A nanopore-based cucumber genome assembly reveals structural variations at two QTLs controlling hypocotyl elongation.

The Xishuangbanna (XIS) cucumber (Cucumis sativus var. xishuangbannanesis) is a semiwild variety that has many distinct agronomic traits. Here, long -reads generated by Nanopore sequencing technology helped assembling a high-quality genome (contig N50 = 8.7 Mb) of landrace XIS49. A total of 10,036 structural/sequence variations (SVs) were identified when comparing with Chinese Long (CL), and known SVs controlling spines, tubercles, and carpel number were confirmed in XIS49 genome. Two QTLs of hypocotyl elongation under low light, SH3.1 and SH6.1 were fine-mapped using introgression lines (donor parent, XIS49; recurrent parent, CL). SH3.1 encodes a red-light receptor Phytochrome B (PhyB, CsaV3_3G015190). An ∼4 kb large deletion (DEL) and highly divergent regions (HDRs) were identified in the promoter of the PhyB gene in XIS49. Loss of function of this PhyB caused a super-long hypocotyl phenotype. SH6.1 encodes a CCCH-type zinc finger protein FRIGIDA-ESSENTIAL LIKE (FEL, CsaV3_6G050300). FEL negatively regulated hypocotyl elongation but it was transcriptionally suppressed by a long terminal repeats (LTRs) retrotransposon insertion in CL cucumber. Mechanistically, FEL physically binds to the promoter of CONSTITUTIVE PHOTOMORPHOGENIC 1a (COP1a), regulating the expression of COP1a and the downstream hypocotyl elongation. These above results demonstrate the genetic mechanism of cucumber hypocotyl elongation under low light.

Integrating molecular imprinting into flexible covalent organic frameworks for selective recognition and efficient extraction of aflatoxins.

Covalent organic frameworks (COFs) are promising adsorbents for extraction, but their selectivity for molecular recognition remains a challenging issue due to the very limited structural design with rigid structure. Herein, we report an elegant strategy for the design and synthesis of molecularly imprinted flexible COFs (MI-FCOFs) via one-pot reaction between the flexible building block of 2,4,6-tris(4-formylphenoxy)- 1,3,5-triazine and linear 4-phenylenediamine for selective extraction of aflatoxins. The flexible chain structure enabled the developed MI-FCOF to adjust the shape and conformation of frameworks to suit the template molecule, giving high selectivity for aflatoxins recognition. Moreover, MI-FCOF with abundant imprinted sites and function groups exhibited an exceptional adsorption capacity of 258.4 mg g-1 for dummy template which is 3 times that of no-imprinted FCOF (NI-FCOF). Coupling MI-FCOF based solid-phase extraction with high-performance liquid chromatography gave low detection limits of 0.003-0.09 ng mL-1 and good precision with relative standard deviations ≤ 6.7% for the determination of aflatoxins. Recoveries for the spiked rice, corn, wheat and peanut samples were in the range of 85.4%- 105.4%. The high selectivity of the developed MI-FCOF allows matrix-free determination of AFTs in food samples. This work offers a new way to the design of MI-FCOF for selective molecular recognition.

Physiological, anatomical and quality indexes of root tuber formation and development in chayote (Sechium edule).

BACKGROUND: Chayote is an underutilized species of Cucurbitaceae. It is rich in nutrients such as protein, minerals, phenols and its extracts have anti-cardiovascular and anti-cancer effects, making it a versatile plant for both medicinal and culinary purposes. Although research on its root tuber is limited, they are rich in starch and have a structure similar to that of potatoes, cassava, and sweet potatoes. Therefore, they can serve as potential substitutes for potatoes and offer promising prospects as agricultural and industrial resources. However, the physiological and cellular mechanisms of chayote root tuber formation and development are still unclear. RESULTS: In this study, we observed the growth habit of 'Tuershao' (high yield of root tuber). The results revealed that the tuber enlargement period of 'Tuershao' lasts approximately 120 days, with the early enlargement phase occurring during 0-30 days, rapid enlargement phase during 30-90 days, and maturation phase during 90-120 days. Physiological indicators demonstrated a gradual increase in starch content as the tuber developed. The activities of sucrose synthase (SUS) and invertase (VIN) showed a consistent trend, reaching the highest level in the rapid expansion period, which was the key enzyme affecting tuber expansion. Moreover, the special petal like structure formed by the secondary phloem and secondary xylem of the tuber resulted in its enlargement, facilitating the accumulation of abundant starch within the thin-walled cells of this structure. Principal component analysis further confirmed that starch content, SUS and VIN activities, as well as the concentrations of calcium (Ca), iron (Fe), and selenium (Se), were the major factors influencing tuber development. Moreover, the low temperature environment not only promoted the growth of 'Tuershao' tubers but also enhanced the accumulation of nutritional substances. CONCLUSIONS: These findings contribute to a deeper understanding of the formation and developmental mechanisms of 'Tuershao' tubers, providing valuable guidance for cultivation practices aimed at improving crop yield.

