New insights into the evolution of the first angiosperms

About 130 years ago, Charles Darwin described the origin of flowering plants (otherwise known as angiosperms) as a very mysterious thing, which until today the scientific world has yet to find out. answer.

A recent study by the University of Florida appeared in the online materials of the National Academy of Sciences, revealing the mystery of the shape of the first flowering plants (or angiosperms) and how they evolved from non-flowering plants (or gymnosperms) into flowering plants.

'No previous plants and later like them. The origin of this flower is the key to finding the source of the angiosperms (flowering plants), 'said Andre Chanderbali, the research author's group and collaborator of the History Museum. Natural Floria said.

Pam Soltis, co-author of the study and also in charge of molecular classification and evolutionary genetics at the Florida Museum, said: "The goal of this study is to learn about the original regulatory mechanism." The trend of genetic modification has made the first flowering plant species appear in the ancient flora community.

Flowering plants are an important breakthrough of evolution. The result of this breakthrough is probably the emergence of about 400,000 angiosperm species. Before angiosperms appeared, gymnosperms dominated the world of seed plants. Coniferous plants have a conical structure, not a flower. These include pine, sagu palm and ginkgo tree. The first fossil found in gymnosperms dates to about 360 thousand years.

A new study has shed light on flowering plants that have evolved from an intermediate form of gymnosperms and angiosperms, and then diversified into the flowering plants we see. nowadays.

The study compared the genetic structure of two angiosperm species with a big difference, to see whether the evolutionary differences produced different species of angiosperms. The researchers examined the gene circulation of Arabidopsis thaliana, a small flowering plant commonly used as a specimen in the study of plant and pear plant genes (Persea Americana), an ancient variety. of typical angiosperms.

The flowers of the pear tree (Persea americana) bear many characteristics of ancient (non-flowering) plant seeds. Petals with vivid colors and blue calyx combine into one part. A recent study conducted by researchers at the University of Florida gave a better insight into how non-flowering plants evolved into flowering plants 130 thousand years ago. . (Photo: University of Florida)

Mr. Chanderbali said: 'Although fossilized, the pear flower still carries the gene message, that the genetic structure of pear flowers allows them to evolve from gymnosperms into angiosperms.'

High-level angiosperms have 4 organs: the ovule, stamens, petals (often showy) and calyx (usually green). Low-level angiosperms often have three parts: the ovule, stamen, and tepal (a petal-like part). Researchers have predicted that each part of the pear plant has a different genome . However, contrary to that prediction, there are many similarities between these 3 agencies.

'From the point of view of genetic evolution, even though the parts that are developing to eventually become different parts, there are more similarities between them than we often think.' Chanderbali said. 'Going back to the past, those distinct boundaries are very faint.'

'With these established facilities, we can now think of large spaces, open to natural selection to establish increasingly clear boundaries', Virginia Walbot, Biology professor at Stanford University, who is very knowledgeable about this research, said. The selection process leads to a 'narrow solution - in terms of 4 discrete parts - but along with the variety of parts, shapes and colors; provide certain patterns for each angiosperm species. '

Soltis said: Scientists do not know exactly which varieties of gymnosperms have evolved into angiosperms. However, precious studies suggest that a certain genetic mechanism in gymnosperms has changed to create the first flower. The male and female fruits of the pine tree are on 2 different trees. In contrast, both the male and female reproductive organs of the angiosperms are on the same flower. However, the male fruit of the pine tree has almost all of the parts that a single seed flower has, in terms of genetics.

Douglas Soltis, head of the Department of Plant Science at the University of Florida, emphasized that this study highlights the importance of studying primitive seed plants such as pear trees to gain a better insight into the period. early in the history of growing angiosperms. Ancient tree varieties that exist until now are an important link to the first angiosperms. They bring insights that only research on their descendants like Arabidopsis will not be possible.

References:
Chanderbali et al.Transcriptional signatures of ancient floral developmental genetics in avocado (Persea americana; Lauraceae).Proceedings of the National Academy of Sciences, 2009;DOI: 10.1073 / pnas.0811476106