Auxin homeostasis in maize (Zea mays) is regulated via 1-O-indole-3-acetyl-myo-inositol synthesis at early stages of seedling development and under abiotic stress

Abstract

Main conclusion Indole-3-acetyl-myo-inositol biosynthesis is regulated during maize seedling development and in response to drought and cold stress. The main purpose of this pathway is maintenance of auxin homeostasis. Abstract Indole-3-acetic acid (IAA) conjugation to myo-inositol is a part of a mechanism controlling free auxin level in maize. In this work, we investigated changes in the indole-3-acetyl-myo-inositol (IAInos) biosynthesis pathway in 3-d- and 6-d-old maize seedlings and germinating seeds as well as in seedlings subjected to drought and cold stress to evaluate a role of this pathway in maize development and stress response. In germinating seeds, activity of the enzymes involved in IAInos biosynthesis remains unchanged between 3-d- and 6-d-old material but increases in coleoptiles and radicles of the seedlings. Under cold stress, in germinating seeds and in coleoptiles, activity of the enzymes decreases and increases, respectively; however, it does not entail changes in auxin level. In drought-exposed germinating maize seeds, totally diminished activities of IAInos synthesis pathway enzymes resulted in almost twofold increase of free IAA content. Similar increase of auxin level was observed in radicles of drought-subjected seedlings together with lack of catalytic activity of the first enzyme of the pathway. Exogenous IAInos has no effect on the level of non-enzymatic antioxidant, ascorbate. It has also either no effect on the protein carbonylation and lipid peroxidation, or it affects it in a similar way as exogenously applied IAA and myo-inositol, which are products of IAInos hydrolysis. Thus, IAInos biosynthesis pathway acts in maize development and stress responses by regulation of free IAA concentration, as IAInos itself does not appear to have a distinct role in these processes.

Multiplication of Dendrobium Sp Orchid Somatic Embries Using In-Vitro Concentrations of MgSO4 and Myo-Inositol in Murashige and Skoog Media

“…This process involves several vitamins, one of which is myoinositol which is conjugated with the hormone auxin which plays a role in spurring cell division. This is in accordance with the opinion of Ciarkowska et al (2023), who explained that myoinositol plays an important role in controlling the auxin hormone. Inositol conjugated with IAA functions as a storage or transport of auxin and can regulate the availability of IAA during plantlet growth.…”

Exogenously Applied Cyclitols and Biosynthesized Silver Nanoparticles Affect the Soluble Carbohydrate Profiles of Wheat (Triticum aestivum L.) Seedling

“…The increasing concentration of MIN in seedlings may also interfere with hormonal homeostasis during grain germination [93] due to possible inhibition of the hydrolysis of IAA conjugated with inositol. Decreased levels of active IAA can, in turn, interfere with other hormones, such as ethylene, abscisic acid and gibberellins, which play a crucial role in starch mobilization and growth in wheat seedlings [94].…”

“…The soluble carbohydrates were analyzed using a high-resolution gas chromatography method described previously [93]. Briefly, sugars were extracted from 40-42 mg of dry pulverized tissues with 50% ethanol containing xylitol as the internal standard.…”