Gray mold and powdery mildew diseases are among the most devastating
problems of grapevine growers. Thus, scientist Julia Rubio of Universidad de
Chile and colleagues developed fungi tolerant lines using two endochitinase
(ech42 and ech33)
[www.isaaa.org] genes
and one N-acetyl-â-d-hexosaminidase (nag70) gene from biocontrol agents
related to Trichoderma spp. Statistical analyses were conducted to consider
the transgene, explant origin, and plant response to both fungi in the field
and in detached leaf assays.

Out of the 103 GM 'Thompson Seedless' lines (568 plants) that were
established in open field in 2004 and evaluated for fungal tolerance
starting in 2006, 19 lines consistently exhibited excellent fungal tolerance
for two years. Plants from these lines were grafted onto the rootstock
Harmony and established in the field in 2009 for further characterization.

Further analyses showed that the most tolerant candidates expressed the
ech42-nag70 double gene construct and the ech33 gene from a local Hypocrea
virens isolate. Gray mold growth assays in Petri dishes supplemented with
berry juices extracted from the most tolerant individuals of the selected
population was inhibited. Based on the findings, the expression of the three
genes from biocontrol agents can confer fungal tolerance in grapevines.

[link.springer.com]
[link.springer.com]