Surface imprinted-covalent organic frameworks for efficient solid-phase extraction of fluoroquinolones in food samples.

Molecularly imprinting on covalent organic frameworks (MI-COF) is a promising way to prepare selective adsorbents for effective extraction of fluoroquinolones (FQs). However, the unstable framework structure and complex imprinting process are challenging for the construction of MI-COF. Here, we report a facile surface imprinting approach with dopamine to generate imprinted cavities on the surface of irreversible COF for highly efficient extraction of FQs in food samples. The irreversible-linked COF was fabricated from hexahydroxytriphenylene and tetrafluorophthalonitrile to ensure COF stability. Moreover, the introduction of dopamine surface imprinted polymer into COF provides abundant imprinted sites and endows excellent selectivity for FQs recognition against other antibiotics. Taking enrofloxacin as a template molecule, the prepared MI-COF gave an exceptional adsorption capacity of 581 mg g-1, a 2.2-fold enhancement of adsorption capacity compared with nonimprinted COF. The MI-COF was further explored as adsorbent to develop a novel solid-phase extraction method coupled with high-performance liquid chromatography for the simultaneous determination of enrofloxacin, norfloxacin and ciprofloxacin. The developed method gave the low limits of detection at 0.003-0.05 ng mL-1, high precision with relative standard deviations less than 3.5%. The recoveries of spiked FQs in food samples ranged from 80.4% to 110.7%.

Characterization and Modelling of Manufacturing-Microstructure-Property-Mechanism Relationship for Advanced and Emerging Materials.

Depending on the state of its raw materials, final products, and processes, materials manufacturing can be classified into either top-down manufacturing and bottom-up manufacturing, or subtractive manufacturing (SM) and additive manufacturing (AM) [...].

Lead exposure disturbs ATP7B-mediated copper export from brain barrier cells by inhibiting XIAP-regulated COMMD1 protein degradation.

The brain barrier is an important structure for metal ion homeostasis. According to studies, lead (Pb) exposure disrupts the transportation of copper (Cu) through the brain barrier, which may cause impairment of the nervous system; however, the specific mechanism is unknown. The previous studies suggested the X-linked inhibitor of apoptosis (XIAP) is a sensor for cellular Cu level which mediate the degradation of the MURR1 domain-containing 1 (COMMD1) protein. XIAP/COMMD1 axis was thought to be an important regulator in Cu metabolism maintenance. In this study, the role of XIAP-regulated COMMD1 protein degradation in Pb-induced Cu disorders in brain barrier cells was investigated. Pb exposure significantly increased Cu levels in both cell types, according to atomic absorption technology testing. Western blotting and reverse transcription PCR (RT-PCR) showed that COMMD1 protein levels were significantly increased, whereas XIAP, ATP7A, and ATP7B protein levels were significantly decreased. However, there were no significant effects at the messenger RNA (mRNA) level (XIAP, ATP7A, and ATP7B). Pb-induced Cu accumulation and ATP7B expression were reduced when COMMD1 was knocked down by transient small interfering RNA (siRNA) transfection. In addition, transient plasmid transfection of XIAP before Pb exposure reduced Pb-induced Cu accumulation, increased COMMD1 protein levels, and decreased ATP7B levels. In conclusion, Pb exposure can reduce XIAP protein expression, increase COMMD1 protein levels, and specifically decrease ATP7B protein levels, resulting in Cu accumulation in brain barrier cells.

Genome-Wide Identification of the MADS-Box Gene Family during Male and Female Flower Development in Chayote (Sechium edule).

