Elucidation of the Mechanisms of Long-Distance mRNA Movement in aNicotiana benthamiana/Tomato Heterograft System

Abstract

Recent heterograft analyses showed that large-scale messenger RNA (mRNA) movement takes place in the phloem, but the number of mobile transcripts reported varies widely. However, our knowledge of the mechanisms underlying large-scale mRNA movement remains limited. In this study, using a /tomato () heterograft system and a transgenic approach involving potato (), we found that: (1) the overall mRNA abundance in the leaf is not a good indicator of transcript mobility to the root; (2) increasing the expression levels of nonmobile mRNAs in the companion cells does not promote their mobility; (3) mobile mRNAs undergo degradation during their movement; and (4) some mRNAs arriving in roots move back to shoots. These results indicate that mRNA movement has both regulated and unregulated components. The cellular origins of mobile mRNAs may differ between herbaceous and woody species. Taken together, these findings suggest that the long-distance movement of mRNAs is a complex process and that elucidating the physiological roles associated with this movement is challenging but remains an important task for future research.

A universal pipeline for mobile mRNA detection and insights into heterografting advantages under chilling stress

“…Large-scale investigations of RNA-Seq data have shed light on mb-mRNAs in various heterografting systems [10][11][12][13][14] . In recognition of the key technical constraints in mb-mRNA detection from previous studies, we propose an improved analytical pipeline to address them.…”

“…Some studies have focused only on unidirectional mRNA mobilization. For example, 1163 mRNAs were detected as moving from scion to rootstock in a Nicotiana benthamiana/tomato heterograft 12 ; a much larger number (346) were detected as moving from rootstock to scion in a cucumber-watermelon heterograft 13 ; strikingly, only 138 mRNAs were identified as mobile from rootstock to scion in an Arabidopsis/N. benthamiana heterograft 14 .…”

m5C Methylation Guides Systemic Transport of Messenger RNA over Graft Junctions in Plants

“…In plants, intercellular communication involves a high number of phloem-delivered proteins and RNAs, such as distinct micro-RNAs (miRNA), short interfering RNAs (siRNAs), and messenger RNAs (mRNAs). In different plant species, such as Arabidopsis thaliana (Arabidopsis), Vitis vinifera (grapevine), and Cucurbitaceae (cucumber, watermelon), thousands of protein-encoding mRNAs move over graft junctions to distant plant regions [1][2][3][4]. In watermelon/cucumber, Nicotiana benthamiana/tomato, and Arabidopsis ecotype heterografts, hundreds of mRNAs are constitutively transferred to specific plant parts or in response to specific stress conditions [1][2][3].…”

Plant lncRNAs are enriched in and move systemically through the phloem in response to phosphate deficiency

“…Recent studies have provided evidence that thousands of mRNAs can move long distance between various tissues in Arabidopsis , cucumber, tomato and grape (Thieme et al ; Yang et al ; Zhang et al ; Xia et al ). In these plants, such mobile mRNAs accounted for a large portion of the local mRNA population.…”