title: Small RNA profiling reveals phosphorus deficiency as a contributing factor in symptom expression for citrus huanglongbing disease.
abstract: 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.
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhao
authors.forename: Ruobai
authors.initials: R
authors.lastname: Sun
authors.forename: Ute
authors.initials: U
authors.lastname: Albrecht
authors.forename: Chellappan
authors.initials: C
authors.lastname: Padmanabhan
authors.forename: Airong
authors.initials: A
authors.lastname: Wang
authors.forename: Michael D
authors.initials: MD
authors.lastname: Coffey
authors.forename: Thomas
authors.initials: T
authors.lastname: Girke
authors.forename: Zonghua
authors.initials: Z
authors.lastname: Wang
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Close
authors.forename: Mikeal
authors.initials: M
authors.lastname: Roose
authors.forename: Raymond K
authors.initials: RK
authors.lastname: Yokomi
authors.forename: Svetlana
authors.initials: S
authors.lastname: Folimonova
authors.forename: Georgios
authors.initials: G
authors.lastname: Vidalakis
authors.forename: Robert
authors.initials: R
authors.lastname: Rouse
authors.forename: Kim D
authors.initials: KD
authors.lastname: Bowman
authors.forename: Hailing
authors.initials: H
authors.lastname: Jin
mesh_terms: D032084:Citrus sinensis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*; D005638:Fruit / Q000187:drug effects / Q000254:growth & development; D035683:MicroRNAs / Q000235:genetics; D010758:Phosphorus / Q000172:deficiency* / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology*; D018749:RNA, Plant / Q000235:genetics*; D022661:RNA, Untranslated / Q000235:genetics*; D012230:Rhizobiaceae / Q000502:physiology
chemical_list: D035683:MicroRNAs; D018749:RNA, Plant; D022661:RNA, Untranslated; D010758:Phosphorus