The MADS-box gene plays an important role in plant growth and development. As an important vegetable of Cucurbitaceae, chayote has great edible and medicinal value. So far, there is little molecular research on chayote, and there are no reports on the MADS-box transcription factor of chayote. In this study, the MADS-box gene family of chayote was analyzed for the first time, and a total of 70 MADS-box genes were identified, including 14 type I and 56 type II MICK MADS genes. They were randomly distributed on 13 chromosomes except for chromosome 11. The light response element, hormone response element and abiotic stress response element were found in the promoter region of 70 MADS genes, indicating that the MADS gene can regulate the growth and development of chayote, resist abiotic stress, and participate in hormone response; GO and KEGG enrichment analysis also found that SeMADS genes were mainly enriched in biological regulation and signal regulation, which further proved the important role of MADS-box gene in plant growth and development. The results of collinearity showed that segmental duplication was the main driving force of MADS gene expansion in chayote. RNA-seq showed that the expression levels of SeMADS06, SeMADS13, SeMADS26, SeMADS28, SeMADS36 and SeMADS37 gradually increased with the growth of chayote, indicating that these genes may be related to the development of root tubers of 'Tuershao'. The gene expression patterns showed that 12 SeMADS genes were specifically expressed in the male flower in 'Tuershao' and chayote. In addition, SeMADS03 and SeMADS52 may be involved in regulating the maturation of male flowers of 'Tuershao' and chayote. SeMADS21 may be the crucial gene in the development stage of the female flower of 'Tuershao'. This study laid a theoretical foundation for the further study of the function of the MADS gene in chayote in the future.

Transcriptome Mechanisms of Tomato Seedlings Induced by Low-Red to Far-Red Light Ratio under Calcium Nitrate Stress.

In recent times, the excessive accumulation of nitrate has been one of the main reasons for the secondary salinization of greenhouse soils. Light plays a key role in a plant's growth, development, and response to stress. A low-red to far-red (R:FR) light ratio could enhance plant salinity tolerance, but the mechanism at a molecular level is unclear. Thus, we analyzed the transcriptome responses of tomato seedlings to calcium nitrate stress under either a low R:FR ratio (0.7) or normal light conditions. Under calcium nitrate stress, a low R:FR ratio enhanced both the antioxidant defense system and the rapid physiological accumulation of proline in tomato leaves, which promoted plant adaptability. Using weighted gene co-expression network analysis (WGCNA), three modules including 368 differentially expressed genes (DEGs) were determined to be significantly associated with these plant traits. Functional annotations showed that the responses of these DEGs to a low R:FR ratio under excessive nitrate stress were enriched in the areas of hormone signal transduction, amino acid biosynthesis, sulfide metabolism, and oxidoreductase activity. Furthermore, we identified important novel hub genes encoding certain proteins, including FBNs, SULTRs, and GATA-like transcription factor, which may play a vital role in low R:FR light-induced salt responses. These findings offer a new perspective on the mechanisms and environmental implications behind low R:FR ratio light-modulated tomato saline tolerance.

A lateral flow immunoassay based on chemisorbed probes in virtue of hydrogen bond receptors on the Bi2S3 NPs.

Improving detection sensitivity is still a major research emphasis for lateral flow immunoassay (LFIA). Increasing the binding efficiency and stability of the probe is an achievable and effective solution. In this work, we developed a highly sensitive lateral flow immunoassay for clenbuterol detection by using bismuth sulfide nanoparticle (Bi2S3) nanoparticles (NPs) as a novel marker. Here, Bi2S3 NPs can link with the antibody by hydrogen bonding to improve the performance of the probe, e.g., stability and sensitivity. Benefiting from the direct hydrogen bonding between Bi2S3 NPs and the monoclonal antibody (mAb), high sensitivity is obtained by the proposed LFIA with a lower visible detection limit of 0.1 ng mL-1 and a cut-off value of 4 ng·mL-1 for CLE detection, which is 5-fold and 7.5-fold improved than the conventional Au NPs based LFIA. In addition, the encouraging practical application results in milk, pork, and beef show that the bismuth sulfide nanoparticle has a great popularizing potential in the performance promotion of LFIAs for food safety monitoring.

Effect of light intensity on celery growth and flavonoid synthesis.

