Ramulosis (
Colletotrichum gossypii
South var.
cephalosporioides Costa) is a fungal disease of cotton (
Gossypium hirsutum
L.) that causes damage to leaves, stems, and bolls by reducing fiber production; it can be controlled by chemical
fungicides. Geraniol is a monoterpenoid produced by some aromatic plant species whose fungicidal properties have
been widely reported.
Geraniol synthase (GES; EC 3.1.7.11) is the precursor enzyme involved in the biosynthetic
chain of geraniol.
Geraniol synthase (
ges) gene transcripts were prospected in 11 aromatic species with molecular and
phytopathological tools to identify promising accessions for further use in
in vitro and
in vivo assays involving the control
of cotton ramulosis.
Mentha pulegium
L. oil highly expressed
ges and inhibited fungal growth at 1000 μL L
-1 in an
in vitro
assay. Validation assays were carried out in two environments and
M. pulegium at 2000 μL L
-1 reduced the initial and final
severity indices of the disease to 48% and 52%, respectively, in preventive treatments; in curative assays, indices were
44% and 54%, respectively. This indicates that it is a promising bioactive compound to control cotton ramulosis.
