RESUMEN
The haustorium in parasitic plants is an organ specialized for invasion and nutrient uptake from host plant tissues. Despite its importance, the developmental processes of haustoria are mostly unknown. To understand the dynamics of cell fate change and cellular lineage during haustorium development, we performed live imaging-based marker expression analysis and cell-lineage tracing during haustorium formation in the model facultative root parasite Phtheirospermum japonicum Our live-imaging analysis revealed that haustorium formation was associated with induction of simultaneous cell division in multiple cellular layers, such as epidermis, cortex and endodermis. In addition, we found that procambium-like cells, monitored by cell type-specific markers, emerged within the central region of the haustorium before xylem connection to the host plant. Our clonal analysis of cell lineages showed that cells in multiple cellular layers differentiated into procambium-like cells, whereas epidermal cells eventually transitioned into specialized cells interfacing with the host plant. Thus, our data provide a cell fate transition map during de novo haustorium organogenesis in parasitic plants.
Asunto(s)
Cámbium , Modelos Biológicos , Orobanchaceae , Epidermis de la Planta , Xilema , Cámbium/citología , Cámbium/embriología , Orobanchaceae/citología , Orobanchaceae/embriología , Epidermis de la Planta/citología , Epidermis de la Planta/embriología , Xilema/citología , Xilema/embriologíaRESUMEN
BACKGROUND AND AIMS: Parasitic plants obtain nutrients from their hosts through organs called haustoria. The hyaline body is a specialized parenchymatous tissue occupying the central parts of haustoria in many Orobanchaceae species. The structure and functions of hyaline bodies are poorly understood despite their apparent necessity for the proper functioning of haustoria. Reported here is a cell wall-focused immunohistochemical study of the hyaline bodies of three species from the ecologically important clade of rhinanthoid Orobanchaceae. METHODS: Haustoria collected from laboratory-grown and field-collected plants of Rhinanthus minor, Odontites vernus and Melampyrum pratense attached to various hosts were immunolabelled for cell wall matrix glycans and glycoproteins using specific monoclonal antibodies (mAbs). KEY RESULTS: Hyaline body cell wall architecture differed from that of the surrounding parenchyma in all species investigated. Enrichment in arabinogalactan protein (AGP) epitopes labelled with mAbs LM2, JIM8, JIM13, JIM14 and CCRC-M7 was prominent and coincided with reduced labelling of de-esterified homogalacturonan with mAbs JIM5, LM18 and LM19. Furthermore, paramural bodies, intercellular deposits and globular ergastic bodies composed of pectins, xyloglucans, extensins and AGPs were common. In Rhinanthus they were particularly abundant in pairings with legume hosts. Hyaline body cells were not in direct contact with haustorial xylem, which was surrounded by a single layer of paratracheal parenchyma with thickened cell walls abutting the xylem. CONCLUSIONS: The distinctive anatomy and cell wall architecture indicate hyaline body specialization. Altered proportions of AGPs and pectins may affect the mechanical properties of hyaline body cell walls. This and the association with a transfer-like type of paratracheal parenchyma suggest a role in nutrient translocation. Organelle-rich protoplasts and the presence of exceptionally profuse intra- and intercellular wall materials when attached to a nitrogen-fixing host suggest subsequent processing and transient storage of nutrients. AGPs might therefore be implicated in nutrient transfer and metabolism in haustoria.
Asunto(s)
Pared Celular/química , Mucoproteínas/metabolismo , Orobanchaceae/citología , Pectinas/metabolismo , Anticuerpos Monoclonales , Pared Celular/metabolismo , Epítopos , Esterificación , Glucanos/inmunología , Glucanos/metabolismo , Glicoproteínas/metabolismo , Inmunohistoquímica , Mucoproteínas/inmunología , Orobanchaceae/química , Orobanchaceae/metabolismo , Pectinas/inmunología , Proteínas de Plantas/inmunología , Proteínas de Plantas/metabolismo , Polisacáridos/inmunología , Polisacáridos/metabolismo , Xilanos/inmunología , Xilanos/metabolismo , Xilema/química , Xilema/citología , Xilema/metabolismoRESUMEN
Phelipanche ramosa L. (Pomel) is a major root-parasitic weed attacking many important crops. Success in controlling this parasite is rare and a better understanding of its unique biology is needed to develop new specific control strategies. In the present study, quantitative polymerase chain reaction experiments showed that sucrose synthase encoding PrSus1 transcripts accumulate at their highest level once the parasite is connected to the host (tomato) vascular system, mainly in the parasite tubercles, which bear numerous adventitious roots. In situ hybridization experiments revealed strong PrSus1 expression in both shoot and root apices, especially in shoot apical meristems and in the vascular tissues of scale leaves and stems, and in the apical meristems and developing xylem in roots. In addition, immunolocalization experiments showed that a sucrose synthase protein co-localized with cell-wall thickening in xylem elements. These findings highlight the role of PrSus1 in the utilization of host-derived sucrose in meristematic areas and in cellulose biosynthesis in differentiating vascular elements. We also demonstrate that PrSus1 is downregulated in response to 2,3,5-triiodobenzoic acid-induced inhibition of polar auxin transport in the host stem, suggesting that PrSus1 activity in xylem maturation is controlled by host-derived auxin.
