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Small RNA Profiling Reveals Phosphorus Deficiency as a Contributing Factor in Symptom Expression for Citrus huanglongbing Disease

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Molecular Plant 2013年第2期6卷 301-310页

作者： Hongwei Zhao Ruobai Sun Ute Albrecht Chellappan Padmanabhan Airong Wanga Michael D. Coffey Thomas Girke Zonghua Wang Timothy J. Close Mikeal Roose Raymond K. Yokomi Svetlana Folimonova Georgios Vidalakis Robert Rouse Kim D. Bowman Hailing Jin Department of Plant Pathology and Microbiology University of California Riverside CA 92521 USA Institute for Integrative Genome Biology University of California Riverside CA 92521 USA Present address: Department of Plant Pathology College of Plant Protection Nanjing Agricultural University Nanjing 210095 China Department of Botany and Plant Sciences University of California Riverside CA 92521 USA US Horticultural Research Laboratory US Department of Agriculture Agricultural Research Service 2001 South Rock Road Fort Pierce FL 34945 USA Fujian Agriculture and Forestry University Fuzhou 350002-China San Joaquin Valley Agricultural Research Center US Department of Agriculture Agricultural Research Service 9611 S. Riverbend Ave Parlier CA 93648 USA Citrus Research and Education Center University of Florida 700 Experiment Station Road Lake Alfred FL 33850 USA University of Florida 2685 State Road29 North immokaleel FL 34142 USA

huanglongbing （HLB） is a devastating citrus disease that is associated with bacteria of the genus ＇Candidatus Liberibacter＇（Ca. L.）. Powerful diagnostic tools and management strategies are desired to control HLB. Host small RNAs （sRNA） play a vital role in regulating host responses to pathogen infection and are used as early diagnostic markers for many human diseases, including cancers. To determine whether citrus sRNAs regulate host responses to HLB, sRNAs were profiled from Citrus sinensis 10 and 14 weeks post grafting with Ca. L. asiaticus （Las）-positive or healthy tissue. Ten new microRNAs （miRNAs）, 76 conserved miRNAs, and many small interfering RNAs （siRNAs） were discovered. Several miRNAs and siRNAs were highly induced by Las infection, and can be potentially developed into early diagnosis markers of HLB. miR399, which is induced by phosphorus starvation in other plant species, was induced specifically by infection of Las but not Spiroplasma citri that causes citrus stubborn--a disease with symptoms similar to HLB. We found a 35% reduction of phosphorus in Las-positive citrus trees compared to healthy trees. Applying phosphorus oxyanion solutions to HLB-positive sweet orange trees reduced HLB symptom severity and significantly improved fruit production during a 3-year field trial in south-west Florida. Our molecular, physiological, and field data suggest that phosphorus deficiency is linked to HLB disease symptomology.

关键词： huanglongbing small RNA miRNA399 disease diagnosis phosphorus deficiency.

Analysis and optimal control of a huanglongbing mathematical model with resistant vector

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Infectious Disease Modelling 2021年第1期6卷 782-804页

作者： Youquan Luo Fumin Zhang Yujiang Liu Shujing Gao Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques Gannan Normal UniversityGanzhou341000PR China National Navel Orange Engineering Research Center Gannan Normal UniversityGanzhou341000PR China

huanglongbing(HLB)is an incurable disease that affects citrus trees.To better understand the transmission of HLB,the mathematical model is developed to investigate the transmission dynamics of the disease between Asian citrus psyllid(ACP)and citrus trees.Through rigorous mathematical derivations,we derive the expression of the basic reproduction number(R_(0))of HLB.The findings show that the disease-free equilibrium is locally asymptotically stable if R_(0)1 the system is uniformly persistent.By applying the global sensitivity analysis of R_(0),we can obtain some parameters that have the greatest influence on the HLB transmission dynamics.Additionally,the optimal control theory is used to explore the corresponding optimal control problem of the HLB model.Numerical simulations are conducted to reinforce the analytical results.These theoretical and numerical results provide useful insights for understanding the transmission dynamics of HLB and may help policy makers to develop intervention strategies for the disease.

关键词： huanglongbing Insecticide resistance Dynamic model Optimal control Sensitivity analysis

Digital Gene Expression Analysis of huanglongbing Affected Mandarins(Citrus reticulata Blanco)In Response to Thermotherapy

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Horticultural Plant Journal 2021年第1期7卷 1-12页

