Deep in the tropical forests of southern China, a team of mycologists has been quietly collecting diseased and healthy leaves from bamboo, banana, grasses, and reeds. What they found on those leaves is rewriting the evolutionary story of one of agriculture’s most notorious fungal genera. In a new study published in IMA Fungus, researchers from Shandong Agricultural University and collaborating institutions describe eight brand-new species of Microdochium, resolve a long-standing taxonomic controversy, and use molecular clock analysis to trace the genus back to a birthplace in Asia roughly 49.5 million years ago during the Paleogene period.
Microdochium is not an obscure group of fungi. It is the type genus of the family Microdochiaceae, which sits within the order Xylariales and the class Sordariomycetes. Some of its members are among the most economically significant plant pathogens known to science. Microdochium nivale and M. majus cause Microdochium patch, a devastating disease of wheat and barley in cold to temperate regions that costs farmers millions annually. Other species live quietly as endophytes inside healthy plant tissues or as saprobes decomposing dead leaves, seeds, and organic litter in soil, air, and water. Currently, around 80 records are listed for the genus in Index Fungorum, but the true diversity has remained poorly understood.
The research team spent three years, from 2023 to 2025, collecting samples across four Chinese provinces: Fujian, Guangdong, Guangxi, and Hainan. They excised small fragments from the margins of leaf lesions, surface-sterilized them through a precise sequence of ethanol, sterile water, and sodium hypochlorite treatments, and cultured the fungi on potato dextrose agar at 25 degrees Celsius in darkness. Pure cultures were obtained by picking hyphal tips from colony peripheries, and every isolate was photographed, measured, and preserved in 10% sterilized glycerol at 4 degrees Celsius. Voucher specimens now reside in the Herbarium of the Department of Plant Pathology at Shandong Agricultural University, with ex-type living cultures deposited in the Shandong Agricultural University Culture Collection and the China General Microbiological Culture Collection Center.
To untangle the evolutionary relationships among these isolates, the team sequenced four genetic regions: the internal transcribed spacer (ITS), the large subunit (LSU) of the ribosomal RNA gene, the RNA polymerase second largest subunit (rpb2), and the partial beta-tubulin (tub2) gene. These four loci were concatenated into a single alignment of 3,096 characters, of which 910 were parsimony-informative. Maximum likelihood analysis was conducted in RAxML-HPC2 with 1,000 rapid bootstrap replicates, while Bayesian inference was performed in MrBayes using Markov chain Monte Carlo algorithms over 3.42 million generations. The resulting phylogeny placed 142 strains into 70 species, with Muscodor species serving as outgroups to root the tree.
The phylogenetic analysis revealed something unexpected. A recently proposed genus called Macroidriella, established in 2024 based on its lunate and curved conidia, clustered firmly within Microdochium rather than outside it. The problem, the researchers argue, is that lunate and curved conidial shapes were already known to occur naturally within Microdochium since its original description by Sydow in 1924. Conidial morphology alone, they conclude, does not justify treating Macroidriella as a separate genus. Based on phylogenetic placement, divergence time estimation, and morphological comparisons, the team formally synonymized Macroidriella under Microdochium, transferring its type species as a new name, Microdochium danzhouense. This decision streamlines the family to a stable five-genus system comprising Peglionia, Idriella, Microdochium, Selenodriella, and Xenoidriella.
Among the eight new species described are Microdochium bambusicola from bamboo leaves in Hainan’s Diaoluoshan forest, M. guangdongense from banana leaves in Guangdong Province, M. ledongense from bamboo in Jianfengling National Forest Park, M. microstegii from the invasive grass Microstegium vimineum, M. nigrum from black bamboo, M. setariae and M. viridis both from foxtail grass, and M. vulgaris from common bamboo. Each new species was validated not only by DNA sequence differences, which ranged from 28 to 246 nucleotides compared to their closest relatives, but also by measurable morphological distinctions in conidiogenous cell dimensions, conidiophore length, and conidial size. A pairwise homoplasy index (PHI) test conducted on seven clades confirmed no significant genetic recombination within any of the newly proposed species, with p-values of 1.0 across the board, providing robust statistical support for their genetic distinctness.
