Phloem Protein 2 (PP2) regulates phloem-based defense, contributing to plant growth and stress tolerance. While PP2s are known to aid stress responses in cotton, rapeseed, and bamboo, their roles in cassava are less explored. This study identified fifteen PP2 gene family members in cassava, grouped into four distinct clusters based on maximum likelihood phylogenetic analysis. These genes typically contain two to three exons and one or two introns. The PP2 proteins harbor six conserved domains, including PP2, PP2 superfamily, F-box, F-box-like, F-box superfamily, and F-box-like superfamily, suggesting their involvement in stress response and regulatory functions. The conserved domain, motifs, and gene structures of PP2s aligned with their phylogenetic relationships. Furthermore, the MePP2 expression profiling revealed remarkably high transcript levels of Manes.18G077300, Manes.02G027400, Manes.08G018500, and Manes.09G061300 across all cassava tissues, indicating their potential role in overall growth and yield improvement. Although Manes.08G114900 and Manes.08G115000 were not inducible to root wounding, their transcripts highly accumulated in response to drought and cold stress exposure in the leaves, suggesting their role in shoot development and stress tolerance. The MePP2 genes also intricately interact with LIP4, ATLTP44, and GDSL, potentially contributing to growth and stress tolerance. This study lays a foundation for further studies to elucidate the putative function of PP2 genes in cassava.

ABSTRACT Tropical regions sustain crops essential to global food security and economic development, notably sugarcane, banana, cassava, rubber and oil palm, yet these species face extreme and variable environments. This review synthesizes their adaptive strategies shaped by long‐term natural selection and domestication. We examine how genomic features underlie crop complexity, how structural variation drives key adaptive traits, and how domestication and breeding reshape genomes to enhance yield while redefining adaptive trajectories. Future efforts should be devoted to resolving synergistic stress‐response mechanisms via multi‐omics, accelerating stress‐resilient cultivar development using wild germplasm and molecular design breeding, optimizing tropical agroforestry through niche‐based frameworks, and applying tropical adaptive mechanisms to other crops via synthetic biology and gene editing. Collectively, these advances provide theoretical and practical strategies for advancing climate‐resilient, sustainable tropical agriculture.

Cassava storage roots (SRs) are a crucial staple food and industrial resource worldwide. However, SRs are highly susceptible to postharvest physiological deterioration (PPD) after harvest, characterized by blue-brown vascular discoloration. This discoloration results from the accumulation of polyphenolics, mainly quinones and coumarins, produced by enzymes such as polyphenol oxidase (PPO). We identified a MePPO gene in the cassava (Manihot esculenta) genome and performed a comparative analysis of PPO homologs across various plant species. Their physicochemical characteristics, evolutionary relationships, gene structures, chromosomal localizations, conserved motifs, cis-acting elements, gene duplications, and synteny relationships were thoroughly compared and analyzed. Expression profiling revealed that MePPO was predominantly transcribed in the roots and leaves of cassava. Virus-induced gene silencing (VIGS) of MePPO significantly delayed the occurrence and progression of cassava PPD in SRs, particularly on the 6th and 9th days postharvest. Silenced lines displayed substantially reduced PPO transcript levels and enzymatic activity, accompanied by a marked decrease in scopoletin, a key coumarin implicated in PPD at 3 days postharvest. Notably, the accumulation of cassava flavanols (catechins) was enhanced in the silenced lines. In summary, these findings establish that targeted suppression of MePPO effectively mitigates PPD in cassava SRs.

Postharvest physiological deterioration (PPD), characterized by rapid tissue discoloration, is a pervasive challenge that inflicts substantial economic losses on a broad range of crops, with cassava being one of the most susceptible species. Wounding-induced reactive oxygen species (ROS) accumulation exerts a central regulatory role in crop PPD. However, the regulatory mechanisms underlying how plants accumulate ROS to initiate PPD in response to wounding remain elusive. Herein, we found that the superoxide anion (O2•-, a ROS) burst after wounding constitutes a primary event spatially correlated with cassava PPD, and identified numerous genes encoding ferrous (Fe2+)-/copper (Cu2+)-core enzymes in O2•--accumulated tissues. Application of Fe2+-competitor (cobalt/Co2+, nickel/Ni2+), Fe2+-chelator (ferrozine), or high concentration of Cu2+, significantly suppressed tissue discoloration and O2•- accumulation. Additionally, Co2+ disrupted the biosynthesis of secondary metabolites associated with PPD in cassava, and its robust effect on inhibiting O2•- burst and tissue discoloration was conserved across multiple crop species. These results suggest that metal ion-dependent enzymatic pathways might be essential for the regulation of wounding-triggered O2•- burst and PPD onset in plants, which provides a promising theoretical basis for developing targeted postharvest preservation strategies applicable to a wide spectrum of crops.

