Phloem-Mediated Remote Control by Long-Distance Signals

Bel, Aart J. E. van; Gaupels, Frank; Will, Torsten; Kogel, Karl‐Heinz

doi:10.1007/978-3-642-18819-0_15

Cited by 1 publication

(3 citation statements)

References 128 publications

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“…The current suggestions have in common that chaperone‐conjugated macromolecules (Aoki et al ., 2002) are directed to the orifices of the PPUs with the help of docking proteins (Lee et al ., 2003; Lucas et al ., 2001). Selectivity of macromolecular traffic, which is supported by several arguments (see van Bel et al ., 2003), may be achieved through the nature of chaperones and recognition molecules at the orifices of plasmodesmal corridors (Kragler et al ., 1998, 2000; Lucas et al ., 2001; Oparka, 2004). DIR1 present in the companion cells (Ivashikina et al ., 2003) may act as macromolecular chaperone for trafficking lipid‐derived molecules through the PPUs into the phloem stream.…”

Section: Phloem‐mediated Production Release and Distribution Of Signmentioning

confidence: 74%

“…Macromolecules in the sieve tube sap encompass a range of molecules, including oligopeptides, proteins and several forms of RNA (van Bel et al ., 2003). Thus far, neither phloem proteins acting as transcription factors nor phloem‐mobile oligopeptides such as systemin have been reported to be related to SAR.…”

Section: Potential Sar‐associated Signalling Via the Phloemmentioning

confidence: 99%

“…Remote control of gene expression by phloem‐mediated long‐distance transport of RNA molecules (Jorgensen et al ., 1998) has become a hot topic in modern plant biology (e.g. van Bel et al ., 2003; Fagard and Vaucheret, 2000; Lucas et al ., 2001). Several RNA species such as mRNAs encoding for the proton‐sucrose symporter SUT1, a putative aquaporin and the H + ‐ATPase PPA1 were found in sieve tube sap of Hordeum (Doering‐Saad et al ., 2002).…”

Section: Potential Sar‐associated Signalling Via the Phloemmentioning

confidence: 99%

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Pathogen‐induced resistance and alarm signals in the phloem

Bel

Gaupels

2004

Molecular Plant Pathology

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SUMMARY Despite a long-standing notion of long-distance signals triggering systemic acquired resistance (SAR), the translocation pathway and the identity of the signals involved have not been determined with any degree of certainty. A critical assessment indicates that, in parallel to signalling via the phloem, alternative modes for SAR induction such as signalling via the xylem or air-borne signalling by volatile substances may occur. This review further evaluates several classes of compounds as being functional in systemic resistance signalling. Evidence in favour of SAR involvement of phloem-mobile substances such as salicylic acid, lipid-derived molecules, reactive oxygen species and components of the antioxidant machinery is contradictory, circumstantial or inconclusive, at best. Nitric oxide bound to proteins or thiols seems a good candidate for signalling, but has not been found in phloem sap thus far. No convincing support of the involvement in SAR of phloem-mobile substances such as calcium, oligosaccharides, peptides or RNA species, which function in other systemic signalling cascades, has yet been produced. Nevertheless, phloem-mobile macromolecules are considered as potential tools for SAR given their pivotal role in remote gene expression under stress conditions. In this framework, the existence of several cascades for signal generation along the phloem pathway is envisaged. Finally, recent methods for detection of molecular signals in phloem sap and their expression in companion cells are presented.

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