In this study, we investigate the genetic mechanisms responsible for the loss of anthocyanins in betalain‐pigmented Caryophyllales, considering our hypothesis of multiple transitions to betalain pigmentation. Utilizing transcriptomic and genomic datasets across 357 species and 31 families, we scrutinize 18 flavonoid pathway genes and six regulatory genes spanning four transitions to betalain pigmentation. We examined evidence for hypotheses of wholesale gene loss, modified gene function, altered gene expression, and degeneration of the MBW (MYB‐bHLH‐WD40) trasnscription factor complex, within betalain‐pigmented lineages. Our analyses reveal that most flavonoid synthesis genes remain conserved in betalain‐pigmented lineages, with the notable exception of Consequently, the loss and exclusion of anthocyanins in betalain‐pigmented species appear to be orchestrated through several mechanisms: loss of a key enzyme, downregulation of synthesis genes, and degeneration of regulatory complexes. These changes have occurred iteratively in Caryophyllales, often coinciding with evolutionary transitions to betalain pigmentation.
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Summary TT19 orthologs, essential for the final step in anthocyanidin synthesis, which appear to have been repeatedly and entirely lost. Additional late‐stage flavonoid pathway genes upstream ofTT19 also manifest strikingly reduced expression in betalain‐pigmented species. Additionally, we find repeated loss and alteration in the MBW transcription complex essential for canonical anthocyanin synthesis.Free, publicly-accessible full text available January 1, 2025 -
Free, publicly-accessible full text available January 1, 2025
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SUMMARY Wounding during mechanical harvesting and post‐harvest handling results in tuber desiccation and provides an entry point for pathogens resulting in substantial post‐harvest crop losses. Poor wound healing is a major culprit of these losses. Wound tissue in potato (
Solanum tuberosum ) tubers, and all higher plants, is composed of a large proportion of suberin that is deposited in a specialized tissue called the wound periderm. However, the genetic regulatory pathway controlling wound‐induced suberization remains unknown. Here, we implicate two potato transcription factors, StMYB102 (PGSC0003DMG400011250) and StMYB74 (PGSC0003DMG400022399), as regulators of wound suberin biosynthesis and deposition. Using targeted metabolomics and transcript profiling from the wound healing tissues of two commercial potato cultivars, as well as heterologous expression, we provide evidence for the molecular–genetic basis of the differential wound suberization capacities of different potato cultivars. Our results suggest that (i) the export of suberin from the cytosol to the apoplast and ligno‐suberin deposition may be limiting factors for wound suberization, (ii) StMYB74 and StMYB102 are important regulators of the wound suberization process in tubers, and (iii) polymorphisms in StMYB102 may influence cultivar‐specific wound suberization capacity. These results represent an important step in understanding the regulated biosynthesis and deposition of wound suberin and provide a practical foundation for targeted breeding approaches aimed at improving potato tuber storage life.
