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


Discovery of new ginger species spices up African wildlife surveys

Scientists from Wildlife Conservation Society (WCS) have discovered a new species of wild ginger, spicing up a wave of recent wildlife discoveries in the Kabobo Massif - a rugged, mountainous region in Democratic Republic of Congo.

Strong interaction between herbivores and plants

In the past decades, we have seen a dramatic decline in biodiversity around the world. Every day, species are irrecoverably lost on an unprecedented scale. This also has an impact on the stability and productivity of ecosystems. Hence it is indispensable to understand the mechanisms that impact biodiversity, particularly in the case of primary producers such as algae and plants that form the basis of nearly all natural food webs and ecosystems.

Scientists follow seeds to solve ecological puzzle

What bothers a plant? Why are some plants rare while others are common? Are the rare plants simply adapted to rare habitat or are they losing the competition for habitat? Are their populations small but stable, or are they dwindling?