Effect of phosphate deficiency-induced anthocyanin accumulation on the expression of Solanum lycopersicum GLABRA3 (SlGL3) in tomato.

In Arabidopsis thaliana, the bHLH transcription factor, GLABRA3 (AtGL3), is an important regulator of epidermal cell differentiation and positively controls anthocyanin accumulation. In contrast, we previously showed that Solanum lycopersicum GLABRA3 (SlGL3), the AtGL3 homolog, suppressed anthocyanin accumulation in Arabidopsis. To clarify this functional discrepancy in anthocyanin accumulation, we analyzed the SlGL3 expression pattern in anthocyanin-induced tomato. The SlGL3 expression was significantly reduced in tomato seedlings rich in anthocyanin as a result of inorganic phosphate (Pi) starvation. This was consistent with the previous result obtained in Arabidopsis, wherein the overexpression of SlGL3 was shown to inhibit anthocyanin accumulation. Our study suggests that the function of SlGL3 is different from that of AtGL3, and it might inhibit anthocyanin accumulation in tomato.