Abortive embryogenesis in hybrid swarm populations of Pinus sylvestris L. and Pinus muga Turra

Abstract

Comparative study on fertilization process in Pinus sylvestris, Pinus mugo and in their putative hybrid swarm individuals was done involving pre-zygotic and post-zygotic stages. The amount of surviving ovules from open pollination reflecting the mode of interaction between pollen grains and nucellar tissue of an ovule averaged at 8.1 of sound ovules per conelet in Pinus sylvestris, 7.3 ovules in the hybrid swarm population and at 4.9 ovules in Pinus mugo. A strong correlation was observed between the number of surviving ovules and the proportion of germinating seeds in the compared species and hybrids. Normal course of embryogenesis in Pinus sylvestris and Pinus mugo contrasted with increased frequency of disturbances observed in the hybrid swarm individuals. The differential survival rates of the ovules and deviations from typical pattern of embryogenesis are discussed from the standpoint of cross-ability relationship between Pinus sylvestris and Pinus mugo.

Pollen fertility and seed viability of putative hybrid swarms of Pinus sylvestris and Pinus mugo in Slovakia

“…These data are rather expressive compared to only 2 times higher frequencies of the underdeveloped and empty seeds in the evaluated progenies from open pollination of P. sylvestris and P. mugo hybrid swarms referred herein.The observed difference in seed germination potentials between pure species populations of the parental species P. sylvestris and P. mugo and their hybrid swarms was not only due to a higher frequency of empty seed formation in hybrid swarms, but also because of a higher content of filled, but non-germinating seeds of the latter. This corroborates our earlier finding concerning a higher frequency of abortive embryogenesis in the hybrid swarms than in the parental species P. sylvestris and P. mugo (Kormutak et al, 2008a). Underdeveloped embryos lacking cotyledons were present in seeds of the hybrid swarms along with a small amount of morphologically differentiated and physiologically mature seeds.…”

“…Based on these findings, the authors postulate a rare hybridization between P. uliginosa and P. sylvestris. This may explain the lowered quality of seed crops in the putative hybrid swarms of Scots and mountain dwarf pines with introgressive hybridization of a varying intensity (Kormutak et al, 2008a). Due to prezygotic reproductive barriers between the hard pine species (Buchholz 1944), the ovules with dormant pollen grains undergo abortion during the first growing season, remaining as the rudimentary remnants on the ovuliferous scales of the conelets (Kriebel, 1967).…”

Geographical patterns of nucleotide diversity and population differentiation in three closely related European pine species in thePinus mugocomplex

“…The retention of ancestral polymorphism could also be a result of interspecific gene flow considering the lack of reproductive isolation between the taxa found in controlled crosses (Lewandowski & Wisniewska, ) and evidence for natural hybridization in contact zones between P. mugo and P. uliginosa and between P. uncinata and closely related P. sylvestris (Kormutak et al ., ; Wachowiak & Prus‐Głowacki, ; Jasińska et al ., ). By comparing spatial differentiation at biparentally and maternally inherited markers, the difference between long‐distance (pollen) and short‐distance (seed) gene flow can be assessed.…”

Cross-species amplification and characterization of microsatellite loci in Pinus mugo Turra

“…To date studies conducted on Pinus mugo have concerned mostly its anatomical and morphological variability (Boratyńska et al 2004;, allozyme variation (Prus-G lowacki & Szweykowski 1983;Slavov & Zhelev 2004), clonal struc-622 K. Celiński et al Table 1. (Wachowiak et al 2006;Wachowiak et al 2008;Kormutak et al 2008;Kormutak et al 2009). However, up to date no data have been available on the genetic diversity of Pinus mugo populations using nuclear microsatellite markers.…”