Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants.it considers that the simultaneous production of large numbers of seeds by a plant population reduces th...Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants.it considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual.orchids produce huge numbers of seeds per fruit and rarely experience seed predation.it remains unclear which factors may affect fluctuating fruit production in orchids,which generally suffer a widespread pol-len limitation.To explore the temporal pattern of fruiting and poten-tial factors related to fluctuation in fruit production,we investigated reproductive success of a long-spurred orchid(Habenaria glaucifo-lia)in an alpine meadow with thousands of individuals over 8 years.Methods To estimate reproductive success,pollinator observation was con-ducted by day and at night,and pollinia removal and receipt were recorded in the field population for 8 years.To examine whether fruit set and seed set are pollen limited,we conducted supple-mentary pollination experiments and compared fruit set,seed set and pollinia movement of open-pollinated flowers from 2011 to 2013.We measured lengths of spurs and pollinator probos-cises,and nectar volume and concentration,to identify potential pollinators.Important Findings Hawkmoths were seen to be effective pollinators for H.glauci-folia in 3 years,whereas in the remaining 5 years no pollinators were observed,and consequently pollinia were rarely transferred.Numerous pollinia movements were observed in 2012,2013 and 2014(pollinia removal:48,59 and 85%;pollinia receipt 51,70 and 80%),and correspondingly fruit set was significantly higher in 2012 and 2013(59 and 46%)than in 2011(25%).it was fruit set,rather than seed set,that was pollen limited in this orchid in the 3 years,in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural.Three species of hawkmoths had proboscis lengths that matched the spur length of H.glaucifolia.Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths,resulting in significant tempo-ral variation in fruit production.mast fruiting in this alpine orchid could be attributed to a‘sit and wait’strategy,awaiting an abun-dance of effective pollinators.展开更多
Transmission electron microscopy was conducted to characterize the mature pollen grains in the massulae of Habenaria sagittifera at anthesis to understand its ultramicroscopic features of mature pollen grains of this ...Transmission electron microscopy was conducted to characterize the mature pollen grains in the massulae of Habenaria sagittifera at anthesis to understand its ultramicroscopic features of mature pollen grains of this species. I found that(a) pollen walls on the surface of the massula consisted of several layers, which included the tectum, baculum, nexine-1, nexine-2, and intine, whereas pollen walls within the massula were comprised of less layers, lacking tectum and baculum;(b) both vegetative and generative nuclei in mature pollen grains were predominated by highly condensed chromatin, which occupied over half of the nuclear volume; and(c) the pollen grains did not contain lipid droplets, starch grains,or storage proteins, indicative of the absence of macromolecular storage reserves. In summary, the structural difference between walls on the surface of the massula and walls within the massula, the highly condensed status of the vegetative nucleus, and the absence of macromolecular storage reserves were the most noticeable ultramicroscopic characteristics of mature pollen grains of H. sagittifera.展开更多
基金National Science Foundation of China(U1402267 and 31270281)to S.-Q.H.
文摘Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants.it considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual.orchids produce huge numbers of seeds per fruit and rarely experience seed predation.it remains unclear which factors may affect fluctuating fruit production in orchids,which generally suffer a widespread pol-len limitation.To explore the temporal pattern of fruiting and poten-tial factors related to fluctuation in fruit production,we investigated reproductive success of a long-spurred orchid(Habenaria glaucifo-lia)in an alpine meadow with thousands of individuals over 8 years.Methods To estimate reproductive success,pollinator observation was con-ducted by day and at night,and pollinia removal and receipt were recorded in the field population for 8 years.To examine whether fruit set and seed set are pollen limited,we conducted supple-mentary pollination experiments and compared fruit set,seed set and pollinia movement of open-pollinated flowers from 2011 to 2013.We measured lengths of spurs and pollinator probos-cises,and nectar volume and concentration,to identify potential pollinators.Important Findings Hawkmoths were seen to be effective pollinators for H.glauci-folia in 3 years,whereas in the remaining 5 years no pollinators were observed,and consequently pollinia were rarely transferred.Numerous pollinia movements were observed in 2012,2013 and 2014(pollinia removal:48,59 and 85%;pollinia receipt 51,70 and 80%),and correspondingly fruit set was significantly higher in 2012 and 2013(59 and 46%)than in 2011(25%).it was fruit set,rather than seed set,that was pollen limited in this orchid in the 3 years,in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural.Three species of hawkmoths had proboscis lengths that matched the spur length of H.glaucifolia.Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths,resulting in significant tempo-ral variation in fruit production.mast fruiting in this alpine orchid could be attributed to a‘sit and wait’strategy,awaiting an abun-dance of effective pollinators.
基金supported by Natural Science Foundation of Shandong Province(ZR2015HL115)National Natural Science Foundation(31300545)
文摘Transmission electron microscopy was conducted to characterize the mature pollen grains in the massulae of Habenaria sagittifera at anthesis to understand its ultramicroscopic features of mature pollen grains of this species. I found that(a) pollen walls on the surface of the massula consisted of several layers, which included the tectum, baculum, nexine-1, nexine-2, and intine, whereas pollen walls within the massula were comprised of less layers, lacking tectum and baculum;(b) both vegetative and generative nuclei in mature pollen grains were predominated by highly condensed chromatin, which occupied over half of the nuclear volume; and(c) the pollen grains did not contain lipid droplets, starch grains,or storage proteins, indicative of the absence of macromolecular storage reserves. In summary, the structural difference between walls on the surface of the massula and walls within the massula, the highly condensed status of the vegetative nucleus, and the absence of macromolecular storage reserves were the most noticeable ultramicroscopic characteristics of mature pollen grains of H. sagittifera.
基金supported by the Fund of Guangxi Key Laboratory of Functional Phytochemicals Research and Utilization(Grant No.ZRJJ2016-7,ZRJJ2016-10)the Traditional Chinese Medicine Public Health Special Project(Grant No.[2011]76)the Special Project for Traditional Chinese Medicine Industry Research(Grant No.201207002)
