The X-ray fluorescence screening of multiple elements in herbarium specimens from the Neotropical region reveals new records of metal accumulation in plants

Abstract

Plants have developed a diversity of strategies to take up and store essential metals in order to colonize various types of soils including mineralized soils. Yet, our knowledge of the capacity of plant species to accumulate metals is still fragmentary across the plant kingdom. In this study, we have used the X-Ray Fluorescence technology to analyze metal concentration in a wide diversity of species of the Neotropical flora that was not extensively investigated so far. In total, we screened more than 11 000 specimens representing about 5000 species from herbaria in Paris and Cuba. Our study provides a large overview of the accumulation of metals such as manganese, zinc and nickel in the Neotropical flora. We report 30 new nickel hyperaccumulating species from Cuba, including the first records in the families Connaraceae, Melastomataceae, Polygonaceae, Santalaceae and Urticaceae. We also identified the first species from this region of the world that can be considered as manganese hyperaccumulators in the genera Lomatia (Proteaceae), Calycogonium (Melastomataceae), Ilex (Aquifoliaceae), Morella (Myricaceae) and Pimenta (Myrtaceae). Finally, we report the first zinc hyperaccumulator, Rinorea multivenosa (Violaceae), from the Amazonas region. The identification of species able to accumulate high amounts of metals will become instrumental to support the development of phytotechnologies in order to limit the impact of soil metal pollution in this region of the world.

Contrasting nickel and manganese accumulation and localization in New Caledonian Cunoniaceae

“…It is more probable that these species have different physiological adaptations to cope with harsh conditions which explains their differences in metal concentrations in sympatry (Pillon et al 2019b). This is in line with the major physiological diversity associated with New Caledonian plant radiation (Pillon Outside of New Caledonia, high foliar Mn concentrations have also been reported in Cunoniaceae from South America (genus Weinmannia), although not reaching the hyperaccumulation threshold (Belloeil et al 2021). Cunoniaceae also generally tend to be over-represented on ultramafic soils (Pillon et al 2019a).…”

“…The Cunoniaceae belong to the Oxalidales order that includes five other small to medium size families. Nickel hyperaccumulation has also been reported in two of these families on ultramafic substrates: the Indonesian Sarcotheca celebica (Oxalidaceae, Galey et al 2017) and the Cuban Rourea glabra (Connaraceae, Belloeil et al 2021). Therefore, the greater capacity to adapt to ultramafic soils and to become a metal hyperaccumulator may be ancestral to the entire Oxalidales order.…”

“…Two areas of the world are especially renowned for their richness in metal hyperaccumulator plants: Cuba (Reeves et al 1996(Reeves et al , 1999Belloeil et al 2021) and New Caledonia (Gei et al 2020b;Jaffré et al 2013). These islands both have large surface areas of ultramafic outcrops where most of the metal hyperaccumulators (particularly those for Ni) have been reported.…”

Toxicological effects, residue levels and risks of endocrine disrupting chemicals in Chinese medicine: A review

“…Since they cannot synthesize these elements themselves, plants needs to take them from the environment. Therefore, many medicinal plants may accumulate heavy metals while growing in their natural habitats (Belloeil et al 2021). Any non-biodegradable metal or metal-like substance that causes environmental problems can be considered a "heavy metal" (Sarma et al 2012).…”

Micro-analytical and molecular approaches for understanding the distribution, biochemistry, and molecular biology of selenium in (hyperaccumulator) plants

“…The main advantage is that this can be done on herbarium specimen collections, and as such a highly efficient botanical survey can be performed without the high costs, and sometimes complex logistics, of a field expedition (Gei et al 2018). This approach has already been successful in doubling the number of trace element hyperaccumulator plant species known globally from projects undertaken in New Caledonia, Malaysia, Papua New Guinea and the Neotropics (van der Ent et al 2019a, b;Do et al 2020;Gei et al 2020;Belloeil et al 2021). Although its potential to find new Se hyperaccumulators has yet to be fully tested, handheld XRF instruments appear as a time-and cost-effective tool for initial discoveries of Se accumulation in plants from existing plant collections held at herbaria (van der Ent et al 2019a, b).…”