The phenylpropanoid pathway remains a key target for most climate-resilient crop development, owing to it being a precursor to over 8000 metabolites, including flavonoids and lignin compounds, including their derivatives. These metabolites are involved in biotic and abiotic stress tolerance, inviting several studies into their roles in plant defense, drought, temperature, UV, and nutrient stress tolerance. Literature is currently inundated with cutting-edge reports on the phenylpropanoid pathways and their functions. Here, we provide a comprehensive update on the biosynthesis of phenylpropanoids, mainly lignin and flavonoids, their roles in biotic and abiotic interaction, and transcending topics, including pest and diseases, drought, temperature, and UV stress tolerance. We further reviewed the post-transcriptional, post-translational, and epigenetic modifications regulating phenylpropanoid metabolism and highlighted their applications and optimization strategies for large-scale production. This review provides an all-inclusive update on recent reports on the metabolism of phenylpropanoids in plants.

Hemizygous genes, which are present on only one of the two homologous chromosomes of diploid organisms, have been mainly studied in the context of sex chromosomes and sex-linked genes. However, these genes can also occur on the autosomes of diploid plants due to structural variants (SVs), such as a deletion/insertion of one allele, and this phenomenon largely unexplored in plants. Here, we investigated the genomic and epigenomic landscapes of hemizygous genes across 22 genomes with varying propagation histories: eleven clonal lineages, seven outcrossed samples, and four inbred and putatively homozygous genomes. We identified SVs leading to genic hemizygosity. As expected, very few genes (0.01 to 1.2%) were hemizygous in the homozygous genomes, representing negative controls. Hemizygosity was appreciable among outcrossed lineages, averaging 8.7% of genes, but consistently elevated for the clonal samples at 13.8% genes, likely reflecting heterozygous SV accumulation during clonal propagation. Compared to diploid genes, hemizygous genes were more often situated in centromeric than telomeric regions and experienced weaker purifying selection. They also had reduced levels of expression, averaging ~20% of the expression levels of diploid genes, violating the evolutionary model of dosage compensation. We also detected higher DNA methylation levels in hemizygous genes and transposable elements, which may contribute to their reduced expression. Finally, expression profiles showed that hemizygous genes were more specifically expressed in contexts related to fruit development, organ differentiation, and stress responses. Overall, hemizygous genes accumulate in clonally propagated lineages and display distinct genetic and epigenetic features compared to diploid genes, shedding unique insights into genetic studies and breeding programs of clonal crops.

Cassava (Manihot esculenta) is a vital tropical staple crop with expanding relevance beyond food security, particularly in developing functional beverages and nutraceutical products. This review discusses the implications of selected chemicals in cassava roots for beverage production, notably cyanogenic glycosides and phenolic compounds. We further highlight the role of cassava as a substrate for beverage production, the nutritional significance of cassava-based beverages, and the health benefits and functional potential of cassava as a key ingredient in beverage production. We also discuss the probiotic and prebiotic properties and the antioxidant activity of chemicals in cassava-based beverages for health benefits. Additionally, we review the challenges, opportunities, and innovations regarding commercialization.

Cassava is a tropical tuberous root crop, feeding over a billion people globally. However, research on the chemical composition and bioactive effects of cassava leaves remains scarce. Two specific varieties of South China No. 9 (green leaves (G.L.)) and South China No. 20 (purple leaves (P.L.)) were investigated in this study. The components of G.L. and P.L. were analyzed under different extraction methods using ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Results showed that cassava leaf extracts are rich in bioactive metabolites such as D-(+)-mannose, trigonelline, rutin, kaempferol-3-O-rutinoside, and oleamide. To assess the anti-inflammatory efficacy of bioactive compounds, animal models were established. Compared to the histamine group (NA), the group treated with the extracts had reduced epidermal thickness in hematoxylin and eosin (HE) staining. Further analysis revealed a drastic reduction in the number of mast cells in toluidine blue (TB) staining and expression levels of inflammatory cytokines (IL-17 and TNF-α) in immunohistochemistry (IHC) staining. The ethanolic extracts from the leaves demonstrated potent anti-inflammatory activities, with the extract from G.L. surpassing that from P.L. Transcriptomic analyses propose that the anti-inflammatory effects of cassava leaves may be related to the modulation of genes involved in mast cell activation, such as Cma1, Cpa3, and Fn1, among others. Network pharmacology unveiled that the extract of cassava leaves modulates pathways associated with apoptosis, inflammation, and metabolism. Molecular docking revealed strong binding interactions between 1-stearoylglycerol and oleamide from cassava leaves extracts and the proteins of AKT1, TNF, and BRAF. Overall, cassava leaf extracts seem to be a promising natural anti-inflammatory agent.

