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2021 APS Fellow​

​​The society grants this honor to a current APS member in recognition of distinguished contributions to plant pathology or to The American Phytopathological Society. Fellow recognition is based on significant contributions in one or more of the following areas: original research, teaching, administration, professional and public service, and/or extension and outreach.

John Hammond was born in Cambridge, England. He earned a B.S. degree in agricultural botany from the University of Reading, England, in 1976. In 1980 he received his Ph.D. degree in plant virology from the University of East Anglia, Norwich, England, for work at the John Innes Institute under the direction of Roger Hull. After postdoctoral training at Purdue University and the USDA Agricultural Research Service, Hammond joined the Florist and Nursery Crops Laboratory, USDA-ARS, Beltsville, MD, as a research plant pathologist, a position he still holds.

Befitting Hammond's long interest in applied virology, he began his research career examining viruses infecting Plantago species: common weeds and potential sources of overwintering viral inoculum. He identified eight viruses, purifying several and characterizing Plantain virus X in detail, publishing a description of the latter in the CMI/AAB Descriptions of Plant Viruses. He and colleagues recently obtained the full sequence of two of his original isolates, partial sequences of isolates he collected in 2018, and isolates from P. lanceolata from the Netherlands, Capsicum annuum originating in Ethiopia, and Browallia from Belgium, demonstrating synonymy of Plantain virus X with the later-described Actinidia virus X.

At Purdue University he developed improved purification methods for Barley yellow dwarf virus and related luteoviruses, which are important disease agents in cereals worldwide. The purified viruses were used to prepare polyclonal and monoclonal antibodies (MAbs) employed by others for epidemiological surveys and to evaluate cereal cultivar sensitivity to the viruses.

At USDA-ARS, Hammond added to and applied his cumulative knowledge, becoming recognized as a national and international authority on viruses affecting ornamentals. He utilized various techniques to purify, detect, and differentiate viruses of diverse taxonomic groups and produced reagents adopted for commercial plant virus diagnosis. Specifically, he developed purification methods for potyviruses, potexviruses, carlaviruses, and carmoviruses and characterized several previously undescribed viruses affecting ornamentals. Hammond teamed with international colleagues to identify, characterize, and produce reagents to detect Angelonia flower break virus, a novel carmovirus affecting the nursery industry and partnered with colleagues from Italy and Virginia to identify Freesia sneak virus for the first time in the United States and Bulgaria. More recently, he identified other viruses not previously known to be infecting specific ornamentals in the United States, including the devastating Plantago asiatica mosaic virus in imported lilies and Butterbur mosaic virus and Helenium virus S in veronica. The availability of purified viruses in sufficient quantity and purity enabled production of superior quality polyclonal antibodies, MAbs, and cloned cDNAs for plant virus detection, characterization, and examination of relationships between viruses. With colleague Ramon Jordan, a panel of MAbs was developed with cross-reactivity to multiple potyviruses: MAb PTY 1 reacts to almost all species and isolates of the genus Potyvirus and is used in commercial detection kits sold worldwide. In collaboration with Austrian colleagues, Hammond developed RT-PCR primers that amplify all known isolates of Plum pox virus, demonstrating that restriction fragment-length polymorphisms could distinguish isolates. With colleagues from several institutions, he secured funding to create a novel Universal Plant Virus Microarray for the detection and identification of any plant virus or viroid, validated by colleagues from the United States and several other countries.

Hammond also has actively advanced basic understanding of virus genome structure, accumulation, and spread. Hammond and colleagues cloned and sequenced the complete genomes of five potyviruses, five potexviruses, four carlaviruses, four tobamoviruses, one carmovirus, one trichovirus, and the sole recognized member of the genus Lolavirus, family Alphaflexiviridae. Infectious clones of multiple viruses were developed. With colleagues, current molecular tools, including bimolecular fluorescence complementation, were used to examine the interactions of several host proteins with viral proteins from potexviruses, tobamoviruses, and potyviruses, furthering identification of host factors involved in pathogenesis caused by these viruses. Viral determinants for silencing suppression and intercellular and vascular-mediated spread were also identified, enriching our understanding of the mechanism by which potexviruses accumulate and spread in their hosts.

In 1995, Hammond demonstrated effective resistance to a potyvirus through transgenic expression of antisense viral RNA. He and colleagues also engineered gladiolus plants for potyvirus resistance. In 1997, Hammond demonstrated that incorporation of transgene coat proteins into virions of a challenge virus was not an important factor in coat-protein-mediated resistance to potyviruses, resulting in invited review articles on transgene-derived resistance to viruses.

Hammond has demonstrated a remarkable ability to conduct and report significant, original, basic and applied research, whether as an individual or within a team. He has authored or coauthored more than 160 publications in scientific journals, books, or technical publications and has two issued patents and additional invention disclosures. He has edited or coedited three books and three conference proceedings. Hammond has trained numerous U.S. and foreign visiting scientists, and he has served on graduate student committees for Ph.D. and M.S. candidates worldwide.

Within APS, Hammond has served as vice-chair and chair of the Virology Committee and as a member of the Emerging Pathogens and Diseases, Diseases of Ornamental Plants, Plant Pathogen and Disease Detection, National Plant Disease Recovery System, and APS/APHIS Widely Prevalent Virus Committees. He organized or co-organized several APS symposia and served as an associate editor of Phytopathology. Outside of APS, Hammond chaired the ISHS International Working Group on Virus Diseases of Ornamental Plants, served as an associate and senior editor of the Journal of Plant Pathology, as a member of the Advisory Board for Archives of Virology, and on the editorial board of Virology. He chaired grant review panels for the U.S. Agency for International Development and the Binational Agricultural Research and Development (BARD) Fund. He served on the BARD Technical Advisory Committee and on an EPA Scientific Advisory Panel on virus-resistant transgenic plants. From 1999 to 2009, Hammond served as research leader of the Floral and Nursery Plants Research Unit. He has given invited talks at national and international meetings, participated in a program review at the International Potato Center in Peru, and as an invited member of an Indo-US Interactive Workshop on Plant Molecular Virology in India. Hammond, thus, has been committed to professional service to APS and phytopathology in general.