Root branching toward water involves posttranslational modification of transcription factor ARF7
Orosa-Puente, Beatriz ; Leftley, Nicola ; Wangenheim, Daniel von; Banda, Jason ; Srivastava, Anjil K. ; Hill, Kristine ; Truskina, Jekaterina ; Bhosale, Rahul ; Morris, Emily ; Srivastava, Moumita ; Kümpers, Britta ; Goh, Tatsuaki ; Fukaki, Hidehiro ; Vermeer, Joop E.M. ; Vernoux, Teva ; Dinneny, José R. ; French, Andrew P. ; Bishopp, Anthony ; Sadanandom, Ari ; Bennett, Malcolm J. - \ 2018
Science 362 (2018)6421. - ISSN 0036-8075 - p. 1407 - 1410.
Plants adapt to heterogeneous soil conditions by altering their root architecture. For example, roots branch when in contact with water by using the hydropatterning response. We report that hydropatterning is dependent on auxin response factor ARF7. This transcription factor induces asymmetric expression of its target gene LBD16 in lateral root founder cells. This differential expression pattern is regulated by posttranslational modification of ARF7 with the small ubiquitin-like modifier (SUMO) protein. SUMOylation negatively regulates ARF7 DNA binding activity. ARF7 SUMOylation is required to recruit the Aux/IAA (indole-3-acetic acid) repressor protein IAA3. Blocking ARF7 SUMOylation disrupts IAA3 recruitment and hydropatterning. We conclude that SUMO-dependent regulation of auxin response controls root branching pattern in response to water availability.
Quiescent center initiation in the Arabidopsis lateral root primordia is dependent on the SCARECROW transcription factor
Goh, Tatsuaki ; Toyokura, Koichi ; Wells, Darren M. ; Swarup, Kamal ; Yamamoto, Mayuko ; Mimura, Tetsuro ; Weijers, Dolf ; Fukaki, Hidehiro ; Laplaze, Laurent ; Bennett, Malcolm J. ; Guyomarc’h, Soazig - \ 2016
Development 143 (2016)18. - ISSN 0950-1991 - p. 3363 - 3371.
3D live imaging - Arabidopsis thaliana - Lateral root organogenesis - Quiescent center - SCARECROW
Lateral root formation is an important determinant of root system architecture. In Arabidopsis, lateral roots originate from pericycle cells, which undergo a program of morphogenesis to generate a new lateral root meristem. Despite its importance for root meristem organization, the onset of quiescent center (QC) formation during lateral root morphogenesis remains unclear. Here, we used live 3D confocal imaging to monitor cell organization and identity acquisition during lateral root development. Our dynamic observations revealed an early morphogenesis phase and a late meristem formation phase as proposed in the bi-phasic growth model. Establishment of lateral root QCs coincided with this developmental phase transition. QC precursor cells originated from the outer layer of stage II lateral root primordia, within which the SCARECROW (SCR) transcription factor was specifically expressed. Disrupting SCR function abolished periclinal divisions in this lateral root primordia cell layer and perturbed the formation of QC precursor cells. We conclude that de novo QC establishment in lateral root primordia operates via SCR-mediated formative cell division and coincides with the developmental phase transition.