The 26 plots including natural forestland, secondary forestland, shrub-grassland, sloping cropland, artificial forest and abandoned field, were selected to discuss the impact of land cover on the soil characteristics ...The 26 plots including natural forestland, secondary forestland, shrub-grassland, sloping cropland, artificial forest and abandoned field, were selected to discuss the impact of land cover on the soil characteristics in the three karst districts of Chongqing. The results showed that： （1） After the vegetation turned into secondary vegetation or artificial vegetation, or reclamation, soil physical properties would be degraded. In the surface-layer soil of sloping cropland, the contents of 〉2 mm water-stable aggregates decreased obviously with apparent sandification. （2） The contents of soil organic matter and total nitrogen are controlled completely by vegetation type and land use intensity. The increasing trend is rather slow in the early days when over-reclamation is stopped and the land is converted to forest and pasture. （3） Herbaceous species increase and woody plants species decrease with the increase of land use intensity, therefore, the soil seed banks degrade more seriously. （4） The soil degradation index has been set up to describe the relative soil degradation degree under the conditions of different vegetation types. （5） Land cover has a significant effect on karst soil characteristics, land degradation in the karst ecosystem is essentially characterized by the different degradation of soil functions that serve as water banks, nutrient banks and soil seed banks.展开更多
Transfer cells （TCs） are specialized cells exhibiting invaginated wall ingrowths （Wls）, thereby amplifying their plasma membrane surface area （PMSA） and hence the capacity to transport nutrients. However, it rem...Transfer cells （TCs） are specialized cells exhibiting invaginated wall ingrowths （Wls）, thereby amplifying their plasma membrane surface area （PMSA） and hence the capacity to transport nutrients. However, it remains unknown as to whether TCs play a role in biomass yield increase during evolution or domestication. Here, we examine this issue from a comparative evolutionary perspective. The cultivated tetraploid AD genome species of cotton and its A and D genome diploid progenitors displayed high, medium, and low seed and fiber biomass yield, respectively. In all three species, cells of the innermost layer of the seed coat juxtaposed to the filial tissues trans-differentiated to a TC morphology. Electron microscopic analyses revealed that these TCs are characterized by sequential formation of flange and reticulate Wls during the phase of rapid increase in seed biomass. Significantly, TCs from the tetraploid species developed substantially more flange and reticulate Wls and exhibited a higher degree of reticulate WI formation than their progenitors. Consequently, the estimated PMSA of TCs of the tetraploid species was about 4 and 70 times higher than that of TCs of the A and D genome progenitors, respectively, which correlates positively with seed and fiber biomass yield. Further, TCs with extensive Wls in the tetraploid species had much stronger expression of sucrose synthase, a key enzyme involved in TC Wl formation and function, than those from the A and D progenitors. The analyses provide a set of novel evidence that the development of TC Wls may play an important role in the increase of seed and fiber biomass yield through polyploidization during evolution.展开更多
The present study was aimed at revealing the responses of metabolite pools to selection for alternative reproductive schedules in the seed beetle, Acanthoscelides obtectus Say （Coleoptera： Chrysomelidae： Bruchinae...The present study was aimed at revealing the responses of metabolite pools to selection for alternative reproductive schedules in the seed beetle, Acanthoscelides obtectus Say （Coleoptera： Chrysomelidae： Bruchinae）. The levels of metabolites （free sugars, glycogen, lipids, soluble and hydrophobic proteins） that were determined in virgin females and males at three ages from adult eclosion onwards were compared among the base population （B） and two derived lines that were selected for either early （Y） or late （O） reproduction. The results showed differences in the accumulation of metabolites during pre-adult development, as well as in the pattern of their changes during adult ageing, Generally, in comparison to the B population, the short-lived beetles from the Y line showed increased protein content and reduced carbohydrate and lipid content, whereas the opposite was true for the long-lived beetles from the O line. Females from the O line exhibited slower utilization of energy reserves and a slower increase in protein contents than females from the Y line. Females contained higher levels of free sugars, glycogen and hydrophobic proteins and lower levels of lipids and soluble proteins than males, although the sexual dimorphism was not evenly expressed among lines. Age-specific changes in metabolite contents were slower in females than males. Our findings suggest that trade-offs among capital resources are a physiological basis of early/late fitness trade-offs and point to a conservation of resources that can be used for somatic maintenance.展开更多
OPVs (open pollinated varieties) of cross pollinated crops are genetically heterogeneous and therefore likely to evolve over generations, under natural and human selection, which gives them a strong potential for orga...OPVs (open pollinated varieties) of cross pollinated crops are genetically heterogeneous and therefore likely to evolve over generations, under natural and human selection, which gives them a strong potential for organic and low input farming. OPVs of maize were cultivated and selected by different farmers in France and Italy for 2 generations. The third year, they were phenotypically evaluated for evolution, adaptation and level of diversity (estimated with Nei index) across evolution in a combined on farm and on station experimentation. The results showed that the varieties evolved and even adapted over 2 generations only (especially on maturity traits) but conserved their identity (no evolution of ear morphological traits). They all conserved their diversity, which demonstrated the pertinence of farmers’ selection (it is not a bottleneck). These results suggested that the genetically heterogeneous nature of OPVs is an asset for farmers because they can adapt these varieties to specific local conditions and production objectives. Therefore, farmer OPVs should receive more support through social and regulatory recognition, as well as further interest from research.展开更多
基金Supported by the key plan of Chongqing Science and Technology Committee (6759, 7355)
文摘The 26 plots including natural forestland, secondary forestland, shrub-grassland, sloping cropland, artificial forest and abandoned field, were selected to discuss the impact of land cover on the soil characteristics in the three karst districts of Chongqing. The results showed that： （1） After the vegetation turned into secondary vegetation or artificial vegetation, or reclamation, soil physical properties would be degraded. In the surface-layer soil of sloping cropland, the contents of 〉2 mm water-stable aggregates decreased obviously with apparent sandification. （2） The contents of soil organic matter and total nitrogen are controlled completely by vegetation type and land use intensity. The increasing trend is rather slow in the early days when over-reclamation is stopped and the land is converted to forest and pasture. （3） Herbaceous species increase and woody plants species decrease with the increase of land use intensity, therefore, the soil seed banks degrade more seriously. （4） The soil degradation index has been set up to describe the relative soil degradation degree under the conditions of different vegetation types. （5） Land cover has a significant effect on karst soil characteristics, land degradation in the karst ecosystem is essentially characterized by the different degradation of soil functions that serve as water banks, nutrient banks and soil seed banks.
