High mobility group A3 enhances transcription of the DNA demethylase gene SlDML2 to promote tomato fruit ripening

Abstract

DNA methylation plays an important role in regulating tomato (Solanum lycopersicum) fruit ripening. Although SlDML2, a DNA demethylase (DML) gene, is critically involved in tomato fruit ripening, little is known about genes that regulate its expression. Using yeast one-hybrid screening, we identified a High Mobility Group A protein, named SlHMGA3, and demonstrated its binding activity to the AT-rich region of the SlDML2 promoter. We produced slhmga3 tomato mutants using CRISPR/Cas9 and observed that slhmga3 fruit reached the breaker stage much later than fruit from the wild type. We further demonstrated that at the initiation stage of fruit ripening, the increased expression of SlDML2 and ethylene biosynthetic and signaling genes was significantly delayed in slhmga3 fruit, along with delays in ethylene production and demethylation and activation of ripening-associated transcription factor genes. Our results demonstrate that SlHMGA3 plays a role in enhancing SlDML2 expression, and its effects on tomato fruit ripening are largely through DNA demethylation of ripening-associated transcription factor genes.

Molecular and Genetic Events Determining the Softening of Fleshy Fruits: A Comprehensive Review

“…Delays in the fruit ripening of the SlALKBH2 mutant may be a result of the feedback regulation of SlDML2 stability [ 148 ]. Recent studies have shown that SlHMGA3 encoding High-Mobility Group (HMG) A proteins can bind to the SlDML2 promoter and activate its expression, resulting in the promoter DNA methylation of ripening-related TFs regulating ETH biosynthesis and signal transduction [ 149 ].…”

Identification of small effect quantitative trait loci of plant architectural, flowering, and early maturity traits in reciprocal interspecific introgression population in cotton

“… Ma et al (2019) identified a putative negative regulator of cotton plant height near one of the two QTL (HATH13.1) that co-localized with the plant height QTL from Ma et al (2019) . Near the second QTL detected in our study in the co-localized region, we identified an AT hook DNA binding motif like gene, reported to enhance plant height upon overexpression in Zoysia japonica ( Jeong et al, 2020 ) and reduced plant height in a CRISPR/Cas9 mutant of sihmg3 (protein that contains 4 AT hook repeats) in tomato ( Li et al, 2022 ).…”

Recent Advances in Studying the Regulation of Fruit Ripening in Tomato Using Genetic Engineering Approaches

“…In DML2 loss-of-function mutants generated by targeted editing, increased DNA methylation was found not only in genes induced during ripening but also in genes repressed during ripening [99]. However, a recent study found that the highly mobile protein positively regulates DML2 expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGA) [100]. In [101], the expression of the mammalian demethylase TET3c (ten-eleven translocation) in tomatoes resulted in the activation of expression of the previously undescribed gene CEN1.1.…”