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​2021 Lee M. Hutchins Award

This award is presented ​to the author or authors of published research on basic or applied aspects of diseases of perennial fruit plants (tree fruits, tree nuts, small fruits, and grapes, including tropical fruits, but excluding vegetables).

Rodrigo Almeida was born in Piracicaba, Brazil, and obtained his B.S. and M.S. degrees at the University of São Paulo, Brazil, in agronomy in 1997 and entomology in 1999, respectively, before obtaining his Ph.D. degree in environmental science policy and management at the University of California, Berkeley (UC Berkeley) in 2002. After serving as an assistant professor in the Department of Plant and Environment Protection Sciences at the University of Hawaii at Manoa from 2003 to 2005, he started his current position at UC Berkeley in 2006, where he has now risen to the rank of professor. At Berkeley, Almeida leads a group of motivated, multidisciplinary undergraduate and graduate students, as well as researchers and visiting scholars; his group also collaborates with various groups nationally and internationally to address pressing issues in his area of expertise.

Almeida has made many seminal contributions to the understanding of the biology and ecology of insect-transmitted plant pathogens, with a focus on diseases of various fruit and nut trees and grapes. He is perhaps best known for his work on the complexity of insect transmission and plant colonization by Xylella fastidiosa, which is responsible for Pierce's disease of grapevines and other diseases in the United States, as well as citrus variegated chlorosis and coffee leaf scorch in Brazil. He also has made important contributions to our understanding of the viral complex associated with grapevine leafroll disease. Of the 83 manuscripts he has published on these topics in the last 10 years, 19 have appeared in APS journals (discussed here).

It has been through his pioneering genomic sequencing and phylogenetic analyzes of the diversity of X. fastidiosa strains that Almeida has provided insights as to the origin and mechanisms of the spread of this pathogen, which has now spread from the New World to southern Europe, where it has caused olive quick decline syndrome in Italy, as well as almond leaf scorch in Spain and France. His work has shown that the evolution of variants of X. fastidiosa has been facilitated by its propensity to undergo interstrain homologous recombination, thereby increasing its genetic diversity and its ability to adapt to different hosts and vectors. His demonstration that X. fastidiosa is highly naturally competent, enabling it to acquire DNA sequences from other strains, has provided great insights into the mechanisms of how this pathogen has rapidly evolved to exploit new habitats into which it is introduced. As the leader in the ecology and epidemiology of X. fastidiosa, Almeida has been invited to write review articles on this topic for Science, Annual Review of Phytopathology, and other journals and has played a major role in guiding research on this pathogen in Europe and informing European policies for the containment and control of this pathogen.

Much of what we know of the interactions of the pathogen with both the plant and insect have come from Almeida's group. Almeida's earlier work described the localization of the pathogen within insect vectors after acquisition from infected plants and the biological and ecological processes impacting vector transmission rates. He has recently published several important papers describing pathogen features such as adhesins, extracellular polysaccharides, and the quorum-sensing system of the pathogen that modulate the attachment of the pathogen to insects—a process required for its acquisition that is also subsequently suppressed to enable it to move and cause disease in plants. It was through his detailed studies of the factors required for X. fastidiosa to bind to insect mouthparts that he was able to demonstrate that insect transmission of this pathogen could be blocked by providing pathogen-derived peptides that could competitively bind to the insect, thus preventing pathogen acquisition. These several findings offer great potential for novel means of management of X. fastidiosa, for which neither bactericides nor insecticides are effective. Almeida's methods of interrogating the pathogen while it is within the plant and insect have provided unparalleled understanding of its biology and interactions with its plant and insect hosts. For example, he has developed an ingenious method for assessing the growth rate of X. fastidiosa within plants and other settings that is determined based on one time point alone. Almeida is clearly one of the very few individuals in the world who has provided such detailed understanding of the interaction between plant pathogenic bacteria and insect vectors.

Almeida has also contributed significantly to our understanding of the epidemiology of diseases caused by X. fastidiosa. His combination of modeling and experimental studies of the complex pathogen-plant-vector interactions has demonstrated a relatively small effect of vine-to-vine spread of the pathogen between grape plants within seasons in the Pierce's disease system. Likewise, he has showed that there is no evidence for successful movement of this pathogen between sympatric citrus and coffee plantings. He also has demonstrated that it is going to be difficult to anticipate the effect of a warming climate on diseases caused by vectored plant pathogens such as X. fastidiosa, because he found that while disease development within plants increased with increasing temperature the spread of the pathogen from vine to vine is suppressed by the reduced quality of the vines as feeding preferences by the insect vectors.

As if his major contributions to our understanding of X. fastidiosa biology and epidemiology was not enough to justify his nomination for this award, Almeida also has made major contributions to our understanding of grapevine leafroll disease. His publications on the diversity of viruses found within grapes, both in California and elsewhere, and findings that despite this genetic variation there is apparently no specificity in transmission by mealybug vectors have provided the information needed for a better understanding of the epidemiology of this important disease complex. Almeida is one of the few individuals in the world who has carefully addressed pathogen-vector-plant interactions to provide the information needed for development of control methods and policies required for disease management.