Figure legends
Figure 1. Effects of E -2-hexenal (0.5 μL
L-1, 2.5 μL L-1, 12.5 μL
L-1, 25 μL L-1 E2H liquid volume /
sealed space volume) and ethylene (12 mg L-1) on
tomato colour development at 0 h and 72 h after treatment (A). Effects
of E -2-hexenal (12.5 μL L-1) on the
longitudinal section appearances (B) and the surface colour
characteristics (C) of the tomatoes at 72 h. The storage temperature was
at 20 oC.
Figure 2. The Photos of tomato treated with E -2-hexenal
(E2H) (24 h), ethylene (ET) (24 h), ET (12 h) and then E2H (12 h), E2H
(12 h) and then ET (12 h) and combined E2H and ET (24 h) at 72 h. The
concentrations of the treatments used were E2H (12.5 μL
L-1) and ET (12 mg L-1). The storage
temperature was at 20 oC.
Figure 3. Electron micrographs of plastids during
transformation of chloroplasts to chromoplasts at 72 h pretreated withE -2-hexenal (A-D) and the control (E and F).
Standards for four stages of the plastids were listed in the table (I).
Four stages (S1: chloroplast; S2: transition stages 1; S3: transition
stages 2 and S4: chromosome) were observed and counted in all the cells
captured. The statistically results of the proportions in S1, S2, S3 and
S4 stages at 72 h pretreated with E -2-hexenal (H) and the control
(G) were analyzed. The plastoglobules (pg) count per plastid were
compared between E -2-hexenal group and the control (J). TheE -2-hexenal treatments was 12.5 μL L-1 and the
storage temperature was at 20 oC. The inner membranes
(im), tubular elements (te), plastoglobules (pg) and crystal remnants
(cr) were marked in the photos in red arrows.
Figure 4. Effect of E -2-hexenal (2.5 μL
L-1 and 12.5 μL L-1) on the a* value
(A); the chlorophyll (B), β-carotene (C) and lycopene (D) contents
comparted to that of the control. The storage temperature was at 20oC. Each value represents the mean of three
replicates. Bars indicate the standard deviation (±SD). The lower-case
letters (a, b and c) indicates differences that are significant atP < 0.05.
Figure 5. Relative expression of the LOXCs (A) andHPLs (B) genes detected in tomato pericarps in response toE -2-hexenal (2.5 μL L-1 and 12.5 μL
L-1) and the control. The storage temperature was at
20 oC. Histograms representing the average of three
biological samples that were independently assessed. Data were
normalized relative to the β-actin -housekeeping gene and referred
to the control at time zero. Bars indicate the standard deviation (±SD).
The lower-case letters (a, b and c) indicates differences that are
significant at P < 0.05.
Figure 6. Scheme of the possible mechanisms of carotenoids
activated inner membrane structures transformation in the chloroplasts
during tomato fruit colour development.
Ten steps were shown at the yellow spots with latin numbers: (I) the
carotenoids are biosynthesis before IMS transform in the chloroplasts;
(II) the carotenoids are packed into the IMS; (III) free linolenic acids
are released from the IMS; (IV) LOXC decompose the free linolenic acids
to produce hydroperoxy-linolenic acid; (V) HPL decompose the
hydroperoxy-linolenic acid to produce E2Hs; (VI) The E2Hs are released
inside or outside the plastid; (VII) The E2Hs altered the structure of
the IMS; (VIII) the te, pg or cr structure in the chromoplasts form and
accumulate more carotenoids; (IX) The E2Hs outside one plastid transfer
to function in the neighbor plastids; (X) Excessive E2H feedback
regulates the HPL enzyme to form a balanced level.