Transcriptome-wide analysis of auxin-induced carotenoid accumulation in Chlorella microalgae

Abstract

Highlight: Transcriptomics of plant hormone-treated Chlorella revealed the active pathway components of auxin-induced carotenogenesis and included the ancient ABP1/SCF SKP2A /IBR5-mediated pathways. The manuscript presents the first documented transcriptomic data of auxin-treated microalgae. AbstractMicroalgae are a commercially viable route for the production of carotenoids, including β carotene and astaxanthin. In the current study, the commercially relevant microalga, Chlorella sp. BR2 was treated with four plant hormones: indole-3-acetic acid, salicylic acid, abscisic acid and methyl jasmonate, over a range of dosages and screened for enhanced carotenoid production. Indole-3-acetic acid was the only hormone with an inductive effect on carotenoid accumulation. As such, the transcriptome under the condition with the highest carotenoid increase was profiled using RNA-Seq and expressed sequences reconstructed with de novo assembly. This allowed for the profiling of transcriptome-wide changes following auxin treatment, revealing the active pathway components of auxininduced carotenogenesis. Data analysis specified the differentially expressed genes involved in auxin biosynthesis and signal transduction, which suggest a close relationship to equivalent pathways in higher plants. However unlike in plants, the ancient ABP1/SCF SKP2A /IBR5-mediated pathways for auxin response likely acted as the primary signaling route in Chlorella. As carotenoids are precursors for abscisic acid, the findings suggest a causative link between auxin signaling and abiotic stress tolerance.

Effects of Foliar Applications of Zinc in the Forms of Free Mineral or Amino Acid Complexed on Qualitative Characteristics of Olive Oil

“…An increase in b* value can be related to the oil carotenoid content (Stoll et al, 2017). It was suggested that Zn promotes the tryptophan synthesis, an auxin precursor, which results in a higher level of auxin in plants, in turn inducing carotenoids biosynthesis pathway (Alsenani et al, 2018; Ljung, 2013). To the best of our knowledge, no data have been reported about the direct effect of Zn on L*, a*, and b* values of olive oil.…”