为清晰地了解青藏高原的生态现状及其未来的可持续性,本文改进了能值生态足迹模型,定量研究了西藏2005-2014年的可持续性,运用灰色预测模型,预测了西藏及其各地级市2015-2024年的可持续状态.结果表明:2005-2014年,西藏的人均生态承载力从38.30 hm2减少到33.81 hm2,人均生态足迹从6.83 hm2增加到11.59 hm2,生态盈余空间缩小,但生态足迹指数一直高于65％,当前的可持续性较强;万元GDP生态足迹、发展能力指数和生态足迹多样性指数表明西藏资源利用率提高 、经济发展速度加快但是产业结构单一;在未来10年,西藏及其各地级市(除拉萨外)的可持续性持续降低,但整体仍处于可持续发展状态,拉萨在2020年将变为严重不可持续.本研究定量地评价了西藏生态环境现状及其未来的可持续性,以期对高寒地区的可持续发展研究提供参考价值.

Controlling the uptake, transport, translocation, and accumulation of excessive amounts of cadmium from polluted environments is critical for plants and, consequently, humans with regard to food safety. Plants adopt various cellular and molecular mechanisms to minimize Cd toxicity. Upon exposure to Cd, plants initially implement avoidance strategies, such as production of organic acids, chelation, and sequestration, to prevent metal access to root cells. Nevertheless, Cd can be transported through the roots, stems, and leaves via apoplastic and symplastic pathways. These processes have been controlled by specific sites at the root surface and root cortex, in cells responsible for loading the root xylem, at the transition between the vascular systems of the root and the shoot, and in connecting tissues and cells at the stem. Although resistance to heavy metal cadmium can be achieved by either avoidance or tolerance, genetic basis to tolerance is therefore implied, in that these mechanisms are heritable attributes of tolerant mutants or genotypes.

植物体外雄核发育(androgenesis)是植物的花粉粒或游离小孢子在人工诱导条件下,偏离原来的发育途径经连续的细胞分裂发育成胚再生单倍体,后者通过染色体加倍可以获得纯合二倍体,对于植物的发育机理研究和遗传育种应用具有重要的意义.本文对植物体外雄核发育的细胞学事件及其影响因素进行了回顾,重点论述雄核发育的小孢子分裂方式和发育途径,围绕供体植物的基因型、生理状态、小孢子发育时期、诱导处理和培养条件等对雄核发育效率的影响进行探讨,并进一步论述体外雄核发育在单倍体和双单倍体生产中的应用及其限制因素,以为加快植物育种进程提供理论依据.

Biomass energy from renewable resources has been considered an alternative source of energy, and the growing contribution of biomass to the world energy also gives a new way to solve the problems such as global warming, the soaring fuel costs and environmental pollution. Lignocellulose is the main component of plant cell walls and is also one of the most abundant renewable resources on earth. Lignocellulosic biomass is principally composed of cellulose, hemicellulose and lignin, which can be converted into liquid biofuels such as bioethanol. The linkages between lignin and carbohydrates (hemicellulose and cellulose) are formed by ester, ether and glycosidic types of bonds, which formed a kind of covalently bonded aggregates called lignin-carbohydrate complex. The compositions of biomass and interaction of these components in the cell wall affect the hydrolysis of carbohydrates, and then determine the efficiency of lignocelluosic biomass utilization. Although lignin is one of the most abundant components in the lignocellulosic biomass besides polysaccharides, it has been considered as a physical barrier to prevent enzyme access to cellulose structure. Therefore, to improve the biomass production in the field and the effects of the factory conversions of biomass into biofuel are the two most concerned issues. That is, how to improve the utilization of lignin efficiency has been becoming a hot issue of biorefinery in biomass energy development. In this paper, the characteristics of development and sedimentary of lignin in plant cell walls, genetic improvement and genetic modification of lignin trait in bioenergy crops have been systematically reviewed, which is mainly from the point of view of cutting the lignin to enhance the overall lignocellulosic biorefinery. To select low-lignin-content energy crops, considerable genetic improvements can be expected through traditional breeding program or down regulation the levels of enzymes involved in the reactions specific for lignin monomer synthesis, which would reduce the amount of chemicals and energy used in pretreatment in lignocellulosic biorefinery. Furthermore, to explore the optimization of lignocellulose characters and the possibility of increased biofuel production rate, the technological means of biological refining pretreatment, transformation and biofuel production have been discussed for overcoming the cost barrier of lignocellulosic biomass utilization in the purpose of loosening lignin’s grip. Several different pretreatment and fractionation processes such as acid, alkaline and organic solvent hydrolysis can be used for treatment of lignocellulosic materials. And successful pretreatment can significantly improve the hydrolysis and increase the yield of bioethanol. In addition, the perspectives on hot issues and biofuel industry involved in studies of lignin were discussed.

