Cell Biology of Sieve Element–Companion Cell Complexes

White, Rosemary G.

doi:10.1002/9781118382806.ch2

Cited by 3 publications

(6 citation statements)

References 199 publications

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“…SLI1 is localized in the region where there is a small, peripheral strip of cytoplasm, which is enclosed by the plasma membrane and the sieve element reticulum, consisting of stacked or fenestrated ER . This parietal layer contains other elements, such as filamentous protein structures, amorphous ground matrices, phloem plastids, and individual or clustered mitochondria, which are often partially covered by ER (White, 2013). SLI1 forms both straight and spherical bodies along the parietal layer.…”

Section: Sli1 Restricts Phloem Feeding But Does Not Occlude Sieve Tubesmentioning

confidence: 99%

“…Surprisingly, the role of nondispersed factors in the parietal sieve element layer has hardly received any attention in this context. The sieve element plasma membrane is covered by a thin layer of cytoplasm with sieve element reticulum membranes, organelles, and protein layers White, 2013). After puncturing the plasma membrane, aphids need to breach this layer to arrive at the sieve element lumen for passive uptake of phloem sap.…”

Section: The Role Of the Parietal Layer In Restricted Sap Uptakementioning

confidence: 99%

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SIEVE ELEMENT-LINING CHAPERONE1 Restricts Aphid Feeding on Arabidopsis during Heat Stress

et al. 2017

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The role of phloem proteins in plant resistance to aphids is still largely elusive. By genome-wide association mapping of aphid behavior on 350 natural accessions, we identified the small heat shock-like (). Detailed behavioral studies on near-isogenic and knockout lines showed that SLI1 impairs phloem feeding. Depending on the haplotype, aphids displayed a different duration of salivation in the phloem. On mutants, aphids prolonged their feeding sessions and ingested phloem at a higher rate than on wild-type plants. The largest phenotypic effects were observed at 26°C, when expression is upregulated. At this moderately high temperature, mutants suffered from retarded elongation of the inflorescence and impaired silique development. Fluorescent reporter fusions showed that SLI1 is confined to the margins of sieve elements where it lines the parietal layer and colocalizes in spherical bodies around mitochondria. This localization pattern is reminiscent of the clamp-like structures observed in previous ultrastructural studies of the phloem and shows that the parietal phloem layer plays an important role in plant resistance to aphids and heat stress.

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Section: Sli1 Restricts Phloem Feeding But Does Not Occlude Sieve Tubesmentioning

confidence: 99%

Section: The Role Of the Parietal Layer In Restricted Sap Uptakementioning

confidence: 99%

SIEVE ELEMENT-LINING CHAPERONE1 Restricts Aphid Feeding on Arabidopsis during Heat Stress

et al. 2017

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“…Unlike xylem vessels, sieve elements are alive and contain organelles, RNAs and a proteome. During differentiation, sieve elements enucleate and break down cytoskeletal elements, vacuoles, ribosomes and the Golgi apparatus [11,12]. What is left in a mature sieve element is a central lumen for intercellular sap transport, and the parietal layer, consisting of a thin cytoplasmic layer at the periphery of the sieve tube.…”

Section: Phloem Sap Transport and The Architecture Of Sieve Tubesmentioning

confidence: 99%

“…Interestingly, plasmodesmata pore units can conduct molecules larger than 60 kDa and thereby are able to support the transport of macromolecules, such as proteins and long RNAs [17,18]. Conversely, not all molecules that are cell-to-cell mobile in epidermis and mesophyll can cross the plasmodesmata pore units, indicating that the plasmodesmata pore units are controlled by different movement factors in comparison to plasmodesmata in other tissues [11,19,20]. Presumably, this selective trafficking through plasmodesmata pore units may serve to prevent leakage of solutes from the phloem sap [15], regulate the long-distance communication of macromolecules within the plant [21,22], and protect the phloem sap from invading organisms [23].…”

