**3. The nature and composition of PGPF**

PGPF are common root-associated and soil-borne fungi from diverse genera. Fungi reported as PGPF include Ascomycetes, Basidiomycetes and Oomycetes [5]. Some strains of hypovirulent binucleate *Rhizoctonia* (HBNR) are known to be PGPF [13]. PGPF also include isolates of mycelial fungi that do not produce any spores, generally known as sterile black fungus (SBF), sterile dark fungus (SDF) and sterile red fungus (SRF) [14]. The non-sporulating PGPF are often difficult to identify and mostly lack formal taxonomic status. Among the PGPF *Aspergillus*, *Fusarium*, *Penicillium, Phoma* and *Trichoderma* have a wide distribution and are, by far, the most extensively reported (**Table 1**). Each of the genera has a variety of species. *Aspergillus, Fusarium, Penicillium* and *Phoma* were frequently found in the rhizosphere or in the roots of plants. Instead, *Trichoderma* were mostly isolated from soil. Among the rhizosphere population, PGPF have a high relative abundance. A total of 619 (44%) out of 1399 fungal isolates collected from rhizosphere of six different plants were PGPF, while frequency of occurrence of PGPF in zoysiagrass, wheat, corn and eggplant rhizosphere were 46, 47, 38 and 10%, respectively [4]. This indicates that abundance of PGPF varies largely according to the host rhizosphere. Similarly, the dominating fungal genus is not necessarily the dominating PGPF in the rhizosphere population. The order of the frequency of the main genera among 1399 fungal isolates was *Fusarium > Trichoderma >* sterile fungi *> Penicillium > Pythium > Rhizoctonia > Mucor,* while that of PGPF from each plant genus was: *Trichodema* (~82%) > *Pythium* (~75%) > *Penicillium* (~69%) > *Alternaria* (~63%) > *Fusarium* (~44%) > sterile fungi (40%) > *Mucor* (~38%) [4]. The important characteristics of these fungi are their high rhizosphere competence and ability to promote plant growth.

Initial search for identification of PGPF was concentrated to rhizosphere fungi. Recent studies have demonstrated the potential of phyllosphere fungi as PGPF. The phyllosphere, which consists of the above ground surfaces of plants, is one of the most prevalent microbial habitats on earth. Phyllosphere fungi can act as mutualists promoting plant growth and tolerance of environmental stressors [53]. A few of other fungi isolated from tree bark, decorticated wood and water damaged building functioned as PGPF [43, 49]. More interestingly, the fungal entomopathogens also show potential to be PGPF and promote plant growth [54]. PGPF seem to have a cosmopolitan occurrence.

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**Table 1.**

more of these effects.

**4. Impact of PGPF on plant growth promotion**

PGPF exhibit traits beneficial to plant and as such, their capacity to enhance

plant growth and development is well founded. PGPF mediate both shortand long-term effects on germination and subsequent plant performance. Improvement in germination, seedling vigor, shoot growth, root growth, photosynthetic efficiency, flowering, and yield are the most common effects decreed by PGPF. A particular PGPF may condition plant growth by exerting all or one or

*Application and Mechanisms of Plant Growth Promoting Fungi (PGPF) for Phytostimulation*

*Alternaria* sp. *Zoysia tenuifolia, Rosa rugosa*,

C*olletotrichum* sp. *Rosa rugosa*, *Camellia japonica*,

*Phoma* sp., *Phoma herbarum, Phoma multirostrata G. max, Rosa rugosa*, *Camellia* 

*Phomopsis* sp., *Phomopsis liquidambari Rosa rugosa*, *Camellia japonica*,

*Rhizoctonia* spp*.* Orchid, *Lycopersicon lycopersicum,*

**PGPF Original source of isolation References**

*peltata*

*Rosa hybrid*

environment

*tenuifolia*

and soil

*Aureobasidium pullulans* Dark chestnut soil [22] *Chaetomium globosum Capsicum annuum* [23] *Cladosporium* sp., *Cladosporium sphaerospermum Cucumis sativus, Glycine max* [24, 25]

*Exophiala* sp*. Cucumis sativus* [26]

Non-sporulating sterile fungi *Zoysia tenuifolia* [14]

*Purpureocillium lilacinum* Soil [44]

*Rhodotorula mucilaginosa* Soil [22] *Talaromyces wortmannii* Soil [40]

*Different fungi reported as plant growth promoting fungi (PGPF) with their original source of isolation.*

*Camellia japonica*, *Delonix regia*, *Dianthus caryophyllus*, *Rosa hybrid*

*Capsicum annuum*, *Glycine max, Cicer arietinum, Elymus mollis, Solanum tuberosum, Nymphoides* 

*Delonix regia*, *Dianthus caryophyllus*,

*Cynodon dactylon*, *Lygeum spartum, Zoysia tenuifolia, Musa* sp. and other

Halophyte, *Ixeris repenes, Cicer arietinum, Elymus mollis, Capsicum annuum, Zoysia tenuifolia*