细胞质雄性不育系是作物杂种优势利用的有效途径,分离其不育系线粒体和叶绿体基因组是深入探究细胞质雄性不育分子机制的重要环节,本研究以紫花苜蓿细胞质雄性不育系CMSI和野生对照植株WT为研究材料,选取新鲜叶片经冷冻匀浆、差速离心分离叶绿体和线粒体、DNase I降解核DNA、蛋白酶K裂解线粒体和叶绿体、酚—氯仿—异戊醇去除蛋白质和用乙醇沉淀叶绿体DNA (cpDNA)和线粒体DNA (mtDNA),结果如下:(1)叶绿体提取液中叶绿体数量的平均值为1 500个/mL,而詹纳斯绿B染色观察发现提取液中线粒体结构完整、含量较多;(2)叶片取材量为4 g时,CMS1 (WT)的cpDNA平均产率为0.41 (0.47)μg/g,而mtDNA的平均产率为1.15 (0.83) μg/g;改进叶片取材量为10 g时,两种苜蓿材料的cpDNA和mtDNA的平均产率升高至2.17 μg/g和2.22 μg/g,并且纯度好(cpDNA和mtDNA的OD260/OD280均保持在2.0左右);延长蛋白酶K消化处理时间(2h,4h和6h)可以提高紫花苜蓿cpDNA和mtDNA的产率,其中消化4h的mtDNA质量浓度最高(59.9 ng/μL),而cpDNA浓度则在孵育6h后达到最高值24.3 ng/μL;(3)紫花苜蓿CMS1和WT的mtD-NA和cpDNA琼脂糖凝胶电泳检测发现,细胞质基因组条带清晰,无拖尾现象,进一步表明采用以上方法提取的紫花苜蓿mtDNA和cpDNA符合分子遗传学研究的标准和要求.

Heavy metal ( HM ) toxicity is a worldwide concern because it damages plants by altering their major physiological and metabolic processes. The heavy metal cadmium ( Cd) is a nonessential element, and is a valid inhibitor of plant growth. The toxic effect of cadmium is closely related to its transfer from the soil to the plant above ground parts. Understanding the transport pathway and regulatory mechanism of cadmium in plants may improve plant resistance to this heavy metal, in addition to providing a theoretical basis for the phytoremediation soils contaminated by cadmium. In this paper, we reviewed the transport pathways of Cd2+ in plants and what limits its mobility based on the cytological structural and molecular regulation mechanism of plants. As the main organ for transporting water and nutrients to the plant body, the plant root is also the main organ that absorbs toxic metals, such as cadmium. During the process of Cd2+ transfer from the root cortex to the xylem, most Cd2+is deposited between the cells of the root cortex, with some reaching stele, before being transferred to the plant organs, such as the leaves in the above ground part of the plant. The transport pathway of Cd2+through the root cortex is mainly apoplastic, with the cytoplasmic accumulation of Cd2+possibly causing apoplastic transport towards the vascular cylinder to decline. The transport pathway of Cd2+ in the vascular cylinder is also mostly apoplastic, with cytoplasmic accumulation reducing Cd2+ transfer to the xylem. Since the aboveground parts of plants are more susceptible to Cd2+ poisoning, two cellular strategies to restrict the absorption and transfer of cadmium have evolved. First, the Casparian strip surrounding radial wall and the endodermis wall prevents Cd2+ from entering the root xylem via the apoplastic pathway. In addition, the Casparian strip promotes Cd2+ transport via the endodermis, leading to vacuolar isolation and cytoplasmic precipitation. Second, heavy metal detoxification occurs by chelating Cd2+ to form stable compounds, which are then deposited inside the vacuole. Third, excess cadmium also activates oxidative stress defense mechanisms and the synthesis of heavy metal stress related proteins to minimize metal toxicity, which includes the use of metallothiones and ion channels, such as H+/Cd2+binding or sequestrating Cd2+into vacuoles. For systematic improvements in the phytoremediation of heavy metal pollution, a more comprehensive understanding of cellular mechanisms involved in Cd avoidance, uptake, transport, and accumulation is required. Furthermore, the excluder strategy by extensive sequestration and retranslocation of cadmium through symplastic and apoplastic pathways should be confirmed and explored in future studies.

The effects of uniconazole(S3307) on the drought resistance of Perennial ryegrass were investigated by pot experiment under different concentration treatments of SS3307(0-80 mg/L).Perennial ryegrass was subjected to soil drought stress by withholding watering at the fifteen days after spraying SS3307.The results showed that S3307 increased the relative water content of Perennial ryegrass and therefore increased the drought resistance.When the soil water content decreased to 14%,the leaves of non-spraying control withered greatly,however,the leaves in uniconazole treatment had normal leaf color,the contents of chlorophyll,the leaf water content and free-proline,and also the ratio of the root to crown of Perennial ryegrass were significantly increased,the treatment with 40 mg/L concentration were better than others.When the concentration increased to 80 mg/L,it restrained the growth of underground part,and decreased the range and depth of imbibing ability,then reduced the resistance of the Perennial ryegrass.This suggested that spraying 40 mg/L uniconazole could effectively increase the drought resistance of the Perennial ryegrass.

为了解白腊种子萌发的最适条件,设置低温层积、0~160mg/L不同浓度赤霉素处理、15~45℃不同温度处理及全光、全暗、光暗交替不同光照处理(其中后3项处理顺次进行,以便将前项处理的结果运用于后项处理之中),调查计算不同处理下的种子发芽率、发芽势、发芽指数、萌发启动速度等萌发指标。结果表明,低温层积有助于白腊种子解除休眠,提高发芽率;80mg/L浓度的赤霉素为白腊种子萌发的最适浓度;30~35℃为其萌发的最适温度;全暗处理最适于种子萌发,表明白腊种子的萌发特性属于中性偏喜暗类型。综合试验结果并考虑可行性因素,认为低温层积与赤霉素处理各有利弊,兴利除弊的方法是在赤霉素处理前对种子进行适度机械破损。