Post germination seedling establishment by ABA in response to light (Plant J.)

Abscisic acid (ABA), is implicated in reversible inhibition of seed germination (emergence of radicle) and post-germination seedling establishment (formation of green open cotyledons) during unfavorable conditions. Yadukrishnan et al. analyzed the role of light in ABA- mediated inhibition of post germination seedling growth and laid out a molecular framework using a combination of genetics and molecular biology. They showed that in dark, ABA mediated inhibition of post germination seedling establishment is enhanced and is dependent on the CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) gene that encodes a E3 ligase. Further, they showed that in regulating the post germination seedling growth, COP1 acts downstream of ABSCISIC ACID INSENSITIVE5 (ABI5), an ABA responsive gene that encodes a basic leucine zipper transcription factor. At the protein level, COP1 helps ABI5 bind to the promoters of ABA responsive genes. Thus, in the dark, COP1 works with ABA to inhibit post-germination seedling establishment. (Summary by Vijaya Batthula @Vijaya_Batthula) Plant J. 10.1111/tpj.14844