To estimate when these fungi first diverged from their ancestors, the team employed BEAST v.2.7.7 with a relaxed clock log-normal model and a Yule speciation prior. Three fossil calibration points were used: Xylaria antiqua and Paleopyrenomycites devonicus representing the divergence of Xylariaceae and Pezizomycotina respectively, alongside a crown age offset of 153 million years for the order Xylariales. Four independent Markov chain Monte Carlo chains of 100 million generations were run, with convergence verified using Tracer v.1.7.2. The results showed that the main Microdochium clade emerged with a mean stem age of 56.0 million years ago and a mean crown age of 49.5 million years ago, with 95% highest posterior density intervals of 44.9 to 68.1 and 38.8 to 61.2 million years respectively, placing the origin squarely in the Paleogene period.
That timing is biogeographically significant. The Paleogene was characterized by a globally warmer climate, with tropical to subtropical vegetation widely distributed across continents. Land bridges connected Asia to Europe, while other connections facilitated dispersal toward Oceania. The researchers used the Reconstructing Ancestral State in Phylogenies (RASP) software with a Bayesian Binary Markov chain Monte Carlo method to reconstruct the historical biogeography of the genus across five geographic areas: Asia, Europe, Africa, Oceania, and South America. The analysis identified at least 17 dispersal events and 14 vicariance events shaping the current distribution of Microdochiaceae. The results point unambiguously to Asia, particularly Southeast Asia, as the most likely center of origin for the genus.
Today, the numbers still tell that story. Of the known Microdochium species, 40 have been found in Asia, 6 in Europe, 2 in Africa, 6 in Oceania, and 3 in South America. Asia remains the undisputed center of diversity for the genus. The researchers suggest that long-distance dispersal mechanisms, including wind currents, ocean currents, hurricanes, monsoons, animal vectors, and human migration, likely drove the colonization of other continents from this Asian epicenter. During the Neogene period, the Africa-Asia collision via the Arabian Peninsula may have facilitated dispersal from Asia to Africa, while the collision of the Indian and Eurasian plates influenced species dispersal, vicariance, and extinction across the region.
The implications of this work extend far beyond taxonomy. By establishing a stable five-genus framework for Microdochiaceae grounded in molecular phylogenetics, morphology, and divergence time estimation, the study provides a robust foundation for future evolutionary research on this agriculturally important fungal family. It also lays the groundwork for understanding how plant-pathogenic, endophytic, and saprobic lifestyles have evolved and diversified over nearly 50 million years. The researchers emphasize that tropical and subtropical regions, especially in Africa, Oceania, and South America, remain markedly undersampled and are confidently predicted to harbor significant undiscovered diversity within Microdochium. As climate change continues to reshape agricultural landscapes worldwide, understanding the evolutionary history and biogeographic patterns of these fungi becomes increasingly urgent for predicting disease emergence and managing crop protection strategies across the globe.
Subject of Research: Microdochium phylogeny, divergence times and biogeography
Article Title: Multilocus phylogeny, morphology and taxonomy of Microdochium ( Microdochiaceae ) : insights into evolutionary divergence times and historical biogeography
Article References: Liu, Q., Shang, Y., Yuan, J., Zhang, Z., Ai, C., Xia, J., Zhang, X., & Li, Z. (2026). Multilocus phylogeny, morphology and taxonomy of Microdochium (Microdochiaceae): insights into evolutionary divergence times and historical biogeography. IMA Fungus, 17, Article e191909. https://doi.org/10.3897/imafungus.17.191909
Image Credits: AI Generated
DOI: 10.3897/imafungus.17.191909
Keywords: Multilocus, phylogeny, morphology, taxonomy, Microdochium, Microdochiaceae, insights, evolutionary, divergence, times, historical, biogeography
News Source: Roger Howard. (October 17, 2026). Ancient Fungal Family Traced Back to Asia Reveals Eight New Species and a 49-Million-Year-Old Origin. Scienmag.
