Characterization of tomato fruit ripening and analysis of gene expression in F₁ hybrids of the ripening inhibitor (rin) mutant

Abstract

The ripening inhibitor (rin) mutation of tomato yields non‐ripening fruit, and the gene corresponding to RIN, LeMADS‐RIN, is known to encode a transcriptional factor that controls ripening‐related genes. In this study, to evaluate the heterozygosity effect of rin on fruit ripening, we developed eight F1 hybrid lines of the rin mutant from various crosses between the lines of the rin mutant and wild type. In the fruit of these F1 hybrid lines, the shelf‐life was improved, but both the shelf‐life and colouring varied between the lines. We then chose one line of the F1 hybrids and investigated the physiological and transcriptional properties of the fruit. Compared with the wild‐type parent, this F1 line showed about half the lycopene content, lower fruit softening and lower mRNA accumulation of the genes that encode phytoene synthase (Psy), polygalacturonase (PG), β‐galactosidase (TBG4) and expansin (LeEXP1). The characteristic climacteric rise in ethylene production typically observed in the wild‐type parent during fruit maturation was not observed in the fruit of this F1 line. The genes that encode ethylene biosynthetic enzymes, namely 1‐aminocyclopropane‐1‐carboxylic acid (ACC) synthase (ACS2 and ACS4) and ACC oxidase (ACO1), were, however, significantly expressed in the F1 hybrid, suggesting that the post‐transcriptional regulator for activating these enzymes is affected by LeMADS‐RIN. These results suggest that the heterologous effect of LeMADS‐RIN in F1 hybrids affects the gene transcription and activation of ripening‐related factors, resulting in changes in fruit properties, including the extension of the shelf‐life.

TomatoFRUITFULLhomologs regulate fruit ripening via ethylene biosynthesis

“…Ethylene production from the fruits was measured with a gas chromatograph (Model GC8A, Shimadzu, Kyoto, Japan), as described previously. 24) Briefly, the fruit was enclosed in a 1 L chamber for 2 h, and then 1 mL of gas was withdrawn and injected into the gas chromatograph. The lycopene content of the fruits was measured by a method described previously.…”

Immunolocalization of α-Expansin Protein (NtEXPA5) in Tobacco Roots in the Presence of the Arbuscular Mycorrhizal Fungus Glomus Mosseae Nicol. & Gerd

“…Recent studies have provided evidence for a broad range of biological roles of expansins, suggesting that different expansins may play different roles in plant growth and development. Expression of expansin genes is correlated with internodal growth in deepwater rice Kende, 2001, 2002), root hair formation in Arabidopsis (Cho and Cosgrove, 2002), root elongation in soybean (Lee et al, 2003), and fruit tissue softening (Rose et al, 1997;Hiwasa et al, 2003;Trivedi and Nath, 2004;Kitagawa et al, 2005). Whether expansins have any symbiosis-specific functions is unclear; however, an expansin gene is up-regulated in nitrogen-fixing nodules (Flemetakis et al, 2004;Giordano and Hirsh, 2004).…”

Banana MaMADS Transcription Factors Are Necessary for Fruit Ripening and Molecular Tools to Promote Shelf-Life and Food Security

“…Reduction in the expression of any of these ripening-associated MADS box family members (except SlMADS1), whether by transgenic manipulation or naturally by mutation, measurably delayed fruit ripening progression (Klee and Giovannoni, 2011;Seymour et al, 2013). For example, either down-regulation of SlMADS-RIN or a spontaneous mutation, resulting in its C-terminal deletion, caused an inhibition of climacteric respiration and of ethylene production, even in heterozygote mutants, indicating that this gene acts in a dose-dependent manner upstream of ethylene production (Kitagawa et al, 2005). Tomato SlMADS-RIN exerts an ethylene-independent effect on ripening downstream of ethylene action, since exogenous application of ethylene to rin/rin tomato fruit does not restore ripening (Lincoln and Fischer, 1988;Giovannoni, 2001;Vrebalov et al, 2002).…”