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Khidir Hilu

Professor Emeritus of Biological Sciences
Hilu
5028-A Derring Hall (MC 0406)
926 West Campus Drive
Blacksburg, VA 24061

Research Program

My research has focused on the molecular systematics and evolution of flowering plants, on crop genetic resources and the molecular differentiation of genes including the allergen genes in peanuts. The research employed molecular and bioinformatic tools to tackle scientific questions in the systematics and evolution of a number of cereal and crop plants, the grass family Poaceae, angiosperms (flowering plants), land plants, and most recently, the co-evolution of land plants and fungi.  Overall, my research has resulted in authoring and co-authoring 118 peer-reviewed publications and co-editing one book.  The publications have resulted in over 7200 Google Scholar citation index and h-Index 45.  The lab was involved in approximately $7 million funded projects and has enjoyed extensive national and international collaborations that included the Assembling Tree of Life project, Fulbright, U.S. Agency for International Development, and FAO projects.  These research programs allowed me to be a major advisor for 20 Ph.D. and M.S. students, both U.S. and international, eight postdoctoral fellows, and a number of visiting scholars.  Our lab encourages the involvement of undergraduate students in research and I have mentored over 60 such students.

 

Academic News

Board of Visitors honors Khidir Hilu of Biological Sciences with emeritus status (October 1, 2017)

Khidir Hilu, professor of biological sciences in the College of Science at Virginia Tech, has been conferred the title of professor emeritus by the Virginia Tech Board of Visitors. The emeritus title may be conferred on retired professors, associate professors, and administrative officers who are specially recommended to the board by the Virginia Tech President.  He was recognized for his scholarly research and excellence in teaching, mentoring, and service.   (VT News story)

 

Recent Publications

Molecular evolution of genes encoding allergen proteins in the peanuts genus Arachis: Structural and functional implications.  2019.  PLoS ONE: 14(11): e0222440.  Hilu, K. W. Friend, Vallanadu, V., Brown, A., Hollingsworth, L. R., IV, and Bevan, D. R. ·  https://doi.org/10.1371/journal.pone.0222440

The project was initiated in Dr. Hilu’s lab where molecular and bioinformatics work were conducted and the sequence data were then provided to Dr. Bevan’s lab (Biochemistry, VT) for the homology modeling work.  Peanuts are among the top 15 crops that feed the world, but they are also among the “big eight food allergens”, and their allergenicity causes significant public health problems and life-threatening situations.  We expanded the peanut allergy research beyond the crop species by exploring frequencies and positions of natural mutations in the hyperallergenic homologues Ara h 2 and Ara h 6 in newly generated sequences for 24 of the ~ 80 Arachis wild species.  We assessed potential mutational impact on allergenicity using immunoblots and structural modeling and evaluated whether these mutations follow evolutionary trends.  The study uncovered a wealth of substitutions and gaps in those genes, including the elimination of whole immunodominant epitopes in Ara h 2.  These molecular alterations are associated with substantial changes in allergenicity.  Phylogenetic analysis revealed a progressive trend towards immunodominant epitope evolution and intensification of allergenicity driven by positive natural selection, reaching its peak in the emergence of the peanut crop on the top of the phylogenetic tree.  The findings provide valuable insight into the interactions among mutations, protein structure and immune system response, thus presenting a valuable platform for future manipulation of allergens to minimize, treat or eliminate allergenicity in peanuts as well as other crops.

plos1
Ara h 2 amino acid sequences from the peanut crop and representative Arachis wild species showing point mutations and gaps. Mutations are concentrated in the immunodominant epitopes region of Ara h 2.

Contemporaneous Radiation of Fungi and Plants Linked to Symbiosis 2018.  Nature Communications. 2018 9:5451.  François Lutzoni, Michael D. Nowak, Michael E. Alfaro, Valérie Reeb, Jolanta Miadlikowska, Michael Krug, A. Elizabeth Arnold, Louise Lewis, David Swofford, David Hibbett, Khidir Hilu, Timothy Y. James, D. Quandt, and Susana Magallón.   https://doi.org/10.1038/s41467-018-07849-9

This was a collaborative study among 12 botanists and mycologists covering the evolutionary history of plants and fungi since their movements to land some 720 million years ago. The land plant section was initially proposed by Dr. Hilu and carried out in collaboration with Susana Magallón, the National University of Mexico, and D. Quandt, the University of Bonn, Germany.  The mycology section was led by colleagues at Duke University.  The authors explored contemporaneous evolutionary events throughout the history of the two kingdoms to assess the roles of co-evolutionary mechanisms such as parasitism, mutualism, and saprotrophy in their extraordinary success on land. The data empirically ascertained the remarkable concomitant events of drastic shifts in diversification rates in the two kingdoms (see figure).  The findings convincingly underscored interactive plant-fungal co-evolution, revealed continued interdependence across their long evolutionary history, and demonstrated the crucial impact of this co-evolution on their explosive biodiversity.  Plant-fungal co-evolution has also hastened biodiversity in other living organisms and played a role in modifying the environment of our planet.  

nature
Pairwise comparison of selected land plant and fungal divergence times (node ages) posterior densities and their differences clearly reveal concomitant events in their evolution. a–l Positive age differences indicate that the fungal evolutionary event preceded the plant evolutionary event; negative age differences indicate that the plant evolutionary event preceded the fungal event.

 

Research Activities

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