AtGRP3 is implicated in root size and aluminum response pathways in Arabidopsis

AtGRP3 is a glycine-rich protein (GRP) from Arabidopsis thaliana shown to interact with the receptor-like kinase AtWAK1 in yeast, in vitro and in planta. In this work, phenotypic analyses using transgenic plants were performed in order to better characterize this GRP. Plants of two independent knockout alleles of AtGRP3 develop longer roots suggesting its involvement in root size determination. Confocal microscopy analysis showed an abnormal cell division and elongation in grp3-1 knockout mutants. Moreover, we also show that grp3-1 exhibits an enhanced Aluminum (Al) tolerance, a feature also described in AtWAK1 overexpressing plants. Together, these results implicate AtGRP3 function root size determination during development and in Al stress

<i>AtGRP3</i> Is Implicated in Root Size and Aluminum Response Pathways in <i>Arabidopsis</i>

<div><p>AtGRP3 is a glycine-rich protein (GRP) from <i>Arabidopsis thaliana</i> shown to interact with the receptor-like kinase AtWAK1 in yeast, <i>in vitro</i> and <i>in planta</i>. In this work, phenotypic analyses using transgenic plants were performed in order to better characterize this GRP. Plants of two independent knockout alleles of <i>AtGRP3</i> develop longer roots suggesting its involvement in root size determination. Confocal microscopy analysis showed an abnormal cell division and elongation in <i>grp3-1</i> knockout mutants. Moreover, we also show that <i>grp3-1</i> exhibits an enhanced Aluminum (Al) tolerance, a feature also described in <i>AtWAK1</i> overexpressing plants. Together, these results implicate <i>AtGRP3</i> function root size determination during development and in Al stress.</p></div

<i>grp3-1</i> loss-of-function mutant analysis.

<p><b>a</b> Relative expression of <i>AtGRP3</i> transcripts analyzed through real-time quantitative PCR of Col and <i>grp3-1</i> mutant. <b>b</b> Summarized data for root length measurements of 2-week-old plants. <i>Error bars</i> indicate standard error. *** indicates p≤ 0.005 and **** indicates p≤ 0.001.</p

Confocal analysis of root cells.

<p><b>a-c Division pattern of stele cells. * labels stele rows. a</b> Col wild-type. <b>b</b> <i>grp3-1</i> individual presenting normal division pattern. <b>c</b> <i>grp3-1</i> individual presenting abnormal division pattern. <b>d</b> Counting of number of stele cell rows. <b>e</b> Root diameter measurements. <b>f</b> Cell length measurements. <i>Error bars</i> indicate standard error. * indicates p≤ 0.05, ** indicates p≤ 0.01, *** indicates p≤ 0.005 and **** indicates p≤ 0.001.</p

Relative expression of cell elongation and/or division molecular markers in Col and <i>grp3-1</i>.

<p>Quantitative real time PCR for <b>a</b> <i>COB</i> (At5g60920). <b>b</b> <i>KOR1</i> (At5g49720). <b>c</b> <i>CESA6</i> (At5g64740). <b>d</b> <i>POM1</i> (At1g05850). <b>e</b> <i>DWF1</i> (At3g19820). <b>f</b> <i>BRI1</i> (At4g39400). <b>g</b> <i>CDC48</i> (At3g09840). <b>h</b> <i>CYCB1;2</i> (At5g06150). <i>Error bars</i> indicate standard error. * indicates p≤ 0.05, *** indicates p≤ 0.005 and **** indicates p≤ 0.001.</p