The genus Odontarrhena (Brassicaceae) in Albania: Taxonomy and Nickel accumulation in a critical group of metallophytes from a major serpentine hot-spot

Abstract

Metal hyperaccumulator plants represent a unique biological resource for scientific research and practical applications. Though essential, however, an adequate knowledge of the systematics of these plants is often missing. This is the case of Odontarrhena, a large but taxonomically critical group of nickel hyperaccumulators from Eurasia. We present a study on this genus in Albania, to fill a gap in our knowledge of this group from a major centre of diversity of metallicolous flora, and to contribute updated information to the Global Hyperaccumulator Database. Morphological and karyological analyses of material from field collections across all major serpentine outcrops in the country, in different years and seasons, allowed to delimit seven taxa: O. albiflora, O. chalcidica, O. moravensis, O. sibirica, O. decipiens, O. smolikana subsp. glabra and O. rigida. The three latter taxa have been long neglected and were resurrected in view of their clear distinctness, while commonly accepted taxa such as O. bertolonii subsp. scutarina and O. markgrafii were reduced to synonymy of O. chalcidica due to the lack of consistent differentiation. Polyploidy was prevalent, while diploid complements were typical of the two vicariant endemics O. rigida and O. moravensis. Types are indicated or newly designated for each entity, and nomenclatural issues are addressed based on in-depth studies of literature and herbarium material. Revised descriptions, phenology, habitat and distribution data are given for each taxon, as well as original iconographies and chromosome counts. A revised identification key is provided. Shoot nickel concentrations were determined to assess accumulation levels of taxa and populations in natural conditions and their potential for phytoextraction of this metal from the soil. With ca. 23000 and 17000 µg of Ni g-1 of shoot dry weight, respectively, the tetraploids O. chalcidica and O. decipiens were the most promising candidates, especially the latter for its robust habit.

Inability to accumulate Ni in a genus of hyperaccumulators: the paradox of Odontarrhena sibirica (Brassicaceae)

“…This confirms that most literature reports on Ni-accumulation ability in “ O. muralis ” are to be referred to closely related Ni-accumulating taxa that are widespread in the Balkans, such as O. chalcidica and O. decipiens (Nyár.) L.Cecchi and Selvi (Cecchi et al 2018 ; Bettarini et al 2019 ).…”

“…Accordingly, populations and plants of O. sibirica with contrasting levels of Ni in their shoots should be compared for their genetic traits as well, also looking at possible hybridization and introgression with other locally coexisting Ni accumulating species of Odontarrhena. Hybridization and genetic admixing are indeed known to occur between some sympatric Ni-accumulating species of this genus in similar habitats of the Balkans, especially in anthropogenic sites with heavy disturbance, and not always associated with detectable phenotypic traits in the plants (Cecchi et al 2018 ; Coppi et al 2020 in press). Though the two Turkish accumulating specimens that we examined did not show clear “hybrid signatures”, these were from heavily disturbed sites and growing near other congeneric Ni accumulators [ O. corsica (Duby) Španiel, Al-Shehbaz, D.A.German and Marhold, O. dudleyi (Adıgüzel and R.D.Reeves) Španiel, Al-Shehbaz, D.A.German and Marhold, and group of O. muralis ], which might have favoured interspecific gene flow and the origin of introgressive populations.…”

“…Endl. (see Cecchi et al 2018 ; Bettarini et al 2019 ), and the obligate Ni-hyperaccumulator O. smolikana (Nyár.) Španiel, Al-Shehbaz, D.A.German and Marhold subsp.…”

Developing Sustainable Agromining Systems in Agricultural Ultramafic Soils for Nickel Recovery

“…While the taxa from Greece are better understood, some of those from Albania, the former Yugoslav Republic of Macedonia (FYROM), and Bulgaria are still poorly known, preventing a correct estimation of the diversity of accumulators in the Balkans to be presented. A recent systematic revision of the genus in Albania (Cecchi et al, 2018) points to the existence of seven taxa, of which six Ni-hyperaccumulators are restricted to ultramafic soils (except for O. chalcidica, facultative serpentinophyte). A polyploid species of likely hybrid origin between O. chalcidica and O. smolikana, originally described from Mt.…”

Polyploidy in Odontarrhena bertolonii (Brassicaceae) in relation to seed germination performance and plant phenotype, with taxonomic implications

“…scutarinum is to be excluded from the circumscription of O. bertolonii and included in that of the Balkan species O. chalcidica (Janka) Španiel, Al-Shehbaz, D.A. German & Marhold (Cecchi et al 2018). In 'Alyssum' bertolonii 'f.…”