*japonica*, *Delonix regia*, *Dianthus caryophyllus*, *Rosa hybrid, Zoysia* 

*Delonix regia*, *Dianthus caryophyllus*, *Rosa hybrid, Bischofia polycarpa* bark

Soil, wood and damaged building [34, 47–52]

[4, 15]

[16–21]

[15]

[27–32]

[9, 16, 22, 33–40]

[4, 14, 15, 34, 41, 42]

[15, 43]

[13, 45, 46]

*DOI: http://dx.doi.org/10.5772/intechopen.92338*

*Aspergillus* sp., *As. fumigatus, As. niger, As. terreus,* 

*Fusarium* sp., *F. equiseti*, *F. oxysporum, F.* 

*Penicillium* sp*., Pe. chrysogenum, Pe. citrinum, Pe. kloeckeri, Pe. menonorum, Pe. resedanum, Pe. simplicissimum, Pe. janthinellum, Pe. viridicatum*

*Trichoderma asperellum*, *T. atroviride, T. hamatum, T. harzianum, T. longibrachiatum,* 

*T. pseudokoningii, T. viride, T. virens*

*As. ustus, As. clavatus*

*verticillioides*

*Application and Mechanisms of Plant Growth Promoting Fungi (PGPF) for Phytostimulation DOI: http://dx.doi.org/10.5772/intechopen.92338*


**Table 1.**

*Organic Agriculture*

biofertilizer and mycofungicide formulation.

**3. The nature and composition of PGPF**

surface and free-living PGPF, which live outside plant cells, i.e., in the rhizosphere [5]. PGPF establish a non-obligate mutualism with a broader range of host plants. That is why symbiotic mycorrhizal fungi are not considered as PGPF, although they are known to improve growth of the plants [8]. Moreover, PGPF encompass a diverse taxonomic group in comparison to mycorrhiza. They are often involved in a range of complex interactions with plants and develop distinct strategies to mediate improvements in seed germination, seedling vigor, plant growth, flowering and productivity of host plants (**Figure 1**). PGPF are not only associated with the root to mediate positive effects on plant growth and development but also have beneficial effects on suppressing phytopathogenic microorganisms [9]. Not every organism identified as PGPF will improve plant growth under all conditions or in association with all plant hosts [10]. Some PGPF biocontrol inoculants usually contain necrotrophic mycoparasites such as *Trichoderma* spp. [11], while a limited number such as *Sphaerodes mycoparasitica* is biotrophic mycoparasitic agent [12]. Therefore, PGPF are considered one of the potential active ingredients in both

PGPF are common root-associated and soil-borne fungi from diverse genera. Fungi reported as PGPF include Ascomycetes, Basidiomycetes and Oomycetes [5]. Some strains of hypovirulent binucleate *Rhizoctonia* (HBNR) are known to be PGPF [13]. PGPF also include isolates of mycelial fungi that do not produce any spores, generally known as sterile black fungus (SBF), sterile dark fungus (SDF) and sterile red fungus (SRF) [14]. The non-sporulating PGPF are often difficult to identify and mostly lack formal taxonomic status. Among the PGPF *Aspergillus*, *Fusarium*, *Penicillium, Phoma* and *Trichoderma* have a wide distribution and are, by far, the most extensively reported (**Table 1**). Each of the genera has a variety of species. *Aspergillus, Fusarium, Penicillium* and *Phoma* were frequently found in the rhizosphere or in the roots of plants. Instead, *Trichoderma* were mostly isolated from soil. Among the rhizosphere population, PGPF have a high relative abundance. A total of 619 (44%) out of 1399 fungal isolates collected from rhizosphere of six different plants were PGPF, while frequency of occurrence of PGPF in zoysiagrass, wheat, corn and eggplant rhizosphere were 46, 47, 38 and 10%, respectively [4]. This indicates that abundance of PGPF varies largely according to the host rhizosphere. Similarly, the dominating fungal genus is not necessarily the dominating PGPF in the rhizosphere population. The order of the frequency of the main genera among 1399 fungal isolates was *Fusarium > Trichoderma >* sterile fungi *> Penicillium > Pythium > Rhizoctonia > Mucor,* while that of PGPF from each plant genus was: *Trichodema* (~82%) > *Pythium* (~75%) > *Penicillium* (~69%) > *Alternaria* (~63%) > *Fusarium* (~44%) > sterile fungi (40%) > *Mucor* (~38%) [4]. The important characteristics of these fungi are their high rhizosphere competence and ability

Initial search for identification of PGPF was concentrated to rhizosphere fungi. Recent studies have demonstrated the potential of phyllosphere fungi as PGPF. The phyllosphere, which consists of the above ground surfaces of plants, is one of the most prevalent microbial habitats on earth. Phyllosphere fungi can act as mutualists promoting plant growth and tolerance of environmental stressors [53]. A few of other fungi isolated from tree bark, decorticated wood and water damaged building functioned as PGPF [43, 49]. More interestingly, the fungal entomopathogens also show potential to be PGPF and promote plant growth [54]. PGPF seem to have a

**68**

to promote plant growth.

cosmopolitan occurrence.

*Different fungi reported as plant growth promoting fungi (PGPF) with their original source of isolation.*
