Expression of nuclear and plastid genes for photosynthesis-specific proteins during tomato fruit development and ripening.

The expression of plastid and nuclear genes coding for photosynthesis-specific proteins has been studied during tomato fruit formation. The steady-state transcript levels for the large (rbcL) and small (rbcS) subunit of RuBPC/Oase, as well as the thylakoid membrane proteins, the 32 kD QB-binding protein of PS II (psbA), the P700 reaction center protein of PS I (psaA) and the chlorophyll a/b-binding protein (cab) vary at different time points during fruit development and ripening. Messenger RNA levels of plastid-encoded photosynthesis-specific genes (rbcL, psbA) are at least several fold higher, relative to respective nuclear-encoded genes (rbcS, cab). The transcript levels for the large and small subunit of RuBPC/Oase are highest in approximately 14-day-old tomato fruits, while the chl a/b-binding protein, the P700 reaction center protein and the 32 kD QB-binding protein reach their maxima in approximately 7-, 14- and 25-day-old tomato fruits, respectively. The inactivation of the photosynthesis-specific genes occurs during the first period of fruit formation. In addition, there is considerable variation in the mRNA levels of these photosynthesis-specific genes in four organs of tomato (leaves, fruits, stems, roots).