Scientists unlock genetic secrets of wine growers' worst enemy
Pest colonizes grape vines, forms root and leaf tumors, repels other
predators

Date:
July 28, 2020
Source:
University of California - Riverside
Summary:
Following a decade-long effort, scientists have mapped out the
genome of an aphid-like pest capable of decimating vineyards. In
so doing, they have discovered how it spreads -- and potentially
how to stop it.



FULL STORY ========================================================================== Following a decade-long effort, scientists have mapped out the genome
of an aphid-like pest capable of decimating vineyards. In so doing,
they have discovered how it spreads -- and potentially how to stop it.


==========================================================================
The research team's work on the genome was published this past week in
a BMC Biology paper. In it, they identified nearly 3,000 genes enabling
the insect, phylloxera, to colonize and feed on grape vines by creating
what are essentially nutritionally enhanced tumors. The insects live in
and feed off of the structures they create.

"In effect, phylloxera creates its own refrigerator on the plant that
it can feed from whenever it wants," said Paul Nabity, an assistant
professor of plant-insect ecology at UC Riverside. In addition to
feeding the insects, these structures also protect them from attack by
other parasites.

A heavy phylloxera infestation, as occurred in the Pacific Northwest last
year, could cause grapevines to lose their leaves. If the infestation
reaches the roots, the plants could die.

The tumor-like structures, known as galls, disrupt the vine's ability
to move nutrients and feed itself. They also create wounds in roots
that make grapevines more susceptible to fungi and other pathogens,
ultimately killing the vines.

Claude Rispe from the French National Institute for Agriculture, Food,
and Environment led the research team, while Nabity helped identify
how phylloxera secrete molecules that can change the immune system
of grapevines.



========================================================================== "These molecules alter the plant's defense systems and make it so that
the plant doesn't know it's being attacked," Nabity said.

When phylloxera was accidentally introduced to Europe in the 1860s,
it nearly brought French viticulture to an end, causing vines to weaken
and die. French and American scientists collaborated on a solution that
is still used today.

Native North American grapevines co-evolved with phylloxera and are now resistant to it. However, most of the grapes we eat and drink are European varieties. As a result, growers have to graft North American roots onto
their European grapevines to give them tolerance to this insect.

Though phylloxera are considered negative, not all of their effects on
plants are necessarily bad. When they feed on plants and start creating
gall structures, they change the cells in the leaf surface. Protective
cells on the leaves become tiny pores called stomata, which allow movement
of gases in and out of the cells.

"We think this is a means to reduce the negative impact on its host,"
Nabity said. "Stomata can create carbon gains for plants that can offset
how much the insects are taking from it." Now that the genes involved in
the attack on non-native grapes have been identified, it may be possible
to engineer phylloxera-resistant grapevines.

"Growers currently have to graft roots to make their plants viable,"
Nabity said. "A lot of money and effort could be saved with pest-resistant rootstocks."

========================================================================== Story Source: Materials provided by
University_of_California_-_Riverside. Original written by Jules
Bernstein. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Claude Rispe, Fabrice Legeai, Paul D. Nabity, Rosa Ferna'ndez,
Arinder K.

Arora, Patrice Baa-Puyoulet, Celeste R. Banfill, Leticia Bao,
Miquel Barbera`, Maryem Boualle`gue, Anthony Bretaudeau, Jennifer
A. Brisson, Federica Calevro, Pierre Capy, Olivier Catrice, Thomas
Chertemps, Carole Couture, Laurent Delie`re, Angela E. Douglas,
Keith Dufault-Thompson, Paula Escuer, Honglin Feng, Astrid Forneck,
Toni Gabaldo'n, Roderic Guigo', Fre'de'rique Hilliou, Silvia
Hinojosa-Alvarez, Yi-min Hsiao, Sylvie Hudaverdian, Emmanuelle
Jacquin-Joly, Edward B. James, Spencer Johnston, Benjamin Joubard,
Gae"lle Le Goff, Gae"l Le Trionnaire, Pablo Librado, Shanlin Liu,
Eric Lombaert, Hsiao-ling Lu, Martine Mai"be`che, Mohamed Makni,
Marina Marcet-Houben, David Marti'nez-Torres, Camille Meslin,
Nicolas Montagne', Nancy A. Moran, Daciana Papura, Nicolas Parisot,
Yvan Rahbe', Me'lanie Ribeiro Lopes, Aida Ripoll-Cladellas,
Ste'phanie Robin, Ce'line Roques, Pascale Roux, Julio Rozas,
Alejandro Sa'nchez-Gracia, Jose F. Sa'nchez-Herrero, Didac
Santesmasses, Iris Scatoni, Re'my-Fe'lix Serre, Ming Tang, Wenhua
Tian, Paul A. Umina, Manuella van Munster, Carole Vincent-Mone'gat,
Joshua Wemmer, Alex C. C.

Wilson, Ying Zhang, Chaoyang Zhao, Jing Zhao, Serena Zhao, Xin
Zhou, Franc,ois Delmotte, Denis Tagu. The genome sequence of the
grape phylloxera provides insights into the evolution, adaptation,
and invasion routes of an iconic pest. BMC Biology, 2020; 18 (1)
DOI: 10.1186/s12915- 020-00820-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200728113528.htm

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