作者： Ruixuan Pan Yanling Chen Xiaoling Deng Meirong Xu Laboratory of Citrus huanglongbing Research Guangdong Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhou 510642China

huanglongbing(HLB),which is mainly associated with“Candidatus Liberibacter asiaticus”(CLas),is currently threatening citrus production around the world.This destructive century-old disease results in callose deposition in phloem plasmodesmata and starch overaccumulation in leaf chloroplasts.Heat treatment with high humidity has proven to be effective in eliminating the CLas titers in potted citrus trees.This study explored the curative mechanisms and impact of heat treatment(from 32 to 48°C with 75%±5%relative humidity,14h in light and 10h in dark for four days)on mandarin trees(Citrus reticulata Blanco)that were severely infected by CLas using Solexa/Illumina’s digital gene expression(DGE)profiling.A total of 838 differentially expressed genes(DEGs)were identified,of which 510 were downregulated.Proteinprotein interaction analysis of the DEGs indicated that the thermotherapy of HLB trees downregulated the circadian clock related genes in chloroplasts and upregulated the RNA-editing process in the mitochondria,characterized by 141 genes encoding pentatricopeptide repeatcontaining proteins(PPR)being all upregulated.Furthermore,the expression of phenylpropanoid and flavonoid biosynthesis genes,and auxininduced genes were suppressed.The defense response pathway of the thermotherapy treated diseased trees was apparently disrupted,as indicated by the downregulation of LRR receptor-like serine/threonine-protein kinase FLS2 gene.This study improves our understanding of the curative mechanisms of heat treatment on HLB trees and CLas biological regulation.Importantly,this provides new insights on the involvement of RNA modification by PPR genes and changes in the circadian clock after the heat stress treatment of CLas-infected citrus.

关键词： Citrus huanglongbing heat transcriptom differentially expressed genes

The Citrus huanglongbing Crisis and Potential Solutions

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Molecular Plant 2019年第5期12卷 607-609页

作者： Nian Wang Citrus Research and Education Center Department of Microbiology and Cell ScienceUniversity of Florida/lnstitute of Food and Agricultural SciencesLake AlfredFLUSA China-USA Citrus huanglongbing Joint Laboratory(A Joint Laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University) National Navel Orange Engineering Research CenterGannan Normal UniversityGanzhouJiangxi 341000China

Citrus is one of the top three fruit crops worldwide.Citrus production is facing an unprecedented crisis due to huanglongbing(HLB,also known as citrus greening),which is the most devastating disease of citrus.HLB was first reported in Asia a century ago.HLB is associated with Candidatus Liberibacter asiaticus(Las),Ca.L.americanus(Lam),and Ca.L.africanus(Bove,2006),which belong to the gramegative a-proteobacteria.Among them,Las is the most widely spread.Las and Lam are vectored by Diaphorina citri Kuwayama(ACP),whereas Laf is transmitted by Trioza erytreae.

关键词： The Citrus huanglongbing Crisis Potential Solutions Citrus

Global Dynamics of a New huanglongbing Transmission Model with Quarantine Measures

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Applied Mathematics 2022年第1期13卷 1-18页

作者： Yujiang Liu Chunmei Zeng Jing Guo Zhenzhen Liao Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques Gannan Normal University Gan-zhou China

An epidemic model which describes huanglongbing transmission is proposed with the goal of investigating the effect of quarantine measures on the spread of diseases. First of all, the analytical formula for the basic reproduction number R0 is obtained by the means of next generation matrix, and the existence of disease-free equilibrium and endemic equilibrium is discussed. Then, the local stability and the global stability of equilibria are investigated by using Routh-Hurwitz criterion and Lyapunov function, respectively. Numerical simulations indicate that comprehensive quarantine measures can effectively control the spread of huanglongbing. It provides a reliable tactic basis for preventing the epidemic outbreak.

关键词： huanglongbing Basic Reproduction Number Sensitivity Analysis PRCC Global Stability

Detection of citrus huanglongbing based on image feature extraction and two-stage BPNN modeling

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International Journal of Agricultural and Biological Engineering 2016年第6期9卷 20-26页

作者： Deng Xiaoling Yubin Lan Xing Xiaqiong Mei Huilan Liu Jiakai Hong Tiansheng International Lab of Agricultural Aviation Pesticides Spraying Technology Guangzhou 510642China College of Electronical Engineering South China Agricultural UniversityGuangzhou 510642China College of Engineering South China Agricultural UniversityGuangzhou 510642China

Citrus huanglongbing(HLB),which is spread by the citrus psyllid,is the most destructive disease of citrus industry.While no effective cure for the disease has been reported,detection and removal of infected trees can prevent spreading.Symptoms indicative of HLB can be present in both HLB-positive trees and HLB-negative trees,making identification of infected trees difficult.A detection method for citrus HLB based on image feature extraction and two-stage back propagation neural network(BPNN)modeling was investigated in this research.The identification method for eight different classes including healthy,HLB and non-HLB symptoms was studied.Thirty-four statistical features including color and texture were extracted for each leaf sample,following the two-stage BPNN to model and identify HLB-positive leaves from HLB-negative leaves.The discrimination accuracy can reach approximately 92%which shows that this method based on visual image processing can perform well in detecting citrus HLB.

