Effects of the Dark Septate Endophyte (DSE) Exophiala pisciphila on the Growth of Root Cell Wall Polysaccharides and the Cadmium Content of Zea mays L. under Cadmium Stress

Abstract

This paper aims to investigate the mechanism by which dark septate endophytes (DSEs) enhance cadmium (Cd) tolerance in there host plants. Maize (Zea mays L.) was inoculated with a DSE, Exophiala pisciphila, under Cd stress at different concentrations (0, 5, 10, and 20 mg·kg−1). The results show that, under 20 mg/kg Cd stress, DSE significantly increased maize biomass and plant height, indicating that DSE colonization can be utilized to increase the Cd tolerance of host plants. More Cd was retained in DSE-inoculated roots, especially that fixed in the root cell wall (RCW). The capability of DSE to induce a higher Cd holding capacity in the RCW is caused by modulation of the total sugar and uronic acid of DSE-colonized RCW, mainly the pectin and hemicellulose fractions. The fourier-transform spectroscopy analysis results show that carboxyl, hydroxyl, and acidic groups are involved in Cd retention in the DSE-inoculated RCW. The promotion of the growth of maize and improvement in its tolerance to Cd due to DSEs are related to restriction of the translocation of Cd from roots to shoots; resistance of Cd uptake Cd inside cells; and the increase in RCW-integrated Cd through modulating RCW polysaccharide components.

Dark septate endophyte Exophiala pisciphila promotes maize growth and alleviates cadmium toxicity

“…In the present study, maize seedlings were subjected to Cd stress, and those treated with E. pisciphila inoculation exhibited a significant increase in both shoot and root biomass. The results are consistent with those reported by Wu et al (2020), Su et al (2021), andXiao et al (2021), who found that the shoot and root biomass of maize, rice, and blueberry seedlings increased after inoculation with DSE. In addition, with E. pisciphila inoculation, the root length, surface area, and volume of the maize seedlings were significantly increased regardless of the presence of Cd stress.…”

“…Based on our previous study, under 20 mg/kg Cd stress, E. pisciphila colonization in maize roots significantly increased maize (Huidan No. 4) biomass, plant height and Cd accumulation in the roots ( He et al, 2017 ; Xiao et al, 2021 ). The four treatments were the Control (non-inoculated E. pisciphila , 0 mg/kg Cd 2+ ), DSE treatment (inoculated E. pisciphila , 0 mg/kg Cd 2+ ), Cd treatment (non-inoculated E. pisciphila , 20 mg/kg Cd 2+ ), Cd + DSE treatment (inoculated E. pisciphila , 20 mg/kg Cd 2+ ), respectively.…”

“…It colonizes the root cortex of the host plants, induces changes in root traits, and promotes root growth of the host plant (e.g., root length, surface area, and biomass) ( He et al, 2017 ). DSE inoculation can also contribute to impeding Cd transport from roots to shoots, decrease the Cd content in shoots and retain Cd in the DSE-inoculated roots ( Hou, L. et al, 2020 ; Su et al, 2021 ; Xiao et al, 2021 ). For example, DSE has been reported to increase the root mass density (root mass per root volume), favoring the mineral nutrients storage of roots, and possibly contributing to the storage of Cd ions in the roots ( Kramer-Walter et al, 2016 ).…”

A Study of Microbial Diversity in a Biofertilizer Consortium

“…[90] Exophiala pisciphila 0.002 9.2x10 -5 Promotes growth in cadmiumcontaminated soils; enhances phosphorus absorption. [91] Glomus sp. 0.003 9.2x10 -5 Mycorrhizal fungi; phosphate solubilization; tolerance to salt stress; resistance against pathogens.…”

Species Diversity, Distribution, and Phylogeny of Exophiala with the Addition of Four New Species from Thailand

“…Examples of these include E . pisciphila , which was able to promote the plant growth of maize by increasing phosphorus absorption, photosynthesis, and tolerance of cadmium [ 113 , 114 ]. Furthermore, by effectively suppressing Fusarium-wilt disease in strawberries, E .…”