SRA

The tomato MADS-box FRUITFULL (FUL) homologs, FUL1 and FUL2, interact with the main ripening regulator RIPENING INHIBITOR (RIN). To clarify their role in fruit ripening, we generated FUL1/FUL2-suppressed transgenic lines by RNAi. We found that five transgenic lines bearing fruits that did not ripen normally: lycopene accumulation and increase of ethylene production were severely inhibited. We then performed next generation RNA sequencing (RNA-Seq) analysis of the fruits of a FUL1/FUL2-suppressed line (TF18) with those of the wild type (Ailsa Craig cultivar; AC) and rin mutant. The comparison of RNA-Seq data among them indicated that FUL1/FUL2-suppression significantly affected the expression of a larger portion of ripening-induced and -repressed genes than the rin mutation did. Moreover, the effect of FUL1/FUL2-suppression was observed not only in the fruits harvested at the wild type ripening age [45 days after pollination (DAP)] but also in those at the pre-ripening age (35 DAP). This suggests that the FUL homologs play an essential role in the regulation of fruit development and ripening, the role which covers a wider range of biological processes than RIN does. Differentially expressed genes (DEGs) between the wild type and TF18 fruits included known ripening-related genes such as ACS2 and ACS4 involved in ethylene production and PSY1 in carotenoid biosynthesis, consistent with the phenotype of TF18 fruits described above. The DEGs also included many direct RIN target genes, which supports the hypothesis that the FUL homologs regulate fruit ripening in a form of MADS-box complex with RIN. Overall design: mRNA profiles of wild type (Ailsa Craig cultivar), rin mutant and FUL1/FUL2-suppressed tomato fruits harvested at 35DAP and 45 DAP were generated by next generation sequencing, in triplicate, using Illumina Hiseq2000.