Abstract
Huanglongbing (HLB) is a destructive disease of citrus trees caused by phloem-limited bacteria, Candidatus Liberibacter spp. One of the early microscopic manifestations of HLB is excessive starch accumulation in leaf chloroplasts. We hypothesize that the causative bacteria in the phloem may intervene photoassimilate export, causing the starch to over-accumulate. We examined citrus leaf phloem cells by microscopy methods to characterize plant responses to Liberibacter infection and the contribution of these responses to the pathogenicity of HLB. Plasmodesmata pore units (PPUs) connecting companion cells and sieve elements were stained with a callose-specific dye in the Liberibacter-infected leaf phloem cells; callose accumulated around PPUs before starch began to accumulate in the chloroplasts. When examined by transmission electron microscopy, PPUs with abnormally large callose deposits were more abundant in the Liberibacter-infected samples than in the uninfected samples. We demonstrated an impairment of symplastic dye movement into the vascular tissue and delayed photoassimilate export in the Liberibacter-infected leaves. Liberibacter infection was also linked to callose deposition in the sieve plates, which effectively reduced the sizes of sieve pores. Our results indicate that Liberibacter infection is accompanied by callose deposition in PPUs and sieve pores of the sieve tubes and suggest that the phloem plugging by callose inhibits phloem transport, contributing to the development of HLB symptoms.
Similar content being viewed by others
References
Achor D, Etxeberria E, Wang N, Folimonova SY, Chung K, Albrigo L (2010) Sequence of anatomical symptom observations in citrus affected with huanglongbing disease. Plant Pathol J 9:56–64
Almon E, Horowitz M, Wang HL, Lucas WJ, Zamski E, Wolf S (1997) Phloem-specific expression of the tobacco mosaic virus movement protein alters carbon metabolism and partitioning in transgenic potato plants. Plant Physiol 115:1599–1607
Benitez-Alfonso Y, Jackson D (2009) Redox homeostasis regulates plasmodesmal communication in Arabidopsis meristems. Plant Signal Behav 4:655–659
Benitez-Alfonso Y, Cilia M, San Roman A, Thomas C, Maule A, Hearn S, Jackson D (2009) Control of Arabidopsis meristem development by thioredoxin-dependent regulation of intercellular transport. Proc Natl Acad Sci U S A 106:3615–3620
Botha CEJ, Cross RHM, van Bel AJE, Peter CI (2000) Phloem loading in the sucrose-export-defective (SXD-1) mutant maize is limited by callose deposition at plasmodesmata in bundle sheath–vascular parenchyma interface. Protoplasma 214:65–72
Bove JM (2006) Huanglongbing: a destructive, newly-emerging, century-old disease of citrus. J Plant Pathol 88:7–37
Braun DM, Slewinski TL (2009) Genetic control of carbon partitioning in grasses: roles of sucrose transporters and tie-dyed loci in phloem loading. Plant Physiol 149:71–81
Brlansky RH, Dewdney ME, Rogers ME (2010) Florida citrus pest management guide: huanglongbing (citrus greening). Extension Digital Information Source (EDIS): PP-225 Department of Food and Resource Economics, University of Florida, Gainesville, FL
da Graca JV, Korsten L (2004) Citrus huanglongbing: review, present status and future strategies. Dis Fruits Veg 1:229–245
Drake GA, Carr DJ, Anderson WP (1978) Plasmolysis, plasmodesmata, and electrical coupling of oat coleoptile cells. J Exp Bot 29:1205–1214
Evert RF (1982) Sieve-tube structure in relation to function. Bioscience 32:789–795
Gottwald TR (2009) Current epidemiological understanding of citrus huanglongbing. Annu Rev Phytopathol 48:119–139
Hofius D, Hajirezaei MR, Geiger M, Tschiersch H, Melzer M, Sonnewald U (2004) RNAi-mediated tocopherol deficiency impairs photoassimilate export in transgenic potato plants. Plant Physiol 135:1256–1268
Hughes JE, Gunning BES (1980) Glutaraldehyde-induced deposition of callose. Can J Bot-Rev Canadienne De Botanique 58:250–258
Kang BH, Staehelin LA (2008) ER-to-Golgi transport by COPII vesicles in Arabidopsis involves a ribosome-excluding scaffold that is transferred with the vesicles to the Golgi matrix. Protoplasma 234:51–64
Kim JS, Sagaram US, Burns JK, Li JL, Wang N (2009) Response of sweet orange (Citrus sinensis) to ‘Candidatus Liberibacter asiaticus’ infection: microscopy and microarray analyses. Phytopathology 99:50–57
Kronberg K, Vogel F, Rutten T, Hajirezaei MR, Sonnewald U, Hofius D (2007) The silver lining of a viral agent: increasing seed yield and harvest index in Arabidopsis by ectopic expression of the potato leaf roll virus movement protein. Plant Physiol 145:905–918
