Molecular and Morphological Confirmation of Three Undescribed Species of Mortierella from Korea

Abstract

Three fungal isolates designated as CNUFC-YR329-1, CNUFC-PTS103-1, and CNUFC-PTS2-1 were discovered during a survey of fungal diversity of the order Mortierellales from freshwater and pine tree rhizosphere soil samples in Korea. The strains were analyzed morphologically and phylogenetically based on the internal transcribed spacer (ITS) and large subunit (LSU) of ribosomal DNA gene sequences. Based on their morphology and phylogeny, the three isolates were identified as Mortierella elongata, M. horticola, and M. humilis, respectively. To the best of our knowledge, M. elongata, M. horticola, and M. humilis, belonging to an undiscovered taxon, have not been previously described in Korea.

Keywords: Freshwater; Mortierellales; soil; taxonomy; undiscovered taxa.

Figure 1.

Phylogenetic tree based on maximum likelihood analysis of internal transcribed rDNA sequences for Mortierella elongata CNUFC-YR329-1, M. elongata CNUFC-YR329-2, M. horticola CNUFC-PTS103-1, M. horticola CNUFC-PTS103-2, M. humilis CNUFC-PTS2-1, and M. humilis CNUFC-PTS2-2. The sequences of Mortierella wolfii were used as the outgroups. Bootstrap support values ≥50% are indicated at the nodes. The bar indicates the number of substitutions per position. The thick colored clade lines with the asterisk were constructed by a previous phylogenetic system described by Wagner et al. [5], whereas the clade lines marked by the asterisk were constructed by Wagner et al. [5] and Hyde et al. [10].

Figure 2.

Phylogenetic tree based on maximum likelihood analysis of large subunit rDNA sequences for Mortierella elongata CNUFC-YR329-1, M. elongata CNUFC-YR329-2, M. horticola CNUFC-PTS103-1, M. horticola CNUFC-PTS103-2, M. humilis CNUFC-PTS2-1, and M. humilis CNUFC-PTS2-2. The sequence of Umbelopsis isabellina was used as the outgroup. Bootstrap support values ≥50% are indicated at the nodes. The bar indicates the number of substitutions per position. The thick colored clade lines with the asterisk were constructed by a previous phylogenetic system described by Wagner et al. [5], whereas the clade lines marked by the asterisk were constructed by Wagner et al. [5] and Hyde et al. [10].

Figure 3.

Morphology of Mortierella elongata CNUFC-YR329-1. A, D colony on potato dextrose agar; B, E colony on oatmeal agar; C, F colony on water agar; (A–C: observed view, D–F: reverse view). G–I young sporangia on sporangiophores; J the collar at the top of the sporangiophore (white arrow). K sporangiosphores (scale bars: G–K = 20 μm).

Figure 4.

Morphology of Mortierella horticola CNUFC-PTS103-1. A, D colony on potato dextrose agar; B, E colony on oatmeal agar; C, F colony on water agar; (A–C: observed view, D–F: reverse view); G, H sporangiophores with different shapes of sporangia; I, J young and mature sporangia; K sporangiospores (scale bars: G–K = 20 μm).

Figure 5.

Morphology of Mortierella humilis CNUFC-PTS2-1. A, D colony on potato dextrose; B, E colony on malt extract agar; C, F colony on water agar; (A–C: observed view, D–F: reverse view); G, H sporangiophore showing different branches and sporangia (observed under stereo-microscope); I, J sporangiophores bearing single-spored sporangia (observed under light microscope). K detail of sporangia with a finely spinulose membrane (scale bars: G–K = 20 μm).