Biology subjects

Iannelli, M. A.

Publications and source records attributed to Iannelli, M. A..

2 recordsLinked to original sources

bioRxiv2024

A survey of duckweed species in southern Italy provided first occurrences of the hybrid Lemna x mediterranea in the wild

Interspecific hybridisation and polyploidization are two main driving forces in plant evolution, shaping genomes and favouring evolutionary novelty and ecological adaptation. Recent studies have demonstrated hybridisation within the genus Lemna (Lemnaceae Martinov) as well as triploid. L. x mediterranea, a recently described hybrids between Lemna minor and Lemna gibba was identified among only long lasting germplasm collections of in vitro propagated plants, originally collected at different times in the Mediterranean area. We report the first distribution record of L. x mediterranea in the nature, in the Campania region of Southern Italy, the same area where Lemna symmeter was described as a new species about 50 years ago, confirming their synonymy. Eight specimens isolated from five different sampling sites over an area of about 4200 Km2 showed identical genetic profiles by Tubulin-Based Polymorphism (TBP) analysis, suggesting their common origin from the same hybridisation event, followed by clonal dispersal. The L. x mediterranea population of Campania is genetically different from any of the previously analysed clones, suggesting that recurrent hybridisation between the parental species may occur. The natural hybrid clone is triploid, with L. gibba as the plastid donor, and remarkably similar to it by morphology, although the typical gibbosity of this species becomes evident only upon in vitro flower induction. Flowers are protogynous and self-sterile. Ecological factors including competition with parental and invasive species, niche and climate change adaptation, stability in time and space likely played a role in the successful establishment of L. x mediterranea. HighlightsO_LIInterspecific hybridisation within the genus Lemna documented in nature C_LIO_LI{beta}-tubulin intron length polymorphism for tracking duckweed species distribution C_LIO_LIFlower induction in Lemna x mediterranea C_LI

ecology↗

bioRxiv2023

Characterization of the cryptic interspecific hybrid Lemna x mediterranea by an integrated approach provides new insights into duckweed diversity

Lemnaceae taxonomy is challenged by the particular morphology of these tiny free-floating angiosperms, reduced to a single leaf-like structure called frond, without or with one to few roots. Although molecular taxonomy has helped clarify the phylogenetic history of this family, inconsistency between morphological data and nuclear and plastid markers still poses challenging questions in some cases, leading to frequent misclassifications in the genus Lemna. Recently, the finding that Lemna japonica is an interspecific hybrid between Lemna minor and Lemna turionifera, provided a clear explanation to one of such taxonomic questions. Here we demonstrated that L. minor is also capable to hybridize with Lemna gibba, generating a cryptic, previously unrecognized, but widespread taxon in the Mediterranean area. The nothotaxon Lemna x mediterranea is described through the detailed investigation of seven hybrid clones from a living germplasm collection and compared with clones of the putative parental species L. minor and L. gibba. Genetic analysis revealed that two different cytotypes, diploid and triploid, originated by at least two independent hybridization events. Despite high overall similarity, morphometrical, physiological and biochemical analyses showed an intermediate position of L. x mediterranea between its parental species in most qualitative and quantitative characters, and also separation of the two hybrid cytotypes by some criteria. These data provide evidence that hybridization and polyploidization, driving forces of terrestrial plant evolution, contribute to the duckweed genetic diversity and may have also shaped the phylogenetic history of these mainly asexual, aquatic plants. Further elucidation of hybridization mechanisms and flowering regulation will provide perspectives for future breeding strategies.

plant biology↗