CIP elicitors on the defense response of A. macrocephala and its related gene expression analysis

AmCERK1 and AmLYK3 interaction mediates CIP-induced defense responses in A. macrocephala

Southern blight caused by Sclerotium rolfsii (S. rolfsii) represents a significant threat to the medicinal plant Atractylodes macrocephala Koidz. (A. macrocephala), with effective control measures remaining limited. Chrysanthemum indicum polysaccharides (CIP) have been identified as an elicitor capable of inducing defense responses in A. macrocephala against S. rolfsii infection. However, the molecular mechanisms underlying CIP recognition remain poorly understood. In this study, comparative transcriptome analysis revealed two potential LysM-receptor kinases, AmCERK1 and AmLYK3, as candidate receptors for CIP recognition. These genes, which are orthologous to Arabidopsis CERK1 and Medicago truncatula LYK3, exhibited significant up-regulation upon CIP treatment. Bimolecular fluorescence complementation (BiFC) assays demonstrated that AmCERK1 and AmLYK3 interact in a CIP-dependent manner. Transient overexpression experiments further confirmed that CIP treatment markedly enhanced the expression of these receptor genes. Virus-induced gene silencing (VIGS) assays indicated that CIP treatment could partially compensate for the suppression of AmCERK1 and AmLYK3, highlighting their critical role in CIP-induced defense responses. Collectively, these findings suggest that AmCERK1 and AmLYK3 form a pattern recognition receptor (PRR) complex essential for CIP perception, potentially facilitating pattern-triggered immunity (PTI) in A. macrocephala. These findings reveal a novel receptor recognition complex comprising AmCERK1 and AmLYK3, offering crucial insights into the mechanisms of innate immune recognition in plants.

Extraction methods, structural features and bioactivity diversity of polysaccharides from the genus Chrysanthemum: A review

The genus Chrysanthemum has been widely used as both folk medicine and food in East Asia for thousands of years, serving as a significant source of nutritional and pharmacological value. According to the theory of traditional Chinese medicine, it clears heat and toxic materials and regulates liver function. Accumulating evidence has demonstrated that polysaccharides from the genus Chrysanthemum, especially Chrysanthemum morifolium, Chrysanthemum indicum, and Coreopsis tinctoria, are vital representative macromolecules with diverse biological activities, including antioxidant, immunomodulatory, anti-inflammatory, hypoglycemic, antitumor, and antiviral properties as well as the ability to regulate the gut microbiota. It is well-known that different extraction and purification methods may cause differences in the primary structures of chrysanthemum polysaccharides (CPs), which in turn lead to different polysaccharide biological activities. However, the lack of a review summarizing the recent advances in CPs may have hindered their development and utilization. The present review aims to review information on the extraction and purification, structural characterization, biological functions, toxicity, and applications of CPs. In addition, this review may deepen our understanding of CPs, and offers a theoretical basis for the further development of CPs into functional foods and therapeutic agents.

Evaluation of inducing activity of CIP elicitors from diverse sources based on monosaccharide composition and physiological indicators

Application of elicitors can greatly enhance plant immune resistance against pathogens. However, it is still obscure whether elicitor activity is influenced by diverse sources. This study investigated the effect of foliar spraying of 19 batches of Chrysanthemum indicum polysaccharides (CIPs) on the disease resistance of Atractylodes macrocephala Koidz. (A. macrocephala) and explored the main reasons for the differences of inducing activity of CIP elicitors. PCA, OPLS-DA, grey relational analysis and entropy weight method had good predictability for the activity evaluation of CIP elicitors and other plant-derived elicitors. The results showed that 19 batches of CIPs had definite regional differences in inducing activity and monosaccharide content. CIP elicitors with high inducing activity could significantly increase the accumulation of Atractylenolide Ⅱ and Atractylenolide Ⅲ, the mRNA relative transcription level of CAT, POD, PAL genes, the amount of pH change in the medium and effectively reduce the disease index of A. macrocephala. Furthermore, CIP with high inducing activity exhibited the high contents of Rha, Ara and GalA, which might be the main contributor to their high activity. The evaluation procedure developed in this work can be applied for screening CIP elicitors with high inducing activity, and it lays a foundation for identifying more functional elicitors related to plant immune resistance.

Structural characterization and evaluation the elicitors activity of polysaccharides from Chrysanthemum indicum

This research evaluates the elicitors activity and structure characterization of four Chrysanthemum indicum polysaccharides (CIPs) which were isolated from C. indicum, obtained CIP1, CIP2, CIP3, CIP4. Results demonstrated that there was a distinct difference in inducibility and CIP3 was significantly stronger than other CIPs through bioactivity-tests. Taking CIP3 with total carbohydrate content 91.93 % as a representative, its structure was elucidated as a relative molecular weight of 8. 741 × 10³ g/mol and mainly composed of xylose, galacturonic acid, galactose and glucuronic acid. Through GC, IR and NMR, CIP3 was determined to possess a backbone comprised of T-α-d-GalpA, 1,4-α-d-GlcpA, 1,2-α-d-Xylp, 1,3-α-l-Rhap, 1,2,4-α-l-Rhap and sidechains comprised of 1,3-β-d-Galp, 1,6-α-d-Galp, T-α-Glcp, 1,3-β-d-Glcp, 1,4-α-d-Glcp, 1,3,4-α-d-Manp, T-α-l-Fucp. Further results indicated that CIP3 with active sidechains could significantly increase the expression of defense genes in Atractylodes macrocephala Koidz (AM). It is believed that the sidechains of CIP3 were necessary to its elicitor activity via bioactivity tests.

Heat-killed endophytic bacterium induces robust plant defense responses against important pathogens

Stress caused by pathogens strongly damages plants. Developing products to control plant disease is an important challenge in sustainable agriculture. In this study, a heat-killed endophytic bacterium (HKEB), Bacillus aryabhattai, is used to induce plant defense against fungal and bacterial pathogens, and the main defense pathways used by the HKEB to activate plant defense are revealed. The HKEB induced high protection against different pathogens through the salicylic and jasmonic acid pathways. We report the presence of gentisic acid in the HKEB for the first time. These results show that HKEBs may be a useful tool for the management of plant diseases.