With the growing importance of cassava worldwide, developing efficient and eco-friendly fertilizer strategies is crucial for sustainable cassava production. Diverse fertilizer treatments can significantly influence soil properties and plant growth. In this study, we investigated the effects of three fertilizer treatments—organic fertilizer (OF), chemical fertilizer combined with organic fertilizer (CFOF), and reduced chemical fertilizer combined with organic fertilizer (RFOF)—on the fungal community structure, chemical properties (SOM, AP, AN, and AK), and enzyme activities (NP, SC, CAT, and UE) in cassava rhizosphere. Our results demonstrated that these fertilizer treatments significantly enhanced cassava growth and yield compared to the control (CK) without fertilization. Soil chemical properties (SOM, AN, AP, and AK) and enzyme activities (NP, SC, CAT, and UE) were notably improved following fertilization. High-throughput sequencing revealed the significant alterations in the relative abundance of specific fungal taxa. Environmental parameters, particularly UE, SC, CAT, and AP, showed strong correlations with fungal community structure. These findings highlight the critical role of combined organic and chemical fertilizers in promoting cassava productivity and soil health. Understanding these interactions provides a foundation for optimizing fertilization practices to enhance crop yields and support sustainable agriculture.

Amyloplasts are the sites of starch synthesis and accumulation. Little is known about amyloplast division and its effects on the size, structure, and physicochemical properties of starch granules. In this study, we created mutants of plastid division-related gene MeMinD by CRISPR/Cas9 technology, leading to the disruption of normal division of amyloplasts in cassava storage roots. The memind mutants exhibited significantly enlarged amyloplasts with an increased number of starch granules, and broader range of granule sizes. The loss of MeMinD function led to transcriptional reprogramming of gene expressions related to starch-synthesizing enzymes, affecting the fine structure of starch. Starch in memind mutant storage roots showed a significantly decreased proportion of shorter amylopectin chains and an increased proportion of medium and long chains, which ultimately led to a significant increase in apparent amylose content (AAC) in memind mutants compared to that in WT. The changes in starch granule size and structure resulted in a significant increase in onset temperature (To), peak temperature (Tp), and conclusion temperature (Tc) of the gelatinization process, extending the time to reach peak temperature. These data suggest that regulating amyloplast division affects starch accumulation in cassava, presenting an effective strategy for developing novel cassava starch.

The feeding value of five varieties of whole-plant cassava (SC5, SC7, SC9, SC14, and SC205) was assessed through analysis of the nutritional composition and in situ ruminal degradability. The results showed abundant nutrients in whole-plant cassava, and the means of starch and crude protein (CP) were 267.7 and 176.8 (g kg−1), and ranged from 223.7 g kg−1 (SC9) to 296.4 g kg−1 (SC14) and from 142.4 g kg−1 (SC5) to 195.8 g kg−1 (SC9) (p < 0.05), respectively. Meanwhile, the moderate neutral detergent fiber (NDF) of whole-plant cassava was also observed and ranged from 266.2 g kg−1 in SC9 to 286.6 g kg−1 in SC14 (p < 0.05). In addition, the trace elements, such as Fe, Mn, Cu, and Zn, in whole-plant cassava were relatively enriched, and their mean concentrations were 135.8, 1225.2, 5.8, and 105.3 mg kg−1 (p < 0.05), respectively. Both the highest essential amino acid and total amino acid concentrations were obtained in SC7 (p < 0.01). The hydrogen cyanide (HCN) content of fresh and dried whole-plant cassava ranged from 76.5 to 131.6 and from 36.0 to 56.7 mg kg−1 (p < 0.05), respectively. The in situ dry matter ruminal degradability and metabolizable energy (ME) varied significantly (p < 0.05) and were consistently lowest and highest in SC9 and SC14, ranging from 50.9% to 80.0% and from 7.5 to 12.3 MJ kg−1, respectively. Collectively, all varieties of whole-plant cassava had a high feeding value, as reflected by abundant starch, minerals, amino acid, and water-soluble carbohydrates, while having a low fiber content and HCN toxicity, as well as excellent ruminal digestibility characteristics, and they could be used as a potential feed resource for ruminants.

