Observation On Sexual Generationand Embryonic Development Of Isoetes Sinensis And I. Hypsophila

Isoetes is Isoetaceae the only remaining relic genera so far. There are about200species all over the world. Most of them are native to swamp and cold region ofnorthern North America and Eurasia. Small ferns belong to the independent evolutionon the classification, without complicated veins and there is a big dispute on origin andevolution route. There are five kinds of in total distribution in China. Isoetes sinensisPalmer plant is bigger and mainly produced the edge of swamp and pond in our countryYangtze River and Qiantang River system. And I. hypsophila Hand.-Mazz. is onlyproduced in alpine meadow at the southwest of Sichuan and northwest of Yunnan inChina. The different of living environment and the geographical position of I.sinensisPalmer and I. hypsophila Hand.-Mazz.. And in genetic aspect also exist difference in thesame. Isoetes is sensitive indicator of swamp plant. And the study has increased theconvenience for endangered mechanism of Isoetes. At the same time the research onaquatic plant and close related species establish a substantial foundation.This article selects I. sinensis Palmer and I. hypsophila Hand.-Mazz. as researchmaterials, using the improved Knop s solid plate culture medium, soil culture andhydroponic methods for gametophyte and embryo research on the spores of Isoetessinensis Palmer. At the same time, mading the further observation and studying forenvironmetal factors which influence on I. sinensis Palmer. The anatomy observationand comparison research on the root, corm and leaf of I. sinensis Palmer and I.hypsophila Hand.-Mazz.. Scanning electron microscope view megaspore andmicrospore of the two kinds of Isoetes. By laser scanning confocal microscope researchthe morphological structure of diaphragm in I. sinensis Palmer. Using Epon-812resinembedding, with semi thin section technology for selecting gametophyte and embryoobservation and taking pictures in a time. Main results are as follows:Megaspore wall of I. sinensis have the perispore, exospore and endospore of threelayers structure of tissue. Spores ornamentation and color depends on of ornamentationand color the perispore and exospore. Gametophyte ultrastructural observation showedthat the primary nuclear of spore first divided into30-50free nuclears. And freenuclears near the upper part of the spores, usually together, morphology and size arebasically identical. Mature archegonium neck channel usually open and there is a egg in abdomen, occupied the whole of the abdominal cavity. For the first time division of thezygote and archegonium is more or less20degrees of angle. In the process ofembryonic development, cell of close to the archegonium neck growth speed is fasterthan in the opposite side, and away from cell of the archegonium neck developmenttowards gametophyte center. It forms on one side of the cave, but on the other side ofpromontory, and at the same time, the direction of the embryo has changed. As a result,the embryo growing towards to the centre of the gametophyte.The microspore wall of I. hypsophila Hand.-Mazz. Consist of the perispore,exospore, mesospore and endospore of the four-story structures, the perispore is dividedinto outer peripheral wall, middle and inner. In the mature microspore stockpile richnutrients, and formation swimming sperm for spore germination. Experimental studieshave found that immature spores or spores in a bad environment, spores frommesospore began to shrink. Inclusion dissolved to form a crescent, close to the side ofthe peripheral wall of the spores, it will form a giant cavity between the perispore andthe mesosporeand.In addition, this article through to the I. sinensis embryo in the process of root,corm, leaf and ligule in detail their respective phases occur and differentiation ofobservation, compares with other true fern. Results further verify the root and leafpriority doctrine, and concluded that the I. sinensis with other true fern of thesimilarities and differences in the process of embryonic development; There are fivereasons that Isoetes endangered, Among them, the suitable habitat loss of water qualitydeterioration and gradually, and habitat fragmentation fuel is the main factor affectingIsoetes endangered; As well as the protection of Isoetes puts forward some suggestionsand opinions, so as to restore populations and wetland protection to provide detaileddata; Sexual generation and research in embryonic development, to discuss somecomplex of system evolution and reproductive patterns provide the necessary evidence,as well as molecular biology, genetics, cell biology, developmental biology and so on toprovide the necessary technical support and reliable basis of knowledge.