Do stress-related phytohormones, abscisic acid and jasmonic acid play a role in the regulation of Medicago sativa L. somatic embryogenesis?

Abstract

This study examined the role of endogenous abscisic acid (ABA) and jasmonic acid (JA) in indirect somatic embryogenesis of Medicago sativa L. A multiplex GC-MS/MS technique allowed quantitative single-run analyses of ABA, JA, 12-oxophytodienoic acid (OPDA) and indole-3-acetic acid (IAA). The preparation of initial explants led to a strong accumulation of ABA, JA and OPDA but not of IAA. Substantially higher levels of ABA, JA and OPDA were detected in developing somatic embryos than in callus or embryogenic suspension. Fluridone (FLD) decreased ABA, JA and OPDA levels. Indoprofen (INP) appeared to be a specific inhibitor of octadecanoid biosynthesis. Somatic embryo production and development were negatively affected by FLD or INP. Only INP (0.5 lM) applied during proliferation phase increased the number of cotyledonary embryos. The results strongly indicate the involvement of ABA and JA in somatic embryogenesis of M. sativa. Surprisingly, low IAA contents in comparison to stress-related compounds (ABA, JA and OPDA) were detected in explants, embryogenic tissues and somatic embryos.

Disturbance of ethylene biosynthesis and perception during somatic embryogenesis in Medicago sativa L. reduces embryos’ ability to regenerate

“…SA, a natural plant growth regulator, not only inhibits ethylene biosynthesis by blocking ACO activity (Leslie and Romani 1988), but also inhibits biosynthesis of jasmonates by depressing allene oxide synthase (AOS) (Harms et al 1998). As revealed by our previous studies, endogenous JA levels detected in embryogenic suspension (low level) and in the developing embryos (high level) are essential for proembryogenic proliferation and somatic embryo formation, respectively (Ruduś et al 2009). Although exogenous methyl jasmonate did not influence ethylene production and ACO oxidase activity by the embryogenic suspension, its application during the proliferation phase negatively affected growth of embryogenic suspension as well as subsequent production and development of somatic embryos of M. sativa L. (Ruduś et al 2006;Kępczyńska et al 2009b).…”

Inhibition of strigolactones promotes adventitious root formation

“…This discrepancy could be due to fluridone inhibiting all carotenoid-derived pigments which are important for stress tolerance. 18 Trials using lower doses or different application lengths may further enhance the root inducing effect of fluridone. In experiment B (Fig.…”

Effect of TIBA, fluridone and salicylic acid on somatic embryogenesis and endogenous hormone and sugar contents in the tree fern Cyathea delgadii Sternb.

“…These fluctuations are consistent with the trend presented for proembryogenic tissue of Araucaria angustifolia (Bertol.) (Farias-Soares et al 2014) and for 14-day-old explants of cotyledonary somatic embryo of Medicago sativa L. (Ruduś et al 2009). The negative effect of fluridone on the content of endogenous ABA was also shown in carrot explants (Kikuchi et al 2006).…”

“…However, some ABA seems to be necessary for the initiation of both direct and indirect SE (Rajasekaran et al 1987;Kikuchi et al 2006;Su et al 2013). Although the biosynthetic inhibitors are often used in study of SE, there are only a few reports describing how the contents of different endogenous hormones are altered by treatment with those substances (Rajasekaran et al 1987;Nissen 1994;Kikuchi et al 2006;Ruduś et al 2009;Farias-Soares et al 2014).…”