Asunto(s)
Glucosiltransferasas/metabolismo , Ácidos Indolacéticos/metabolismo , Orobanchaceae/enzimología , Enfermedades de las Plantas/parasitología , Solanum lycopersicum/parasitología , Secuencia de Bases , Transporte Biológico/efectos de los fármacos , Pared Celular/metabolismo , ADN de Plantas/genética , Regulación hacia Abajo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Glucosiltransferasas/genética , Solanum lycopersicum/efectos de los fármacos , Solanum lycopersicum/fisiología , Meristema/citología , Meristema/enzimología , Meristema/genética , Datos de Secuencia Molecular , Especificidad de Órganos , Orobanchaceae/citología , Orobanchaceae/genética , Orobanchaceae/crecimiento & desarrollo , Hojas de la Planta/citología , Hojas de la Planta/enzimología , Hojas de la Planta/genética , Raíces de Plantas/citología , Raíces de Plantas/enzimología , Raíces de Plantas/genética , Brotes de la Planta/citología , Brotes de la Planta/enzimología , Brotes de la Planta/genética , Regiones Promotoras Genéticas/genética , Análisis de Secuencia de ADN , Sacarosa/metabolismo , Ácidos Triyodobenzoicos/farmacología , Xilema/citología , Xilema/enzimología , Xilema/genéticaRESUMEN
BACKGROUND: Plants within the Orobanchaceae are an agriculturally important group of parasites that attack economically important crops to obtain water and nutrients from their hosts. Despite their agricultural importance, molecular mechanisms of the parasitism are poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We developed transient and stable transformation systems for Phtheirospermum japonicum, a facultative parasitic plant in the Orobanchaceae. The transformation protocol was established by a combination of sonication and acetosyringone treatments using the hairy-root-inducing bacterium, Agrobacterium rhizogenes and young seedlings. Transgenic hairy roots of P. japonicum were obtained from cotyledons 2 to 3 weeks after A. rhizogenes inoculation. The presence and the expression of transgenes in P. japonicum were verified by genomic PCR, Southern blot and RT-PCR methods. Transgenic roots derived from A. rhizogenes-mediated transformation were able to develop haustoria on rice and maize roots. Transgenic roots also formed apparently competent haustoria in response to 2,6-dimethoxy-1,4-benzoquinone (DMBQ), a haustorium-inducing chemical. Using this system, we introduced a reporter gene with a Cyclin B1 promoter into P. japonicum, and visualized cell division during haustorium formation. CONCLUSIONS: We provide an easy and efficient method for hairy-root transformation of P. japonicum. Transgenic marker analysis revealed that cell divisions during haustorium development occur 24 h after DMBQ treatment. The protocols described here will allow functional analysis of genes involved in plant parasitism.
Asunto(s)
Agrobacterium/fisiología , Orobanchaceae/microbiología , Transformación Genética , División Celular , Hipocótilo/microbiología , Agujas , Orobanchaceae/citología , Orobanchaceae/genética , Orobanchaceae/crecimiento & desarrollo , Raíces de Plantas/citología , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/microbiología , Plantas Modificadas Genéticamente , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sonicación , Transgenes/genéticaRESUMEN
To survive changes in climate, successful species shift their geographic ranges to remain in suitable habitats. For parasites and other highly specialized species, distributional changes not only are dictated by climate but can also be engineered by their hosts. The extent of host control on parasite range expansion is revealed through comparisons of host and parasite migration and demographic histories. However, understanding the codistributional history of entire forest communities is complicated by challenges in synthesizing datasets from multiple interacting species of differing datatypes. Here we integrate genetic and fossil pollen datasets from a host-parasite pair; specifically, the population structure of the parasitic plant (Epifagus virginiana) was compared with both its host (Fagus grandifolia) genetic patterns and abundance data from the paleopollen record of the last 21,000 y. Through tests of phylogeographic structure and spatial linear regression models we find, surprisingly, host range changes had little effect on the parasite's range expansion and instead host density is the main driver of parasite spread. Unlike other symbionts that have been used as proxies to track their host's movements, this parasite's migration routes are incongruent with the host and instead reflect the greater importance of host density in this community's assembly. Furthermore, these results confirm predictions of disease ecological models regarding the role of host density in the spread of pathogens. Due to host density constraints, highly specialized species may have low migration capacities and long lag times before colonization of new areas.
Asunto(s)
Cambio Climático , Interacciones Huésped-Parásitos , Orobanchaceae/fisiología , Árboles/parasitología , Datos de Secuencia Molecular , Orobanchaceae/citología , Orobanchaceae/genética , Filogenia , Densidad de PoblaciónRESUMEN
This paper deals with the morphological characters of the plants and drugs, and the histological characters of the stems of Herba Boschniakiae (Boschniakia rossica). This results provide authentic methods for the identification of Herba Boschniakiae.