Light is one of the important environmental factors affecting the growth and development of facility vegetables. In this experiment, we investigated the effects of different light intensities on the growth, nutritional quality and flavonoid accumulation of celery under hydroponic and full LED light conditions. Four light intensities of 40, 100, 200, or 300 µmol·m-2·s-1 were set up in the experiment, and three harvest periods were set up on the basis of different light intensities, which were 15, 30, and 45 d after treatment (labeled as S1, S2, and S3, respectively). The results showed that the plant height and aboveground biomass of celery increased with the increase of light intensity, and the light intensity of 200 µmol·m-2·s-1 was beneficial to increase the contents of chlorophyll, carotenoids, total phenols, vitamin C, cellulose, total flavones and apigenin in celery. During the S1-S3 period, the activities of PAL, CHS, CHI and ANS increased gradually under 200 and 300 µmol·m-2·s-1 light intensity treatments, and the activities of FNS and CHS enzymes were the highest under 200 µmol·m-2·s-1 light intensity treatment. The expression and ANS activity of Ag3GT, a key gene for anthocyanin synthesis, reached the maximum value at 300 µmol·m-2·s-1, and the expression level and FNS activity of AgFNS, a key gene for apigenin synthesis, reached a maximum value at 200 µmol·m-2·s-1. In general, the anthocyanin content was the highest at 300 µmol·m-2·s-1, and the apigenin content was the highest at 200 µmol·m-2·s-1. In conclusion, light intensity of 200 µmol·m-2·s-1 treatment was more favorable for celery growth and nutrient synthesis.

Corrigendum: Transcriptome and Metabolome Analyses Reveal Molecular Responses of Two Pepper (Capsicum annuum L.) Cultivars to Cold Stress.

[This corrects the article DOI: 10.3389/fpls.2022.819630.].

Transcriptome and Metabolome Analysis Provide New Insights into the Process of Tuberization of Sechium edule Roots.

Chayote (Sechium edule) produces edible tubers with high starch content after 1 year of growth but the mechanism of chayote tuberization remains unknown. 'Tuershao', a chayote cultivar lacking edible fruits but showing higher tuber yield than traditional chayote cultivars, was used to study tuber formation through integrative analysis of the metabolome and transcriptome profiles at three tuber-growth stages. Starch biosynthesis- and galactose metabolism-related genes and metabolites were significantly upregulated during tuber bulking, whereas genes encoding sugars will eventually be exported transporter (SWEET) and sugar transporter (SUT) were highly expressed during tuber formation. Auxin precursor (indole-3-acetamide) and ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, were upregulated, suggesting that both hormones play pivotal roles in tuber development and maturation. Our data revealed a similar tuber-formation signaling pathway in chayote as in potatoes, including complexes BEL1/KNOX and SP6A/14-3-3/FDL. Down-regulation of the BEL1/KNOX complex and upregulation of 14-3-3 protein implied that these two complexes might have distinct functions in tuber formation. Finally, gene expression and microscopic analysis indicated active cell division during the initial stages of tuber formation. Altogether, the integration of transcriptome and metabolome analyses unraveled an overall molecular network of chayote tuberization that might facilitate its utilization.

Transcriptome and Metabolome Analyses Reveal Molecular Responses of Two Pepper (Capsicum annuum L.) Cultivars to Cold Stress.

Low temperature is a significant factor affecting field-grown pepper. The molecular mechanisms behind peppers' response to cold stress remain unknown. Transcriptomic and metabolomic analyses were used to investigate the responses of two pepper cultivars, XS (cold-sensitive) and GZ (cold-resistant), to cold stress; these were screened from 45 pepper materials. In this study, compared with the control group (0 h), we identified 10,931 differentially expressed genes (DEGs) in XS and GZ, 657 differentially expressed metabolites (DEMs) in the positive ion mode, and 390 DEMs in the negative ion mode. Most DEGs were involved in amino acid biosynthesis, plant hormone signal transduction, and the mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, metabolomic analysis revealed that the content of free polyamines (PAs), plant hormones, and osmolytes, mainly contained increased putrescine, spermine, spermidine, abscisic acid (ABA), jasmonic acid (JA), raffinose, and proline, in response to cold stress. Importantly, the regulation of the ICE (inducer of CBF expression)-CBF (C repeat binding factors)-COR (cold regulated) pathway by Ca2+ signaling, MAPK signaling, and reactive oxygen species (ROS) signaling plays a key role in regulating responses of peppers to cold stress. Above all, the results of the present study provide important insights into the response of peppers to cold stress, which will reveal the potential molecular mechanisms and contribute to pepper screening and breeding in the future.

Expanded detection range of lateral flow immunoassay endowed with a third-stage amplifier indirect probe.

