of newly hatched and 40-day-old slugs decreased. The A. adenophora extract contained tannins, flavonoids, and saponins, possibly contributing to their biological effects. These results suggest that the extract could be used as an alternative treatment for slug extermination, effectively controlling this species.

The Potential Threats of Spodoptera frugiperda on Six Economic Tree Species in the Tropical Region

Spodoptera frugiperda (J.E. Smith) is a highly significant agricultural pest that poses a threat to crop production worldwide. It is polyphagous, has a strong migratory ability, and is difficult to control, which makes it a threat not only to crops but also to woody plants. However, research on its adaptability to woody plants is limited. This study compares the feeding adaptations (survival rate, pupation time, pupation rate, weight, length, and daily food consumption), protective enzyme activities, and feeding preferences of S. frugiperda on leaves of six economically important tree species (Areca catechu L., Aquilaria sinensis (Lour.) Spreng, Cocos nucifera L., Camellia oleifera Abel, Dalbergia odorifera T. Chen, and Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.), with Zea mays L. used as a control treatment. The results indicate that S. frugiperda did not survive when fed with A. catechu, C. oleifera, and D. odorifera. A. catechu had similar survival rates (83.33%), pupation (86.67%), weight, and length data compared to the maize control. C. nucifera had lower survival rates (46.67%) but no significant differences in pupation (76.67%), weight, and length data of S. frugiperda. H. brasiliensis exhibited significantly lower survival (50.00%) and pupation rates (46.67%) compared to maize. However, there was no significant difference in weight and length data, and its preference index was higher among the six tree species treatments. Therefore, A. sinensis is a vulnerable tree with a high risk, while H. brasiliensis and C. nucifera showed varying degrees of susceptibility. A. catechu, C. oleifera, and D. odorifera were found to be unsuitable hosts for S. frugiperda. In conclusion, this study extensively explores the feeding effects of S. frugiperda on six economically important tree species. It provides insights into the feeding preferences of the pest, thereby informing the potential threat posed by S. frugiperda to economically important trees. It helps to prevent further damage from S. frugiperda and provides a reference for agriculture and forestry to develop effective joint prevention and control measures.

Isolation and functional analysis of drought related PobZIP4 transcription factor in Paeonia ostii

Drought, as a natural disaster of force majeure, significantly disrupts the physiological balance of plants and crop yields. The basic leucine zipper (bZIP) transcription factors assume the pivotal role of paramount regulators in orchestrating drought response. In this study, a bZIP transcription factor PobZIP4 was isolated on the base of Paeonia ostii transcriptome, and its function in response to drought stress was verified. PobZIP4 had a 579 bp open reading frame, encoded 192 amino acids, and existed in a conserved structural domain typical of bZIP, and was highly expressed when P. ostii was stressed by drought. Moreover, the subcellular localization of PobZIP4 was observed with fluorescent protein labeling method and it was found that PobZIP4 localized in the Nicotiana benthamiana epidermal cell nucleus. Then, we silenced PobZIP4 in P. ostii using virus-induced gene silencing technology, and found that PobZIP4-silenced plants showed significantly less tolerant to drought stress than the negative control. The accumulation of reactive oxygen species was found to be heightened, while the photosynthetic capacity, proline content, and protective enzyme activities exhibited a significant decline upon silencing PobZIP4, which unequivocally demonstrated that PobZIP4 amplifies the drought tolerance of P. ostii. This study highlighted the positive role of PobZIP4 in mitigating drought stress in P. ostii, thereby establishing a molecular basis for enhancing the drought tolerance of P. ostii.

Aphid-resistant alfalfa cultivar minimizes the survival of spotted alfalfa aphid through upregulating plant defense compounds

The spotted alfalfa aphid, Therioaphis trifolii, is one of the most important pests of alfalfa, Medicago sativa. Previous studies have revealed a significant difference in aphid numbers between the aphid-susceptible cultivar WL343 and the aphid-resistant cultivar Zhongmu No.1. To explore the reasons for this phenomenon, we constructed life tables for T. trifolii reared on these two alfalfa cultivars, and analyzed the changes in jasmonic acid (JA), salicylic acid (SA), secondary metabolites (total phenolic compounds, tannic acid, total flavonoids, and saponin), the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) in both cultivars following the introduction of aphids. In addition, we measured the gastric toxicity of M. sativa secondary metabolites (tannic acid and saponin) against T. trifolii. Results revealed a lower fitness of T. trifolii on the resistant cultivar compared to the susceptible cultivar. The concentrations of JA, phenolic compounds, tannic acid, flavonoids, saponin, and the activities of CAT, SOD, and POD in the resistant cultivar were significantly higher than those in the susceptible cultivar. Subsequently, it was confirmed that tannic acid and saponin have direct gastric toxicity against T. trifolii. This indicated that the aphid-resistant cultivar inhibited aphid growth and fecundity by producing more defense substances, i.e., JA, secondary metabolites, and enhanced activities of protective enzymes including tannic acid and saponin found in alfalfa leaves directly associated with toxicity to T. trifolii, while reducing the content of SA. This study provides important support for breeding insect-resistant varieties while elucidating plant-resistant responses to insect herbivory.

