CYP78A5 encodes a cytochrome P450 that marks the shoot apical meristem boundary in Arabidopsis

Abstract

SummaryThe normal development of shoot structures depends on controlling the growth, proliferation and differentiation of cells derived from the shoot apical meristem. We have identi®ed the CYP78A5 gene encoding a putative cytochrome P450 monooxygenase that is the ®rst member of the CYP78 family from Arabidopsis. This gene is strongly expressed in the peripheral regions of the vegetative and reproductive shoot apical meristems, de®ning a boundary between the central meristematic zone and the developing organ primordia. In addition, CYP78A5 shows a dynamic pattern of expression durinḡ oral development. Overexpression of CYP78A5 affects multiple cell types, causing twisting and kinking of the stem and defects in¯oral development. To de®ne the relationship of CYP78A5 to genes controlling meristem function, we examined CYP78A5 expression in plants mutant for SHOOT MERISTEMLESS, ZWILLE and ARGONAUTE, and have found that CYP78A5 expression is altered in these mutant backgrounds. We propose that CYP78A5 has a role in regulating directional growth in the peripheral region of the shoot apical meristem in response to cues established by genes regulating meristem function.

Dual Effects of miR156-TargetedSPLGenes andCYP78A5/KLUHon Plastochron Length and Organ Size inArabidopsis thaliana

“…Both genes are expressed at the periphery of the meristem proper and at the base of new leaf primordia (Zondlo and Irish, 1999;Miyoshi et al, 2004;Anastasiou et al, 2007). We found that CYP78A5 loss-of-function mutants had shortened plastochrons in both long and short days.…”

“…By comparing endogenous expression domains of SPL genes with the results of misexpression studies, we demonstrate that miR156 limits plastochron length in developing leaf primordia. The effects of miR156/SPLs on leaf initiation rate appear to be independent of CYP78A5/KLUH, a likely ortholog of rice PLA1 (Itoh et al, 1998;Zondlo and Irish, 1999;Miyoshi et al, 2004;Anastasiou et al, 2007). Interestingly, organ size and plastochron length are coordinately affected by both miR156/SPL and CYP78A5, suggesting either that there are common regulators of organ size and plastochron length or that these two developmental parameters reciprocally influence each other.…”

“…Genetic Interaction between miR156/SPL and CYP78A5 Our miR156 misexpression experiments indicated that miR156-targeted SPLs act predominantly in leaf primordia, while CYP78A5 is expressed in the periphery of the shoot apical meristem (Zondlo and Irish, 1999). Nevertheless, given the phenotypic similarity of Pro35S:MIR156f and cyp78a5 mutants, we wanted to test whether miR156/SPL and CYP78A5 operate in the same genetic pathway.…”

Cytochrome P450CYP78A9Is Involved in Arabidopsis Reproductive Development

“…This phenotype included large siliques and short stamens, a delay in bud opening and organ abscission, reduced fertility, a more severe phenotype in basipetal flowers, and longevity. This shared phenotype between the different genes indicates that they might act on a related metabolic network (Zondlo and Irish, 1999;Ito and Meyerowitz, 2000;Marsch-Martinez et al, 2002;Fang et al, 2012). An insertional knockout line for KLUH/ CYP78A5 showed a higher rate of leaf initiation (Wang et al, 2008).…”

“…Although the catalytic function of the Arabidopsis CYP78A enzymes remains unknown, the expression pattern and the in vivo effect of the related genes bring up their possible engagement in the biosynthesis of some unknown type of plant growth regulator (Zondlo and Irish, 1999;Ito and Meyerowitz, 2000;Anastasiou et al, 2007;Kai et al, 2009).…”