Abstract
Somatic embryogenesis in Arabidopsis encompasses an induction phase requiring auxin as the inductive signal to promote cellular dedifferentiation and formation of the embryogenic tissue, and a developmental phase favoring the maturation of the embryos. Strigolactones (SLs) have been categorized as a novel group of plant hormones based on their ability to affect physiological phenomena in plants. The study analyzed the effects of synthetic strigolactone GR24, applied during the induction phase, on auxin response and formation of somatic embryos. The expression level of two SL biosynthetic genes, MORE AXILLARY GROWTH 3 and 4 (MAX3 and MAX4), which are responsible for the conversion of carotene to carotenal, increased during the induction phase of embryogenesis. Arabidopsis mutant studies indicated that the somatic embryo number was inhibited in max3 and max4 mutants, and this effect was reversed by applications of GR24, a synthetic strigolactone, and exacerbated by TIS108, a SL biosynthetic inhibitor. The transcriptional studies revealed that the regulation of GR24 and TIS108 on somatic embryogenesis correlated with changes in expression of AUXIN RESPONSIVE FACTORs 5, 8, 10, and 16, known to be required for the production of the embryogenic tissue, as well as the expression of WUSCHEL (WUS) and Somatic Embryogenesis Receptor-like Kinase 1 (SERK1), which are markers of cell dedifferentiation and embryogenic tissue formation. Collectively, this work demonstrated the novel role of SL in enhancing the embryogenic process in Arabidopsis and its requirement for inducing the expression of genes related to auxin signaling and production of embryogenic tissue.
Highlights
Strigolactones (SLs) are semiochemicals first identified as stimulants of seed germination in species of the parasitic weed Striga [1], and later as potent branching factors for mycorrhizal fungi [2,3]
Somatic Embryogenesis Is Influenced by the Expression of MAX3–9 and MAX4
Somatic embryogenesis in Arabidopsis was a two-step process with an induction and developmental phase
Summary
Strigolactones (SLs) are semiochemicals first identified as stimulants of seed germination in species of the parasitic weed Striga [1], and later as potent branching factors for mycorrhizal fungi [2,3]. Production of SLs during apical dominance is induced by auxin [25,26], while applications of the synthetic SL, GR24, regulates the expression of auxin-related genes in young Arabidopsis seedlings [27] These observations suggest that SLs might interfere with auxin signaling during somatic embryogenesis and influence the formation of somatic embryos. To test this hypothesis, we examined the in vitro embryogenic response of Arabidopsis mutants deficient in SLs, and the effects of pharmacological treatments altering the level of SLs during the induction phase of somatic embryogenesis. The responsiveness of explants with or without SL to auxin was validated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
