02351nas a2200361 4500008004100000020001400041245007900055210006900134260000800203300001000211490000800221520137900229653001601608653001101624653001501635653003101650653002401681653002201705653002001727653001701747653001801764653001101782653001401793653001101807653002401818653001701842653002601859653001201885653001201897100001701909700001501926856004801941 2007 eng d a0378-269700aOctad pollen formation in Cymbopetalum (Annonaceae): the binding mechanism0 aOctad pollen formation in Cymbopetalum Annonaceae the binding me cJan a13-230 v2633 aOur recent study of tetrad pollen formation in Annona (Annonaceae) revealed that after meiosis the callose-cellulose envelope forms a special conjugation with individual microspores and the forthcoming callose digestion is incomplete. The undigested part forms a central binder holding the four microspores of the tetrad together. This process causes the microspores to rotate 180 degrees. In this paper we describe pollen formation in another annonaceous genus, Cymbopetalum, in which the pollen is shed in octads, through use of light microscopy, epifluorescence microscopy, and TEM. In Cymbopetalum, two meiocytes, connected by abundant cytomictic channels, are produced in each sporangium. Octad pollen formation in Cymbopetalum is shown to be comparable to the synchronized formation of two connected Annona tetrads, which then integrate into a single octad. Unique features of Annona polyad formation, e.g. special binding between the callose-cellulose envelopes and microspores, incomplete callose digestion, and microspore rotation, also occur in Cymbopetalum. In addition, formation of the Cymbopetalum octad involves development of a cushion-like structure that binds the distal pronexine of all eight microspores, and there is the production of intine protrusions. The evolutionary origin of the callose-cellulose binding mechanism within the family is discussed.10aangiosperms10aAnnona10aAnnonaceae10aASIMINA-TRILOBA ANNONACEAE10aCALLOSE DISSOLUTION10acallosic envelope10acompound pollen10aCymbopetalum10aDEVELOPMENTAL10aEVENTS10aEVOLUTION10aGENERA10amicrospore rotation10aoctad pollen10aSPORODERM DEVELOPMENT10aTAPETUM10aTETRADS1 aTsou, C., H.1 aFu, Y., L. uhttps://annonaceae.myspecies.info/node/561202158nas a2200241 4500008004100000245013100041210006900172300001200241490000700253520140000260653001501660653001401675653001401689653001501703653002101718653002601739100002101765700002101786700001701807700002001824700002401844856004801868 2007 eng d00aA rapid diversification of rainforest trees (Guatteria; Annonaceae) following dispersal from Central into South America0 arapid diversification of rainforest trees iGuatteriai Annonaceae a399-4110 v443 aSeveral recent studies have suggested that a substantial portion of today's plant diversity in the Neotropics has resulted from the dispersal of taxa into that region rather than vicariance, but more data are needed to substantiate this claim. Guatteria (Annonaceae) is, with 265 species, the third largest genus of Neotropical trees after Inga (Fabaceae) and Ocotea (Lauraceae), and its widespread distribution and frequent occurrence makes the genus an excellent model taxon to study diversification patterns. This study reconstructed the phylogeny of Guatteria and inferred three major biogeographical events in the history of the genus: (1) a trans-oceanic Miocene migration from Central into South America before the closing of the Isthmus of Panama; (2) a major diversification of the lineage within South America; and (3) several migrations of South American lineages back into Central America via the closed Panamanian land bridge. Therefore, Guatteria is not an Amazonian centred-genus sensu Gentry but a major Miocene diversification that followed its dispersal into South America. This study provides further evidence that migration into the Neotropics was an important factor in the historical assembly of its biodiversity. Furthermore, it is shown that phylogenetic patterns are comparable to those found in Ocotea and Inga and that a closer comparison of these genera is desirable.10aAnnonaceae10aDispersal10aGuatteria10aNeotropics10aRainforest trees10aRapid diversification1 aErkens, Roy, H J1 aChatrou, Lars, W1 aMaas, Jan, W1 aNiet, Timotheus1 aSavolainen, Vincent uhttps://annonaceae.myspecies.info/node/506002224nas a2200241 4500008004100000245013100041210006900172300001200241490000700253520141300260653001501673653001401688653001401702653001501716653002101731653002601752100002101778700002101799700001701820700002001837700002401857856010101881 2007 eng d00aA rapid diversification of rainforest trees (Guatteria; Annonaceae) following dispersal from Central into South America0 arapid diversification of rainforest trees iGuatteriai Annonaceae a399-4110 v443 a

Several recent studies have suggested that a substantial portion of today's plant diversity in the Neotropics has resulted from the dispersal of taxa into that region rather than vicariance, but more data are needed to substantiate this claim. Guatteria (Annonaceae) is, with 265 species, the third largest genus of Neotropical trees after Inga (Fabaceae) and Ocotea (Lauraceae), and its widespread distribution and frequent occurrence makes the genus an excellent model taxon to study diversification patterns. This study reconstructed the phylogeny of Guatteria and inferred three major biogeographical events in the history of the genus: (1) a trans-oceanic Miocene migration from Central into South America before the closing of the Isthmus of Panama; (2) a major diversification of the lineage within South America; and (3) several migrations of South American lineages back into Central America via the closed Panamanian land bridge. Therefore, Guatteria is not an Amazonian centred-genus sensu Gentry but a major Miocene diversification that followed its dispersal into South America. This study provides further evidence that migration into the Neotropics was an important factor in the historical assembly of its biodiversity. Furthermore, it is shown that phylogenetic patterns are comparable to those found in Ocotea and Inga and that a closer comparison of these genera is desirable.

10aAnnonaceae10aDispersal10aGuatteria10aNeotropics10aRainforest trees10aRapid diversification1 aErkens, Roy, H J1 aChatrou, Lars, W1 aMaas, Jan, W1 aNiet, Timotheus1 aSavolainen, Vincent uhttp://www.sciencedirect.com/science/article/B6WNH-4N4J30W-1/2/53ce435f1fe55962b5e1cbbeb334aa50