Tomato fruit localized phytochromes regulate chloroplast biogenesis, starch synthesis and carotenoid metabolism (J. Exp. Bot)

The earliest report about the influence of light quality in tomato fruit biology dates back to 1954, in which it was shown that red /far red light regulates fruit pigmentation reversibly. Using fruit-specific RNAi silencing of SlPHYA, SlPHYB2 or SlPHYB1/B2, Bianchetti and co-workers  have shown the different roles of these fruit-localized phytochromes. The plastids of the SlPHYA knockdown contained reduced grana compared to the WT or the other knockdowns during early fruit development. Also, the level of starch and expression of genes related to starch biosynthesis was higher in SlPHYA and SlPHYB2 knockdowns compared to the WT.  Lycopene content was also reduced in SlPHYA and SlPHYB2 knockdowns and further analysis showed that the levels of transcripts for carotenoid biosynthesis were reduced.(Summary by Cecilia Vasquez-Robinet) J. Exp. Bot. 10.1093/jxb/ery145