苹果茎沟病毒 (apple stem grooving virus, ASGV) 是一种重要的潜隐类果树病毒，对柑橘、梨和苹果等多种果树的生产构成了严重的威胁。2018年，在中国南方广泛种植的黄金蜜柚 (Citrus grandis cv. Huangjinmiyou) 上观察到了严重的黄化、斑驳和花叶症状，推测其可能由病毒引起。取5株表现相关症状果树的叶片样品构建混库并送高通量测序分析，从其中鉴定到了3个ASGV变异体，通过RT-PCR和RACE技术验证了其基因组序列。序列分析显示，这3个变异体的基因组核苷酸序列一致性为81.03%–82.34%，其基因组结构与过往报道的侵染其它果树的变异体类似。基于病毒全基因组核苷酸序列和外壳蛋白氨基酸序列的系统发育分析显示，3个黄金蜜柚ASGV变异体分别与来自不同寄主和地区的ASGV变异体聚在一枝。重组分析显示，3个ASGV变异体可能来自于ASGV不同株系间的重组。在全国11个主要柑橘种植省份采集了507份黄金蜜柚样品进行RT-PCR检测发现，在每个省份表现上述相关症状的样品中，ASGV的检出率均在92.7%以上，而在40份没有症状的样品中，均未检测到ASGV。将其中6个省份的感病样品嫁接到ASGV的指示植物——Rusk枳橙上，新生的系统叶表现出典型的碎叶症状，进一步验证了黄金蜜柚中ASGV的侵染。进一步探究了病毒和症状与温度的关系，发现嫁接的感病黄金蜜柚样品在30°C–35°C条件下症状消失，同时RT-PCR也检测不到ASGV的存在。而后，再将其置于20°C–24°C的条件下一段时间后，黄金蜜柚症状恢复，且ASGV可以由RT-PCR检测到。本文揭示了黄金蜜柚黄化斑驳花叶病与ASGV侵染的相关性，并提示了该病害大面积流行的风险，为进一步的病害防控提供了相应参考。

杂交水稻为世界粮食的供应做出了重大贡献，而骨干亲本在杂交水稻品种选育中发挥着重要作用。为明确水稻骨干亲本蜀恢527（SH527，Oryza sativa）在育种过程中所利用的关键基因组区域，本研究对其进行了基于系谱的全基因组分析。利用高密度单核苷酸多态性（SNP）阵列对包括SH527、6个亲本品种及17个衍生恢复系在内的24个品种进行了扫描，分析了上游亲本对SH527基因组的独特贡献，确定了SH527及其衍生品种中保守的关键基因组区域。同时，利用多年的产量性状数据和SNP 芯片结果进行全基因组关联分析，发现了一些可能的已知或新的产量性状的关联位点。这项研究初步揭示了SH527育种的关键区域，将为后续育种提供参考。杂交水稻为世界粮食的供应做出了重大贡献，而骨干亲本在杂交水稻品种选育中发挥着重要作用。为明确水稻骨干亲本蜀恢527（SH527，Oryza sativa）在育种过程中所利用的关键基因组区域，本研究对其进行了基于系谱的全基因组分析。利用高密度单核苷酸多态性（SNP）阵列对包括SH527、6个亲本品种及17个衍生恢复系在内的24个品种进行了扫描，分析了上游亲本对SH527基因组的独特贡献，确定了SH527及其衍生品种中保守的关键基因组区域。同时，利用多年的产量性状数据和SNP 芯片结果进行全基因组关联分析，发现了一些可能的已知或新的产量性状的关联位点。这项研究初步揭示了SH527育种的关键区域，将为后续育种提供参考。

Citrus leaf blotch virus (CLBV) is a member of the genus Citrivirus, in the family Betaflexiviridae.  It has been reported CLBV could infect kiwi, citrus and sweet cherry in China.  Of 289 citrus samples from six regions of China, 15 were detected to be infected with CLBV in this study.  The complete genome of four isolates of CLBV was obtained from Reikou in Sichuan (CLBV-LH), Yura Wase in Zhejiang (CLBV-YL), Bingtangcheng in Hunan (CLBV-BT), Fengjie 72-1 in Chongqing (CLBV-FJ), respectively.  While they all represented 8 747 nucleotides in monopartite size, excluding the poly(A) tail, each of the isolates coded three open reading frames (ORFs).  Identity of the four isolates ranged from 98.9 to 99.8% to each other and from 96.8 to 98.1% to the citrus references in GenBank by multiple alignment of genomes.  A phylogenetic tree based on the genome sequences of available CLBV isolates indicated that the four isolates were clustered together, suggesting that CLBV isolates from citrus in China did not have obvious variation.  This is the first report of the complete nucleotide sequences of CLBV isolates infecting citrus in China.

