A "developmental hourglass" in fungi.
The "developmental hourglass" concept suggests that intermediate developmental stages are most resistant to evolutionary changes and that differences between species arise through divergence later in development. This high conservation during middevelopment is illustrated by the "waist" of the hourglass and it represents a low probability of evolutionary change. Earlier molecular surveys both on animals and on plants have shown that the genes expressed at the waist stage are more ancient and more conserved in their expression. The existence of such a developmental hourglass has not been explored in fungi, another eukaryotic kingdom. In this study, we generated a series of transcriptomic data covering the entire lifecycle of a model mushroom-forming fungus, Coprinopsis cinerea, and we observed a molecular hourglass over its development. The "young fruiting body" is the stage that expresses the evolutionarily oldest (lowest transcriptome age index) transcriptome and gives the strongest signal of purifying selection (lowest transcriptome divergence index). We also demonstrated that all three kingdoms-animals, plants, and fungi-display high expression levels of genes in "information storage and processing" at the waist stages, whereas the genes in "metabolism" become more highly expressed later. Besides, the three kingdoms all show underrepresented "signal transduction mechanisms" at the waist stages. The synchronic existence of a molecular "hourglass" across the three kingdoms reveals a mutual strategy for eukaryotes to incorporate evolutionary innovations.
School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Xuanjin
X
Cheng
Simon F.S. Li Marine Science Laboratory of School of Life Sciences and Center of Soybean of State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Jerome Ho Lam
JH
Hui
School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Yung Yung
YY
Lee
School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Patrick Tik
PT
Wan Law
School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong hoishankwan@cuhk.edu.hk.
Hoi Shan
HS
Kwan
D000363:Agaricales / Q000235:genetics*; D019143:Evolution, Molecular; D048690:Fruiting Bodies, Fungal / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D046228:Microarray Analysis; D008957:Models, Genetic; D012331:RNA, Fungal / Q000235:genetics; D059467:Transcriptome
D012331:RNA, Fungal
Coprinopsis; mushroom-forming fungus; transcriptomics; “developmental hourglass”