Silencing SlAGL6, a tomato AGAMOUS-LIKE6 lineage gene, generates fused sepal and green petal.

KEY MESSAGE: Silencing SlAGL6 in tomato leads to fused sepal and green petal by influencing the expression of A-, B-class genes. AGAMOUS-LIKE6 (AGL6) lineage is an important clade MADS-box transcription factor and plays essential roles in various developmental programs especially in flower meristem and floral organ development. Here, we isolated a tomato AGL6 lineage gene SlAGL6 and successfully obtained several RNA interference (RNAi) lines. Silencing SlAGL6 led to abnormal fused sepals and light green petals with smaller size. The total chlorophyll content in transgenic petals increased and the morphology of epidermis cells altered. Further analysis showed that A-class gene MACROCALYX (MC) participating in sepal development and a NAC-domain gene GOBLET involving in boundary establishment were down-regulated in transgenic lines. In transgenic petals, two chlorophyll synthesis genes, Golden2-like1 (SlGLK1) and Golden2-like2 (SlGLK2), two photosystem-related genes, ribulose bisphosphate carboxylase small chain 3B (SlrbcS3B) and chlorophyll a/b-binding protein 7 (SlCab-7) were induced and three B-class genes TM6, TAP3 and SlGLO1 were repressed. These results suggest that SlAGL6 involves in tomato sepal and petal development.