Login


The protective layer of prehistoric land plants

An international research team has discovered a biochemical pathway that is responsible for the development of moss cuticles. These waxy coverings of epidermal cells are the outer layer of plants and protect them from water loss. The biologists discovered this mechanism that facilitated the evolutionary transition of plants from fresh water to land in the moss Physcomitrella patens. The team was led by Professor Ralf Reski from the University of Freiburg/Germany and Doctor Danièle Werck-Reichhart from the Centre National de la Recherche Scientifique (CNRS) Institute of Plant Molecular Biology (IBMP) in Strasbourg/France and published their results in the journal Nature Communications.

Plant cuticles came into being more than 450 million years ago when the first plants colonized the hitherto hostile land masses. Because the waxy cuticles protect against water loss, they enabled the spread of plants on land and the subsequent evolution of our complex ecosystems. The seed plants that evolved later use similar chemical reactions to form the biopolymers lignin, cutin and suberin. Especially lignification of cell walls contributes to wood production and helps trees to grow several meters in height. In contrast, mosses do not contain lignin and are tiny. It remained unknown which biochemical pathway contributes to the protective layer on moss cells.

The researchers now found that the enzyme CYP98 from the family of cytochromes P450 plays a crucial role: While it initiates the production of lignin in seed plants, it is responsible for the development of a phenol-enriched cuticle in Physcomitrella. When they switched off the gene that is responsible for the synthesis of this enzyme, moss developed without cuticles. As a result, these moss plants were not protected against the environment and, moreover, were not able to form complex tissues: the developing organs fused and their further development was halted. The researchers could compensate this genetic defect by feeding the plants with caffeic acid, which they identified as the main component of the moss phenolic metabolism. The biologists conclude that the moss cuticle predated the evolution of lignin, cutin and suberin and may therefore originate from the last common ancestor of mosses and seed plants -- the prehistoric plants which left the fresh water to dwell on rocks and thus laid the foundation for the development of all current ecosystems on the mainland.

"Our results reveal one of the earliest evolutionary innovations that helped the first plants to survive on land over 450 million years ago," explains Reski. "It furthers suggests new biotechnology strategies for engineering biopolymers in plants beyond the well-known lignin production of trees."

Read the paper: A phenol-enriched cuticle is ancestral to lignin evolution in land plants.

Article source: University of Freiburg.

Image credit: Ralf Reski

News

How plants form their sugar transport routes

In experiments on transport tissues in plants, researchers from Heidelberg University were able to identify factors of crucial importance for the formation of the plant tissue known as phloem. According to Prof. Dr Thomas Greb of the Centre for Organismal Studies (COS), these factors differ from all previously known factors that trigger the specification of cells. The findings of the Heidelberg researchers substantially expand our understanding of the metabolic processes in plants. Their results were published in the journal Current Biology.


Scientists examine impact of high-severity fires on conifer forests

The ability of some Western conifer forests to recover after severe fire may become increasingly limited as the climate continues to warm, scientists from the Smithsonian Conservation Biology Institute (SCBI) and Harvard Forest found in a new study published in Global Change Biology. Although most of these cone-bearing evergreen trees are well adapted to fire, the study examines whether two likely facets of climate change -- hotter, drier conditions and larger, more frequent and severe wildfires -- could potentially transform landscapes from forested to shrub-dominated systems.


From Elsevier: 200 Years of Flora - free access to all articles

2018 will mark the 200th anniversary of the journal Flora. To kickstart the celebrations, all journals in the Elsevier archives have been scanned and have been added to ScienceDirect. Articles published before 1905 are available via the Biodiversity Library, and all articles from 1905 onwards are freely available via ScienceDirect until March 2020 and can be accessed through this page: https://www.journals.elsevier.com/flora/news/200-years-of-flora-free-access-to-all-articles.