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Phloem-mobile messenger RNAs and root development.

Hannapel DJ, Sharma P, Lin T - Front Plant Sci (2013)

Bottom Line: In another example, heterografting techniques were used to identify phloem-mobile Aux/IAA transcripts in Arabidopsis.Movement assays confirmed that these Aux/IAA transcripts are transported into the root system where they suppress lateral root formation.The mechanisms of transport for these mobile RNAs, the impact they have on controlling root growth, and a potential transcriptional connection between the BEL1/KNOX complex and Aux/IAA genes are discussed.

View Article: PubMed Central - PubMed

Affiliation: Plant Biology Major, Iowa State University Ames, IA, USA.

ABSTRACT
Numerous signal molecules move through the phloem to regulate development, including proteins, secondary metabolites, small RNAs and full-length transcripts. Several full-length mRNAs have been identified that move long distances in a shootward or rootward direction through the plant vasculature to modulate both floral and vegetative processes of growth. Here we discuss two recently discovered examples of long-distance transport of full-length mRNAs into roots and the potential target genes and pathways for these mobile signals. In both cases, the mobile RNAs regulate root growth. Previously, RNA movement assays demonstrated that transcripts of StBEL5, a transcription factor from the three-amino-loop-extension superclass, move through the phloem to stolon tips to enhance tuber formation in potato (Solanum tuberosum L.). StBEL5 mRNA originates in the leaf and its movement to stolons is induced by a short-day photoperiod. Movement of StBEL5 RNA to roots correlated with increased growth and the accumulation of several transcripts associated with hormone metabolism, including GA2-oxidase1, YUCCA1a and -c, several Aux/IAA types, and PIN1, -2, and -4 was observed. In another example, heterografting techniques were used to identify phloem-mobile Aux/IAA transcripts in Arabidopsis. Movement assays confirmed that these Aux/IAA transcripts are transported into the root system where they suppress lateral root formation. Phloem transport of both StBEL5 and Aux/IAA RNAs are linked to hormone metabolism and both target auxin synthesis genes or auxin signaling processes. The mechanisms of transport for these mobile RNAs, the impact they have on controlling root growth, and a potential transcriptional connection between the BEL1/KNOX complex and Aux/IAA genes are discussed.

No MeSH data available.


Related in: MedlinePlus

Gel-shift assays of various tandem TGAC core motifs (bold, upper case nucleotides) in four putative target genes of StBEL5 and POTH1 with a range of linker sequence (lower case nucleotides) between motifs. Included here are YUCCA1c, StIPT (isopentenyl transferase), and StPIN1 and −2. The StBEL5 and POTH1 proteins were expressed and purified with a carboxyl-terminal glutatione S-transferase (GST) fusion tag. Each DNA bait was tested for binding with StBEL5-GST, POTH1-GST or GST alone or with StBEL5-GST and POTH1-GST together. Ten fm of synthesized DNA probes 50 nt in length labeled with biotin were used in the binding reaction. The amounts of StBEL5 and POTH1 proteins used in these assays were adjusted to achieve equivalent molarity. Unlabeled DNA bait at 100X, 200X, and 500X concentrations relative to the labeled probe was used in the competition assays. Arrows indicate approximate location of shifted bands.
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Figure 6: Gel-shift assays of various tandem TGAC core motifs (bold, upper case nucleotides) in four putative target genes of StBEL5 and POTH1 with a range of linker sequence (lower case nucleotides) between motifs. Included here are YUCCA1c, StIPT (isopentenyl transferase), and StPIN1 and −2. The StBEL5 and POTH1 proteins were expressed and purified with a carboxyl-terminal glutatione S-transferase (GST) fusion tag. Each DNA bait was tested for binding with StBEL5-GST, POTH1-GST or GST alone or with StBEL5-GST and POTH1-GST together. Ten fm of synthesized DNA probes 50 nt in length labeled with biotin were used in the binding reaction. The amounts of StBEL5 and POTH1 proteins used in these assays were adjusted to achieve equivalent molarity. Unlabeled DNA bait at 100X, 200X, and 500X concentrations relative to the labeled probe was used in the competition assays. Arrows indicate approximate location of shifted bands.

Mentions: To determine if the StBEL5/POTH1 complex interacts with the double elements identified in upstream sequence of the induced genes, gel-shift assays were undertaken on select targets from Table 1 and Figure 4 (Figure 6). The four cis-elements tested for binding represented three of the four strand orientations: tail-to-head for YUCCA1c, tail-to-tail for StIPT and StPIN1, and head-to-tail for StPIN2. The linker region between the TTGAC core motifs of these four elements ranges from no linkers for YUCCA1c to a 13-nt linker for the StPIN1 motif. StIPT and StPIN2 contain linkers of 2 and 4 nt, respectively. Despite the diversity in strand orientation and linker length, binding of proteins to these elements was consistently strongest for the BEL5/POTH1 complex and the StBEL5 protein alone (Figure 6). No interaction was observed with the glutatione S-transferase (GST) protein alone.