文摘Transfer cells （TCs） are specialized cells exhibiting invaginated wall ingrowths （Wls）, thereby amplifying their plasma membrane surface area （PMSA） and hence the capacity to transport nutrients. However, it remains unknown as to whether TCs play a role in biomass yield increase during evolution or domestication. Here, we examine this issue from a comparative evolutionary perspective. The cultivated tetraploid AD genome species of cotton and its A and D genome diploid progenitors displayed high, medium, and low seed and fiber biomass yield, respectively. In all three species, cells of the innermost layer of the seed coat juxtaposed to the filial tissues trans-differentiated to a TC morphology. Electron microscopic analyses revealed that these TCs are characterized by sequential formation of flange and reticulate Wls during the phase of rapid increase in seed biomass. Significantly, TCs from the tetraploid species developed substantially more flange and reticulate Wls and exhibited a higher degree of reticulate WI formation than their progenitors. Consequently, the estimated PMSA of TCs of the tetraploid species was about 4 and 70 times higher than that of TCs of the A and D genome progenitors, respectively, which correlates positively with seed and fiber biomass yield. Further, TCs with extensive Wls in the tetraploid species had much stronger expression of sucrose synthase, a key enzyme involved in TC Wl formation and function, than those from the A and D progenitors. The analyses provide a set of novel evidence that the development of TC Wls may play an important role in the increase of seed and fiber biomass yield through polyploidization during evolution.
基金Acknowledgments This work was supported by Ministry of Science and Technological Development of Serbia grant # 173007 and by grant No. P501/10/1215 from the Czech Science Foundation （DK）.
文摘The present study was aimed at revealing the responses of metabolite pools to selection for alternative reproductive schedules in the seed beetle, Acanthoscelides obtectus Say （Coleoptera： Chrysomelidae： Bruchinae）. The levels of metabolites （free sugars, glycogen, lipids, soluble and hydrophobic proteins） that were determined in virgin females and males at three ages from adult eclosion onwards were compared among the base population （B） and two derived lines that were selected for either early （Y） or late （O） reproduction. The results showed differences in the accumulation of metabolites during pre-adult development, as well as in the pattern of their changes during adult ageing, Generally, in comparison to the B population, the short-lived beetles from the Y line showed increased protein content and reduced carbohydrate and lipid content, whereas the opposite was true for the long-lived beetles from the O line. Females from the O line exhibited slower utilization of energy reserves and a slower increase in protein contents than females from the Y line. Females contained higher levels of free sugars, glycogen and hydrophobic proteins and lower levels of lipids and soluble proteins than males, although the sexual dimorphism was not evenly expressed among lines. Age-specific changes in metabolite contents were slower in females than males. Our findings suggest that trade-offs among capital resources are a physiological basis of early/late fitness trade-offs and point to a conservation of resources that can be used for somatic maintenance.
文摘OPVs (open pollinated varieties) of cross pollinated crops are genetically heterogeneous and therefore likely to evolve over generations, under natural and human selection, which gives them a strong potential for organic and low input farming. OPVs of maize were cultivated and selected by different farmers in France and Italy for 2 generations. The third year, they were phenotypically evaluated for evolution, adaptation and level of diversity (estimated with Nei index) across evolution in a combined on farm and on station experimentation. The results showed that the varieties evolved and even adapted over 2 generations only (especially on maturity traits) but conserved their identity (no evolution of ear morphological traits). They all conserved their diversity, which demonstrated the pertinence of farmers’ selection (it is not a bottleneck). These results suggested that the genetically heterogeneous nature of OPVs is an asset for farmers because they can adapt these varieties to specific local conditions and production objectives. Therefore, farmer OPVs should receive more support through social and regulatory recognition, as well as further interest from research.