关键词： citrus leaf huanglongbing texture and color features feature extraction two-stage back propagation neural network

Curent Situation of “Candidatus Liberibacter asiaticus” in Guangdong,China,Where Citrus huanglongbing Was First Described

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Journal of Integrative Agriculture 2012年第3期11卷 424-429页

作者： DENG Xiao-ling GAO Yi-di CHEN Jian-chi PU Xue-lian KONG Wei-wen LI Hua-ping Laboratory of Citrus huanglongbing Research South China Agricultural University Guangzhou 510642 P.R. China San Joaquin Valley Agricultural Sciences Center USDA-ARS Parlier California 93648 USA School of Horticulture and Plant Protection Yangzhou University Yangzhou 225009 P.R. China

Citrus huanglongbing （HLB,yellow shoot disease） was first observed in the coastal Chaoshan Plain of Guangdong Province,China,in the late 19th century based on descriptions of yellow shoot symptoms. “Candidatus Liberibacter asiaticus”has been considered as a putative pathogen associated with HLB since 1994.Information about the curent prevalence of this bacterium is important for HLB control in Guangdong and also provides useful reference for HLB study elsewhere.In 2007,we collected HLB symptomatic citrus samples from 16 cultivars in 12 prefecture cities,mostly in the north and west regions of Guangdong,where major citrus fruits are currently produced.Among the 359 samples collected,241 （67.1%） were positive for “Ca.L.asiaticus”,distributed in 15 out of the 16 cultivars from all 12 cities,indicating the widespread prevalence of “Ca.L.asiaticus” in Guangdong Province.The detection rates varied from 16.7 to 100% depending on location and cultivar.Lower detection rates were found in newer citrus cultivation cities among the previously less popular but now promoted cultivars.In reviewing the citrus management and pest control practice,we believe that infected nursery stocks play a key role in the current spread of “Ca.L.asiaticus”.

关键词： citrus huanglongbing Candidatus Liberibacter asiaticus

Transcriptomic analysis reveals the defense mechanisms of citrus infested with Diaphorina citri

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Horticultural Plant Journal 2023年第3期9卷 450-462页

作者： Xueli Sun Ting Yu Minliang Bin Chunhua Hu Fangcheng Bi Xinxiang Peng Ganjun Yi Xinxin Zhang State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources College of Life SciencesSouth China Agricultural UniversityGuangzhouGuangdong 510642China Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization(MOA) Guangdong Province Key Laboratory of Tropical and Subtropical Fruit Tree ResearchInstitute of Fruit Tree ResearchGuangdong Academy of Agricultural SciencesGuangzhouGuangdong 510640China Agricultural Biological Gene Research Center Guangdong Academy of Agricultural SciencesGuangzhouGuangdong 510640China

huanglongbing(HLB) is a devastating disease that has led to an acute crisis for growers of citrus, one of the world's most important fruit crops. The phloem-feeding Asian citrus psyllid(ACP), Diaphorina citri, is the main pest at the new shoot stage and is the only natural vector of HLB pathogenic bacteria. Little is known about how plants perceive and defend themselves from this destructive pest. Here, we characterized changes in the expression of various genes in citrus plants that were continuously infested by D. citri for different durations(12, 24, and 48 h). A total of 5 219 differentially expressed genes(DEGs) and 643 common DEGs were identified across all time points. Several pathways related to defense were activated, such as peroxisome, alpha-linolenic acid metabolism, and phenylpropanoid and terpenoid biosynthesis, and some pathways related to growth and signal transduction were suppressed in response to D. citri infestation. The expression of genes including kinases(CML44, CIPK6, and XTH6), phytohormones(SAMT, LOX6, and NPR3), transcription factors(bHLH162, WRKY70, and WRKY40), and secondary metabolite synthesis-related genes(PAL, 4CL2, UGT74B1 and CYP82G1) was significantly altered in response to D. citri infestation. The findings of this study greatly enhance our understanding of the mechanisms underlying the defense response of citrus plants to D. citri infestation at the molecular level. Functional characterization of the candidate defense-related genes identified in this study will aid the molecular breeding of insect-resistant citrus varieties.

关键词： Asian citrus psyllid Citrus Diaphorina citri huanglongbing Infestation RNA-seq

Threshold Dynamics of a Vector-Borne Epidemic Model for huanglongbing with Impulsive Control

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Applied Mathematics 2019年第4期10卷 196-211页

作者： Jianping Wang Feifei Feng Zhicai Guo Hengmin Lv Juanjuan Wang The Department of Basic Course Education Ji’an College Ji’an China

In this paper, the basic reproduction number is calculated for huanglongbing (HLB) model with impulses which is a vector-borne epidemic model with impulses. For controlling HLB, farmers’ experience is replanting of healthy plants and removing infected plants. To reflect the real world, we construct an impulsive control model which considers replanting of healthy plants and removing infected plants at one fixed time. By analyzing the model, we conclude that the disease-free equilibrium is globally asymptotically stable if the basic reproduction number Ro 1, and we prove that the HLB is permanence if the basic reproduction number Ro > 1.

关键词： huanglongbing Impulsive Control Basic Reproduction Number Disease-Free Periodic Solution Permanence