Light-dependent accumulation of mRNAs for chloroplast-encoded genes in Vigna aconitifolia

Abstract

In Vigna aconitifolia, steady-state transcript levels of psbA and rbcL were found to vary in dark as a function of developmental stage of etioplasts - as reflected by the age of the seedlings - being high after 7 days of growth as compared to that of 5 days. The increase in mRNAs for these genes on exposure to light was several-fold more in dark-grown 5-day-old seedlings as compared to 7-day-old seedlings. When the 5-day-old dark-grown seedlings were illuminated for various durations, significant increase in the levels of mRNAs could be detected within 1he 1 hour for pssA, psbC, psbD, psbE, psbA, psaB and rbcL. Later, transcript levels continued to increase for 12-24 h. But, levels of some of them declined after longer exposures. Interestingly, for rbcL an additional transcript of distinctly larger size was produced and illumination of the seedlings for longer durations caused appearance of a novel transcript in case of psbD-psbC operon.