Cassava (Manihot esculenta Crantz) is used as a biomass energy material and an effective supplement for food and feed. Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step of lignin biosynthesis and is responsible for various stresses. However, systematic investigations of the CAD gene family in cassava have been poorly understood. In this study, a genome-wide survey and bioinformatics analysis of CAD gene family was performed, transcriptomics, qRT-PCR, gene silencing and stress of yeast cell were used for excavate and validate the candidate MeCADs gene. 36 MeCADs genes unevenly distributed across 12 chromosomes were identified. Through phylogenetic analyses alongside their Arabidopsis counterparts, these MeCADs were divided into four groups, each containing a similar structure and conserved motifs. Interestingly, transcriptome data analysis revealed that 32 MeCAD genes were involved in the postharvest physiological deterioration (PPD) process, whereas 27 MeCAD genes showed significant changes. Additionally, the relative quantitative analysis of 6 MeCAD genes demonstrated that they were sensitive to PPD, suggesting that they may be involved in the regulation of PPD. Silencing MeCAD13 and MeCAD28 further showed that lignin content significantly decreased in the leaves. The wound-stress tolerance of transgenic yeast cells was enhanced after transformation with MeCAD13 and MeCAD28. MeCAD13 and MeCAD28 may play positive roles in lignin biosynthesis and PPD response, respectively. These results provided a systematic functional analysis of MeCADs in cassava and paved a new way to genetically modify lignin biosynthesis and PPD tolerance.

The objective of this study was to explore excellent silage production through co-ensiling whole-plant cassava and corn stalk, and different ratios of whole-plant cassava (0%, 10%, 20%, 30%, 40%, and 50%, fresh-matter basis) co-ensiled with corn stalk were analyzed based on the silage bacterial community, function profile, and microbial ecological network features. The results demonstrated that co-ensiling 30% whole-plant cassava with 70% corn stalk could be considered an efficient mode of production. The mixed silage showed great quality, as reflected by the reduced pH value and concentrations of acetic acid, butyric acid, and ammonia nitrogen and the enhanced lactic acid concentration, V-score, and nutritional value compared with corn stalk ensiled alone. Meanwhile, co-ensiling restricted the undesirable bacterial Acetobacter fabarum of corn stalk and Pseudomonas aeruginosa of whole-plant cassava and raised the abundance of lactic acid bacteria (LAB) such as Levilactobacillus brevis, Lactiplantibacillus plantarum, Lactobacillus harbinensis, etc. Besides that, the predicted functions of the bacterial community showed large differences in mixed silage compared with whole-plant cassava or corn stalk ensiled alone. Moreover, the analysis of co-occurrence networks showed that mixed silage affected microbial network features, module numbers, and bacterial relative abundances and weakened the complexity and stability of the networks compared with whole-plant cassava single silage. Furthermore, silage microbial community composition had a huge impact on the network properties, and undesirable Pseudomonas aeruginosa played a crucial role in the complexity and stability. Overall, this study revealed the characteristics of whole-plant cassava with corn stalk mixed-silage microbial communities and co-occurrence network modules, complexity, and stability and partly clarified the microbial mechanism of co-ensiling for producing high-quality silage. The findings of this study have important implications for deeply understanding the ensiling process and precisely regulating silage fermentation quality.

