The Scientist - USA (2022 - Spring)

SPRING 2022 | THE SCIENTIST 23

LILY PECK; JULIE FLOOD/CABI

trees, which are often interplanted with

coffee crops—something that might be a

cause for concern in the future, Peck says.

She adds that understanding the genetics

of disease-causing strains could be use-

ful to coffee cultivators. Different fungal

pathogens often rely on similar genes to

bypass plants’ defenses, she notes; identi-

fying those genes and their expression pat-

terns might lead to novel solutions to com-

bat malignant fungal infections.

Helen Fones, a plant pathologist at

the University of Exeter who was not

involved with the study, praises the

researchers for the way they unraveled

the evolution of the different fungal dis-

ease strains. She says she is impressed by

the researchers’ use of a historical data set

to see long-term changes in the fungus,

and notes that the paper provides “fan-

tastically, really strong evidence” that

intercropping could promote the spread

of fungal disease—findings that could

help inform agricultural practices. Fones

adds that it would be interesting to study

how the fungus might affect wild rela-

tives of coffee crops, which may harbor

genes conferring resistance to infection

that could perhaps then be bred into the

crop varieties.

Morgan Carter, a postdoc at the Uni-

versity of Arizona who specializes in

plant-associated bacterial-fungal inter-

actions and who was not involved with

the research, notes that the study used

short-read sequencing and that long-read

sequencing could provide a clearer picture

of which genetic elements contribute to

fungal evolution. Nevertheless, the study

will help researchers think about emerg-

ing epidemics, she says. “It’s so cool to have

better reconstruction of how populations

have changed over large scales of time, or

how an organism might have differenti-

ated to be able to infect one plant a little

bit better than another plant.”

Peck is now studying the gene expres-

sion of the half-century-old F. xylarioi-

des strains as they infect coffee plants in a

controlled environment at Imperial, and

notes that it should be possible to do simi-

lar experiments with other cryopreserved

specimens. “We can use this approach to

study historic emergence of disease for lots

of different cases,” she says, adding that she

is also keen to better understand the differ-

ences between the robusta and arabica fun-

gus types. “Are they actually different spe-

cies?” she wonders. “Can we break them

down into these host-specific forms, espe-

cially to try and understand where did they

come from? How did they evolve?”

—Chloe Tenn

FUNGUS, REANIMATED: Spores of Fusarium

xylarioides

UNDER ATTACK: Trees in the Coffea genus

showing defoliation and dieback caused by

coffee wilt disease