Intercellular and systemic spread of RNA and RNAi in plants

Abstract

Plants possess dynamic networks of intercellular communication that are crucial for plant development and physiology. In plants, intercellular communication involves a combination of ligand-receptor-based apoplasmic signaling, and plasmodesmata and phloem-mediated symplasmic signaling. The intercellular trafficking of macromolecules, including RNAs and proteins, has emerged as a novel mechanism of intercellular communication in plants. Various forms of regulatory RNAs move over distinct cellular boundaries through plasmodesmata and phloem. This plant-specific, non-cell-autonomous RNA trafficking network is also involved in development, nutrient homeostasis, gene silencing, pathogen defense, and many other physiological processes. However, the mechanism underlying macromolecular trafficking in plants remains poorly understood. Current progress made in RNA trafficking research and its biological relevance to plant development will be summarized. Diverse plant regulatory mechanisms of cell-to-cell and systemic long-distance transport of RNAs, including mRNAs, viral RNAs, and small RNAs, will also be discussed.

Intercellular communication in Arabidopsis thaliana pollen discovered via AHG3 transcript movement from the vegetative cell to sperm

“…Analogously, a subset of these mRNAs might move to and be translated in sperm cells. The mechanisms for mRNA and small RNA movement in sporophytic tissues reported so far differ (11,12); therefore, we cannot make any assumptions about mechanisms for the transport of small RNAs or mRNAs between the vegetative cell and sperm cells; these mechanisms must be addressed using different experimental strategies. In conclusion, our findings document that the vegetative cell provides proteinencoding transcripts to sperm cells.…”

“…It has been proposed that small RNAs move from the vegetative cell to sperm cells (9); however, this notion has been challenged (10). Moreover, the reported mechanism of mRNA movement and small RNA movement in sporophytic tissues is different (11,12). Thus, to date there is no unequivocal evidence of intercellular mRNA communication between the vegetative cell and the sperm cells during pollen development.…”

New Biotechnological Tools for the Genetic Improvement of Major Woody Fruit Species

“…This discovery helped in understanding the regulation and coordination of tissue formation by plants, making it possible to manipulate flowering time and meiosis thereby controlling crop breeding processes. Recent studies have shown that phloem transports some specific RNA molecules to coordinate organ development (Palauqui et al, 1997 ; Melnyk et al, 2011 ; Nazim and Kim, 2013 ). Research of functional analyses of phloem shows that over 15% of the transcripts are signal transduction related (Omid et al, 2007 ).…”

“…Recent researches show that siRNA molecules derived from hairpin gene constructs can spread between cells and systemically over long distances (i.e., 1.2 m above the graft union) in woody plants (Haroldsen et al, 2012a ; Zhao and Song, 2014 ), and can induce direct epigenetic modifications at the DNA level of the recipient cells in Arabodopsis thaliana (Molnar et al, 2010 ). In addition, microRNAs and trans-acting siRNAs have been associated with the transmission of silencing signals systemically via phloem and from cell to cell through the plasmodesmata (Nazim and Kim, 2013 ; Zhao and Song, 2014 ). Compatibility is important for scion-rootstock interactions for the downward flow of photosynthesis products and upward movement of water and mineral nutrients (Aloni et al, 2010 ), as well as for the transmission of the RNAi silencing signal into the scion, and initiation of systemic silencing.…”

Estudio de la función de las proteínas de Citrus psorosis virus y Mirafiori lettuce big-vein virus

“…Si bien la localización de 54K CPsV (Haywood et al, 2002;Hyun et al, 2011;Nazim Uddin & Kim, 2013) proteoma de PD contiene proteínas de membrana con actividad tipo receptor, lo cual sugiere que el PD es una estructura que en su participa en diversos procesos celulares que involucran señalización célula-a-célula (Fernandez-Calvino et al, 2011). A su vez los PD se clasifican por el número de canales que los constituyen, si presenta sólo un canal se denomina simple, como se observa en la Figura V.1 y con más de un canal se lo llama ramificado.…”