The Anthropocene epoch is associated with the spreading of metals in the environment increasing oxidative and genotoxic stress on organisms. Interestingly, c. 520 plant species growing on metalliferous soils acquired the capacity to accumulate and tolerate a tremendous amount of nickel in their shoots. The wide phylogenetic distribution of these species suggests that nickel hyperaccumulation evolved multiple times independently. However, the exact nature of these mechanisms and whether they have been recruited convergently in distant species is not known. To address these questions, we have developed a cross-species RNA-Seq approach combining differential gene expression analysis and cluster of orthologous group annotation to identify genes linked to nickel hyperaccumulation in distant plant families. Our analysis reveals candidate orthologous genes encoding convergent function involved in nickel hyperaccumulation, including the biosynthesis of specialized metabolites and cell wall organization. Our data also point out that the high expression of IREG/Ferroportin transporters recurrently emerged as a mechanism involved in nickel hyperaccumulation in plants. We further provide genetic evidence in the hyperaccumulator Noccaea caerulescens for the role of the NcIREG2 transporter in nickel sequestration in vacuoles. Our results provide molecular tools to better understand the mechanisms of nickel hyperaccumulation and study their evolution in plants.

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.

Aim Alexander von Humboldt observed that plant communities on different continents but under similar climatic conditions shared few common species but often contained representatives of the same genera or higher taxonomic groups. To test if this observation can be extended to substrate type, we explored whether a phylogenetic signature could be seen among floras growing on ultramafic substrates that present challenging edaphic conditions for plant growth and are well‐known for their distinctive vegetation. Location Cuba, Madagascar, New Caledonia. Taxon Angiosperms. Methods We compared the floras of Cuba, Madagascar and New Caledonia to test whether the same plant families were under‐ or over‐represented on the ultramafic substrates of the three islands. Results Pairwise comparisons showed that plant orders and families tended to have the same behaviour on the three islands, i.e. ultramafic substrates filtered (in favour of or against) the same plant groups in the three biogeographical distinct areas. The COM clade (comprising Celastrales, Oxalidales and Malpighiales) appears to be over‐represented on ultramafic substrates in all three islands and contains over half of the world's known nickel hyperaccumulators. Main conclusions Our analyses provide support for Humboldt's observation by showing that ecological sorting can favour the same plant lineages in similar environments in different biogeographical regions.

Conservation of plant genetic resources (PGR) is essential to preserve diversity and to provide genes for plant breeding. This paper assesses the current status of pineapple PGR diversity in Cuba and actions are proposed to minimize the loss of diversity. In situ diversity was evaluated through field trips to different locations across the country, evidence was found that pineapple germplasm diversity is low. Only three (Spanish, Cayenne and Pernambuco) out of the five horticultural groups of this crop are presently planted at Cuba. Red Spanish is the predominant cultivar, and White Pineapple is an endangered one. The highest diversity was found at the Eastern region, where it was possible to find at least two different cultivars from each of these three groups. The ex situ pineapple collection contains 56 accessions, 45 % belong to the Spanish group, 20 % to Cayenne and 14 % to Pernambuco, while the rest are hybrids, improved cultivars and other related species. Threats of diversity loss were identified by the Research-Action-Participation method. Farmers and experts agreed that growing of the most common cultivars is being abandoned and consequently, there is high risk of loss of in situ diversity. Results document the low diversity of pineapple genetic resources in the country and the need to use in situ and ex situ conservation approaches as complementary strategies for germplasm preservation for future generations.

Más de 700 especies vegetales en el mundo son capaces de acumular en sus tejidos altas cantidades de elementos metálicos (Ni, Cu, Co, Cr, Mn y Zn, entre otros) por lo que se denominan hiperacumuladoras de metales. Este proceso fisiológico se ha interpretado como una adaptación de las plantas a los suelos metalíferos donde habitan. Leucocroton havanensis Borhidi es una especie hiperacumuladora de Ni endémica del matorral xeromorfo espinoso sobre "suelo serpentina" en Cuba. La naturaleza química de estos suelos metalíferos, debido a las altas concentraciones de Ni, Cr, Co, Mn, Mg y Fe, unido a las bajas concentraciones de Ca y macronutrientes como N, P y K, hacen que las áreas alberguen una alta representación de plantas endémicas con características fisiológicas distintivas. La especie L. havanensis está clasificada como amenazada en la Lista Roja de la Flora de Cuba, debido al reducido número de poblaciones existentes como consecuencia de la actividad económica del hombre. En el contexto de un desarrollo sostenible se han implementado en varios países la fitorremediación y la agrominería. Estas nuevas tecnologías utilizan plantas hiperacumuladoras como vía alternativa para la extracción de metales del suelo. De esta forma se evita el daño al medio ambiente y se conservan los recursos fitogenéticos de las zonas mineras. La función ecológica de la hiperacumulación de metales pudiera estar relacionada con la defensa de estas especies ante patógenos y herbívoros. El Ni hiperacumulado en las hojas de Streptanthus polygaloides protege la planta del ataque de bacterias y hongos y de la babosa Ambigolimax valentianus.