The PXY-CLE41 receptor ligand pair defines a multifunctional pathway that controls the rate and orientation of vascular cell division

Abstract

SUMMARYControlling the orientation of cell division is fundamental to the development of complex body plans. This is particularly apparent in plants, where development is determined by differential growth that results solely from changes in cell expansion and orientation of the cell division plane. Despite the fundamental importance of cell division orientation to plant development, the mechanisms regulating this process remain almost completely unknown. During vascular development, the meristematic cambial cells divide down their long axis in a highly orientated manner to generate clear files of cells. The receptor kinase PXY has previously be shown to be essential for this orientation. Here, we demonstrate that the division plane is determined by the interactions of PXY and its peptide ligand, CLE41. PXY is expressed within dividing meristematic cells of the procambium, whereas CLE41 localises to the adjacent phloem cells. Altering the pattern of CLE41 expression leads to a loss of cell division orientation and a dramatic loss of ordered vascular tissue development. By contrast, increasing phloem-specific expression of CLE41 results in more cell divisions, but the orientation of cell division is retained, leading to both increased and well-ordered vascular development. We demonstrate that PXY signalling is down-regulated by CLE41. This feedback mechanism is crucial in integrating the different roles of PXY signalling in controlling xylem differentiation, regulating the rate of vascular cell division and determining the orientation of cell division. Parallels with animal systems indicate that localised signalling from adjacent cells is a general mechanism for defining the plane of cell division.

Plant GSK3 proteins regulate xylem cell differentiation downstream of TDIF–TDR signalling

“…In hypocotyls, TDIF did not reduce xylem cell numbers (Fig. 6e), which is consistent with results reported previously 16,31,32 . This might result from a counterbalance between TDIF-dependent reduced xylem cells and ectopic xylem formation as a secondary effect arising from TDIF-induced random procambial cell proliferation (Fig.…”

Signature motif-guided identification of receptors for peptide hormones essential for root meristem growth

“…The identity of the peptide was then determined by mass spectrometry (MS; Figure 1C). The previously reported HSL2-IDA [21] and PXY-TDIF [24] pairs were successfully matched (Supplementary information, Figure S1B) using this method, validating the reliability of the screening.…”

“…Intriguingly, the RxR motif is largely conserved in this subfamily of LRR-RKs ( Figure 1B). Furthermore, several members of this LRR-RK subfamily have been shown to recognize small peptides ending with histidine or asparagine [20][21][22][23][24][25]. These findings prompted us to hypothesize that members of the LRR XI subfamily may act as receptors of small peptides with a free C-terminal histidine or asparagine.…”

RGF1 INSENSITIVE 1 to 5, a group of LRR receptor-like kinases, are essential for the perception of root meristem growth factor 1 in Arabidopsis thaliana

“…TRACHEARY ELEMENT DIFFERENTIATION INHIBITORY FACTOR (TDIF)/ CLE41/CLE44 peptide regulates vascular development in Arabidopsis. TDIF peptide derived from CLE41 or CLE44 is perceived by PHLOEM INTERCALATED WITH XYLEM (PXY), an LRR-RLK [21][22][23][24].…”