In order to study vegetation evolution and environmental changes around 2.5 Ma B.P., a total of 146 pollen samples with an average time resolution of 7 000 years were analyzed in the deep-sea record at the depth of 13...In order to study vegetation evolution and environmental changes around 2.5 Ma B.P., a total of 146 pollen samples with an average time resolution of 7 000 years were analyzed in the deep-sea record at the depth of 135 - 95 m （in composition depth） from ODP Site 1143 （9° 22＇ N, 113° 17＇ E） in the southern South China Sea. The results show that the pollen influx has a distinct change. During 2.6 - 2.0 Ma B.P., the average value of pollen influx increased evidently compared with that of 3.0 - 2.6 Ma B.P. It shows that the sea level of SCS dropped dramatically around 2.6 Ma B.P., corresponding to the formation of the Northern Hemisphere ice-sheets and the enhancement of the East Asian Monsoon. The pollen influx variations reflect the glacial-interglacial cycles corresponding with the deep-sea oxygen isotope curve and indicate that the sea level of SCS rose and dropped many times after 2.6 Ma B.P. The spectrum analysis results of pollen influx show that there are cycles at 0.1Ma （eccentricity） and 46.9 ka （obliquity） during 3.0 - 2.0 Ma B.P.展开更多
The pollen wall is a solid and variously sculptured structure. This pattern is determined inside a tetrad. During meiosis, the callose wall is formed outside of the meiocyte/microspore to form a tetrad. Then, primexin...The pollen wall is a solid and variously sculptured structure. This pattern is determined inside a tetrad. During meiosis, the callose wall is formed outside of the meiocyte/microspore to form a tetrad. Then, primexine is deposited between the callose wall and the microspore plasma membrane which will become undulated. The sporopollenin deposits on top of the undulated membrane and develops into the pollen wall pattern, while the callose wall is gradually degraded. In recent years, much progress has been made in the study of pollen wall pattern formation, at both molecular and genetic levels. In this review,we summarize these achievements mainly in Arabidopsis.展开更多
基金the National Natural Science Foundation of China projects （40371116） the National Major Basic Research Program of China （G200078502）.
文摘In order to study vegetation evolution and environmental changes around 2.5 Ma B.P., a total of 146 pollen samples with an average time resolution of 7 000 years were analyzed in the deep-sea record at the depth of 135 - 95 m （in composition depth） from ODP Site 1143 （9° 22＇ N, 113° 17＇ E） in the southern South China Sea. The results show that the pollen influx has a distinct change. During 2.6 - 2.0 Ma B.P., the average value of pollen influx increased evidently compared with that of 3.0 - 2.6 Ma B.P. It shows that the sea level of SCS dropped dramatically around 2.6 Ma B.P., corresponding to the formation of the Northern Hemisphere ice-sheets and the enhancement of the East Asian Monsoon. The pollen influx variations reflect the glacial-interglacial cycles corresponding with the deep-sea oxygen isotope curve and indicate that the sea level of SCS rose and dropped many times after 2.6 Ma B.P. The spectrum analysis results of pollen influx show that there are cycles at 0.1Ma （eccentricity） and 46.9 ka （obliquity） during 3.0 - 2.0 Ma B.P.
基金supported by the Major Research Plan from the Ministry of Science and Technology of China(2013CB945100)the National Natural Foundation of China(31300262)
文摘The pollen wall is a solid and variously sculptured structure. This pattern is determined inside a tetrad. During meiosis, the callose wall is formed outside of the meiocyte/microspore to form a tetrad. Then, primexine is deposited between the callose wall and the microspore plasma membrane which will become undulated. The sporopollenin deposits on top of the undulated membrane and develops into the pollen wall pattern, while the callose wall is gradually degraded. In recent years, much progress has been made in the study of pollen wall pattern formation, at both molecular and genetic levels. In this review,we summarize these achievements mainly in Arabidopsis.