Here, a third-stage amplifier indirect probe (TsAIP) based lateral flow immunoassay (LFIA) was proposed to detect furazolidone (FZD) with Prussian blue nanoparticles (PBNPs) as carrier to label the goat anti-mouse antibody-horseradish peroxidase conjugation [GAMA(HRP)]. In this strategy, owing to the fact that one monoclonal antibody (mAb) can combine several GAMA molecules simultaneously, the indirect probe can generate primary signal amplification, then realize second-stage amplification attributing to PBNPs, and finally achieve third-stage amplification because of the conjugated HRP. The TsAIP-based LFIA shows improved performance for FZD metabolite derivative with a detection limit of 1 ng mL-1. The detection range is expanded about 2-fold compared with the original outcome. Besides, the proposed sensor could be successfully applied in food samples. This method provides a platform for broadening the detection range and application of PBNPs based LFIAs.

Controllable assembly metal-organic frameworks and gold nanoparticles composites for sensitive immunochromatographic assay.

Creating universal signal labels from fundamental building blocks with excellent biocompatibility and well-controlled size/uniformity simultaneously for immunochromatographic assay (ICA) is highly desired but extremely challenging. Here, a nano-signal label strategy was reported, in which the amino-terminated zirconium MOFs (NU66) are adopted to construct powerful matrix materials and gold nanoparticles (AuNPs) act as the linker between metal-organic frameworks (MOFs) and antibodies. Particularly, AuNPs were immobilized directly on the surface of NU66, giving NU66 excellent biocompatibility with bright color signal labels and improving the salt ion stability of AuNPs. As a proof of concept, the furazolidone residues was monitored by the developed NU66@AuNPs-ICA in food samples (pork, shrimp and eggs). With 3-[(4-carboxyphenyl) monomethyl] amino-2-oxazolidinone (CPAOZ) as analyte target, the visual limit of detection (vLOD) and cut-off level were 0.6 ng/mL and 3.0 ng/mL, respectively. This work may open a new avenue for the application of MOFs in immunochromatography assays.

Rational construction of a robust metal-organic framework nanozyme with dual-metal active sites for colorimetric detection of organophosphorus pesticides.

While nanomaterials with enzyme-mimicking activities are emerging as promising candidates in the colorimetric detection of organophosphorus pesticides (OPs), the catalytic activities and recognition ability to analyte of most nanozymes are inherently deficient. In this work, we introduced manganese ions into a typical iron based MOF (Fe-MIL(53)) via a one-pot hydrothermal reaction strategy, which brought out a catalytically favorable bimetallic Mn/Fe-MIL(53) MOF nanozyme. The catalytic performance of Mn/Fe-MIL(53) is superior to that of pure Fe-MIL (53) and the mechanism for superior catalytic activity of material is revealed by active species scavenging experiments and X-ray photoelectron spectroscopy (XPS). Besides, the introduction of manganese endows the material with the characteristic of being specially destroyed by choline, which motivates the establishment of a simple, selective and sensitive colorimetric strategy for OPs detection. The proposed colorimetric strategy could quantify the methyl parathion and chlorpyrifos in the concentration range of 10-120 nM and 5-50 nM, respectively. The low detection limit of 2.8 nM for methyl parathion and 0.95 nM (3 S/N) for chlorpyrifos were achieved. Good recoveries were obtained when applied in the real sample detection. Our work paves the way to boost catalytic performance of MOF nanozymes, which will be useful in biosensing.

Effect of Y2O3 Addition on Microstructure and Properties of Laser Cladded Al-Si Coatings on AZ91D Magnesium Alloy.

The effect of Y2O3 addition on the microstructure and properties of the laser cladded Al-Si alloy coating on the surface of AZ91D magnesium alloy was investigated in this study. The experimental results showed that the Al-Si + Y2O3 cladding layers contained α-Mg, Mg2Si, Al4MgY and a small amount of Al12Mg17 phases. The coarse dendrites, reticulated eutectic structures and massive phases in the coatings tended to be refined and gradually uniformly distributed with the increased amount of Y2O3. The introduction of Y2O3 into the cladding layer favored the improvement of microhardness and wear resistance due to the grain refinement strengthening and dispersion strengthening. The addition of Y2O3 also promoted the reduction of localized corrosion sites and made the corrosion surface smoother, implying that the corrosion resistance of the Y2O3-modified coatings was better than that of the unmodified cladding layer.

