骨干亲本在改良小麦产量和品质利用方面发挥重要作用。研究骨干亲本中某些有益性状的遗传基础将为分子育种提供理论参考。科农9204是具有理想株型、产量潜力高、氮肥利用率高的候选骨干亲本。为了更好地了解其高产潜力的遗传基础，我们对KN9204和它的亲本及其衍生品系进行了高通量全基因组重测序（10×）。通过鉴定双亲本定位群体中优良的产量相关数量性状位点（QTL），构建了KN9204的高分辨率遗传组成图谱，显示了有利基因组片段的亲本来源。小偃693是小麦-偃麦草部分双二倍体，对KN9204的高产潜力贡献很大。本研究对来源于小偃693的4个主要稳定QTL进行了精细定位，并阐述了KN9204关键基因组片段在其衍生品系中的的传递，表明含有有益基因组合的单倍型块和育种者的定向选择都是保守的，选择育种在本研究中被证实。本研究为利用分子设计方法育种高产小麦品种提供了理论参考。

地膜覆盖已成为干旱、半干旱地区农业生产中维持作物高产的重要手段。然而，农田土壤中残留地膜也引发了更多的关注。为研究残留地膜对土壤养分、土壤微生物、作物生长和产量的影响，共开展了以下三个试验，包括残膜量为0、450、1350和2700 kg ha^-1的7年大田试验和4年盆栽试验，以及残膜量为1350 kg ha^-1时，残膜碎片单边长分别是2–5、5–10、10–15和15–20 cm的6年田间试验。研究发现，残膜对0–2.0（或0–1.8）m的田间土壤水分几乎没有影响，对0-20 cm土壤的有机碳、全氮、无机氮、全磷和速效磷均无显著影响。相对于非膜际土壤，附着于残膜表面的土壤细菌群落的多样性和丰度有所降低，而对离开残膜表面的土壤微生物群落没有显著影响。不同大小的残膜碎片使小麦和小扁豆的田间出苗率偶有显著降低。含有450-2700 kg hm^-1的残膜降低了玉米的株高和茎粗，收获期玉米的地上生物量显著降低11-19%。随着残膜量的增加，玉米和马铃薯的7年平均产量虽然呈下降趋势，但各处理间差异不显著。这些结果为全面科学地认识旱地农业系统中残留地膜对土壤和作物的影响提供了重要数据。

家畜脊椎数特别是胸腰椎数存在遗传变异，这些变异与家畜体长和产肉量有关。德州驴是我国著名的地方驴种之一，它的特点是体型大，适应性好，抗粗饲。德州驴群体中胸腰椎数也存在变异。【目的】本研究利用低深度重测序填充数据通过全基因组关联分析挖掘调控德州驴胸腰椎数性状相关的分子标记和候选基因，为未来多胸腰椎数驴的新品种培育奠定理论基础。【方法】对347头德州驴群体进行低深度的全基因组重测序，选用STITCH + Beagle的方法进行基因型的填充，对获得的SNPs进行质控后利用GEMMA软件的线性混合模型和GMMAT软件的logistic混合模型对胸腰椎数性状进行关联分析。SNPs数据进行了连锁不平衡过滤（=0.2）最终获得约35万个有效SNPs，用Bonferroni进行多重检验校正，设置了5%全基因组水平显著关联阈值线P ≤ 1.41×10-7（= 0.05/353,672）以及潜在显著关联的水平P ≤ 2.83×10-6（= 1/353,672）。最终对显著关联的SNPs进行候选基因的鉴定和单倍型分析。【结果】347头德州驴群体平均测序深度为4×，基因型填充后最终获得6,220,779 SNPs，利用18头高深度的德州驴群体对填充准确性进行评估，结果显示平均基因型相关系数是0.98。综合两个关联分析的模型，对于胸椎数性状，我们鉴定出38个全基因组水平显著关联的SNPs和64个潜在显著关联的SNPs，涉及7个基因（NLGN1、DCC、SLC26A7、TOX、WNT7A、LOC123286078和LOC123280142）。对于腰椎数性状，我们鉴定了9个全基因组水平显著关联的SNPs和38个潜在显著关联的SNPs，涉及8个基因（GABBR2、FBXO4、LOC123277146、LOC123277359、BMP7、B3GAT1、EML2和LRP5）。其中多个显著关联SNPs存在紧密的连锁不平衡关系。【结论】本研究利用测序填充数据进行全基因组关联分析，鉴定了多个与胸腰椎数性状显著关联的SNPs和候选基因，其中WNT7A、BMP7和LRP5已知的功能是通过Wnt信号通路和TGF-β信号通路在胚胎体节发育和骨形成过程中发挥作用，可能是驴差异胸腰椎数性状的关键候选基因。