The objective of this study was to explore the preservation of food products through the co-fermentation of whole-plant cassava and Piper sarmentosum (PS) without additives. We assessed fermentation quality, antioxidant activity, bacterial community structure, function profile, and microbial ecological network features. Our results demonstrate that co-fermentation of whole-plant cassava with 10% PS significantly improves food quality. The co-fermented samples exhibited enhanced lactic acid concentrations and increased antioxidant activity, with reduced pH values and concentrations of acetic acid, butyric acid, and ammonia-N(NH3-N) compared to whole-plant cassava fermented alone. In addition, PS addition also optimized microbial community structure by elevating the total abundance of lactic acid bacteria and influenced bacterial predicted functions. Furthermore, our analysis of co-occurrence networks reveals that co-fermentation impacts microbial network features, including module numbers and bacterial relative abundances, leading to altered complexity and stability of the networks. Moreover, out study also highlights the impact of ferment undesirable bacteria like Pseudomonas aeruginosa and unclassified_Muribaculaceae playing crucial roles in microbial network complexity and stability. These findings provide valuable insights into the anaerobic fermentation process and offers strategies for regulating food fermentation quality.

The significant reduction in cassava (Manihot esculenta Crantz) yields attributed to cassava bacterial blight (CBB) constitutes an urgent matter demanding prompt attention. The current study centered on the MebHLH149 transcription factor, which is acknowledged to be reactive to CBB and exhibits augmented expression levels, as indicated by laboratory transcriptome data. Our exploration, encompassing Xanthomonas phaseoli pv. manihotis strain CHN01 (Xpm CHN01) and hormone stress, disclosed that the MebHLH149 gene interacts with the pathogen at the early stage of infection. Furthermore, the MebHLH149 gene has been discovered to be responsive to the plant hormones abscisic acid (ABA), methyl jasmonate (MeJA), and salicylic acid (SA), intimating a potential role in the signaling pathways mediated by these hormones. An analysis of the protein’s subcellular localization suggested that MebHLH149 is predominantly located within the nucleus. Through virus-induced gene silencing (VIGS) in cassava, we discovered that MebHLH149-silenced plants manifested higher disease susceptibility, less ROS accumulation, and significantly larger leaf spot areas compared to control plants. The proteins MePRE5 and MePRE6, which are predicted to interact with MebHLH149, demonstrated complementary downregulation and upregulation patterns in response to silencing and overexpression of the MebHLH149 gene. This implies a potential interaction between MebHLH149 and these proteins. Both MePRE5 and MePRE6 genes are involved in the initial immune response to CBB. Notably, MebHLH149 was identified as a protein that physically interacts with MePRE5 and MePRE6. Based on these findings, it is hypothesized that the MebHLH149 gene likely functions as a positive regulator in the defense mechanisms of cassava against CBB.

木薯原产热带美洲,是世界热区重要的粮食作物,也是世界近十亿人的食粮.然而木薯基因组高度杂合、后代分离严重,定向选育难度大、育种周期长,这些因素严重制约着木薯产业的发展.因此,缩短育种周期、定向选育出木薯优良品种是当今育种工作的重点.近年来,随着测序技术的发展以及多组学、基因编辑、遗传转化等核心技术在育种中的应用,木薯育种工作取得了重大突破.本文综述了木薯育种的最新进展,包括木薯种质资源重要农艺性状评价已从传统表型评价发展到表型与基因型的精准评价、木薯参考基因组的组装与注释及关键性状基因资源的发掘、木薯现代育种策略的发展等.此外,本文还讨论了今后木薯育种的研究方向,这将对推动木薯产业发展、服务国家“一带一路”倡议,以及解决世界热区粮食安全和饲料有效供给具有重要意义.

Cassava tuberous root, as a staple food crop and industrial raw material worldwide, is highly sensitive to postharvest physiological deterioration (PPD) caused by wound. However, the molecular mechanism underlying PPD tolerance remains elusive in cassava. The reactive oxygen species (ROS) scavenging system is activated at the preliminary stage of PPD and peroxidase (POD) can effectively eliminate ROS. The expression level of MePOD12 and POD enzymatic activity in cassava tuberous roots was considerably up-regulated with PPD occurrence. Yeast two-hybrid and luciferase reporter assay showed that MePOD12 physically interacted with lignin-related cinnamyl alcohol dehydrogenase 15 (MeCAD15) in vitro and in vivo. The MePOD12-silenced tuberous roots decayed more than control, especially stored at room temperature for 3 and 5 days after harvesting. The total antioxidant capacity, activities of POD, SOD, CAT, CAD and lignin content were lower than those of control. Particularly, after harvest for 3 days, the accumulation of hydrogen peroxide and superoxide anion substantially increased compared to control. In addition, a proposed model was generated to elaborate the response mechanism of MePOD12 participating in PPD regulation via ROS elimination and lignin accumulation. It provides a new clue for breeding cassava PPD-tolerant varieties.

