Abstract Detail

IAPT Early Career Investigator Program: Life at the Edge

Del-Bem, Luiz-Eduardo [1].

On the origins of a green planet: how land plants came to be.

The colonization of land environments by living matter is one of the key evolutionary events in the history of life on Earth. The most complex life forms we know evolved on land: mammals, birds, and flowering plants. Terrestrial life has also developed into some of the most diverse and ecologically complex communities: the rainforest ecosystems. Besides the immense scientific importance of addressing the question of how life colonized land masses, little is known about how and when this process happened. Some questions that remain to be answered are the nature of the first terrestrial ecological communities, the origins of biologically active soils, and the origin of land plants that ultimately gave rise to ancestral and extant forests. Most biologists tend to believe that the terrestrialization of plants started with early embryophytes that emerged from a group of multicellular aquatic charophycean green algae, evolving in the margins of drying pools. However, Stebbins and Hill proposed a very different hypothesis in 1980, that embryophytes emerged from unicellular charophycean green algae that colonized land environments long before the origin of embryophytes themselves. This view has been further supported by recent studies of plant cell wall evolution. Among the evidence from cell wall studies, the presence of the complete gene repertoire for xyloglucan synthesis and degradation in early-branching terrestrial charophytes from the class Klebsormidiophyceae stands out. Xyloglucan is a polysaccharide that was recently demonstrated to be released by roots and rhizoids of all groups of land plants as a sticky molecule able to modify soil properties. Xyloglucan likely evolved during the process of land colonization by early charophytes and could represent a key adaptation of photosynthetic biological soil crusts that could impact the early process of soil formation.This talk will present evidence for a new theory regarding the origin of land plants from a group of simple terrestrial charophycean green algae that was part of complex terrestrial ecosystems of microorganisms that relied on photosynthesis as carbon source, hundreds of millions of years before the first embryophytes. Emphasis will be put on the possible role of these early terrestrial communities of microorganisms as a main source of the genetic adaptations that allowed the efficient colonization of land environments by the plant lineage and eventually led to the evolution of embryophytes from terrestrial charophytes.

Related Links:
Del-Bem Lab Website

1 - Federal University of Minas Gerais, Department of Botany, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil

Keywords:
Plant terrestrialization
Genome Evolution
biological soil crust.

Presentation Type:
Session: SYM6, IAPT Early Career Investigator Program: Life at the Edge
Location: Tucson E/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 9:00 AM
Number: SYM6002
Abstract ID:1215
Candidate for Awards:None