秸秆还田是实现农学和环境双赢的重要途径。然而，在表层土壤（0-20 cm）中，最佳稻草替代氮磷肥料量仍不清楚。因此，我们在 2016-2018年进行了三年的田间试验，探讨不同秸秆用量替代肥料中氮磷对水稻收获后土壤理化性质、土壤有机碳（SOC）储量、土壤氮残留、土壤磷残留、水稻产量、产量构成、氮（N）肥利用效率和磷（ P) 肥利用效率的影响。与单施化肥相比，5 t ha^-1秸秆替代氮磷肥提高了水稻穗粒数、有效穗数、结实率、千粒重和籽粒产量，也增加了水稻地上氮磷养分吸收量。同时，秸秆用量超过 2.5 t ha^-1 比单施化肥处理增加了土壤有效氮磷钾含量。此外，与单施化肥处理相比，所有秸秆替代氮磷处理均提高了土壤有机碳储存量。相比单施化肥处理，5 t ha^-1秸秆替代氮磷肥使土壤中氮残留和磷残留分别减少了 68.3% 和 28.9%。同时，水稻地上氮磷养分吸收和土壤理化性质共同解释了19.3%的水稻籽粒产量和产量构成的变化。综上，5 t ha^-1秸秆替代氮磷肥是一种合理的施肥制度，不仅可以提高土壤理化性质、土壤有机碳固存、水稻产量、产量构成、氮肥利用效率和磷肥利用效率，同时可以降低环境污染的风险。

It is generally known that the culture for mycoplasma is time-consuming and a variety of nutrients are needed in the culture medium.  This brings a lot of difficulties to mycoplasma research and application, including Mycoplasma mycoides subsp. capri (Mmc).  Furthermore, little research on the characteristics of Mmc metabolism has been reported.  In this study, Mmc PG3 strain cultures were investigated for dynamic gene expression.  Culture samples were harvested during logarithmic phase (PG3-1), stationary phase (PG3-2), decline phase (PG3-3) and late decline phase (PG3-4).  Twelve RNA samples (three replicates for each of the four growth stages considered) from these cultures were collected and sequenced.  Paired comparison between consecutive growth phases in the four growth stages showed 45 significant differentially expressed genes (P<0.01) were linked to PG3 metabolism.  The enzymes these genes coded were mainly involved in ATP synthase, pyrimidine metabolism, nicotinate and nicotinamide metabolism, arginine and proline metabolism.  Among these, cytidylate kinase, fructose 1,6-bisphosphate aldolases Class II, nicotinate-nucleotide adenylyltransferase and dihydrolipoamide dehydrogenase play a key role in Mmc metabolism.  These results provide a baseline to build our understanding of the metabolic pathway of Mmc.  

The introduction and use of foreign germplasms have played an important role in the improvement of crop varieties in China.  Based on published materials and scientist interviews, we collected data on the sown area, morphological characteristics, and pedigree of the popular rice varieties grown in the 15 major rice production provinces and 1 autonomous region in China, from 1982 to 2011.  Results showed that China’s scientists developed the largest number of rice varieties worldwide, and that rice yield potential and grain quality have substantiality improved during the studied period.  In contrast, resistance of newly-released varieties to diseases and insect pests has decreased since the 1990s.  Germplasms from the International Rice Research Institute (IRRI) and from Japan have contributed 16.4 and 11.2% of genetic materials to China’s rice varieties developed between 1982 and 2011, respectively.  While IRRI’s materials contributed to the improvement of yield potential, growth duration, and blast and bacterial blight resistance, Japanese materials contributed to the improvement of grain quality.  Materials from other countries contributed to the improvement of resistance to diseases and insect pests, particularly to rice blast disease, brown planthoppers, white-backed planthoppers, and striped stem borers.

