Pollen limitation and reproductive incompatibility system in a critically endangered tree, Polylepis incarum (Bitter) M. Kessler & Schmidt-Leb (Rosaceae)

Abstract

Anemophilous species depend on wind for sexual reproduction. When plants do not receive enough pollen and/or pollen has poor quality, they may experience pollen limitation. This can reduce the production of fruits and seeds with negative consequences on population dynamics. The self-compatibility system also plays an important role on the likelihood of a species suffering pollen limitation as it determines if plants can produce fruits and seeds in the absence of compatible mates. Here, we studied the breeding system of the Andean anemophilous tree Polylepis incarum, a critically endangered species endemic to Lake Titicaca. We conducted controlled experimental pollination experiments and florescence microscopy analysis to assess whether pollen limitation and the incompatibility system constrain fruit and seed production. Results showed that the seed set is limited by pollen availability, that P. incarum exhibits a pre-zygotic compatibility system and early inbreeding depression manifested during seed development. Therefore, self-pollination is a factor that could be partially associated with the production of non-viable seeds.

Performance and physiological quality of Escallonia resinosa seeds: prospects for their use in reforestation and restoration

“…These seeds may be post‐zygotically degraded, incompletely formed, or produced from unfertilized ovules, or they may be derived from a lack of adequate pollination; inbreeding depression, which decreases the number of viable seeds, has also been reported in several species of Escallonia (Valdivia & Niemeyer 2010; Rivera‐Hutinel et al 2017). Similarly, in Polylepis incarum seed production was found to be limited by pollen availability (López et al 2021). In this sense, we assumed that E. resinosa exhibits pollen limitation, and a self‐incompatible reproduction system or various agents might degrade the seed.…”

“…Viable seeds, that is, type II seeds, germinated regardless of the fruit maturity stage; thus, seeds would be physiologically mature long before being dispersed. The higher germination rate of seeds collected from immature fruits is attributed to a greater presence of viable seeds than at other fruit maturity stages; it is possible that seeds degrade over time, as in Polylepis species (e.g., P. incarum and P. tomentella ) (Domic et al 2020; López et al 2021).…”

A monograph of the genus Polylepis (Rosaceae)

“…At many of its locations, the species grows in habitats that are strongly affected by human activities including livestock grazing, logging and burning. In addition, there is indication of reduced reproduction due to pollen limitation and reproductive incompatibility ( López et al 2021 ). We assess P. incarum as Critically Endangered (A1, B1a+B2a, C1+C2a).…”

Impact of a heterogeneous environment on the population expansion of the harmful plant Iris ruthenica Ker-Gawl. in the high mountain grasslands

“…High mountain ecosystems not only have a strong impact on the adaptability and evolution of plants but also on the types and numbers of pollinators, thereby affecting the survival of high mountain plants in extreme environments (Peñuelas et al, 2004;Natsuki et al, 2022). For instance, adverse factors such as low temperatures, strong winds, heavy rain, and short growing seasons caused by changes in slope orientation and altitude can limit the types and activities of pollinating insects, resulting in a generally lower frequency of flower visits (Wang et al, 2020;Xiao et al, 2022), affecting the types of alpine plant breeding systems, and potentially leading to stronger pollen limitation for plants (Jacobi and del Sarto, 2007;Loṕez et al, 2021). Some alpine plants increase their flower lifespan and display area with changes in altitude and slope direction, and their reproductive allocation ratio compensates for the impact of limited pollinator activity on pollination efficiency, thereby improving the success of plant pollination (Buxton et al, 2016;Mao et al, 2019).…”