DETEKSI Liberibacter spp. PADA JERUK SIAM BERGEJALA KLOROSIS DISERTAI BERCAK HITAM DENGAN Polymerase Chain Reaction

Liberibacter bacteria are one of the pathogenic bacteria in citrus plants. Siam Citrus Plant in Setapok Village, Singkawang City, suspected to be infected with Liberibacter spp. bacteria by showing patterns of symptoms of chlorosis accompanied by patches. This study aims to detect Liberibacter spp. on Siam Citrus leaves with symptomatic chlorosis with patches. Leaf sampling uses the roaming method in one of the citrus plantations in Setapok Village, Singkawang City. Detection of Liberibacter spp. done by PCR (Polymerase Chain Reaction) technique. Detection of bacterial DNA through several stages namely, isolation of bacterial plasmid DNA, 16S rDNA gene amplification with a thermocycler machine, and visualization using a set of electrophoresis devices. Electrophoresis results show the presence of DNA band lines, with a size of around 1100 bp for OI1 and OI2c primers, and DNA bands of 703 bp for A2 and J5 specifics. The results showed that there were Liberibacter spp. in the symptomatic chlorosis of Siam Citrus leaves accompanied by patches

Detection of Citrus Greening Using Microscopic Imaging

Citrus greening reduces fruit production and quality and will likely result in rapid tree decline and death. Because citrus greening symptoms are usually observed on the leaf surface, detection of citrus greening leaf symptoms can significantly aid in scouting for infected trees and managing the disease, thus reducing its spread and minimizing losses for citrus growers. This article presents the microscopic image analysis using color co-occurrence method to differentiate citrus leaves with eight conditions: greening blotchy mottle, green islands, iron deficiency, manganese deficiency, zinc deficiency, young flush leaves and normal mature leaves. Thirty-nine statistical features were extracted from transformed hue (H), saturation (S), and intensity (I) images using the color co-occurrence method for each leaf sample. The number of extracted texture features was reduced by a stepwise discriminant analysis. A discriminant function based on a measure of the generalized squared distance was used for classification. Three classification models were performed using (1) all leaf conditions, (2) all conditions except young flush leaves and (3) all conditions except young flush leaves and blotchy mottle. The three classification models obtained accuracies of 86.67 %, 95.60 % and 97.33 %, respectively. The overall performance was demonstrated in a confusion matrix. The model HSI_14, which used all conditions except young flush and blotchy mottle, resulted in the best accuracy for positive (96.67 %) and negative (97.5 %) symptoms

EXPLORATION OF CHEMICAL AND BIOLOGICAL MANAGEMENT STRATEGIES FOR DIAPHORINA CITRI THE PRIMARY VECTOR OF CANDIDATUS LIBERIBACTER ASIATICUS

Diaphorina citri (Hemipteran: Psyllidae), the Asian citrus psyllid, is a phloem-feeding, invasive species endemic to southern Asia that was first identified in the United States in Florida in 1998. Since introduction, D. citri has spread across the major citrus growing regions of the United States. This is of great concern to the citrus industry because D. citri is the primary vector of Candidatus Liberibacter asiaticus the causal agent of Haunglongbing (HLB). Haunglongbing is the most economically devastating disease of citrus causing an estimated 8.92 billion dollars lost in revenue and 4.62 billion dollars lost in gross domestic product between 2006-2007 in Florida alone (Hodges and Spreen, 2012). Current management strategies have had some effect on the spread of Candidatus Liberibacter asiaticus; however, due to concerns about insecticide resistance and the effect on non-target organisms, new pest management strategies need to be considered. Most of the current insecticides used to treat psyllids are neuromuscular toxins which affect the nervous system and muscles. Cyclaniliprole is an anthranilic diamide that acts on the endoplasmic reticulum’s ryanodine receptor in insects. When D. citri were exposed to citrus leaf substrate containing cyclaniliprole significant mortality was observed. Flonicamid is an antifeedent currently used on sap feeding insects like aphids. D. citri exposed to leaves treated with flonicamid had an alteration in feeding behavior. Flonicamid also has very low toxicity to humans. Possible biological management strategies were also considered. Paratransgenesis is a strategy that attempts to remove a pathogens transmission ability from a vector by transforming a symbiont of the vector that would produce a protein that is toxic to the pathogen. In this case, the paratransgeneic model would be to remove Candidatus Liberibacter asiaticus from D. citri using an alimentary associated bacterium isolated from D. citri an alimentary canal associated bacterium that was isolated from D. citri. This bacterium was identified as Enterobacter cloacae and the bacterium and associated plasmid were annotated for use in a future paratransgeneic management strategy for D. citri

Impact of factors contributing to internal disorders of mango (Mangifera indica L.) fruit—A systematic literature review

The expression of internal disorders is a complex phenomenon due to the interaction of genotype, environment, and management practices at the pre-harvest, harvest, and post-harvest stages. This study aims to provide a comprehensive overview of factors associated with, and have been investigated in relation to, the susceptibility and expression of internal disorders in mango. In this context, a systematic literature review was conducted to identify, extract, and analyse the most pertinent data. Six hundred and fifty-seven studies were sourced from three databases. Of these, 72 were relevant after screening based on exclusion-inclusion criteria. An additional nine relevant studies were identified through manual searches and included in the final data synthesis. From the 81 studies, the prevalent disorders were spongy tissue and jelly seed, followed by flesh browning and soft nose. ‘Alphonso’ expressed only spongy tissue disorder. By contrast, ‘Tommy Atkins’ simultaneously expressed multiple disorders, viz., soft nose, jelly seed, and stem-end cavity. Mineral composition of flesh and exposure to heat post-harvest (viz., sunlight, phytosanitary heat treatment, and elevated storage temperature) were prominent in association with IDs expression. Relatively high N, N/Ca, Mg/Ca, and K/Ca ratios and relatively low Ca and B were related to most disorders. With K and Mg, studies inconsistently suggested positive and inverse relationship with a particular disorder. While individual studies suggest casual relationships, there was a relative dearth of pre-harvest work on soil characteristics, growing conditions (e.g., temperature, rain, and VPD), crop physiology (e.g., age and biennial bearing) and management practices (e.g., fertilisation and irrigation) in the literature. This review provides a benchmark against which future research might adopt holistic approaches to contiguously ascertain predisposition of mango fruit to internal disorders across the pre-harvest, harvest, and post-harvest continuum

Streptomyces tamarix sp. nov.: antagonism against Alternaria gaisen producing streptochlorin, isolated from Tamarix root soil

By the end of 2021, the pear yield in Xinjiang reached 1,795,900 tons, accounting for 1/9 of the country. Pear black spot, caused by Alternaria gaisen disease, has had a significant impact on the pear industry. A. gaisen can infect nearly all pear plants, resulting in black spots on the fruit that negatively affect both yield and quality. This study focused on the TRM76323 strain of Streptomyces, which was isolated from the soil of Tamarix chinensis in Xinjiang Province. Through a multiphase classification and identification method, the genetic classification status of the antagonistic strains was determined. The study also identified the antibacterial active components of streptochlorin using modern isolation and purification techniques. The antagonistic activity of Streptomyces against Alternaria was analyzed through in vitro and in vivo experiments. This research not only expanded the resource bank of antagonistic microorganisms in extreme environments in Xinjiang, but also identified active components that could contribute to the development of new drug lead compounds. Additionally, this study presents a novel approach for the prevention and control of pear black spot disease