Flexible Diodes/Transistors Based on Tunable p-n-Type Semiconductivity in Graphene/Mn-Co-Ni-O Nanocomposites.

We report a novel Mn-Co-Ni-O (MCN) nanocomposite in which the p-type semiconductivity of Mn-Co-Ni-O can be manipulated by addition of graphene. With an increase of graphene content, the semiconductivity of the nanocomposite can be tuned from p-type through electrically neutral to n-type. The very low effective mass of electrons in graphene facilitates electron tunneling into the MCN, neutralizing holes in the MCN nanoparticles. XPS analysis shows that the multivalent manganese ions in the MCN nanoparticles are chemically reduced by the graphene electrons to lower-valent states. Unlike traditional semiconductor devices, electrons are excited from the filled graphite band into the empty band at the Dirac points from where they move freely in the graphene and tunnel into the MCN. The new composite film demonstrates inherent flexibility, high mobility, short carrier lifetime, and high carrier concentration. This work is useful not only in manufacturing flexible transistors, FETs, and thermosensitive and thermoelectric devices with unique properties but also in providing a new method for future development of 2D-based semiconductors.

Network response of two cherry tomato (Lycopersicon esculentum) cultivars to Cadmium stress as revealed by transcriptome analysis.

Soil cadmium (Cd) contamination severely threatens human health. Therefore, screening and breeding low-Cd absorption cultivars of cherry tomato (Solanum lycopersicum L.) is essential to restrict human Cd intake. In this study, a hydroponic experiment was conducted to perform a comparative transcriptome analysis of the leaves of two cherry tomato cultivars with different Cd contents under different Cd stress (0, 10, and 50 µM), for the purpose of exploring the differences in the transcriptional responses to Cd stress between the two cultivars. Our results revealed that the Cd content in the leaves of HLZ (Hanluzhe; a low-Cd accumulation cultivar) was significantly lower than that in the leaves of LFC (Lvfeicui; a high-Cd accumulation cultivar). Transcriptome analysis showed that the different expression genes (DEGs) were mainly involved in plant hormone signal transduction, antioxidant enzymes, cell wall biosynthesis, and metal transportation. In the LFC leaves, DEGs in the IAA signal transduction and antioxidant enzymes exhibited higher transcription levels. However, the DEGs in the ETH signal transduction demonstrated a lower transcription level compared to that of HLZ. Over-expressed genes in the pectin biosynthesis and pectin methylesterase (PME) of the LFC leaves might result in the trapping of Cd by increased levels of low-methylated pectin around the cell wall. Furthermore, Cd transporter genes, such as HMA5, NRAMP6, CAX3, ABCC3, and PDR1, were up-regulated in the HLZ leaves, indicating that the HLZ cultivar comprised an active Cd transport capacity from apoplast to vacuolar. This may contribute to the low Cd concentration observed in the HLZ leaves. Overall, our study provides a molecular basis for tomato screening and breeding.

Drought resistance mechanisms of Phedimus aizoon L.

Phedimus aizoon L. is a drought-resistant Chinese herbal medicine and vegetable. However, its drought tolerant limit and the mechanism of drought tolerance are unknown, which restricts the promotion of water-saving cultivation of Phedimus aizoon L. in arid areas. To solve the above problem, we carried out a 30-day-long drought stress experiment in pots that presented different soil water contents and were divided into four groups: control check, 75-80% of the maximum water-holding capacity (MWHC); mild drought, 55-60%; moderate drought, 40-45%; and severe drought, 20-25%. The dynamic changes in both plant physiological indexes from 10 to 30 days and leaf anatomical structure on the 30th day of stress were recorded. The results show that Phedimus aizoon L. grew normally under mild drought stress for 30 days, but the growth of the plants became inhibited after 20 days of severe drought and after 30 days of moderate drought. At the same time, Phedimus aizoon L. physiologically responded to cope with drought stress: the growth of the root system accelerated, the waxy layer of the leaves thickened, and the dark reactions of the plants transformed from those of the C3 cycle to CAM. The activity of antioxidant enzymes (SOD, POD and CAT) continuously increased to alleviate the damage caused by drought stress. To ensure the relative stability of the osmotic potential, the contents of osmoregulatory substances such as proline, soluble sugars, soluble protein and trehalose increased correspondingly. Although Phedimus aizoon L. has strong drought stress resistance, our experimental results show that the soil available water content should not be less than 27% during cultivation.