Evolution of growth-promoting plant hormones

Abstract

Abstract. The plant growth hormones auxin, gibberellins (GAs) and brassinosteroids (BRs) are major determinants of plant growth and development. Recently, key signalling components for these hormones have been identified in vascular plants and, at least for the GAs and BRs, biosynthetic pathways have been clarified. The genome sequencing of a range of species, including a few non-flowering plants, has allowed insight into the evolution of the hormone systems. It appears that the moss Physcomitrella patens can respond to auxin and contains key elements of the auxin signalling pathway, although there is some doubt as to whether it shows a fully developed rapid auxin response. On the other hand, P. patens does not show a GA response, even though it contains genes for components of GA signalling. The GA response system appears to be more advanced in the lycophyte Selaginella moellendorffii than in P. patens. Signalling systems for BRs probably arose after the evolutionary divergence of the mosses and vascular plants, although detailed information is limited. Certainly, the processes affected by the growth hormones (e.g. GAs) can differ in the different plant groups, and there is evidence that with the evolution of the angiosperms, the hormone systems have become more complex at the gene level. The intermediate nature of mosses in terms of overall hormone biology allows us to speculate about the possible relationship between the evolution of plant growth hormones and the evolution of terrestrial vascular plants in general.

Unraveling the Evolution of Auxin Signaling

“…Chlorophyta appear to encode at least some of the proteins necessary for auxin biosynthesis and metabolism, which correlates with auxin measurements in members of this division of green algae (Cooke et al, 2002;Lau et al, 2009;Ross and Reid, 2010). On top, putative auxin transport proteins such as AUX1-like and ABCB/PGP-like proteins appear to be present in Chlorophyta, while PIN-like proteins are only encoded in some Streptophyta.…”

“…As summarized recently, various measurements showed that auxin is present in several kingdoms and in a wide range of organisms, including several single-celled and multicellular green algae (Cooke et al, 2002;Lau et al, 2009;Ross and Reid, 2010). Recently, an in silico survey of components of auxin signaling, such as biosynthesis, conjugation, response, and transport, showed that IAA biosynthesis genes from land plants have orthologs in the brown alga Ectocarpus siliculosus Le Bail et al, 2010), and even several bacteria are able to produce auxin (Costacurta and Vanderleyden, 1995).…”

“…It has been suggested that auxin signaling emerged to coordinate multicellular growth in land plants , but particular aspects of auxin biology could of course have an earlier origin. This is suggested by (1) the presence of auxin in various green, red, and brown algae (Sztein et al, 2000;Basu et al, 2002;Lau et al, 2009;Le Bail et al, 2010;Ross and Reid, 2010), (2) the circumstance that auxin seems to play a role in establishing polarity, regulating rhizoid growth, and/or controlling overall growth (Lau et al, 2009), and (3) possible alternative ways to convey an auxin response in single-celled green algae, such as AUXIN BINDING PROTEIN1 (ABP1)-or INDOLE-3-BUTYRIC ACID RESPONSE5 (IBR5)-mediated auxin responses (Lau et al, 2009;Tromas et al, 2010).…”

Mendel’s Genes: Toward a Full Molecular Characterization

“…If the mutation affected an earlier step in the somewhat long pathway, then the mutation would have been much less instructive. It turns out also that Mendel's LE gene is regulated by auxin (O'Neill et al 2010;Ross and Reid 2010), another hormone of historical interest, and arguably the most studied of the plant growth substances. Interestingly, even though gibberellins are implicated in a wide range of processes critical for plant yield, including root growth, seed development, and nodulation (e.g., Ferguson et al 2011;Ross et al 2011), Mendel's le-1 mutation has been used in agriculture for many centuries.…”

Cloning and Identification of an ACO Gene Involved in Ethylene Production Pathway from Ginkgo biloba

“…A simplified overview of the pathway is presented in figure 1. The number of sequenced lower plant genomes has increased extensively in the past few years, providing opportunities to trace the evolutionary origins of biosynthetic and signaling pathways of plant hormones (Ross and Reid, 2010;Ju et al, 2015). The ethylene biosynthetic pathway, which includes three key enzymes reactions, has been well-documented in higher plants.…”