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DTSTAMP:20240329T055330Z
UID:https://www.mpimp-golm.mpg.de/events/9979/2162
DTSTART:20170725T090000Z
DTEND:20170725T103000Z
CLASS:PUBLIC
CREATED:20170511T124153Z
DESCRIPTION:Abstract: Kiwifruit is one of the most recent successful fruit
crops on the market. Alongside the well-known green-fleshed Actinidia c
hinensis var. deliciosa ‘Hayward’\, other species with diff
erent flavour\, shape and colour (yellow and red) have been used in breedi
ng programmes to develop new cultivars. Novel coloured kiwifruit are attra
ctive to consumers\, but achieving uniform fruit pigmentation\, particular
ly in red-fleshed Actinidia chinensis var. chinensis genotyp
es\, is challenging. Colour inconsistency between fruit can affect consume
r perception\, lowering returns to growers. To investigate the cause of co
lour inconsistency we focused on a solid red-fleshed genotype characterise
d by variable outer pericarp red pigmentation\, we hypothesised that the c
arbohydrate supply could be responsible for the variation of the red flesh
colour. Early in fruit development (28 days after anthesis\, DAA) we adju
sted the leaf-to-fruit ratio of the shoots to two different carbohydrate s
upplies (standard and low). Carbohydrate import or redistribution outside
of the shoot was controlled by applying a girdle at the base of the shoot\
, and this girdle was maintained open until harvest to guarantee long-term
control of carbohydrate supply. From 84 DAA we observed a reduction in fr
uit size by about 30 percent\, dry matter was reduced by more than 20 perc
ent and colour development by more than 80 percent when fruit had low carb
ohydrate supply. Both anthocyanin and carbohydrate metabolites were affect
ed. The concentration of major non-structural carbohydrates (starch\, gluc
ose\, sucrose\, and fructose) were also reduced by more than 50 percent in
fruit with low carbohydrate supply from 84 DAA. A minor sugar\, galactose
\, was also dramatically reduced by low carbohydrate supply. By 112 DAA\,
total anthocyanin concentration in the outer pericarp of fruit with low ca
rbohydrate supply was reduced by more than 80 percent. Despite these signi
ficant changes in fruit development and metabolites\, transcription for ca
ndidate genes considered critical steps in the anthocyanin biosynthetic pa
thway (i.e. GT1\, MYB10 and bHLH5) were unchanged bet
ween fruit with the two carbohydrate supplies. Interestingly\, in low carb
ohydrate supply fruit\, a vacuolar invertase gene (INV3) was upregu
lated at 112 DAA and a beta-amylase gene (BAM9) was upregulated at
84 and 112 DAA. The upregulation of these two genes could be correlated to
the low carbohydrate supply available to the fruit and the need to deplet
e the starch stored in the fruit to support further development. This work
suggested a link between carbohydrate and anthocyanin metabolism\, and we
now have two further hypothesis to test: i) Galactose is the glycosyl moi
ety of the main kiwifruit anthocyanin measured in these fruit\, and given
that galactose content was affected by low carbohydrate supply\, repressio
n of colour development could be due to substrate limitation\; and/or ii)
Carbohydrate depletion could have an effect on an unknown repressor of the
anthocyanin pathway. We are currently performing a transcriptomic (RNAseq
) experiment to test these hypotheses and results should be available soon
.\nVortragende(r): Simona Nardozza
LAST-MODIFIED:20170606T132821Z
LOCATION:Central Building\, Raum: Seminar Room
ORGANIZER:John Lunn
SUMMARY:Simona Nardozza - The effect of long-term regulation of carbohyd
rate supply on carbohydrate and anthocyanin metabolism in a red Actindia c
hinensis var. chinensis genotype
URL:https://www.mpimp-golm.mpg.de/events/9979/2162
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