Strigolactones positively affect ripening of tomato berries
Author(s)
Date Issued
2025
Type
conferenceObject
Abstract
Strigolactones (SLs) play a role in several plant
developmental processes through the interaction with
other phytohormones. Nevertheless, there is a lack of
information regarding their role during fruit ripening. It
is known that in grapevine berries, exogenous SLs
interact with abscisic acid-mediated accumulation of
anthocyanins. In Arabidopsis, SLs enhance ethylene
action in leaf senescence. Onset of ripening in tomato, a
climacteric fruit, is caused by a peak of ethylene, which is
linked to a previous increase in ABA content.
To investigate the effects of SLs on metabolic and
physiological processes of tomato fruits during the postharvest
phase, we applied GR24, a synthetic SL analogue,
to berries of the tomato genotypes Micro-Tom and
Butalina. Berries were collected at the ‘mature green’
stage and divided into two homogenous groups, one
injected with a solution of GR24 5 μM, and the other with
a mock solution used as reference control. The treatment
was effective in promoting a faster change of berry skin
color from green to red, particularly evident in Butalina.
GR24 treatment on Micro-Tom induced upregulation of
genes involved in lycopene (SlPDS and SlPSY1) and in
ethylene biosynthesis, such as SlACO1 and SlACS2. In
Butalina, GR24-treated berries showed up-regulation of
the same genes within 72 hours after treatment, together
with the activation of other genes involved in berry
ripening (i.e. SlCNR) and in cell-wall degradation (i.e.
SlPL). Quantification of secondary metabolites revealed
an increase in phytoene and carotene isomers, as well as
in ethylene production, and a progressive reduction of
fruit firmness in response to GR24 treatment. ABA
content and SlNCED1 transcription were negatively
affected by GR24 treatment, while ABA catabolismrelated
genes, SlCYP707A1 and SlUGT75C1, were activated
in both genotypes. To further support the findings
obtained by treatment with exogenous SL, we monitored
the maturation of genetically SL-depleted plants,
silenced for the SlCCD7 SL-biosynthetic gene in the M82
background (ccd7), compared to their WT. In agreement
with the observations on GR24-treated berries, we
observed a delay in ripening of the ccd7 berries.
Our results show that exogenous and endogenous SLs
positively affect tomato berry ripening. Since ABA levels
were negatively affected by SL, we hypothesize that ABA
sensitivity was increased, similarly as previously reported
in tomato leaves.
Conference(s)
Plant Biology Europe Congress