Are endophytes essential partners for plants and what are the prospects for metal phytoremediation?

Natural Fungal Endophytes From Noccaea caerulescens Mediate Neutral to Positive Effects on Plant Biomass, Mineral Nutrition and Zn Phytoextraction

“…Long-term endophyte-host interactions should be considered a basis for mutual interactions, with both sides constantly shaping the organization and structure of the other, resulting in a beneficial relation ( Saikkonen et al, 2004 ). This plant-microbiome superorganism, which is also called a holobiont, is subjected to evolutionary forces that may result in the coevolution of host symbiont interactions ( Rosenberg and Zilber-Rosenberg, 2018 ), where microorganisms could be considered a genetic extension of the host plant genome, favoring hologenome plasticity and thus plant adaptability to its environment ( Durand et al, 2021 ). The success of inoculation could be mainly dependent on the host-symbiont combination at the species level ( Fernando and Currah, 1996 ; Newsham, 2011 ; Mayerhofer et al, 2013 ; Berthelot et al, 2016 ), but in some cases, the plant population-fungal strain level appeared to be important ( Ważny et al, 2021 ).…”

“…When applied to phytoextraction, it consists of inoculating metal-(hyper)accumulating plants with plant-associated microorganisms to enhance metal recovery rates ( Thijs et al, 2016 ; Benizri et al, 2021 ). MAP is based on the ability of PGP microorganisms such as PGP rhizobacteria ( Hansda et al, 2014 ), endophytic bacteria ( Ma et al, 2016 ), arbuscular mycorrhizal fungi ( Ciadamidaro et al, 2017 ; Miransari, 2017 ; Berthelot et al, 2018 ), ectomycorrhizal fungi ( Ciadamidaro et al, 2017 ; Phanthavongsa et al, 2017 ; Gil-Martínez et al, 2018 ), and endophytic fungi ( Lacercat-Didier et al, 2016 ; Berthelot et al, 2017 , 2018 ; Deng and Cao, 2017 ) to enhance plant development, health, tolerance to abiotic stress and resistance to phytopathogens ( Kong and Glick, 2017 ; Thijs et al, 2016 ; Otero-Blanca et al, 2018 ; Durand et al, 2021 ). Additionally, root-associated microorganisms are able to increase the mobility of TEs in the soil, suggesting that their presence is essential for plants to reach their full phytoextraction potential ( Lebeau et al, 2008 ; Sessitsch et al, 2013 ).…”

“…Additionally, root-associated microorganisms are able to increase the mobility of TEs in the soil, suggesting that their presence is essential for plants to reach their full phytoextraction potential ( Lebeau et al, 2008 ; Sessitsch et al, 2013 ). In this context, hyperaccumulating plants and associated microorganisms could be considered together as plant-microbiome superorganisms ( Bosch and McFall-Ngai, 2011 ), in which the microbial component acts as a dynamic system, increasing the adaptability of the plant-microbiome superorganism under environmental pressure ( Durand et al, 2021 ). Indeed, in the case of TE-enriched soils, the host plant can promote metal-tolerant beneficial microorganisms from the enormous and diverse pool of microorganisms present in the bulk soil ( Becerra-Castro et al, 2012 ; Álvarez-López et al, 2016 ; Yung et al, 2021a ).…”

“…Bacterial endophytes of N. caerulescens were mainly studied utilizing cultivation-dependent methods ( Aboudrar et al, 2007 ; Visioli et al, 2014 ). Recently, 16S DNA profiling has been used to investigate root-associated bacterial communities ( Visioli et al, 2019 ) and endophytic bacterial communities associated with seeds ( Durand et al, 2021 ) of N. caerulescens. Several promising strains of metal-resistant or PGP endophytic bacteria have already been isolated ( Visioli et al, 2014 ; Fones et al, 2016 ; Burges et al, 2017 ), and their potential to improve biomass production and metal accumulation has been tested in planta ( Visioli et al, 2015b ; Burges et al, 2017 ).…”

Community composition and differential analysis of rhizosphere soil microorganism and endophytes in Schisandra sphenanthera Rehd. et Wils.

“…Several studies have shown that the diversity and community structures of endophytes are closely related to the species, growth stage, nutrition supply, living environment, and genotype of the host plants (Liu et al, 2019;Rim et al, 2021;Robinson et al, 2016). Endophytes play a positive role in plant growth and development, pest control, plant resistance, bioremediation, and other aspects (Durand et al, 2021;Jauri et al, 2020). For example, endophytes can not only relieve plant stress, but also signi cantly improve plant yield and height (Rojas-Tapias et al, 2012; Yaish et al, 2015).…”