Home Latest Articles
Latest Articles
  • Jingyu ZHANG, Rui LI, Wei HU, Yahui LIU, Weinong YANG, Ning ZHANG
    Chinese Journal of Tropical Crops. 2026, 47(2): 391-404.

    Date palm (Phoenix dactylifera) is a key economic crop in arid and semi-arid regions, which possesses ecological functions of sand fixation and water conservation, economic value driven by deep processing, as well as profound religious and cultural significance. This paper reviews the research progress in its genetic breeding from the following aspects. In germplasm resources, core germplasm banks have been established by institutions such as King Faisal University of Saudi Arabia, the National Plant Gene Bank of Iran, and the Chinese Academy of Tropical Agricultural Sciences. The institutions preserve germplasm resources by combining technologies like smart irrigation and cryopreservation, while molecular marker technologies including SSR and SNP have been applied to reveal genetic differences among date palm varieties. In breeding methods, traditional selection and hybrid breeding have laid the foundation for date palm breeding. Modern biotechnologies such as high-throughput sequencing, somatic embryogenesis, and CRISPR/Cas9 have accelerated the process of precision breeding. The current core challenges in date palm breeding include difficulty in early sex identification due to dioecy, a complete growth cycle exceeding 10 years, highly heterozygous genome, and lagging molecular research. Future breeding efforts should focus on developing varieties resistant to abiotic stresses such as hot temperature, drought and salinity-alkalinity, preventing and controlling pests and diseases including red palm weevil, Fusarium spp., and leaf spot disease, and optimizing fruit yield and quality. Meanwhile, it is necessary to deepen research on genetic mechanisms, break through bottlenecks in gene editing technology, and strengthen international exchange and cooperation of germplasm resources, to promote the sustainable development of the global date palm industry.

  • Oluwole Gregory IJITI, Xiao LIANG, Ying LIU, Chunling WU, Xingkui AN, Changying NIU, Qing CHEN
    Chinese Journal of Tropical Crops. 2026, 47(2): 489-497.

    Tetranychus urticae is a significant pest on cassava. Long-term use of abamectin has led to prominent resistance issues. Selecting mite-resistant cassava varieties represents a green, effective and straightforward approach to pest control. However, the effectiveness of resistant cassava varieties against resistant mite strains remains unclear, limiting its utility in supporting resistance management decisions. Accordingly, this study used mite-resistant cassava cultivar C1115, mite-susceptible cassava cultivar SC205 and the preferred host plant cowpea as test materials to investigate the effects on the development, reproduction and detoxification metabolism capabilities of abamectin-resistant (AB-R) and abamectin-sensitive (AB-S) strains. Results showed that compared to feeding on cowpea, feeding on SC205 did not significantly alter the developmental duration or population growth parameters [net reproductive rate (R0), intrinsic rate of increase (rm), mean generation time (T), population doubling time (DT)] of either AB-R or AB-S strains. In contrast, feeding on C1115 significantly prolonged the developmental duration and inhibited population growth (significantly decreased R0 and rm, significantly increased T and DT) of both strains. Furthermore, on C1115, the T and DT of the AB-R strain were also significantly lower than those of the AB-S strain. Regarding detoxification enzyme activities, compared to feeding on cowpea, feeding on both SC205 and C1115 significantly increased the activities of three detoxification enzymes-cytochrome P450 monooxygenases (P450s), glutathione S-transferases (GSTs) and uridine diphosphate-glycosyltransferases (UGTs) - in both mite strains. Enzyme activities were significantly higher in mites feeding on C1115 compared to those on SC205. Additionally, on all three host plants, the enzyme activities of the AB-R strain were consistently significantly higher than those of the AB-S strain. Detoxification genes associated with abamectin resistance exhibited different expression patterns. Although feeding on both C1115 and SC205 significantly upregulated the expression of six tested genes in both mite strains compared to feeding on cowpea, differences emerged when comparing strains on the same cassava variety. When AB-R and AB-S fed on the same cassava cultivar (C1115 or SC205), the expression levels of CYP389C10, UGT201D3 and UGT11 showed no significant difference. However, the expression of CYP392A16, GSTd01 and GSTm09 was significantly higher in the AB-R strain than in the AB-S strain. The results indicate that the AB-R strain of T. urticae, likely due to its enhanced detoxification capacity, might possess an advantage in neutralizing toxic secondary metabolites from the mite-resistant cassava, potentially compromising the pest control efficacy of this resistant cultivar. This hypothesis, however, requires further validation through subsequent field experiments. This study provides a preliminary theoretical basis for evaluating the application potential of mite-resistant cassava in the management of mite resistance to acaricides.

