Synthesis of Indoleacetic Acid, Gibberellic Acid and ACC-Deaminase by Mortierella Strains Promote Winter Wheat Seedlings Growth under Different Conditions

Abstract

The endogenous pool of phytoregulators in plant tissues supplied with microbial secondary metabolites may be crucial for the development of winter wheat seedlings during cool springs. The phytohormones may be synthesized by psychrotrophic microorganisms in lower temperatures occurring in a temperate climate. Two fungal isolates from the Spitzbergen soils after the microscopic observations and “the internal transcribed spacer” (ITS) region molecular characterization were identified as Mortierella antarctica (MA DEM7) and Mortierella verticillata (MV DEM32). In order to study the synthesis of indoleacetic acid (IAA) and gibberellic acid (GA), Mortierella strains were grown on media supplemented with precursor of phytohormones tryptophan at 9, 15 °C, and 20 °C for nine days. The highest amount of IAA synthesis was identified in MV DEM32 nine-day-culture at 15 °C with 1.5 mM of tryptophan. At the same temperature (15 °C), the significant promoting effect (about 40% root and shoot fresh weight) of this strain on seedlings was observed. However, only MA DEM-7 had the ACC (1-aminocyclopropane-1-carboxylate) deaminase activity with the highest efficiency at 9 °C and synthesized IAA without tryptophan. Moreover, at the same conditions, the strain was confirmed to possess the strong promoting effect (about 40% root and 24% shoot fresh weight) on seedlings. Both strains synthesized GA in all tested terms and temperatures. The studied Mortierella strains had some important traits that led them to be considered as microbial biofertilizers components, improving plant growth in difficult temperate climates.

Phytohormones (Auxin, Gibberellin) and ACC Deaminase In Vitro Synthesized by the Mycoparasitic Trichoderma DEMTkZ3A0 Strain and Changes in the Level of Auxin and Plant Resistance Markers in Wheat Seedlings Inoculated with this Strain Conidia

“…The concentration of IAA and GA in the DEMTkZ3A0 cultures and the efficiency of their synthesis in terms of mycelium biomass or protein had a clear upward trend during the 5-day culture. Such a tendency was also observed in the cultures of Zygomycota fungal strains belonging to two Mortierella species: M. antarctica and M. verticillata ; yet, it is surprising that IAA synthesis in these psychrophic strains was positively correlated with temperature and was the highest at 20 °C [81] and bacterial isolate (S17) from Spitsbergen [92]. The non-pathogenic PGPF Fusarium culmorum strain synthesized higher amounts of IAA and GA than DRMO and pathogenic strains.…”

“…Such dependence of IAA synthesis on tryptophan and its concentration was also found in Mortierella spp. cultures [81]. Tryptophan had a positive effect on GA synthesis by the DEMTkZ3A0 only at the low temperature (12 °C); at the higher temperatures, the addition of amino acids slightly influenced the synthesis of this hormone.…”

“…The activity of the ACC (1-aminocyclopropane-1-carboxylic acid) deaminase enzyme limits the level of ethylene in the plant by converting the ACC direct precursor to this hormone, which is greatly important in promoting plant growth [78,79,80,81].…”

Resolving the Mortierellaceae phylogeny through synthesis of multi-gene phylogenetics and phylogenomics

“…However, our research reveals novel species and genera in both thoroughly sampled and historically undersampled regions, including Michigan, USA and Uganda, respectively. Based 1 3 on these results, we believe that there is a need for continued geographic sampling efforts to identify new species and to establish the ranges and ecological niches of recognized species of Mortierellaceae, including L. elongata (Ozimek et al 2018;Liao et al 2019).…”

Transcriptome analysis reveal the mechanism of susceptible wheat seedlings response to Puccinia striiformis f. sp.

“…Jasmonic acid (JA) was proved involving in plant development and certain stress responses, such as attack by herbivores and pathogen infection (Wasternack et al 2007, Wu et al 2009, Browse 2009. Phytohormone ethylene (ET) plays role in plant development regulation and stress resistance (Ozimek et al 2018). In our results, Ethylene and jasmonic acid were involved in Pst response of wheat.…”