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Alkaloids are important chemical components in tobacco. In order to understand the genetic architecture of alkaloids in tobacco and identify major effect loci controlling alkaloids related traits, QTL mapping on tobacco alkaloids was performed. A set of 271 recombinant inbred lines (RIL) were constructed with Y3 and K326 as the parents. The RIL population was planted in Yanhe, Yuxi, Yunnan province and Shilin, Kunming, Yunnan province in 2018, 2019, and 2020, respectively. Five alkaloid phenotypes including total plant alkali (TPA), nicotine (NIC), nornicotine (NOR), anabasine (ANAB), and anatabine (ANAT) were measured. A linkage map of 46,129 markers was constructed by genome sequencing of the population. QTL mapping was performed by the software QTLNetwork 2.0 which was developed based on the mixed linear model. A total of 15 QTLs with significant additive effects were identified. The contribution rate of additive effect to the corresponding phenotypes varied from 0.58% to 11.57%. Four major QTLs, qTPA14 for total plant alkali, qNIC14 for nicotine, qANAB14 for anabasine, and qANAT14 for anatabine, accounted for more than 10% of phenotypic variation of the corresponding traits, which were located in linkage group 14. Six QTLs with significant additive-by-environment interaction effects were detected, their additive-by-environment interaction effects explained the phenotypic variation of 0.80%--1.81%. Five pairs of QTLs with significant additive-by-additive epistasis effects were detected, accounting for phenotypic variation from 0.15% to 2.31%, while two pairs of QTLs were detected with significant epistasis-by-environment interaction effects, which explaining the proportion of phenotypic variation from 0.81% to 1.16%. The results pave a foundation for further isolation of candidate genes, the dissection of genetic mechanism, and the molecular improvement of tobacco alkaloid traits. [ABSTRACT FROM AUTHOR]

To achieve efficient resource utilization of fly ash and multi-source organic waste, a composting experiment was carried out to investigate the effects of fly ash on co-aerobic composting using kitchens, chicken manure, and sawdust (15:5:2). The effects of different application doses (5 % and 10 %, calculated in total wet weight of organic solid waste) of fly ash on physical and chemical properties, nutrient elements, and bacterial community structure during co-composting were evaluated. The results showed that the addition dose of 5 % and 10 % fly ash significantly increased the highest temperature (56.6 ℃ and 56.9 ℃) and extended the thermophilic period to nine days. Compared with that in the control, the total nutrient content of compost products in the treatments of 5 % FA and 10 % FA was increased by 4.09 % and 13.55 %, respectively. The bacterial community structure changed greatly throughout the composting, and the bacterial diversity of all treatments increased obviously. In the initial stage of composting, Proteobacteria was the dominant phylum of bacteria, with a relative abundance ranging from 35.26 % to 39.40 %. In the thermophilic period, Firmicutes dominated; its relative abundance peaked at 52.46 % in the 5 % FA treatment and 67.72 % in the 10 % FA treatment. Bacillus and Thermobifida were the predominant groups in the thermophilic period of composting. The relative abundance of Bacillus and Thermobifida in the 5 % FA and 10 % FA treatments were 33.41 % and 62.89 %( Bacillus ) and 33.06 % and 12.23 %( Thermobifida ), respectively. The results of the redundancy analysis (RDA) revealed that different physicochemical indicators had varying degrees of influence on bacteria, with organic matter, pH, available phosphorus, and available potassium being the main environmental factors influencing bacterial community structure. In summary, the addition of fly ash promoted the harmlessness and maturation of co- aerobic composting of urban multi-source organic waste, while optimizing microbial community structure and improving the quality and efficiency of composting.