The ecological effect of reclaimed water irrigation and fertilizer application on the soil environment is receiving more attention.  Soil microbial activity and nitrogen (N) levels are important indicators of the effect of reclaimed water irrigation on environment.  This study evaluated soil physicochemical properties and microbial community structure in soils irrigated with reclaimed water and receiving varied amounts of N fertilizer.  The results indicated that the reclaimed water irrigation increased soil electrical conductivity (EC) and soil water content (SWC).  The N treatment has highly significant effect on the ACE, Chao, Shannon (H) and Coverage indices.  Based on a 16S ribosomal RNA (16S rRNA) sequence analysis, the Proteobacteria, Gemmatimonadetes and Bacteroidetes were more abundant in soil irrigated with reclaimed water than in soil irrigated with clean water.  Stronger clustering of microbial communities using either clean or reclaimed water for irrigation indicated that the type of irrigation water may have a greater influence on the structure of soil microbial community than N fertilizer treatment.  Based on a canonical correspondence analysis (CCA) between the species of soil microbes and the chemical properties of the soil, which indicated that nitrate N (NO₃^–-N) and total phosphorus (TP) had significant impact on abundance of Verrucomicrobia and Gemmatimonadetes, meanwhile the pH and organic matter (OM) had impact on abundance of Firmicutes and Actinobacteria significantly.  It was beneficial to the improvement of soil bacterial activity and fertility under 120 mg kg^–1 N with reclaimed water irrigation.

Mung bean (Vigna radiata L.) has the potential to establish symbiosis with rhizobia, and symbiotic association of soil micro flora may facilitate the photosynthesis and plant growth response to elevated [CO2]. Mung bean was grown at either ambient CO2 400 μmol mol–1 or [CO2] ((550±17) μmol mol–1) under free air carbon dioxide enrichment (FACE) experimental facility in North China. Elevated [CO2] increased net photosynthetic rate (Pn), water use efficiency (WUE) and the non-photochemical quenching (NPQ) of upper most fully-expanded leaves, but decreased stomatal conductance (Gs), intrinsic efficiency of PSII (Fv´/Fm´), quantum yield of PSII (ΦPSII) and proportion of open PSII reaction centers (qP). At elevated [CO2], the decrease of Fv´/Fm´, ΦPSII, qP at the bloom stage were smaller than that at the pod stage. On the other hand, Pn was increased at elevated [CO2] by 18.7 and 7.4% at full bloom (R2) and pod maturity stages (R4), respectively. From these findings, we concluded that as a legume despite greater nutrient supply to the carbon assimilation at elevated [CO2], photosynthetic capacity of mung bean was still suppressed under elevated [CO2] particularly at pod maturity stage but plant biomass and yield was increased by 11.6 and 14.2%, respectively. Further, these findings suggest that even under higher nutrient acquisition systems such as legumes, nutrient assimilation does not match carbon assimilation under elevated [CO2] and leads photosynthesis down-regulation to elevated [CO2].

Humankind has been through different periods of agricultural improvement aiming at enhancing our food supply and the performance of food crops. In recent years, whole genome sequencing and deep understanding of genetic and epigenetic mechanisms have facilitated new plant breeding approaches to meet the challenge of growing population, dwindling resources, and changing climate. Here we proposed a simple and fast molecular breeding method, marker-assisted reverse breeding (MARB), which will revert any maize hybrid into inbred lines with any level of required similarity to its original parent lines. Since all the pericarp DNA of a hybrid is from the maternal parent, whereas one half of the embryo DNA is from the maternal parent and the other half from the paternal parent, so we firstly extract DNA from seed embryo and pericarp of a selected elite hybrid separately and then we derived the genotypes of the two parents with high-density single nucleotide polymorphism (SNP) chips. The following marker-assisted selection was performed based on an Illumina low-density SNP chip designed with 192 SNPs polymorphic between the two parental genotypes, which were uniformly distributed on 10 maize chromosomes. This method has the advantages of fast speed, fixed heterotic mode, and quick recovery of beneficial parental genotypes compared to traditional pedigree breeding using elite hybrids. Meanwhile, MARB has the advantage of not requiring sophisticated transformation and double haploid (DH) technologies over RNA interference (RNAi)-mediated reverse breeding. In addition, MARB can also be used with feed corn harvested from big farms, which is often similar to F2 populations, and the relevant transgenes in the population can be eliminated by marker-assisted selection. As a result, the whole global commercial maize hybrids can be utilized as germplasm for breeding with MARB technology. Starting with an F2 population derived from an elite hybrid, our experiment indicates that with three cycles of marker-assisted selection, selected lines could recover over 80% of the parental genotypes and associated beneficial genes in a fixed heterotic mode. The success application of MARB in maize suggests that this technology is applicable to any hybrid crop to breed new inbreds with improved hybrid performance but the same heterotic mode. As chip technology becomes cheap, it would be expected that polymorphism screening and following marker-assisted selection could be done with one all-purpose high density chip.Several issues associated with MARB were discussed, including its rationale, efficiency and advantages, along with food/ feed and environmental safety issues and applications of MARB in variety protection and marker-assisted plant breeding.