Genome-wide characterization of heavy metal-associated isoprenylated plant protein gene family from Citrus sinensis in response to huanglongbing.

Introduction: Heavy metal-associated isoprenylated plant proteins (HIPPs) play vital roles in maintaining heavy metal balance and responding to both biotic and abiotic stresses in vascular plants. However, the role of HIPPs in the response to Huanglongbing (HLB), a harmful disease of citrus caused by the phloem-colonizing bacterium Candidatus Liberibacter asiaticus (CLas), has not been examined. Methods and results: In this study, a total of 26 HIPP genes were identified in Citrus sinensis, and they were grouped into 5 clades. The CsHIPP genes are distributed on 8 chromosomes and exhibited considerable synteny with HIPPs found in Arabidopsis thaliana. Additionally, we analyzed the gene structure, conserved motifs and domains of the CsHIPPs. Various cis-acting elements related to plant hormones and stress responses were identified in the promoters of CsHIPPs. Public transcriptome data and RT-qPCR analysis showed that the expression level of CsHIPP03 was significantly reduced in samples infected by CLas and Xanthomonas citri ssp. citri (Xcc). Furthermore, silencing the homologous gene of CsHIPP03 in Nicotiana benthamiana increased the disease resistance of plants to bacteria. Discussion: Our results provide a basis for functional studies of HIPP gene family in C. sinensis, highlighting their functions in bacterial resistance, and improve our understanding to the susceptibility mechanism of HLB.

Transcriptome analysis of Citrus sinensis reveals potential responsive events triggered by Candidatus Liberibacter asiaticus.

Citrus Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus (CLas), is a devastating immune-mediated disorder that has a detrimental effect on the citrus industry, with the distinguishing feature being an eruption of reactive oxygen species (ROS). This study explored the alterations in antioxidant enzyme activity, transcriptome, and RNA editing events of organelles in C. sinensis during CLas infection. Results indicated that there were fluctuations in the performance of antioxidant enzymes, such as ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), peroxidase (POD), and superoxide dismutase (SOD), in plants affected by HLB. Transcriptome analysis revealed 3604 genes with altered expression patterns between CLas-infected and healthy samples, including those associated with photosynthesis, biotic interactions, and phytohormones. Samples infected with CLas showed a decrease in the expression of most genes associated with photosynthesis and gibberellin metabolism. It was discovered that RNA editing frequency and the expression level of various genes in the chloroplast and mitochondrion genomes were affected by CLas infection. Our findings provide insights into the inhibition of photosynthesis, gibberellin metabolism, and antioxidant enzymes during CLas infection in C. sinensis.

An Ultra-Micro-Volume Adhesive Transfer Method and Its Application in fL-pL-Level Adhesive Distribution.

This study is aimed at addressing the urgent demand for ultra-micro-precision dispensing technology in high-performance micro- and nanometer encapsulation, connection, and assembly manufacturing, considering the great influence of colloid viscosity and surface tension on the dispensing process in micro- and nanometer scale. According to the principle of liquid transfer, a method of adhesive transfer that can realize fL-pL levels is studied in this paper. A mathematical model describing the initial droplet volume and the transfer droplet volume was established, and the factors affecting the transfer process of adhesive were analyzed by the model. The theoretical model of the transfer droplet volume was verified by a 3D scanning method. The relationships between the transfer droplet volume and the initial droplet volume, stay time, initial distance, and stretching speed were systematically analyzed by a single-factor experiment, and the adhesive transfer rate was calculated. Combined with trajectory planning, continuous automatic dispensing experiments with different patterns were developed, and the problems of the transfer droplet size, appearance quality, and position accuracy were analyzed comprehensively. The results show that the average relative deviation of the transfer droplet lattice position obtained by the dispensing method in this paper was 6.2%. The minimum radius of the transfer droplet was 11.7 µm, and the minimum volume of the transfer droplet was 573.3 fL. Furthermore, microporous encapsulation was realized using the method of ultra-micro-dispensing.