During meiosis in flowering plants, degradation of the callose wall in tetrads releases newly produced microspores, which develop into mature pollen grains. In this study, we identified zbs1, a male-sterile mutant of naked oat (Avena nuda L.) that displayed complete spikelet sterility due to inviable mature pollen. The abnormal pollen grains originated from microspores with a defective callose wall and cell plate during meiosis. The defective callose wall and cell plate of the zbs1 mutant were detected by the labeling of cell wall epitopes (β-1,3-glucan) with immunogold during meiosis, and an abnormal chromosome configuration was observed by propidium iodide staining. The mature pollen grains of the zbs1 mutant were irregular in shape, and abnormal germination was observed by scanning electron microscopy. Together, our results indicate that the cause of male sterility in zbs1 is abnormal meiosis.

Improving nitrogen use efficiency (NUE) and decreasing N loss are critical to sustainable agriculture. The objective of this research was to investigate the effect of various fertilization regimes on yield, NUE, N agronomic efficiency (NAE) and N loss in long-term (16- or 24-yr) experiments carried out at three rice-wheat rotation sites (Chongqing, Suining and Wuchang) in subtropical China. Three treatments were examined: sole chemical N, N+phosphorus (NP), and NP+potassium (NPK) fertilizations. Grain yields at three sites were significantly increased by 9.3-81.6% (rice) and 54.5-93.8% (wheat) under NP compared with N alone, 1.7-9.8% (rice) and 0-17.6% (wheat) with NPK compared with NP. Compared to NP, NUE significantly increased for wheat at Chongqing (9.3%) and Wuchang (11.8%), but not at Suining, China. No changes in NUE were observed in rice between NP and NPK at all three sites. The rice-wheat rotation’s NAE was 3.3 kg kg-1 higher under NPK than under NP at Chongqing, while NAE was similar for NP and NPK at Suining and Wuchang. We estimated that an uptake increase of 1.0 kg N ha-1 would increase 40 kg rice and 30 kg wheat ha-1. Nitrogen loss/input ratios were ~60, ~40 or ~30% under N, NP or NPK at three sites, indicating significant decrease of N loss by P or PK additions. We attribute part of the increase in NUE soil N accumulation which significantly increased by 25-55 kg ha-1 yr-1 under NPK at three sites, whereas by 35 kg ha-1 yr-1 under NP at Chongqing only. This paper illustrates that apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China.

Long-term fertilization experiment provides the platform for understanding the proton budgets in nitrogen transformations of agricultural ecosystems. We analyzed the historical (1990-2005) observations on four agricultural long-term experiments in China (Changping, Chongqing, Gongzhuling and Qiyang) under four different fertilizations, i.e., no-fertilizer (control), sole chemical nitrogen fertilizer (FN), sole chemical phosphorous and potassium fertilizers (FPK) and chemical nitrogen, phosphorous and potassium fertilizers (FNPK). The significant decline in topsoil pH was caused not only by chemical N fertilization (0.29 and 0.89 ΔpH at Gongzhuling and Qiyang, respectively) but also by chemical PK fertilization (0.59 ΔpH at Gongzhuling). The enhancement of available nutrients in the topsoil due to long-term direct nutrients supply with chemical fertilizers was in the descending order of available P (168-599%)>available K (16-189%)>available N (9-33%). The relative rate of soil pH decline was lower under long-term judicious chemical fertilization (-0.036-0.034 ΔpH yr-1) than that under long-term sole N or PK fertilization (0.016-0.086 ΔpH yr-1). Long-term judicious chemical fertilization with N, P and K elements decreases the nutritional limitation to normal crop growth, under which more N output was distributed in biomass removal rather than the loss via nitrate leaching. We concluded that the N distribution percentage of nitrate leaching to biomass removal might be a suitable indicator to the sensitivity of agricultural ecosystems to acid inputs.