Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

PHOSPHOLIPASE D, MEMBRANE DETERIORATION, AND SENESCENCE 225
YNG
INT
MG
TOR
OR
RED
(a)
YNG
INT
MG
TOR
OR
RED
YNG
INT
MG
TOR
OR
RED
(b)
Fig. 9.15 Analysis of PLD gene expression in cherry tomato fruits, control and antisense Celebrity fruits, during
development. The stages analyzed include young (YNG), intermediate (INT), mature green (MG), turning orange
(TOR), orange (OR), and red (RED). (a) Northern blot analysis of cherry fruit RNA using DIG-labeled RNA probe
synthesized for PLD alpha (top profile). The bottom profile indicates the 18S rRNA stained with ethidium bromide
to indicate loading variability of RNA. (b) Northern blot analysis of RNA samples from Celebrity tomatoes. The
top profile shows the intensity of binding with DIG-labeled RNA probe for PLD alpha. The bottom profile shows
staining intensity of 18S rRNA with ethidium bromide, indicative of loading variability. The first six lanes from
left to right are representative of RNA samples from young, intermediate, mature green, turning orange, orange,
and red stages of control Celebrity tomato fruits. The next set of six lanes (7–12) is representative of RNA samples
from equivalent developmental stages of the antisense PLD Celebrity tomato fruits. (Reproduced with permission
from Pinhero et al., 2003.)
antisense PLD Celebrity tomatoes were used in these analyses. A northern blot of RNA from
developing Celebrity tomatoes is shown in Fig. 9.15b. As with cherry tomato fruit RNA,
the PLD alpha mRNA probe showed hybridization with a 2,500-bp RNA. PLD mRNA
levels increased during development of normal fruits (Fig. 9.15b; lanes 1–6 from the left
depicting young, intermediate, mature green, turning orange, orange, and red stages) and
peaked at the orange/red stages. By contrast, in the fruits from antisense PLD Celebrity
plants, the highest level of expression was observed at the young and intermediate stages
(Fig. 9.15b; lanes 7 and 8 from the left). PLD expression progressively declined during
further development, and only trace levels of hybridization could be detected at the mature
green, turning orange, orange, and red stages (lanes 9, 10, 11, and 12 from the left). This
result conclusively showed that PLD alpha expression was reduced during fruit ripening by
the introduction of antisense PLD alpha cDNA in Celebrity tomatoes.
9.7.5 Antisense suppression of LePLDα2 in “Rutgers” tomato fruit
A study of LePLDα2 antisense suppression in the Rutgers tomato cultivar took a somewhat
different approach from that of the prior investigation of LePLDα1 antisense suppression in