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Abstract

The aquatic fern Marsilea quadrifolia produces different types of leaves in response to changes in natural environment and culture conditions. When the conditions are in favor of producing the submerged-type leaves, exogenous application of the plant hormone abscisic acid (ABA) induces the formation of aerial-type leaves. Tissues responsive to ABA were localized to the shoot apical meristem and the associated organ primordia. From these tissues, at least two tiers of ABA-regulated early genes were identified, including seven primary genes and seventeen secondary genes. These genes, designated ABRH for ABA-responsive heterophylly, showed diverse expression patterns during the course of heterophyllous induction. Changes in the transcript level of ABRH genes started early, within 0.5-1.0 h after the addition of ABA to the culture medium. Some changes were transient while the others were persistent. The ABRHs contain extensive sequence homology to known genes, including those encoding transcription factors, protein kinases, membrane transporters, metabolic enzymes, structural proteins and those encoded by the chloroplast genome. Identification of these ABRHs is a first step toward the understanding of the regulation mechanisms of heterophylly, and the results suggest the involvement of novel metabolic and regulatory pathways in ABA-controlled morphogenesis.

Investigating the molecular basis for heterophylly in the aquatic plantPotamogeton octandrus(Potamogetonaceae) with comparative transcriptomics

“…However, few studies have investigated the molecular biological changes that occur during the course of heterophyllous transitions. Hsu et al (2001) identified several early-response ABA-regulated genes, designated ABRH (ABA-responsive heterophylly), in the aquatic fern M . quadrifolia .…”

“…Heterophylly occurs across diverse taxa and may have evolved through convergent evolution ( Minorsky, 2003 ), and thus different developmental processes and molecular mechanisms may exist among different species. Further, heterophylly within a single plant is controlled through multiple signalling pathways ( Lin & Yang, 1999 ; Hsu et al, 2001 ). Thus, additional study systems in diverse heterophyllous plants and the use of large comparative datasets generated at the whole genomic or transcriptomic levels would aid in elucidating the complex molecular mechanisms that regulate heterophylly.…”

Loss of heterophylly in aquatic plants: not ABA-mediated stress but exogenous ABA treatment induces stomatal leaves in Potamogeton perfoliatus

“…Because continuous exposure to ABA is required for the stable production of underwater leaves with stomata (Goliber and Feldman 1989; Hsu et al 2001), we examined the effects of temporary ABA treatment on stomatal formation. Plants were treated with 10 μM ABA for 4 days and transferred to ABA-free basal medium (Fig.…”

“…It has been shown that treatment with exogenous ABA (1.0–10 μM) effectively induces stomatal development, even in freshwater (Anderson 1978, 1982; Deschamp and Cooke 1983, 1984; Goliber and Feldman 1989; Kane and Albert 1987; Kuwabara et al 2003; Liu 1984). To consistently produce leaves with stomata underwater, plants must be continuously exposed to a source of exogenous ABA (Goliber and Feldman 1989; Hsu et al 2001). Even in homophyllous plants, the results of our exogenous ABA experiments are consistent with those of previous studies (Figs.…”

How Do Plants and Phytohormones Accomplish Heterophylly, Leaf Phenotypic Plasticity, in Response to Environmental Cues

“…Hence, when submerged L. arcuata leaves were brought in contact with air, the endogenous levels of ABA increased and this is presumed to initiate and induce heterophylly in L. arcuata ( Kuwabara et al, 2003 ). Interestingly, ABA application was sufficient for the formation of the terrestrial leaf form in other heterophyllous aquatic plants also ( Kane and Albert, 1987 ; Goliber and Feldman, 1989 ; Hsu et al, 2001 ). Regulation of heterophylly by ABA in many plants is not surprising, since the origin of ABA signaling pathway is thought to be ancient and is conserved in the green plant lineage ( Takezawa et al, 2011 ).…”