Anthocyanins are key pigments in plants for plant resistance to abiotic stress. It can provide photoprotection by potentially absorbing visible light and scavenging reactive oxygen species (ROS) when biotic stress occurs. However, comparative studies of anthocyanin function are challenged due to the absence of isogenic plant models with variable anthocyanin levels. Genetic advances in tomatoes have identified the ANTHOCYANIN1 (ANT1) gene, a MYB transcription factor of tomato (Solanum lycopersicum), offering a promising avenue for study. The critical problem remains determining the primary protective mechanism of anthocyanins in plant photosynthesis.
In November 2022, Horticulture Research published a perspective entitled by “Promoter replacement of ANT1 induces anthocyanin accumulation and triggers the shade avoidance response through developmental, physiological and metabolic reprogramming in tomato”.
In this study, germination rates were first compared to examine the effects of anthocyanin overproduction on plant growth and development. Results revealed that the seeds of ANT1 plants (promoter replacement of ANT1) with high anthocyanin content had significantly lower germination rates than the control (MT) and anthocyanin-deficient mutants (a and aa) (Figure 1). Flowering times and vegetative growth were also affected, with ANT1 showing delayed flowering and reduced vertical growth post-flowering. The number of side branches and total leaf area were notably reduced in ANT1 plants. Productivity was assessed in ANT1 and its hybrids with M82, showing that despite similar soluble solids content, fruit yield was reduced due to smaller fruit size and fewer fruits per plant. Light absorbance and leaf structure analyses revealed that the spectral properties of ANT1 leaves were altered, with increased absorbance in blue and red ends of the spectrum, and structural differences such as differential elongation of the palisade parenchyma and reduced thickness of both epidermes leading to leaf thickness.
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