Pollen vacuoles and their significance

Abstract

Vacuoles of several types can be observed in pollen throughout its development. Their physiological significance reflects the complexity of the biological process leading to functional pollen grains. Vacuolisation always occurs during pollen development but when ripe pollen is shed the extensive translucent vacuoles present in the vegetative parts in previous stages are absent. Vacuole functions vary according to developmental stage but in ripe pollen they are mainly storage sites for reserves. Vacuoles cause pollen to increase in size by water accumulation and therefore confer some degree of resistance to water stress. Modalities of vacuolisation occur in pollen in the same manner as in other tissues. In most cases, autophagic vacuoles degrade organelles, as in the microspore after meiosis, and can be regarded as cytoplasm clean-up following the transition from the diploid sporophytic to the haploid gametophytic state. This also occurs in the generative cell but not in sperm cells. Finally, vacuoles have a function when microspores are used for pollen embryogenesis in biotechnology being targets for stress induction and afterwards contributing to cytoplasmic rearrangement in competent microspores.

Adaptor Protein Complex 2–Mediated Endocytosis Is Crucial for Male Reproductive Organ Development in Arabidopsis

“…Until stage 10, the ap2m-1 mutant plants did not display any noticeable difference to the wild type (see Supplemental Figure 8 online). However, the most prominent difference was detected at stage 13 when the central vacuole (CV) undergoes degeneration (Yamamoto et al, 2003;Pacini et al, 2011). In wild-type pollen grains, the CV was fragmented into numerous small vacuoles <0.3 mm in diameter and uniformly distributed in the entire cellular space.…”

Adaptor Protein-3-Dependent Vacuolar Trafficking Involves a Subpopulation of COPII and HOPS Tethering Proteins

“…Plant vacuoles are versatile organelles critical for plant growth and responses to the environment (Pacini et al, 2011). The functionality of vacuoles is fulfilled through proteins localized at the vacuolar membrane (i.e.…”

Pollen-Specific Aquaporins NIP4;1 and NIP4;2 Are Required for Pollen Development and Pollination in Arabidopsis thaliana

“…In angiosperms, water and nutrient status regulation is relevant for pollen development, germination, and pollen tube growth (Samuel et al, 2009;Pacini et al, 2011;Firon et al, 2012). During its developmental program and functioning, pollen grains experience changes in water and nutrient content in relation to the surrounding environment (reviewed in Firon et al, 2012).…”