Pollen tube growth and the pollen-tube pathway of Nymphaea odorata (Nymphaeaceae)

Abstract

An important aspect of the evolution of carpel closure, or angiospermy, is the relationship between pollen tube growth patterns and internalization of the pollen‐tube pathway. True carpel closure, involving postgenital fusion of inner carpel margins, is inferred to have arisen once within the ancient order Nymphaeales, in the common ancestor of Nymphaeaceae. We studied pollen tube development, from pollination to fertilization, in a natural population of Nymphaea odorata, using hand pollinations and timed flower collections. Pollen germinates in stigmatic secretions within 15 min and pollen tubes enter subdermal transmitting tissue within an hour, following wide intercellular spaces towards the zone of postgenital fusion. At the zone of fusion they turn downwards to grow in narrow spaces between interlocked cells and then wander freely to ovules within ovarian secretions. The pollen‐tube pathway is 2–6 mm long and upper ovules are first penetrated 2.5 h after pollination. Pollen tubes grow at rates of approximately 1 mm/h whether in stigmatic fluid, transmitting tissues or ovarian secretions. Pollen‐tube pathways are structurally diverse across Nymphaeales, yet their pollen tubes have similar morphologies and rapid growth rates. This pattern suggests pollen tube growth innovations preceded and were essential for the evolution of complete carpel closure. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162, 581–593.

Morphology, viability, and germinability of pollen from two forms of Nymphaea nouchali var. versicolor, a day-blooming waterlily

“…2). The high pollen viability measured by acetocarmine staining in N. nouchali is consistent with high viability found for N. odorata, based on pollen germination in vivo 12 . The shape of viable pollen from both forms under a light microscope was nearly spheroidal (Fig.…”

“…The flower of Bua Phan has pale bluish purple petals which typically change its colour to pink after the second day of blooming whereas that of Bua Phuean comprises white petals with pale bluish purple tips and does not change colour after blooming 3 . Pollen development and morphology of Nymphaea have been studied or compared in many species such as N. alba, N. candida, N. mexicana, N. odorata, and N. tetragona [10][11][12] . However, there is a paucity of assessment on pollen viability and germinability of this genus.…”

Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

“…Pollen tube transmitting tracts are short because long styles are lacking (Endress, 2015). However, the growth pattern of the pollen tubes, in which callose plugs are formed intermittently and keep the active part of the pollen tube constantly short even in long pollen tubes, and pollen tube growth is restricted to on or in the cell walls (without destroying the cells) or in secretion outside of the gynoecium tissue, is the same in the ANITA grade as in Mesangiospermae but differs markedly from the pattern in living gymnosperms (Willliams, 2008(Willliams, , 2009Williams & al., 2010;Taylor & Williams, 2012). Pollen germination time is comparable to that in mesangiosperms and much faster than in gymnosperms (Williams, 2012).…”

Pollen tube development in two species of Trithuria (Hydatellaceae) with contrasting breeding systems

“…It is important to note that in comparing PTGRs, single-donor crosses were used in both species. Pollen tube growth rates of T. austinensis are comparable to those of other water lilies, which range from 589 lm/h in Nuphar polysepala to about 1 mm/h in others (Williams 2008;Taylor and Williams 2009;Williams et al 2010), whereas average PTGR in T. submersa was much slower (321 lm/h).…”

“…Such rapid pollen germination appears to be a trait shared by most water lilies. Substantial pollen germination occurs within 15 min of pollination in Brasenia schreberi and Cabomba caroliniana (Cabombaceae; Taylor and Williams 2009), as well as in Nymphaea odorata (Nymphaeaceae; Williams et al 2010). These taxa also exhibit rapid pollen tube growth, suggesting that the origin of the aquatic habit in Nymphaeales was accompanied by an overall shift to faster development during this stage.…”