Effects and Underlying Mechanisms of Rice-Paddy-Upland Rotation Combined with Bacterial Fertilizer for the Abatement of Radix pseudostellariae Continuous Cropping Obstacles

Radix pseudostellariae is one of the well-known genuine medicinal herbs in Fujian province, China. However, the continuous cropping obstacles with respect to R. pseudostellariae have seriously affected the sustainable utilization of medicinal resources and the development of related industrial systems. The occurrence of continuous cropping obstacles is a comprehensive effect of multiple deteriorating biological and abiotic factors in the rhizosphere soil. Therefore, intensive ecological methods have been the key to abating such obstacles. In this study, four treatments were set up, i.e., fallow (RP-F), fallow + bacterial fertilizer (RP-F-BF), rice-paddy-upland rotation (RP-R), and rice-paddy-upland rotation + bacterial fertilizer (RP-R-BF), during the interval between two plantings of R. pseudostellariae, with a newly planted (NP) treatment as the control. The results show that the yield of R. pseudostellariae under the RP-F treatment decreased by 46.25% compared to the NP treatment. Compared with the RP-F treatment, the yields of the RP-F-BF, RP-R, and RP-R-BF treatments significantly increased by 14.11%, 27.79%, and 62.51%, respectively. The medicinal quality of R. pseudostellariae treated with RP-R-BF was superior to that achieved with the other treatments, with the total saponin and polysaccharide contents increasing by 8.54% and 27.23%, respectively, compared to the RP-F treatment. The ecological intensive treatment of RP-R-BF significantly increased the soil pH, content of organic matter, abundance of beneficial microbial populations, and soil enzyme activity, thus remediating the deteriorating environment of continuous cropping soil. On this basis, the ecological intensive treatment RP-R-BF significantly increased the activity of protective enzymes and the expression levels of genes related to disease and stress resistance in leaves and root tubers. Redundancy and Pearson correlation analyses indicated that rice-paddy-upland rotation improved the soil structure, promoted the growth of eutrophic r-strategy bacterial communities, enhanced compound oxidation and reduction, broke the relationship between the deteriorating environment and harmful biological factors, and eventually weakened the intensity of harmful factors. The subsequent application of bacterial fertilizer improved the beneficial biological and abiotic factors, activated various ecological functions of the soil, enhanced the ecological relationship between various biological and abiotic factors, and reduced the stress intensity of R. pseudostellariae, thereby improving its disease and stress resistance, and ultimately reflecting the recovery of yield and quality. The results indirectly prove that the intensive ecological amelioration of the soil environment was the main factor for the yield recovery of R. pseudostellariae under continuous cropping.

CsAFS2 Gene from the Tea Plant Intercropped with Chinese Chestnut Plays an Important Role in Insect Resistance and Cold Resistance

α-Farnesene, a crucial secondary metabolite in sesquiterpenes, is crucial for plant biotic and abiotic stress resistance. In this study, we screened an AFS gene from transcriptome data of tea plants (Camellia sinensis) intercropped with Chinese chestnut (Castanea mollissima), resulting in the cloning of CsAFS2. CsAFS2 expression increased following treatment with MJ (Methyl jasmonate), SA (Salicylic acid), GA3 (Gibberellin A3), and various plant growth regulators, as well as under high-salt, drought, and low-temperature conditions. The heterologous genetic transformation of tobacco with CsAFS2 led to an enhanced resistance to low-temperature stress and aphid feeding, evident from elevated levels of osmotic regulatory substances, increased protective enzyme activity, and the upregulation of cold and insect resistance-related genes. Trichomes, crucial in cold and insect resistance, exhibited significantly greater length and density in transgenic tobacco as compared to control plants. These results confirm the vital role of CsAFS2 in enhancing cold and insect resistance, providing comprehensive insights into stress regulation mechanisms in tea plants and advancing stress-resistant tea plant breeding.