  • Shihan ZENG, Sang SHANG, Libo TIAN, Feifan CHEN, Xuzhen LI
    Chinese Journal of Tropical Crops. 2026, 47(2): 444-458.

    Ten melon germplasm accessions were treated under simulated low-temperature and weak-light conditions in this study to establish an efficient identification system for low-temperature and weak-light tolerance of melon (Cucumis melo L.) germplasm at the seedling stage. The relative changes in 8 growth indicators (including plant height, stem diameter, leaf area, etc.) and 10 physiological indicators (including chlorophyll content, root activity, relative electrical conductivity, etc.) were determined, and the damage indexs were calculated to initially evaluate the low-temperature and weak-light tolerance of each germplasm. Based on the membership function method in fuzzy mathematics, 19 identification indicators were standardized. Dimensionality reduction was performed via principal component analysis (PCA), and 5 principal components with strong correlations to the low-temperature and weak-light tolerance index, peroxidase (POD) activity, root length, root activity, and soluble protein content were extracted (cumulative contribution rate: 87.026%). Cluster analysis was conducted on the 10 melon germplasm accessions, which were classified into three groups. Group Ⅰ including Vedrantais and M18, was classified as strong low-temperature and weak-light tolerant. Group Ⅱ includding IranH, Topmark, M4 and Nantais oblong, was classified as moderate low-temperature and weak-light tolerant. Group Ⅲ including PI124111, MR1, M76 and PMR5, was classified as weak low-temperature and weak-light tolerant. Finally, stepwise linear regression was used to establish a prediction model for low-temperature and weak-light tolerance of melon at the seedling stage, D=-0.058+0.008X15+0.442X9+0.058X1-0.017X19 (R2=0.998, P<0.001), X15 is proline content; X9 is root length; X1 is low temperature and low light tolerance index; X19 is peroxidase activity. To verify the reliability of the above identification results, the expression patterns of CmADF1 and CmCYP195 (key genes responding to low-temperature and weak-light stress) were analyzed in germplasm accessions M4, PI124111 and PMR5 at different time points after low-temperature and weak-light treatment. The results showed that the expression characteristics of CmADF1 and CmCYP195 were consistent with the identified low-temperature and weak-light tolerance types of the germplasm, which further confirmed the reliability of the identification system. The results could serve as identification criteria for evaluating low-temperature and weak-light tolerance of different melon germplasm accessions and provide breeding materials for subsequent improvement of melon varieties with low-temperature and weak-light tolerance.

  • Yiying WANG, Xinyu WU, Junqin ZHOU, Jun YUAN, Zhusan ZHANG, Shufen HE, Xian TANG
    Chinese Journal of Tropical Crops. 2026, 47(2): 325-335.

    Plant annexin is a conserved calcium-dependent phospholipid binding protein involved in plant growth, development and stress resistance. The sequence characteristics and expression patterns of the ANX gene family in C. oleifera remain unclear. For this reason, the present study aims to investigate the expression regulatory mechanisms of this gene family in the stress resistance responses of C. oleifera. Three ANX genes were identified from the whole genome of C. oleifera, and the physical and chemical characteristics, evolutionary relationship, gene structure, conserved sequence, chromosome location, expression level in different tissues and the content of annexin under drought stress were analyzed in the study. Phylogenetic analysis showed that 15 different families were clustered into 5 groups, among which CsANX and CoANX1/2 from Camellia were clustered into a large branch with similar motif patterns. Many cis-elements involved in light response and plant hormone response were identified in the promoter region of CoANX. Chromosome localization showed that the three CoANX genes were distributed on three chromosomes (A_chr 09/13/14) of C. oleifera. The expression pattern analysis showed that CoANX showed tissue-specific patterns in different growth stages and tissues. In addition, stress analysis showed that CoANX3 showed a high expression trend under drought conditions, while the expression of CoANX3 in the treatment group sprayed with brassinolide decreased. Under phosphorus and aluminum stress, the expression of ANX in C. oleifera increased significantly. The above results indicate that CoANX may play a key role in the stress resistance of C. oleifera. This study would lay a foundation for elucidating the molecular mechanism of ANXs in regulating the biological processes of plant growth and development.

