Inoculation of selenium hyperaccumulator Stanleya pinnata and related non‐accumulator Stanleya elata with hyperaccumulator rhizosphere fungi—investigation of effects on Se accumulation and speciation

Abstract

Little is known about how fungi affect elemental accumulation in hyperaccumulators (HAs). Here, two rhizosphere fungi from selenium (Se) HA Stanleya pinnata, Alternaria seleniiphila (A1) and Aspergillus leporis (AS117), were used to inoculate S. pinnata and related non-HA Stanleya elata. Growth and Se and sulfur (S) accumulation were analyzed. Furthermore, X-ray microprobe analysis was used to investigate elemental distribution and speciation. Growth of S. pinnata was not affected by inoculation or by Se. Stanleya elata growth was negatively affected by AS117 and by Se, but combination of both did not reduce growth. Selenium translocation was reduced in inoculated S. pinnata, and inoculation reduced S translocation in both species. Root Se distribution and speciation were not affected by inoculation in either species; both species accumulated mainly (90%) organic Se. Sulfur, in contrast, was present equally in organic and inorganic forms in S. pinnata roots. Thus, these rhizosphere fungi can affect growth and Se and/or S accumulation, depending on host species. They generally enhanced root accumulation and reduced translocation. These effects cannot be attributed to altered plant Se speciation but may involve altered rhizosphere speciation, as these fungi are known to produce elemental Se. Reduced Se translocation may be useful in applications where toxicity to herbivores and movement of Se into the food chain is a concern. The finding that fungal inoculation can enhance root Se accumulation may be useful in Se biofortification or phytoremediation using root crop species.

Biofortification and phytoremediation of selenium in China

“…The mixture of organic acids increased the efficiency of Se mineral fertilizers and resulted in a better developed and extensive root system ( White and Broadley, 2005 ; Lynch, 2007 ; Kirkby and Johnston, 2008 ; White and Hammond, 2008 ). Moreover, the rhizosphere microbes and endophytic microbes may also play an important role in increasing phytoavailability of Se ( Morgan et al, 2005 ; Lynch, 2007 ; Kirkby and Johnston, 2008 ; Duran et al, 2014 ; Lindblom et al, 2014 ). In this regard, the inoculation of soil with specific microbes might be beneficial for enhancing Se biofortification strategy for crops ( Acuna et al, 2013 ; Duran et al, 2013 , 2014 ; Lindblom et al, 2013a , b ; Yasin et al, 2015a ).…”

Fungal Endophyte Alternaria tenuissima Can Affect Growth and Selenium Accumulation in Its Hyperaccumulator Host Astragalus bisulcatus

“…Perhaps related to its effect on Se speciation toward more insoluble Se 0 in roots, the A2-containing A. bisulcatus seedlings showed significantly lower Se and S levels in their shoots. In previous studies where hyperaccumulators were inoculated with the related Alternaria species A1 and A3, there was a reduction in root-to-shoot translocation ( Lindblom et al, 2013b , 2014 ). The same may be the case for A2; the root biomass was too small to determine root elemental concentrations.…”

“…To test this hypothesis, hyperaccumulator plants were grown from surface-sterilized seeds and inoculated with several root-associated fungi shown earlier to be able to produce Se 0 . However, no significant effect on plant Se speciation was observed ( Lindblom et al, 2013b , 2014 ).…”

Phytoremediation of Heavy Metals: The Use of Green Approaches to Clean the Environment

“…It is believed that the rhizospheric microorganisms help the plant to uptake the mineral nutrients such as Fe (Crowley et al 1991 ), Mn (Barber and Lee 1974 ), and Cd (Salt et al 1995b ). In a recent report by Lindblom et al ( 2014 ), two rhizosphere fungi Alternaria seleniiphila (A1) and Aspergillus leporis (AS117) inoculated with selenium (Se) hyperaccumulator Stanleya pinnata and nonhyperaccumulator Stanleya elata were studied. They concluded that rhizosphere fungi affect the growth and Se and/or S accumulation in these plant species.…”