Phloem-mobile messenger RNAs and root development.

Hannapel DJ, Sharma P, Lin T - Front Plant Sci (2013)

Gel-shift assays of various tandem TGAC core motifs (bold, upper case nucleotides) in four putative target genes of StBEL5 and POTH1 with a range of linker sequence (lower case nucleotides) between motifs. Included here are YUCCA1c, StIPT (isopentenyl transferase), and StPIN1 and −2. The StBEL5 and POTH1 proteins were expressed and purified with a carboxyl-terminal glutatione S-transferase (GST) fusion tag. Each DNA bait was tested for binding with StBEL5-GST, POTH1-GST or GST alone or with StBEL5-GST and POTH1-GST together. Ten fm of synthesized DNA probes 50 nt in length labeled with biotin were used in the binding reaction. The amounts of StBEL5 and POTH1 proteins used in these assays were adjusted to achieve equivalent molarity. Unlabeled DNA bait at 100X, 200X, and 500X concentrations relative to the labeled probe was used in the competition assays. Arrows indicate approximate location of shifted bands.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3713340&req=5

Figure 6: Gel-shift assays of various tandem TGAC core motifs (bold, upper case nucleotides) in four putative target genes of StBEL5 and POTH1 with a range of linker sequence (lower case nucleotides) between motifs. Included here are YUCCA1c, StIPT (isopentenyl transferase), and StPIN1 and −2. The StBEL5 and POTH1 proteins were expressed and purified with a carboxyl-terminal glutatione S-transferase (GST) fusion tag. Each DNA bait was tested for binding with StBEL5-GST, POTH1-GST or GST alone or with StBEL5-GST and POTH1-GST together. Ten fm of synthesized DNA probes 50 nt in length labeled with biotin were used in the binding reaction. The amounts of StBEL5 and POTH1 proteins used in these assays were adjusted to achieve equivalent molarity. Unlabeled DNA bait at 100X, 200X, and 500X concentrations relative to the labeled probe was used in the competition assays. Arrows indicate approximate location of shifted bands.
Mentions: To determine if the StBEL5/POTH1 complex interacts with the double elements identified in upstream sequence of the induced genes, gel-shift assays were undertaken on select targets from Table 1 and Figure 4 (Figure 6). The four cis-elements tested for binding represented three of the four strand orientations: tail-to-head for YUCCA1c, tail-to-tail for StIPT and StPIN1, and head-to-tail for StPIN2. The linker region between the TTGAC core motifs of these four elements ranges from no linkers for YUCCA1c to a 13-nt linker for the StPIN1 motif. StIPT and StPIN2 contain linkers of 2 and 4 nt, respectively. Despite the diversity in strand orientation and linker length, binding of proteins to these elements was consistently strongest for the BEL5/POTH1 complex and the StBEL5 protein alone (Figure 6). No interaction was observed with the glutatione S-transferase (GST) protein alone.

Bottom Line: In another example, heterografting techniques were used to identify phloem-mobile Aux/IAA transcripts in Arabidopsis.Movement assays confirmed that these Aux/IAA transcripts are transported into the root system where they suppress lateral root formation.The mechanisms of transport for these mobile RNAs, the impact they have on controlling root growth, and a potential transcriptional connection between the BEL1/KNOX complex and Aux/IAA genes are discussed.

View Article: PubMed Central - PubMed

Affiliation: Plant Biology Major, Iowa State University Ames, IA, USA.

ABSTRACT
Numerous signal molecules move through the phloem to regulate development, including proteins, secondary metabolites, small RNAs and full-length transcripts. Several full-length mRNAs have been identified that move long distances in a shootward or rootward direction through the plant vasculature to modulate both floral and vegetative processes of growth. Here we discuss two recently discovered examples of long-distance transport of full-length mRNAs into roots and the potential target genes and pathways for these mobile signals. In both cases, the mobile RNAs regulate root growth. Previously, RNA movement assays demonstrated that transcripts of StBEL5, a transcription factor from the three-amino-loop-extension superclass, move through the phloem to stolon tips to enhance tuber formation in potato (Solanum tuberosum L.). StBEL5 mRNA originates in the leaf and its movement to stolons is induced by a short-day photoperiod. Movement of StBEL5 RNA to roots correlated with increased growth and the accumulation of several transcripts associated with hormone metabolism, including GA2-oxidase1, YUCCA1a and -c, several Aux/IAA types, and PIN1, -2, and -4 was observed. In another example, heterografting techniques were used to identify phloem-mobile Aux/IAA transcripts in Arabidopsis. Movement assays confirmed that these Aux/IAA transcripts are transported into the root system where they suppress lateral root formation. Phloem transport of both StBEL5 and Aux/IAA RNAs are linked to hormone metabolism and both target auxin synthesis genes or auxin signaling processes. The mechanisms of transport for these mobile RNAs, the impact they have on controlling root growth, and a potential transcriptional connection between the BEL1/KNOX complex and Aux/IAA genes are discussed.

No MeSH data available.


Related in: MedlinePlus