Li WB, Hartung JS, Levy L (2006) Quantitative real-time PCR for detection and identification of Candidatus Liberibacter species associated with citrus huanglongbing. J Microbiol Method 66:104–115
Lucas W, Ham B, Kim J (2009) Plasmodesmata—bridging the gap between neighboring plant cells. Trends Cell Biol 19:495–503
Ma Y, Baker RF, Magallanes-Lundback M, Dellapenna D, Braun DM (2008) Tie-dyed1 and sucrose export defective1 act independently to promote carbohydrate export from maize leaves. Planta 227:527–538
Maeda H, Song W, Sage T, Dellapenna D (2006) Tocopherols play a crucial role in low-temperature adaptation and phloem loading in Arabidopsis. Plant Cell 18:2710–2732
Maule A (2008) Plasmodesmata: structure, function and biogenesis. Curr Opin Plant Biol 11:680–686
Mullendore D, Windt C, Van As H (2010) Sieve tube geometry in relation to phloem flow. Plant Cell 22:579–593
Radford J, Vesk M, Overall R (1998) Callose deposition at plasmodesmata. Protoplasma 201:30–37
Rinne P, Schoot C (2003) Plasmodesmata at the crossroads between development, dormancy, and defense. Can J Bot-Rev Canadienne De Botanique 81:1182–1197
Rinne P, Kaikuranta P, Van Der Schoot C (2001) The shoot apical meristem restores its symplasmic organization during chilling-induced release from dormancy. Plant J 26:249–264
Rinne PL, van den Boogaard R, Mensink MG, Kopperud C, Kormelink R, Goldbach R, van der Schoot C (2005) Tobacco plants respond to the constitutive expression of the tospovirus movement protein NS(M) with a heat-reversible sealing of plasmodesmata that impairs development. Plant J 43:688–707
Roberts AG, Oparka KJ (2003) Plasmodesmata and the control of symplastic transport. Plant Cell Env 26:103–124
Ruan YL, Llewellyn DJ, Furbank RT (2001) The control of single-celled cotton fiber elongation by developmentally reversible gating of plasmodesmata and coordinated expression of sucrose and K+ transporters and expansin. Plant Cell 13:47–60
Russin WA, Evert RF, Vanderveer PJ, Sharkey TD, Briggs SP (1996) Modification of a specific class of plasmodesmata and loss of sucrose export ability in the sucrose export defective1 maize mutant. Plant Cell 8:645–658
Ruzin SE (1999) Staining. In: Ruzin SE Plant microtechnique and microscopy. Oxford University Press, New York, pp 87–116
Sivaguru M, Fujiwara T, Šamaj J, Baluška F, Yang Z, Osawa H, Maeda T, Mori T, Volkmann D, Matsumoto H (2000) Aluminum-induced 1→3-β-d-glucan inhibits cell-to-cell trafficking of molecules through plasmodesmata. A new mechanism of aluminum toxicity in plants. Plant Physiol 124:991–1005
Thompson MV, Holbrook NM (2003) Application of a single-solute non-steadystate phloem model to the study of long-distance assimilate transport. J Theor Biol 220:419–455
Torres M, Jones J, Dangl J (2006) Reactive oxygen species signaling in response to pathogens. Plant Physiol 141:373–378
van Bel AJE, Ehlers K, Knoblauch M (2002) Sieve elements caught in the act. Trends Plant Sci 7:126–132
Zavaliev R, Sagi G, Gera A, Epel BL (2010) The constitutive expression of Arabidopsis plasmodesmal-associated class 1 reversibly glycosylated polypeptide impairs plant development and virus spread. J Exp Bot 61:131–142
Acknowledgments
We are grateful to Dr. Karen Koch (University of Florida) and her lab assistants for their help in 14CO2 pulse labeling. We also thank Dr. Rob Ferl (University of Florida) and Dr. Tony Romeo (University of Florida) for allowing us to use their fluorescence stereomicroscope and phosphorimager scanner, respectively. We are indebted to Dr. Dean Gabriel (University of Florida) for the use of his citrus plants in the University of Florida Plant Containment Facility. We thank Dr. Mullendore (Washington State University) for his advice in carrying out scanning electron microscopy of sieve pores. This work was supported by the Florida Citrus Production Research Advisory Council (grant no. 113 to B-H. K.) and by the United States Department of Agriculture, (NIFA Award no. 2010-34446-21694 to B-H. K.)
Conflict of Interest
The authors declare that they have no conflict of interest.
Author information
Authors and Affiliations
Corresponding author
Additional information
Handling Editor: Manfred Heinlein
Electronic supplementary materials
Below is the link to the electronic supplementary material.
Supplementary Fig. S1
(JPEG 16 kb)
Supplementary Table S1
(DOC 27 kb)
Rights and permissions
About this article
Cite this article
Koh, EJ., Zhou, L., Williams, D.S. et al. Callose deposition in the phloem plasmodesmata and inhibition of phloem transport in citrus leaves infected with “Candidatus Liberibacter asiaticus”. Protoplasma 249, 687–697 (2012). https://doi.org/10.1007/s00709-011-0312-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00709-011-0312-3