Regulatory roles of abscisic acid for anthocyanin synthesis in maize kernels

Abscisic acid (ABA) is required as a co-regulatory factor for all of the regulatory factor functions associated with Viviparous-1 (Vp1) during maize kernel development. Anthocyanin synthesis has been an apparent exception, because ABA-deficient viviparous mutants still accumulate anthocyanin pigments. However, if full color kernel blocks are cultured on fluridone medium to reduce endogenous ABA to near zero levels, anthocyanin synthesis is completely repressed. Addition of exogenous ABA to fluridone medium induces anthocyanin synthesis. Vp1 is expressed in the presence or absence of ABA, but C1 is expressed only when ABA is present. The level of C1 transcripts id increased by adding exogenous ABA (10 -4 M) into standard medium. When all the genes required for anthocyanin expression in aleurone tissue are present as dominate functional alleles, the initiation of synthesis and the intensity of anthocyanin expression depend on ABA concentration. Both maternal and exogenous ABA are transported into developing maize kernels, and the source of ABA is irrelevant for anthocyanin expression. For anthocyanin synthesis, Vp1 transcription activator regulates C1 in a tissue-specific manner. In developing maize of kernels, the timing and level of C1 expression are controlled by ABA concentration.

Regulatory roles of abscisic acid for anthocyanin synthesis in maize kernels Academic Article