Genomic Study Reveals Evolutionary Secrets of Banyan Tree and a Wasp That Coevolved With It

The banyan tree Ficus macrocarpa produces aerial roots that give it its distinctive look. A new study reveals the genomic changes that allow the tree to produce roots that spring from its branches. Credit: Photo by Gang Wang

The banyan fig tree Ficus microcarpa is famous for its aerial roots, which sprout from branches and eventually reach the soil. The tree also has a unique relationship with a wasp that has coevolved with it and is the only insect that can pollinate it.

In a new study, researchers identify regions in the banyan fig’s genome that promote the development of its unusual aerial roots and enhance its ability to signal its wasp pollinator.

The study, published in the journal Cell, also identifies a sex-determining region in a related fig tree, Ficus hispida. Unlike F. microcarpa, which produces aerial roots and bears male and female flowers on the same tree, F. hispida produces distinct male and female trees and no aerial roots.

Understanding the evolutionary history of Ficus species and their wasp pollinators is important because their ability to produce large fruits in a variety of habitats makes them a keystone species in most tropical forests, said Ray Ming, a plant biology professor at the University of Illinois, Urbana-Champaign who led the study with Jin Chen, of the Chinese Academy of Sciences. Figs are known to sustain at least 1,200 bird and mammal species. Fig trees were among the earliest domesticated crops and appear as sacred symbols in Hinduism, Buddhism and other spiritual traditions.

Ray Ming, a professor of plant biology at the University of Illinois Urbana-Champaign, led a genomic study of the banyan tree, Ficus macrocarpa, and its key pollinator, a wasp. Credit: Photo by L. Brian Stauffer

The relationship between figs and wasps also presents an intriguing scientific challenge. The body shapes and sizes of the wasps correspond exactly to those of the fig fruits, and each species of fig produces a unique perfume to attract its specific wasp pollinator.

To better understand these evolutionary developments, Ming and his colleagues analyzed the genomes of the two fig species, along with that of a wasp that pollinates the banyan tree.

“When we sequenced the trees’ genomes, we found more segmental duplications in the genome of the banyan tree than in F. hispida, the fig without the aerial roots,” Ming said. “Those duplicated regions account for about 27% of the genome.”

The duplications increased the number of genes involved in the synthesis and transport of auxins, a class of hormones that promote plant growth. The duplicated regions also contained genes involved in plant immunity, nutrition and the production of volatile organic compounds that signal pollinators.

“The levels of auxin in the aerial roots are five times higher than in the leaves of trees with or without aerial roots,” Ming said. The elevated auxin levels appear to have triggered aerial root production. The duplicated regions also include genes that code for a light receptor that accelerates auxin production.

When they studied the genome of the fig wasp and compared it with those of other related wasps, the researchers observed that the wasps were retaining and preserving genes for odorant receptors that detect the same smelly compounds the fig trees produce. These genomic signatures are a signal of coevolution between the fig trees and the wasps, the researchers report.

Ming and his colleagues also discovered a Y chromosome-specific gene that is expressed only in male plants of F. hispida and three other fig species that produce separate male and female plants, a condition known as dioecy.

“This gene had been duplicated twice in the dioecious genomes, giving the plants three copies of the gene. But Ficus species that have male and female flowers together on one plant have only one copy of this gene,” Ming said. “This strongly suggests that this gene is a dominant factor affecting sex determination.”

Reference: “Genomes of the Banyan Tree and Pollinator Wasp Provide Insights into Fig-Wasp Coevolution” by Xingtan Zhang, Gang Wang, Shengcheng Zhang, Shuai Chen, Yibin Wang, Ping Wen, Xiaokai Ma, Yan Shi, Rui Qi, Yang Yang, Zhenyang Liao, Jing Lin, Jishan Lin, Xiuming Xu, Xuequn Chen, Xindan Xu, Fang Deng, Lihua Zhao, Yi-lun Lee, Rong Wang, Xiao-Yong Chen, Yann-rong Lin, Jisen Zhang, Haibao Tang, Jin Chen and Ray Ming, 8 October 2020, Cell.
DOI: 10.1016/j.cell.2020.09.043

Ming is an affiliate of the Carl R. Woese Institute for Genomic Biology at the U. of I. The Fujian Agriculture and Forestry University, National Science Foundation and the National Natural Science Foundation of China supported this research.

BiodiversityDevelopmental BiologyEntomologyEvolutionGeneticsUniversity of Illinois at Urbana-ChampaignWasp
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  • Bob

    “New Study” aka, a ‘new’ rescue device to defend the idea that evolution is true.

    • Amelia

      Got nothing better to do than troll science websites, eh? You know it’s funny, according to the rules dry by your own religion, you’ll never get into heaven. You’re combative, rude, smug, and feel superior to others, all things that god hates and says in no uncertain terms that He will “spit you out of [His] mouth”

  • Bob

    Of course the atheistic Chinese Communist Party is a supporter of Darwin’s dumb and completely disproven idea that everything evolved.
    Except for nature, the CCP cannot have an authority higher than themselves. But in the end, bow the they will, because nothing evolved and there is a Creator to whom we must all answer to.

  • Jacob

    Evolution has been completely disproven? CCP makes us believe in evolution? Do you hear yourself Bob? Not everything is some grand conspiracy. Communism sucks and is nonsensical but evolution is real and makes way more sense than you do. Evolution wasn’t made up at all let alone to upset religious people. It explains how so many fossil species have been found while the earth still has so many species alive. You honestly believe that there was a time when every species that jas died off existed at the same time as all that still exist now? We cam force evolution and prove its validity. We dis it with dogs, cats, chickens, cows amd many other animals. Human selection in place of natural selection can show how breeding certain desired traits can drastically alter a species amd sometimes very quickly. It also happens in the wild look up pictures of some species of fish from the early to mid 1900’s and compare them to that species now. You can find various examples of evolution in action since the invention of the camera. Believe what you want but don’t act like people are leaser than or ridicule them for not be indoctrinated by the same religion or belief system as you. Happy New Year.

  • Rezo

    Wow evolution… evolution is a big step in creating, genetically modifying, or natural selection. The world is full of mystery but it cultivates its own, not only that the solar system effects evolution as well.
    It shocks me to see science and religion talk because science is forbidden knowledge yet religion practices medicine by earth remedies known for scientific use. So yes everything falls hand in hand but it does not stay their. Evolution, time, life, all will and must move on. After all Man has tainted our wisdom by topics like this nothing but God has all control so say what you want science isn’t heaven.

  • B

    Guys it can be both. I know it’s called neutral force when they’ve identified animals spawning out of step woth natural selection. In seemingly random occurrences but that is God force is God acting.

    When things mutate there’s intelligent design behind it. If u truly believe there are just super random mutations that protect a species out of nowhere you may want to reexamine your logic.

    Things happen because there’s a driving force behind it. 5 ingredients for life. 1. Force of need. 2. Power to create 3. Time (which is actually space its just replicated moments time doesn’t move it replicates and mutates according to intent of all participants. 4 space 5 a director ( concious entity applying the will to create the change)

    it’s pretty obvious. However I do agree that all religions have been massively corrupted although the force of God is in a all things, which means for those with ears to hear and eyes to see will find all the info they need to keep faith. Not in a mean angry father figure but rather the one of 4 forces that make up a human and the only one that can truly create new understandings to invite real postive change in one’s persona.

    There is also a consumer force which eats that which doesn’t work any longer like all things in nature.