ABSTRACT. Gossypium tomentosum is a wild allotetraploid species with the (AD) 5 genome. It is characterized by many useful traits including finer fiber fineness, drought tolerance, and Fusarium and Verticillium resistance. We constructed the first bacterial artificial chromosome library for Gossypium tomentosum. With high quality and broad coverage, this library includes 200,832 clones, with an average insert size of about 122 kb and fewer than 3% empty clones. Our library is approximately 10-fold the size of the (AD) 5 -genome (2400 Mb) and provides a 99.7% probability of isolating genes of interest or their sequences. Seven of eight simple sequence repeats markers that are located on five different chromosomes and linked with resistance to Verticillium wilt could amplify the 50 superpools and obtained one to five hits. This high capacity library will be an important genomic resource for classifying and analyzing the evolution of allotetraploid cotton species as well as for isolating disease-resistance and drought-tolerance 16975-16980 (2015) genes.
2We had previously reported that manganese (Mn)-induced chlorosis is a serious problem 3 in ratoon sugarcane seedlings grown in acidic soils. To further monitor the progression of 4 chlorosis and elucidate the corresponding mechanism, both plant growth and nutrient 5 status of sugarcane plants and soils were investigated in the growth seasons of ratoon 6 cane seedlings in 2016 and 2018. The impacts of rainfall and ammonium on chlorosis 7 were also investigated hydroponically. The results showed that the chlorotic seedlings 8 could green in mid-summer; Mn content in the first expanded leaf decreased significantly, 9 whereas iron (Fe) content increased significantly during the progression of greening. The 10 leaf Mn content in the greened seedlings decreased by up to 78.1% when compared with 11 that in the initial chlorotic seedlings. The seedlings also showed a significant increase in 12 seedling height and weight of the expanded leaves, accompanied by a decrease in plant 13 Mn content during the progression of greening. Moreover, young seedlings with less Mn 14 content showed earlier greening than older seedlings with more Mn content. The 15 exchangeable ammonium content in the soils increased significantly during the 16 progression of greening, and the addition of 1 mM ammonium to the chlorotic seedlings 17 resulted in a decrease in leaf Mn content by up to 80%. Furthermore, leaf SPAD value 18 and Fe content increased by 2.0-fold and 1.4-fold, respectively, after rainwater was 19 applied to the chlorotic seedling. These results indicate Mn-induced chlorotic seedlings 20 can turn naturally green, and downregulation of plant Mn content, rainfall in summer, and 21 soil ammonium contribute to the greening of chlorotic seedlings.22
Abstract. Economic growth and population agglomeration play important roles in environmental degradation. The existing research is primarily concerned with economic growth and the environment, with little attention being devoted to the context of different types of cities and urbanization. This paper attempts to examine the determinants of environmental degradation within the framework of the Human Impact, Population, Affluence and Technology (IPAT) model and further incorporate the variable of population agglomeration based on the Environmental Kuznets Curve (EKC) hypothesis using city-level panel data from 2003 to 2012. Our results indicate that population agglomeration has little or very small impact on environmental degradation, whereas the population size has a positive impact on environmental pollution. The EKC hypothesis is verified with the whole sample of our study; however, the situation varies for different types of cities. The results of this study can serve as a useful reference for policy makers in terms of achieving economic and environmental sustainability.
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