A KNOX-Cytokinin Regulatory Module Predates the Origin of Indeterminate Vascular Plants

0508110 - ÚEB 2020 RIV US eng J - Journal Article
Coudert, Y. - Novák, Ondřej - Harrison, C.J.
A KNOX-Cytokinin Regulatory Module Predates the Origin of Indeterminate Vascular Plants.
Current Biology. Roč. 29, č. 16 (2019), s. 2743-2750. ISSN 0960-9822. E-ISSN 1879-0445
R&D Projects: GA MŠMT(CZ) LO1204; GA MŠMT(CZ) EF16_019/0000827
Institutional support: RVO:61389030
Keywords : evo-devo * indeterminacy * isopentenyl transferase * KNOX-cytokinin * plant evolution * vascular plant origins
OECD category: Biochemistry and molecular biology
Impact factor: 9.601, year: 2019
Method of publishing: Open access
http://dx.doi.org/10.1016/j.cub.2019.06.083

The diverse forms of today's dominant vascular plant flora are generated by the sustained proliferative activity of sporophyte meristems at plants’ shoot and root tips, a trait known as indeterminacy [1]. Bryophyte sister lineages to the vascular plants lack such indeterminate meristems and have an overall sporophyte form comprising a single small axis that ceases growth in the formation of a reproductive sporangium [1]. Genetic mechanisms regulating indeterminacy are well characterized in flowering plants, involving a feedback loop between class I KNOX genes and cytokinin [2, 3], and class I KNOX expression is a conserved feature of vascular plant meristems [4]. The transition from determinate growth to indeterminacy during evolution was a pre-requisite to vascular plant diversification, but mechanisms enabling the innovation of indeterminacy are unknown [5]. Here, we show that class I KNOX gene activity is necessary and sufficient for axis extension from an intercalary region of determinate moss shoots. As in Arabidopsis, class I KNOX activity can promote cytokinin biosynthesis by an ISOPENTENYL TRANSFERASE gene, PpIPT3. PpIPT3 promotes axis extension, and PpIPT3 and exogenously applied cytokinin can partially compensate for loss of class I KNOX function. By outgroup comparison, the results suggest that a pre-existing KNOX-cytokinin regulatory module was recruited into vascular plant shoot meristems during evolution to promote indeterminacy, thereby enabling the radiation of vascular plant shoot forms.
Permanent Link: http://hdl.handle.net/11104/0299098