本研究以来源于辽宁、吉林和黑龙江三个省份的200个粳稻品种为实验材料，对碾磨和外观品质相关的性状进行考察。材料的系谱分析和遗传多样性分析结果表明，来自吉林省的品种遗传多样性最高。稻米品质的评价结果表明，来自辽宁省的品种具较好的碾磨品质，而来自黑龙江的品种具较好的外观品质。本研究同时用单位点和多位点的全基因组关联分析（GWAS）对碾磨和外观品质相关的基因位点进行计算，结果共检测到99个显著的SNP位点。其中，共3个SNP位点同时在混合线性模型（MLM）、mrMLM和FASTmrMLM这3种计算模型中检测到，进一步利用连锁不平衡分析获得对应的3个候选区域（qBRR-1、qBRR-9和qDEC-3），以便于后续的候选基因分析。由于候选区域内的候选基因超过300个，研究还结合基因GO分析以鉴定潜在的候选基因。此外，候选区域的遗传多样性分析结果表明，qBRR-9很可能在东北粳稻的育种过程中受到了较强的选择。这些结果为水稻育种和品质改良提供了具有参考意义的信息。

   Use of saline water in irrigated agriculture has become an important means for alleviating water scarcity in arid and semi-arid regions. The objective of this field experiment was to evaluate the effects of irrigation water salinity and N fertilization on soil physicochemical and biological properties related to nitrification and denitrification. A 3×2 factorial design was used with three levels of irrigation water salinity (0.35, 4.61 and 8.04 dS m^–1) and two N rates (0 and 360 kg N ha–¹). The results indicated that irrigation water salinity and N fertilization had significant effects on many soil physicochemical properties including water content, salinity, pH, NH₄-N concentration, and NO₃-N concentration. The abundance (i.e., gene copy number) of ammonia-oxidizing archaea (AOA) was greater than that of ammonia-oxidizing bacteria (AOB) in all treatments. Irrigation water salinity had no significant effect on the abundance of AOA or AOB in unfertilized plots. However, saline irrigation water (i.e., the 4.61 and 8.04 dS m^–1 treatments) reduced AOA abundance, AOB abundance and potential nitrification rate in N fertilized plots. Regardless of N application rate, saline irrigation water increased urease activity but reduced the activities of both nitrate reductase and nitrite reductase. Irrigation with saline irrigation water significantly reduced cotton biomass, N uptake and yield. Nitrogen application exacerbated the negative effect of saline water. These results suggest that brackish water and saline water irrigation could significantly reduce both the abundance of ammonia oxidizers and potential nitrification rates. The AOA may play a more important role than AOB in nitrification in desert soil.

Citrus fruits are rich in carotenoids. In the carotenoid biosynthetic pathway, lycopene β-cyclase (LCYb, EC:1.14.-.-) is a key regulatory enzyme in the catalysis of lycopene to β-carotene, an important dietary precursor of vitamin A for human nutrition. Two closely related lycopene β-cyclase cDNAs, designated CsLCYb1 and CsLCYb2, were isolated from the pulp of orange fruits (Citrus sinensis). The expression level of CsLCYb genes is lower in the flavedo and juice sacs of a lycopeneaccumulating genotype Cara Cara than that in common genotype Washington, and this might be correlated with lycopene accumulation in Cara Cara fruit. The CsLCYb1 efficiently converted lycopene into the bicyclic β-carotene in an Escherichia coli expression system, but the CsLCYb2 exhibited a lower enzyme activity and converted lycopene into the β-carotene and the monocyclic γ-carotene. In tomato transformation studies, expression of CsLCYb1 under the control of the cauliflower mosaic virus (CaMV) 35S constitutive promoter resulted in a virtually complete conversion of lycopene into β-carotene, and the ripe fruits displayed a bright orange colour. However, the CsLCYb2 transgenic tomato plants did not show an altered fruit colour during development and maturation. In fruits of the CsLCYb1 transgenic plants, most of the lycopene was converted into β-carotene with provitamin A levels reaching about 700 μg g-1 DW. Unexpectedly, most transgenic tomatoes showed a reduction in total carotenoid accumulation, and this is consistent with the decrease in expression of endogenous carotenogenic genes in transgenic fruits. Collectively, these results suggested that the cloned CsLCYb1 and CsLCYb2 genes encoded two functional lycopene β-cyclases with different catalytic efficiency, and they may have potential for metabolite engineering toward altering pigmentation and enhancing nutritional value of food crops.