First Report of 16SrII Group Related Phytoplasma Associated with Witches'-broom Disease on Cowpea (Vigna unguiculata) in Hainan Province, China.

Cowpea (Vigna unguiculata L.), a significant vegetable crop in China, holds particular prominence in the tropical island of Hainan. This region serves as the primary production area for the winter cultivation of cowpea. Phytoplasmas are an idiopathic parasitic pathogen and cannot be cultured in vitro. It is mainly transmitted by the insect vectors with the piercing and sucking mouthparts, such as leafhoppers, plant hoppers, and psyllids. (Kumari et al. 2019). On September 11, 2023, typical characteristics of phytoplasma diseases on cowpeas were observed in the experimental base of Hainan Academy of Agricultural Sciences (20°0'38.6964″N, 110°21'35.4024″E, Haikou City, Hainan Province, China), including reduced leaf size, chlorosis, and the development of broom-like branch deformities reminiscent, as depicted in Figure 1. At the same time, we found a large number of leafhoppers near the diseased plants, and we speculated that leafhoppers are the insect carriers that spread the disease. Following an on-site investigation, it was determined that the disease incidence ranges from 10% to 15%, leading to a consequential decrease of about 10% in yield, which is a potential disease that seriously threatens the cowpea industry in Hainan. Ten disease and healthy samples were meticulously collected and subsequently preserved at -80°C within the laboratory refrigerator. Three disease samples denoted as HNNKY-1, HNNKY-2, and HNNKY-3, were randomly chosen, and total DNA extraction was carried out employing the NuClean Plant Genomic DNA Kit (CWBIO, Taizhou, China), while three healthy samples were randomly selected as control. The 16S rRNA gene was amplified by PCR using the primer pairs P1/P7 (Schneider et al. 1995) and R16F2n / R16R2 (Lee et al. 1993) and the secA gene was amplified by PCR using the primer pairs secAfor1/secArev3 (Hodgetts et al. 2008). After agarose gel electrophoresis analysis, no DNA fragments were observed in the healthy leaf samples, whereas all three disease samples yielded amplification products. The PCR products were subsequently sequenced by Hainan Nanshan Biotech Co., Ltd., Haikou, China. After sequence analysis, it was found that the 16S rRNA gene and secA gene sequences HNNKY-1, HNNKY-2, and HNNKY-3 were identical to each other. We selected two gene sequences of strain HNNKY-3 to submission to the GenBank database, The length of the 16S rRNA gene sequence is 1193 base pairs, identified by the accession number OR666421, while the secA gene sequence is 825 base pairs in length, associated with the accession number OR661282. The phytoplasma strain HNNKY-3 was named 'Vigna unguiculata' witches'-broom phytoplasma. A BLAST analysis of the 16S rRNA gene revealed that strain HNNKY-3 displayed a 100% sequence match with 'Emilia sonchifolia' witches'-broom phytoplasma (MT420682), Peanut witches'-broom phytoplasma (OR239773), and 'Raphanus sativus' witches'-broom phytoplasma (OK491387). All of these phytoplasmas were classified within the 16SrII group. Based on the BLAST analysis of partial secA gene sequences, it was discerned that sequence homogeneity ranged from 99.27% to 99.74% among the studied sequences. These sequences were collectively classified as members of the 16SrII group. In addition, a phylogenetic tree was constructed by MEGA 11 (version 11.0.13) based on the 16Sr RNA gene and secA gene by the neighbor-joining method (Tamura et al. 2004). The results demonstrated the clustering of HNNKY-3 phytoplasma strains within the 16SrII group, as illustrated in Figures 2 and 3. A virtual RFLP analysis based on the 16S rRNA gene fragment of HNNKY-3 was conducted using the interactive online phytoplasma classification tool, iPhyClassifier (Zhao et al. 2009). The results indicated that the phytoplasma strain was the same as the reference pattern of the onion yellows phytoplasma of 16SrII-A (GenBank accession: L33765), and the similarity coefficient was 1.00. To best of our knowledge, this is the inaugural documentation of 16SrII Group-related phytoplasma infecting cowpea in Hainan, China, and lays the groundwork for further research on the dissemination of cowpea phytoplasma disease within China.

