Deciphering the effect of mutations on fruit ripening quality associated gene expression pattern in spontaneous monogenic tomato mutants

To decipher the effect of spontaneous monogenic mutations on fruit ripening associated gene expression pattern, an integrated effort has been made to investigate tomato colored mutants high pigment-1(hp-1), high pigment-2^darkgreen (hp-2^dg), old gold crimson(og)^c and ripening impaired mutant ripening inhibitor (rin), during fruit ripening. Quantitative real time polymerase chain reaction was performed to assess relative transcript accumulation for carotenogenic pathway genes, ethylene anabolic genes, cell wall modifying genes and MADS-BOX transcription factor gene LeMADS-RIN. The non photomorphogenic high pigment mutant og^c was studied at the transcriptional level for the first time which provided the basis to select the mutant og^c as a suitable candidate of non-transgenic source for pigment enrichment by future development of hybrids. Regression analysis found that LeZDS and CYC-B were the sole positive contributors for lycopene and β-carotene content, respectively, and fruit firmness was negatively correlated to LeEXP, LePG, LeTBG-4, PME. Highly similar fruit firmness was observed in hp-2^dg with the mutant rin, which is desirable for extended shelf life. Expression of the major ripening regulator gene LeMADS-RIN was also induced in high pigment mutants. Future characterization of the promoter region of candidate genes may decipher unknown regulatory aspects of these mutants.