  • Jiangmin YU, Jitao YAO, Fanya MENG, Yubo LI, Gangqiang DONG, Yaqi ZHAO, Can WANG
    Chinese Journal of Tropical Crops. 2026, 47(2): 433-443.

    The study was aimed to solve the problems of relatively extensive cultivation and low soil quality of Pandanus amaryllifolius that restrict the improvement of yield and quality. Different ratios of biochar combined with mushroom residue were used to improve the soil, clarify its yield-increasing effect and mechanism, and to provide technical support for efficient cultivation of Pandanus. Under basic fertilization, four treatments were set up, 800 kg/hm2 mushroom residue (MD), 800 kg/hm2 mushroom residue + 1600 kg/hm2 biochar (MDB1), 800 kg/hm2 mushroom residue +3200 kg/hm2 biochar (MDB2), and no mushroom residue or biochar added (CK). A field plot experiment was conducted to study the effects of different treatments on plant growth and yield, soil physicochemical properties and microbial community structure of Pandanus. Compared with CK, the yield increase effect of mushroom residue alone (MD) did not reach a significant level, while the biochar combined application treatments (MDB1, MDB2) significantly increased the fresh leaf yield of P. amaryllifolius. This was related to the significant increase in leaf SPAD value and net photosynthetic rate of MDB1 and MDB2, which significantly increased the average fresh leaf weight, but there was no significant difference in yield between MDB1 and MDB2 treatments. Soil nutrient results showed that compared with CK, MD, MDB1 and MDB2 all significantly increased soil pH and available potassium content, but MD treatment significantly reduced soil organic matter, alkali-hydrolyzable nitrogen and available phosphorus content, which may be related to the utilization of soil organic matter by a large number of organic matter-decomposing microorganisms in the mushroom residue leading to nutrient consumption, while the combined application of high-dose biochar (MDB2) alleviated this effect, thus increasing organic matter content and alkali-hydrolyzable nitrogen content. PCA analysis based on soil bacterial OTUs found that there were significant differences in community structure among different treatments. Compared with CK, MD soil bacterial Shannon diversity index decreased and Simpson dominance index increased, while MDB1 and MDB2 significantly improved soil bacterial diversity. Compared with MD, they significantly increased beneficial plant growth-promoting bacteria such as Pedomicrobium, Streptomyces, MND1, Nocardioides and Pseudomonas. RDA analysis showed that soil alkali-hydrolyzable nitrogen was the main environmental factor affecting bacterial community structure. In summary, although mushroom residue application alone has yield-increasing potential, its effect on soil improvement is poor; combined application of biochar can significantly increase soil pH, available potassium content, improve soil microbial diversity, promote the enrichment of beneficial microorganisms, thereby increasing leaf chlorophyll content, enhancing leaf photosynthesis, and ultimately promoting a significant increase in P. amaryllifolius yield. Therefore, the synergistic application of biochar and mushroom residue is an efficient and safe soil improvement strategy, providing green and sustainable technical support for efficient cultivation of Pandanus.

  • Kexin XU, Xulei YANG, Manti LI, Lekang WU, Yubo HUANG, Wenli HE, Taoli LIU, Yanning TAN
    Chinese Journal of Tropical Crops. 2026, 47(2): 459-466.