Section: Phloem Sap Transport and The Architecture Of Sieve Tubesmentioning

confidence: 99%

“…These 6K 2 bodies, which co-localize with lipids, viral RNA-dependent RNA polymerase (RdRp) and double-stranded (ds)RNA, indicate that TuMV replication takes place in sieve element reticulum membrane-derived structures prior to long-distance transport [48]. Although reported, it remains questionable how replication can take place in absence of native ribosomes in the sieve element reticulum [11,12]. Nonetheless, potyvirus replication and the accumulation of viral dsRNAs may induce a (local) RNA silencing response in the sieve tube.…”

Section: Sieve Element Reticulum Defenses Against Virus Replication Amentioning

confidence: 99%

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Defenses against Virus and Vector: A Phloem-Biological Perspective on RTM- and SLI1-Mediated Resistance to Potyviruses and Aphids

Kloth

Kormelink

2020

Viruses

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Combining plant resistance against virus and vector presents an attractive approach to reduce virus transmission and virus proliferation in crops. Restricted Tobacco-etch virus Movement (RTM) genes confer resistance to potyviruses by limiting their long-distance transport. Recently, a close homologue of one of the RTM genes, SLI1, has been discovered but this gene instead confers resistance to Myzus persicae aphids, a vector of potyviruses. The functional connection between resistance to potyviruses and aphids, raises the question whether plants have a basic defense system in the phloem against biotic intruders. This paper provides an overview on restricted potyvirus phloem transport and restricted aphid phloem feeding and their possible interplay, followed by a discussion on various ways in which viruses and aphids gain access to the phloem sap. From a phloem-biological perspective, hypotheses are proposed on the underlying mechanisms of RTM- and SLI1-mediated resistance, and their possible efficacy to defend against systemic viruses and phloem-feeding vectors.

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SLI1 confers broad‐spectrum resistance to phloem‐feeding insects

Kloth

Shah

Broekgaarden

et al. 2021

Plant Cell & Environment

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Resistance (R) genes usually compete in a coevolutionary arms race with reciprocal effectors to confer strain-specific resistance to pathogens or herbivorous insects.Here, we investigate the specificity of SLI1, a recently identified R gene in Arabidopsis that encodes a small heat shock-like protein involved in resistance to Myzus persicae aphids. In a panel with several aphid and whitefly species, SLI1 compromised reproductive rates of three species: the tobacco aphid M. persicae nicotianae, the cabbage aphid Brevicoryne brassicae and the cabbage whitefly Aleyrodes proletella. Electrical penetration graph recording of aphid behaviour, revealed shorter salivations and a 3-to-5-fold increase in phloem feeding on sli1 loss-of-function plants. The mustard aphid Lipaphis erysimi and Bemisia tabaci whitefly were not affected by SLI1. Unlike the other two aphid species, L. erysimi exhibited repetitive salivations preceding successful phloem feeding, indicating a role of salivary effectors in overcoming SLI1-mediated resistance. Microscopic characterization showed that SLI1 proteins localize in the sieve tubes of virtually all above-and below-ground tissues and co-localize with the aphid stylet tip after penetration of the sieve element plasma membrane. These observations reveal an unconventional R gene that escapes the paradigm of strain specificity and confers broad-spectrum quantitative resistance to phloem-feeding insects.

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Cell Biology of Sieve Element–Companion Cell Complexes

Cited by 3 publications

References 199 publications

SIEVE ELEMENT-LINING CHAPERONE1 Restricts Aphid Feeding on Arabidopsis during Heat Stress

SIEVE ELEMENT-LINING CHAPERONE1 Restricts Aphid Feeding on Arabidopsis during Heat Stress

Defenses against Virus and Vector: A Phloem-Biological Perspective on RTM- and SLI1-Mediated Resistance to Potyviruses and Aphids

SLI1 confers broad‐spectrum resistance to phloem‐feeding insects

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