Embryology of Petrosavia (Petrosaviaceae, Petrosaviales): evidence for the distinctness of the family from other monocots.
ABSTRACT The affinities of Petrosavia, a rare, leafless, mycoheterotrophic genus composed of two species indigenous to East to Southeast Asia, have long been uncertain. However, recent molecular analyses show that the genus is sister to Japonolirion osense. Japonolirion and Petrosavia comprise the Petrosaviaceae, which are now placed in its own order, Petrosaviales, distinct from other monocots based on molecular analyses. We conducted an embryological study of Petrosavia, comparing it to Japonolirion, as well as to basal monocots (Acorus and Araceae) and more derived monocots (Nartheciaceae, Velloziaceae, and Triuridaceae). Our results showed that Petrosavia is very similar in embryology to Japonolirion, with both genera sharing a glandular anther tapetum, simultaneous cytokinesis in microspore mother cells, anatropous and crassinucellate ovules, T-shaped tetrads of megaspores, ab initio Cellular-type endosperm, and a mature seed coat composed of the exotesta, endotesta, and endotegmen. The two genera of Petrosaviaceae are clearly distinct from Acorus, and all Araceae, Nartheciaceae, Velloziaceae, and Triuridaceae genera in various combinations of characters. Thus, both molecular and embryological evidence support the distinctness of the Petrosaviaceae from other monocots and its placement in its own order, Petrosaviales.
Conference Paper: Research of inverter output filters for PWM drives[Show abstract] [Hide abstract]
ABSTRACT: When long motor cables are used between a PWM inverter and motor, there will be voltage reflection, which contributes to overvoltage and damped high-frequency ringing at motor terminals which further stresses the motor insulation. In this paper, cable transmission line theory is analyzed, which indicates that overvoltage is dependent on the risetime of the PWM pulse and the cable length. The problem can be solved by some passive filtering techniques. Then the analysis and design of the motor terminal filter and inverter output filters are presented, experimental results show that the filters can effectively reduce the overvoltage at the motor terminalsElectrical Machines and Systems, 2001. ICEMS 2001. Proceedings of the Fifth International Conference on; 02/2001
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ABSTRACT: The Araceae, a basal-most family of Alismatales that basally diverged subsequent to Acorales in monocot phylogeny, are known to have diverse modes of endosperm development: nuclear, helobial, and cellular. However, the occurrence of nuclear and helobial endosperm development has long been debated. Here, we report a (re-)investigation of endosperm development in Lysichiton, Orontium, and Symplocarpus of the Orontioideae (a basal Araceae), in which nuclear endosperm development was recorded more than 100 years ago. The results show that all three genera exhibit a cellular, rather than nuclear, endosperm development and suggest that the helobial endosperm development reported as an "unmistakable record" from Ariopsis is likely cellular. Thus the Araceae are very likely characterized by cellular endosperm development alone. An extensive comparison with other monocots in light of phylogenetic relationships demonstrates that a plesiomorphic cellular endosperm development is restricted to the three basal monocot orders Acorales, Alismatales, and Petrosaviales, in which evolutionary changes from cellular to nuclear endosperm development occurred twice as major events, once within Alismatales and once as a synapomorphy of the eight remaining monocot orders, including Dioscoreales, Liliales, Asparagales, and Poales, and that helobial endosperm development, which is known for many monocot families, evolved as homoplasy throughout the monocots.Journal of Plant Research 04/2010; 123(6):731-9. DOI:10.1007/s10265-010-0327-4 · 2.51 Impact Factor
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ABSTRACT: The Irvingiaceae, one of 40 families of the Malpighiales, comprise a small woody family of 10 species in three genera distributed in Old World tropics. Its relationships with other families are unclear, although recent molecular analyses suggest affinities with Linaceae, Caryocaraceae, Erythroxylaceae, and Rhizophoraceae. To gain insight into family relationships, we investigated 63 embryological characters of two previously unstudied African species, Irvingia gabonensis and I. smithii, and compared them with other Malpighiales and the sister group Oxalidales. Embryologically, Irvingia is characterized by the absence of an integumentary tapetum and by having a non-multiplicative inner integument, a multiplicative testa, many discrete fascicles of vascular bundles running in the testa from the raphe to antiraphe (each fascicle comprised several strands arranged in a concentric manner), and a fibrous exotegmen. Comparisons showed that Irvingia did not resemble any of the Linaceae, Caryocaraceae, Erythroxylaceae, Rhizophoraceae, or any of the other malpighialean families for which embryological data are available. The genus rather resembled Huaceae and Connaraceae (Oxalidales) in seed coat structure. However, 18 families (45%) of the Malpighiales are still poorly understood embryologically, and therefore additional studies are required for further critical comparisons.Journal of Plant Research 11/2010; 124(5):577-91. DOI:10.1007/s10265-010-0393-7 · 2.51 Impact Factor