    The regulatory effects of exogenous homogentisic acid (HGA) on plant growth, anthocyanin synthesis, and the antioxidant system at phenotypic, physiological and gene expression levels using one-leaf seedlings of Wushansimiao (R534) were studied to explore the role of HGA in rice salt stress response. The results showed that under 140 mmol/L NaCl stress and treatment with 0.25 mmol/L HGA significantly improved the salt tolerance of rice seedlings. On the 3rd day after treatment, plant height, root length, fresh weight and dry weight increased by 43.95%, 60.00%, 41.86% and 76.38%, respectively, compared to the control without HGA. After 7 days of treatment and 7 days of rewatering, the survival rate of seedlings increased by 56.69%. RT-qPCR analysis revealed that HGA significantly upregulated the key genes involved in anthocyanin biosynthesis in leaves, including OsPAL3, OsCHS8, OsCHI, OsF3H, OsDFR6, OsANS1 and OsUF3GT. Anthocyanin content increased by 15.18%, 24.58% and 39.56% on the 3rd, 5th and 7th day, respectively. On the 3rd day, the accumulation of reactive oxygen species (H2O2 and ) and malondialdehyde (MDA) content decreased, while the activities of antioxidant enzymes SOD, POD and CAT significantly increased. This study preliminarily clarified that HGA could activate the anthocyanin biosynthesis pathway under salt stress to enhance antioxidant capacity, laying a foundation for further understanding the physiological role of HGA.

  • Shidong LI, Shuren GAO, Fulai YU, Yiming FANG, Qian JIANG, Lingliang GUAN, Songbi CHEN
    Chinese Journal of Tropical Crops. 2026, 47(2): 350-363.

    Ocimum gratissimum is widely utilized due to its significant medicinal and culinary value. However, substantial variations in volatile components and medicinal metabolite content exist among different germplasms, influenced by geographical origin, cultivation conditions, and environmental factors. The variations directly impact the stability of pharmacological efficacy and industrial-scale production. To address this, the present study employed an integrated metabolomics and transcriptomics approach to systematically investigate the aroma profiles, metabolite composition, and regulatory mechanisms of two distinct O. gratissimum germplasms (G096 and G134). Sensory evaluation confirmed that both accessions exhibited a characteristic clove-like aroma. Metabolomic analysis identified 1094 volatile metabolites, with 784 showing significant differential accumulation between the two germplasms. Correlation analysis between differential metabolites and sensory attributes revealed that eugenol was the key metabolite responsible for the distinctive flavor of O. gratissimum. Transcriptomic profiling identified 54 936 differentially expressed genes (DEGs), including 27 220 upregulated and 27 716 downregulated genes. Through metabolic pathway prediction, a biosynthetic pathway for eugenol in O. gratissimum was constructed, identifying PAL, C4H, 4CL, HCT and C3'H as critical regulatory genes governing eugenol biosynthesis. This study would not only elucidate the biosynthetic mechanism of the primary flavor compounds in O. gratissimum, but also provide a crucial molecular theoretical foundation for quality improvement and standardized production. The findings would hold significant scientific and practical value for advancing the industrial development of O. gratissimum.

  • Xi'ao WANG, Zhenyang LIAO, Na AN, Lisong HU, Lifang HUANG, Xinchuan ZHAO, Wenyan XIONG, Yongqing PANG, Yunlei WANG, Xiaoyang WANG, William Solano SANCHEZ, Lin YAN
    Chinese Journal of Tropical Crops. 2026, 47(2): 302-312.

    S-adenosylmethionine synthase (SAMS) is a key enzyme catalyzing the synthesis of S-adenosylmethionine (SAM, S-adenosylmethionine), widely involved in various biological processes in plants, such as epigenetic regulation, oxidative stress, and growth and development. In this study, the full-length cDNA sequence of CaSAMS3 was successfully cloned from coffee, and the physicochemical properties, protein structure, conserved domains, and evolutionary characteristics of the encoded CaSAMS3 protein were analyzed. Through cis-acting element analysis and protein interaction network prediction, and the metabolic processes involving CaSAMS3 were explored, and its expression pattern was analyzed in combination with qPCR and subcellular localization studies. The results showed that the open reading frame length of CaSAMS3 was 1173 bp, encoding a hydrophilic protein (molecular weight 42.57 kDa, theoretical isoelectric point 6.07), with a secondary structure mainly composed of α- helices and irregular curls, and located on cell membrane and nucleus. The protein contained a typical SAMS conserved domain and had the highest homology with SAMS in kiwifruit. Its promoter contained response elements related to light, hormones, stress, and growth and development, including MYB and MYC binding sites. CaSAMS3 exhibited tissue-specific expression, and its expression trend during developmental stages was consistent with accumulation pattern of caffeine. This study would provide an important theoretical basis for elucidating the biological function of CaSAMS3 in the regulation of caffeine synthesis, and provides a potential target for improving coffee quality and resistance.