Background Metabolites play critical roles in regulating nutritional qualities of plants, thereby influencing their consumption and human health. However, the genetic basis underlying the metabolite-based nutrient quality and domestication of root and tuber crops remain largely unknown. Results We report a comprehensive study combining metabolic and phenotypic genome-wide association studies to dissect the genetic basis of metabolites in the storage root (SR) of cassava. We quantify 2,980 metabolic features in 299 cultivated cassava accessions. We detect 18,218 significant marker-metabolite associations via metabolic genome-wide association mapping and identify 12 candidate genes responsible for the levels of metabolites that are of potential nutritional importance. Me3GT , MeMYB4 , and UGT85K4 / UGT85K5 , which are involved in flavone, anthocyanin, and cyanogenic glucoside metabolism, respectively, are functionally validated through in vitro enzyme assays and in vivo gene silencing analyses. We identify a cluster of cyanogenic glucoside biosynthesis genes, among which CYP79D1 , CYP71E7b , and UGT85K5 are highly co-expressed and their allelic combination contributes to low linamarin content. We find MeMYB4 is responsible for variations in cyanidin 3-O-glucoside and delphinidin 3-O-rutinoside contents, thus controlling SR endothelium color. We find human selection affects quercetin 3-O-glucoside content and SR weight per plant. The candidate gene MeFLS1 is subject to selection during cassava domestication, leading to decreased quercetin 3-O-glucoside content and thus increased SR weight per plant. Conclusions These findings reveal the genetic basis of cassava SR metabolome variation, establish a linkage between metabolites and agronomic traits, and offer useful resources for genetically improving the nutrition of cassava and other root crops.

As a starchy and edible tropical plant, cassava (Manihot esculenta Crantz) has been widely used as an industrial raw material and a dietary source. However, the metabolomic and genetic differences in specific germplasms of cassava storage root were unclear. In this study, two specific germplasms, M. esculenta Crantz cv. sugar cassava GPMS0991L and M. esculenta Crantz cv. pink cassava BRA117315, were used as research materials. Results showed that sugar cassava GPMS0991L was rich in glucose and fructose, whereas pink cassava BRA117315 was rich in starch and sucrose. Metabolomic and transcriptomic analysis indicated that sucrose and starch metabolism had significantly changing metabolites enrichment and the highest degree of differential expression genes, respectively. Sugar transport in storage roots may contribute to the activities of sugar, which will eventually be exported to transporters (SWEETs), such as (MeSWEET1a, MeSWEET2b, MeSWEET4, MeSWEET5, MeSWEET10b, and MeSWEET17c), which transport hexose to plant cells. The expression level of genes involved in starch biosynthesis and metabolism were altered, which may result in starch accumulation. These results provide a theoretical basis for sugar transport and starch accumulation and may be useful in improving the quality of tuberous crops and increasing yield.

The reactive oxygen species (ROS) signal regulates stress-induced leaf abscission in cassava. The relationship between the function of the cassava transcription factor bHLH gene and low temperature-induced leaf abscission is still unclear. Here, we report that MebHLH18, a transcription factor, involved in regulating low temperature-induced leaf abscission in cassava. The expression of the MebHLH18 gene was significantly related to low temperature-induced leaf abscission and POD level. Under low temperatures, the levels of ROS scavengers in different cassava genotypes were significantly different in the low temperature-induced leaf abscission process. Cassava gene transformation showed that MebHLH18 overexpression significantly decreased the low temperature-induced leaf abscission rate. Simultaneously, interference expression increased the rate of leaf abscission under the same conditions. ROS analysis showed a connection between the decrease in the low temperature-induced leaf abscission rate caused by MebHLH18 expression and the increase in antioxidant activity. A Genome-wide association studies analysis showed a relationship between the natural variation of the promoter region of MebHLH18 and low temperature-induced leaf abscission. Furthermore, studies showed that the change in MebHLH18 expression was caused by a single nucleotide polymorphism variation in the promoter region upstream of the gene. The high expression of MebHLH18 led to a significant increase in POD activity. The increased POD activity decreased the accumulation of ROS at low temperatures and the rate of leaf abscission. It indicates that the natural variation in the promoter region of MebHLH18 increases antioxidant levels under low temperatures and slows down low temperature-induced leaf abscission.