Fruit ripening mutants reveal cell metabolism and redox state during ripening

Abstract

Ripening which leads to fruit senescence is an inimitable process characterized by vivid changes in color, texture, flavor, and aroma of the fleshy fruits. Our understanding of the mechanisms underlying the regulation of fruit ripening and senescence is far from complete. Molecular and biochemical studies on tomato (Solanum lycopersicum) ripening mutants such as ripening inhibitor (rin), nonripening (nor), and never ripe (Nr) have been useful in our understanding of fruit development and ripening. The MADS-box transcription factor RIN, a global regulator of fruit ripening, is vital for the broad aspects of ripening, in both ethylene-dependent and independent manners. Here, we have carried out microarray analysis to study the expression profiles of tomato genes during ripening of wild type and rin mutant fruits. Analysis of the differentially expressed genes revealed the role of RIN in regulation of several molecular and biochemical events during fruit ripening including fruit specialized metabolism and cellular redox state. The role of reactive oxygen species (ROS) during fruit ripening and senescence was further examined by determining the changes in ROS level during ripening of wild type and mutant fruits and by analyzing expression profiles of the genes involved in maintaining cellular redox state. Taken together, our findings suggest an important role of ROS during fruit ripening and senescence, and therefore, modulation of ROS level during ripening could be useful in achieving desired fruit quality.

Proteomics and SSH Analyses of ALA-Promoted Fruit Coloration and Evidence for the Involvement of a MADS-Box Gene, MdMADS1

“…It is well-documented that the expression of genes related to stress responses, primary and secondary metabolism, cell wall metabolism, and hormonal metabolism contribute to fruit ripening process (Shi et al, 2014; Kumar et al, 2015). Previous studies have suggested that ALA enhanced fruit maturation with a promotion of many ripening-related biological events (Watanabe et al, 2006).…”

Photo-Oxidative Stress during Leaf, Flower and Fruit Development

“…H 2 O 2 levels increase in the berry skin of grape (Vitis vinifera 'Pinot Noir') at the onset of ripening (veraison), when the most crucial events during berry ripening occur, including the change in color of the skin (Pilati et al, 2014). Studies on tomatoes also have revealed an elevation in H 2 O 2 levels during changes in color of the skin (Jimenez et al, 2002;Kumar et al, 2016). It appears, therefore, that color break during ripening is associated with increased oxidative stress in ripening fruits that is linked to a respiratory burst in the mitochondria and enhanced ROS production during chromoplast generation, which is essential for carotenoid production (Bouvier et al, 1998).…”

Arabidopsis NAC Transcription Factor JUNGBRUNNEN1 Exerts Conserved Control Over Gibberellin and Brassinosteroid Metabolism and Signaling Genes in Tomato

“…A group of genes associated with cellular oxidation and peroxidation processes, including several peroxidases ( Solyc01g006300 , Solyc03g080150 , Solyc06g076630 ), were lower expressed in AtJUB1-OX fruits. Peroxidases are considered to affect fruit softening and ripening (Kumar et al, 2016). Expression of Solyc12g005350 , encoding dihydroflavonol-4-reductase, a key gene in anthocyanin biosynthesis (Holton and Cornish, 1995), is slightly decreased in AtJUB1-OX .…”

“…Apart from ACS and ACO , a PECTIN ESTERASE gene ( Solyc06g051960 ) is repressed in AtJUB1-OX fruits compared to wild type; similarly, several pectin esterase encoding genes are repressed in the rin mutant during fruit ripening (Kumar et al, 2016). The absence of the AtJUB1 binding site in the promoters of the ripening-related genes, however, indicates indirect regulation by AtJUB1; the details of the mechanisms that underlie this regulation are currently unknown.…”