  • Mengyuan WANG, Ke CHENG, Lan YANG, Huiping ZHAO
    Chinese Journal of Tropical Crops. 2026, 47(2): 364-371.

    Flg22 is an artificially synthesized 22-amino-acid peptide derived from the conserved N-terminal region of bacterial flagellin, playing a crucial role in regulating plant immune responses. Due to the high cost of artificially synthesized flg22 short peptides and limitations for large-scale application, this study aimed to determine the suitable conditions for prokaryotic induction expression of the flg22 protein and to verify its function, thereby determining whether it could replace the commercially used flg22 short peptides. In this study, the pET32a-flg22 prokaryotic expression vector was synthesized, and we then compared protein expression efficiency under induction at 28 ℃ and 37 ℃. Additionally, we detected the dynamic burst of reactive oxygen species (ROS) in cassava treated with flg22 peptides and flg22 proteins at different concentrations to validate the functions. The results indicated that 28 ℃ was the optimal induction temperature for inducing flg22 protein expression. ROS measurements showed that within a specific concentration range, the peak intensity of ROS increased with the increase in flg22 protein concentration. Furthermore, after spraying cassava leaves with 60 μg/mL and 600 μg/mL of flg22 recombinant proteins, as well as 2.27 μg/mL of flg22 peptides, for three days, we inoculated plants with the pathogen Xam (Xanthomonas axonopodis pv. manihotis, Xam). Compared to treatment with sterile water, both flg22 protein and flg22 peptide treatments showed significant antibacterial effects against Xam in cassava plants, with the 60 μg/mL and 600 μg/mL flg22 protein treatments showing notably stronger antibacterial activity than the flg22 peptide. The results preliminarily identified the prokaryotic expression conditions of flg22 recombinant protein and verified that its function in inducing plant defense responses is consistent with that of the peptide, providing a theoretical basis for substituting commercial peptides with flg22 recombinant protein.

  • Chun WANG, Zhenzhen YU, Hongxuan WANG, Hailiang LI, Haitian SUN, Yunlong ZHAO
    Chinese Journal of Tropical Crops. 2026, 47(2): 417-432.

    To identify periods of oxygen deficiency in the root zone of pineapples, understand the mechanisms of oxygen changes, and provide sufficient response time for oxygen-enriching irrigation technology management and soil regulation to address abnormal fluctuations in oxygen content in the root zone, this study utilized a soil oxygen diffusion-consumption coupling mechanism constructed based on the Monte Carlo method. In model construction, the study fully considered soil oxygen diffusion, root respiration, and microbial oxygen consumption processes. Using parameter perturbation and uncertainty sampling, the model incorporated measured boundary conditions and depth-stratified initial concentration settings. Combined with multi-layer soil profile monitoring data, the model established a simulation system for oxygen content changes at depths of 10-40 cm in three typical soil types (loam, sandy soil, and clay). Finally, the model was validated using field trial data from spring 2025. The results showed that the model demonstrated strong predictive capability under various soil and depth conditions (R2>0.95, with the lowest RMSE of 0.214 mol/m3). The error distribution fluctuated slightly with increasing depth but remained within an acceptable range overall. Further analysis revealed that the model successfully identified periods prone to oxygen deficiency within 3-12 hours after irrigation or rainfall events. In oxygen deficiency identification, the model achieved over 90% accuracy in determining responses below the critical concentration (1.5 mol/m3). The above results validate the effectiveness of the constructed model in simulating root zone oxygen dynamics and providing risk warnings, aiming to provide a theoretical basis and predictive foundation for intelligent oxygen management in pineapple fields.