Utilization of current pyrolysis technology to convert biomass and manure waste into biochar for soil remediation: A review.

Traditional disposal of animal manures and lignocellulosic biomass is restricted by its inefficiency and sluggishness. To advance the carbon management and greenhouse gas mitigation, this review scrutinizes the effect of pyrolysis in promoting the sustainable biomass and manure disposal as well as stimulating the biochar industry development. This review has examined the advancement of pyrolysis of animal manure (AM) and lignocellulosic biomass (LB) in terms of efficiency, cost-effectiveness, and operability. In particular, the applicability of pyrolysis biochar in enhancing the crops yields via soil remediation is highlighted. Through pyrolysis, the heavy metals of animal manures are fixated in the biochar, thereby both soil contamination via leaching and heavy metal uptake by crops are minimized. Pyrolysis biochar is potentially use in soil remediation for agronomic and environmental co-benefits. Fast pyrolysis assures high bio-oil yield and revenue with better return on investment whereas slow pyrolysis has low revenue despite its minimum investment cost because of relatively low selling price of biochar. For future commercialization, both continuous reactors and catalysis can be integrated to pyrolysis to ameliorate the efficiency and economic value of pyrolysis biochar.

A perspective on the interaction between biochar and soil microbes: A way to regain soil eminence.

Soil ecosystem imparts a fundamental role in the growth and survival of the living creatures. The interaction between living and non-living constituents of the environment is important for the regulation of life in the ecosystem. Biochar is a carbon rich product present in the soil that is responsible for various applications in diversified fields. In this review, we focused on the collaboration between the soil, biochar and microbial community present in the soil and consequences of it in the ecosystem. Herein, it primarily discusses on the different approaches of the production and characterization of biochar. Furthermore, this review also discusses about the optimistic interaction of biochar with soil microbes and their role in plant growth. Eventually, it reveals the various physio-chemical properties of biochar, including its specific surface area, porous nature, ion exchange capacity, and pH, which aid in the modification of the soil environment. Furthermore, it elaborately discloses the impact of the biochar addition in the soil focusing mainly on its interaction with microbial communities such as bacteria and fungi. The physicochemical properties of biochar significantly interact with microbes and improve the beneficial microbes growth and increase soil nutrients, which resulting reasonable plant growth. The main focus remains on the role of biochar-soil microbiota in remediation of pollutants, soil amendment and inhibition of pathogenicity among plants by promoting resistance potential. It highlights the fact that adding biochar to soil modulates the soil microbial community by increasing soil fertility, paving the way for its use in farming, and pollutant removal.

Transcriptome Analysis of Colletotrichum fructicola Infecting Camellia oleifera Indicates That Two Distinct Geographical Fungi Groups Have Different Destructive Proliferation Capacities Related to Purine Metabolism.

Anthracnose, caused by Colletotrichum spp., is a significant disease affecting oil tea (Camellia oleifera Abel.). Extensive molecular studies have demonstrated that Colletotrichum fructicola is the dominant pathogen of oil tea anthracnose in China. This study aims to investigate differences in molecular processes and regulatory genes at a late stage of infection of C. fructicola, to aid in understanding differences in pathogenic mechanisms of C. fructicola of different geographic populations. We compared the pathogenicity of C. fructicola from different populations (Wuzhishan, Hainan province, and Shaoyang, Hunan province) and gene expression of representative strains of the two populations before and after inoculation in oil tea using RNA sequencing. The results revealed that C. fructicola from Wuzhishan has a more vital ability to impact oil tea leaf tissue. Following infection with oil tea leaves, up-regulated genes in the strains from two geographic populations were associated with galactosidase activity, glutamine family amino acid metabolism, arginine, and proline metabolism. Additionally, up-regulated gene lists associated with infection by Wuzhishan strains were significantly enriched in purine metabolism pathways, while Shaoyang strains were not. These results indicate that more transcriptional and translational activity and the greater regulation of the purine metabolism pathway in the C. fructicola of the Wuzhishan strain might contribute to its stronger pathogenicity.