Lycophytes, some of the oldest terrestrial plants and related to ferns, have revealed a surprising genetic phenomenon to an international team of experts. Their research, which was just released in the PNAS journal, shows that these plants have deviated significantly from the standard in plant genetics by retaining a constant genetic structure for more than 350 million years.
Senior study author and Boyce Thompson Institute professor Dr. Fay-Wei Li stated, “The extraordinarily slow pace of genomic evolution sets these plants apart.”
“Understanding why these plants have changed so little could reveal important aspects of plant evolution and genetics.”
A class of vascular plants known as homosporous lycophytes exhibit remarkable genetic stability.
The two species that the scientists sequenced were Huperzia asiatica and Diphasiastrum complanatum. These species split off from a common ancestor roughly 350 million years ago, which is when amphibians first began to crawl on land. Remarkably, it was found that almost 30% of their genes had stayed in the same order since their split, displaying a peculiar pattern of evolution called synteny.
Dr. Li Wang, a co-author of the study, said, “This study opens a window into the past, showing us how remarkably stable the genetic makeup of these plants has been.”
“It’s like finding a living fossil at the genetic level.”
The remarkable retention of duplicated gene copies after whole genome duplication events was also noted by the scientists.
According to Dr. David Wickell, a post-doctoral researcher and co-first author of the paper, “the vast majority are lost relatively quickly through a process known as diploidization, while a handful of duplicate genes may evolve new roles.”
Nevertheless, even after hundreds of millions of years of development, the researchers discovered that these homosporous lycophytes frequently kept both sets of genes with very minor modifications.
“That homosporous lycophytes have retained so many duplicate genes and so much synteny is fascinating, a little bit surprising, and doesn’t necessarily fit with our traditional ideas of how genomes reorganise themselves after a large-scale duplication,” Wickell says. Although the exact cause of this variation is yet unknown, we think that studying homosporous plants in greater detail could yield new understandings of plant genetics and the evolution of all terrestrial plants. It also emphasises how crucial it is to protect biodiversity because these incredible plants provide important hints about the evolution of life on Earth.”