The Faculty of Life Sciences professor proposes a new hypothesis for the origin of seed programs

On August 29, 2022, at the invitation of the featured editors of the international mainstream plant science journal Frontiersin Plant Science, the article "Origins of the seed: The 'golden-trio hypothesis'" written by Bai Shunong, Professor Rao Guangyuan and their former colleagues and Professor Yang Ji of the School of Life Sciences of Fudan University was published in the journal
。

The role of seeds in human evolution is widely known
.
But how seeds originated is still poorly
known to humans.
Historically, paleontological and comparative morphological methods have been used primarily to explore possible mechanisms
for the origin of seed traits.
The paper by Bai Shunong, Rao Guangyuan, and Yang Ji reviews their work starting from molecular biology methods to explore the origin of "seed procedures" in seed traits that cannot be studied by paleontology and comparative morphology (Figures 1 and 2).

In the paper, they propose the "Golden Triangle hypothesis" (Figure 3) that seed programs integrate the results of different gene regulatory pathways that already exist during fern development (Figure 3), providing a completely new perspective on
the mechanisms of seed origin.
This hypothesis is supported by significant evidence in a recent article published in Nature Plant in the journal Clematis Fern Genome Sequencing and Evolutionary Mechanisms of Key Traits (Fang et al, 2022
).

In addition to providing a fresh perspective on the origin of seed programs, this paper also reveals a noteworthy phenomenon: in current biological research, a considerable part of the "function" of specific genes is defined based on the phenotype of mutants of these genes, and mutants often come from model organisms at the end of the evolutionary system of life (i.
e.
, living organisms
).
This definition of gene function would not bother research efforts in terms of the mechanism of phenotypic regulation of model organisms alone
.
However, recent genome sequencing studies of non-modal organisms have found that many genes that are thought to play a key role in the formation of certain important traits (such as the seeds covered herein) (such as LEC1 covered herein) are also present
in other species without related traits (such as ferns covered herein).
These findings present entirely new challenges
not only for the study of the origin of specific traits, but also for the definition and interpretation of the function of related genes.
This phenomenon deserves the great attention
of genetic function researchers.
In this paper, we make some preliminary discussions
on how to understand the relationship between genes and phenotypes in the evolutionary process.

Figure 1.
Comparison
of the morphological construction process from zygote to plant between the angiosperm Arabidopsis thaliana and the fern clematis fern.
The orange box shows the three main processes of seed procedures peculiar to seed plants: assimilates accumulation, desiccation, and dormancy.

Figure 2.
Professor John Harada of the University of California, Davis, proposed the seed program in the early 1990s
.
His term at the time was "seed maturation", seed maturation) and the view of the relationship between the process by which plant forms were built (marked by green arrows
).
This view has very important implications for the research presented in this article

Figure 3.
Illustration
of the "Golden Triangle hypothesis" of the seed program.
The three elements of the "Golden Triangle" are assimilation logistics (assimilateflow), expression of the LEC1 gene, and ABA-mediated anti-dehydration mechanism

References:

Fang YH, Qin X, Liao QG, Du R, Luo XZ, Zhou Q, Li Z, Chen HC, Jin WT, Yuan YN, Sun PB, Zhang R, Zhang J, Wang Li, Chen SF, Yang XY, Yan YH, Zhang XT, Zhang ZH, Bai SN, va de Peer Y, Lucas WJ, Huang SW, Yan JB (2022) The genome of homosporousmaidenhair fern sheds light onthe euphyllophyte evolution and defenses.
Nat.
Plant https://doi.
org/10.
1038/s41477-022-01222-x