Pollen biology of the serpentine-endemic Orobanche nowackiana (Orobanchaceae) from Albania

Abstract

The holoparasite flowering plant Orobanche nowackiana Markgr. is a rare endemic plant that parasitises the Ni hyperaccumulator species Alyssum murale Waldst. and Kit. in Komjan Mt. (Albania). The purpose of this study was to establish baseline data concerning aspects of its pollen biology. To achieve this goal three objectives were addressed: (1) describe pollen morphology; (2) study pollen production and fertility/sterility; (3) study the localisation of metals in anthers and pollen. Pollen morphology was investigated with light microscope and scanning electron microscope (SEM) observations. The pollen grains are 3-colpate, most often oblate-spheroidal, with long colpi reaching the poles. The ornamentation is microreticulate. The anther and pollen grains were micromorphologically analysed by SEM coupled with an energy-dispersive X-ray probe (SEM-EDX). Low concentration of Ni was recorded for anthers (0.38%) and pollen (0.1–5.6%). Variation in pollen production was found for the flowers of the same individual. The mean pollen production per flower and stamen was 59365 and 14938 pollen grains respectively. The sterile pollen was above the limit considered as a normal abortion and was between 10.1 and 38.0%. From a palynological point of view our results are important for taxonomy and support keeping the species in the genus Phelipanche.

Broomrape Species Parasitizing Odontarrhena lesbiaca (Brassicaceae) Individuals Act as Nickel Hyperaccumulators

“…This finding is in accordance with the hypothesis that within Ni-hyperaccumulating plants there is a gradation of filtering out Ni, from leaves to tissues related with the flower-pollinator interface, which was interpreted as a "corrective" adaptation mechanism related to the hyperaccumulator-pollinator interaction [33]. This filtering is also supported by the low Ni-concentrations recorded on the anthers and pollen of O. nowackiana in Albania [49].…”

Elemental localization in inflorescences of the hyperaccumulators Noccaea praecox and Noccaea caerulescens (Brassicaceae)

“…Although it is a useful defense against herbivory, excessive metal concentrations in nectar can affect the health of pollinators and associated agents in the food chain. Hence, pollen analyses in Orobanche nowackiana (Pavlova & Bani, 2019) and several Odontarrhena species (Pavlova et al, 2016) showed significantly lower Ni concentrations compared to other parts of the stamens, thus protecting the reproductive potential of the species. In line with this, Ni concentrations in the seeds of two subspecies of Odontarrhena serpylifollia from the Iberian Peninsula were significantly lower compared to those in the vegetative organs (de la Fuente et al, 2007).…”