posted on 2020-04-27, 14:11authored byWei Li, Wenfang Li, Shijin Yang, Zonghuan Ma, Qi Zhou, Juan Mao, Shunyu Han, Baihong Chen
Monoterpene
is one of the important sources of varietal aroma,
which provides a strong floral and fruity aroma in wines. Methyl jasmonate
(MeJA) affects plant secondary metabolism. However, the regulatory
mechanisms of monoterpene biosynthesis after MeJA application on grapes
are not illuminated. In the present study, 10 mM MeJA was used as
treatments in Italian Riesling grape at the preveraison
stage in different ways, including grape cluster soaking, foliar spraying,
and whole vine spraying, designated as T1, T2, and T3, respectively,
while a blank group was used as the control (CK). HS-SPME/GC-MS and
transcriptome sequencing analysis were performed to investigate the
effect of exogenous MeJA on monoterpene synthesis in grape berry skin.
The results of GC-MS showed that the application of MeJA induced the
accumulation of volatile monoterpenes in grape berry skin, especially
linalool, α-terpineol, and oxides. In addition, transcriptome
analysis showed that differentially expressed genes were increased
from T2 to T3 to T1 compared with CK, and significantly enriched in
JA and monoterpene synthesis pathways. T1 application significantly
upregulated the mRNA expression levels of LOX2S, AOS, OPR, and JMT involved
in the JA biosynthesis pathway, as well as DXS, HMGCR, TPS14, and α-terpineol synthesis genes involved in the monoterpene synthesis pathway compared
with T2, T3, and CK. Thus, grape cluster soaking treatment with MeJA
could greatly activate volatile monoterpene synthesis. The results
will deeply increase our understanding of the monoterpene biosynthesis
of grape berry skin in response to MeJA.