Data from: Tomato GOLDEN2-LIKE transcription factors reveal molecular gradients that function during fruit development and ripening

Fruit ripening is the summation of changes rendering fleshy fruit tissues
attractive and palatable to seed dispersing organisms. For example, sugar
content is influenced by plastid numbers and photosynthetic activity in
unripe fruit and later by starch and sugar catabolism during ripening.
Tomato fruit are sinks of photosynthate, yet unripe green fruit contribute
significantly to the sugars that ultimately accumulate in the ripe fruit.
Plastid numbers and chlorophyll content are influenced by numerous
environmental and genetic factors and are positively correlated with
photosynthesis and photosynthate accumulation. GOLDEN2-LIKE (GLK)
transcription factors regulate plastid and chlorophyll levels. Tomato
(Solanum lycopersicum), like most plants, contains two GLKs (i.e., GLK1
and GLK2/UNIFORM). Mutant and transgene analysis demonstrated that these
genes encode functionally similar peptides, though differential expression
renders GLK1 more important in leaves, while GLK2 is predominant in fruit.
A latitudinal gradient of GLK2 expression influences the typical uneven
coloration of green and ripe wild-type fruit. Transcriptome profiling
revealed a broader fruit gene expression gradient throughout development.
The gradient influenced general ripening activities beyond plastid
development and was consistent with the easily observed yet poorly studied
ripening gradient present in tomato and many fleshy fruits.