水稻细菌性褐条病是世界性的水稻重要病害之一,在我国常见于南方稻区,发病严重时会导致水稻整株枯死,严重威胁了水稻的高产稳产.在鉴于目前国内外对该病的研究主要集中在病原鉴定、病原菌致病机理及病害防治、而对其分子生物学水平上的研究尚不深入的前提下,介绍了水稻细菌性褐条病研究的新进展,通过查阅国内外水稻细菌性褐条病研究进展的相关文献,并分析、归纳后,综述了病原菌的特性及发病机理、病害侵染循环和农业、化学、生物方面的防治措施等,以期更好地为农业防治褐条病提供参考.

Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 is the third generation of novel targeted genome editing technology after zinc finger nucleases (ZFNs) and transcription activator like effector nucleases (TALENs). It is also one of the most promising techniques for mutating and modifying genes. The CRISPR-Cas9 system has the advantages of simplicity, high efficiency, high specificity, and low production cost, thus greatly promoting the study of gene function. Meanwhile, it has attracted the attention of biologists. After the development and improvement in recent years, CRISPR-Cas9 system has become increasingly mature and has been widely used in crop improvement. Firstly, this review systematically summarizes the generation and advantages of CRISPR-Cas9 system. Secondly, three derivative technologies of the CRISPR-Cas9 system are introduced. Thirdly, this review focuses on the application of CRISPR-Cas9 system in gene knockout, gene knock-in, and gene regulation, as well as the improvement of yield, quality, and biological resistance of important crops such as rice, wheat, soybean, corn, and potato. Finally, this review proposes the potential challenges of CRISPR-Cas9 system, and discusses the future development of CRISPR-Cas9 system.

叶色突变体往往伴随着叶绿素含量变化及叶绿体结构异常,是研究叶绿体发育与光合作用相关基因功能的重要材料.该研究通过甲基磺酸乙酯(EMS)诱变籼稻(Oryza sativa subsp.indica)品种华占(HZ)获得黄绿叶突变体,将其命名为ygl18(yellow-green leaf 18).与野生型相比,黄绿叶突变体ygl18自三叶期起叶片开始变黄且程度不断加深,同时伴随着光合速率与叶绿素含量下降,且结实率、千粒重及有效穗数均显著降低.透射电镜观察结果显示,ygl18的叶绿体结构紊乱,基质片层疏松,发育受到抑制,与叶片出现黄绿色表型一致.遗传分析表明,ygl18突变性状受1对隐性等位核基因控制,这对等位基因位于水稻第3号染色体长臂标记InDel2和InDel3之间115.2 kb范围内.进一步研究发现该突变体表型是编码铁氧还蛋白FdC2的基因LOC_Os03g48040的5'UTR发生突变所致.通过CRISPR转基因实验验证了该基因对表型的控制作用.研究结果揭示了叶色调控网络的遗传基础,可为今后选育高光效水稻品种提供新线索.

为挖掘水稻糙米率相关基因,以粳稻品种热研(Nekken)为母本,籼稻品种华占(HZ)为父本,杂交获得F1代,连续自交多代后得到120个重组自交系(recombination inbred lines,RILs)群体,以其为实验材料,称出糙米质量,计算糙米率.利用已构建好的高密度遗传图谱,对水稻糙米率的数量性状位点(quantitative trait locus,QTL)进行定位分析.结果表明:共检测到4个QTL,分别位于水稻第5,8,10,12号染色体上;同时,对这些区间的候选基因进行筛选和分析,并通过qRT-PCR验证发现,LOC_Os08g01450基因很可能是影响水稻糙米率的新基因.这些结果为挖掘新的糙米率基因提供了新线索.

Xanthine dehydrogenase, a member of the molybdenum enzyme family, participates in purine metabolism and catalyzes the generation of ureides from xanthine and hypoxanthine. However, the mechanisms by which xanthine dehydrogenase affects rice growth and development are poorly understood. In the present study, we identified a mutant with early leaf senescence and reduced tillering that we named early senescence and less-tillering 1 (esl1). Map-based cloning revealed that ESL1 encodes a xanthine dehydrogenase, and it was expressed in all tissues. Chlorophyll content was reduced and chloroplast maldevelopment was severe in the esl1 mutant. Mutation of ESL1 led to decreases in allantoin, allantoate, and ABA contents. Further analysis revealed that the accumulation of reactive oxygen species in esl1 resulted in decreased photosynthesis and impaired chloroplast development, along with increased sensitivity to abscisic acid and abiotic stresses. Ttranscriptome analysis showed that the ESL1 mutation altered the expression of genes involved in the photosynthesis process and reactive oxygen species metabolism. Our results suggest that ESL1 is involved in purine metabolism and the induction of leaf senescence. These findings reveal novel molecular mechanisms of ESL1 gene-mediated plant growth and leaf senescence.

Leaf is an important organ of rice, and it is the main place for photosynthesis. Leaf morphology related traits such as leaf length, leaf width and leaf area can directly affect leaf photosynthetic efficiency. The study of quantitative trait loci (QTL) sites for morphological characters of rice flag leaf and the improvement of morphological characters of rice flag leaf by means of genetic breeding can provide theoretical basis for the cultivation of ideal plant type rice. In this study, an indica rice variety HZ was used as the male parent, and a japonica rice variety Nekken2 was used as the female parent. After F1 generation was obtained by cross-breeding, 120 recombinant inbred lines (RIL populations) were obtained from successive generations of self-crossing, which were used as experimental materials in this study. Leaf length, leaf width, leaf area of rice at tillering stage and mature stage were studied and analyzed after incubation under the same and appropriate conditions. At the same time, the genetic map was constructed by using the RIL population to locate the QTLs for the traits of leaf length, leaf width and leaf area in rice at tillering stage and mature stage, 35 QTLs related to leaf morphology were detected. There were 6 QTLs related to blade length (5 at tillering stage, 1 at maturation stage), LOD value of one of them was as high as 6.92; 8 QTLs related to blade width (detected only at tillering stage), LOD value of one was as high as 4.51; 21 QTLs related to blade area (12 at tillering stage, 9 at mature stage), LOD values of two of them were as high as 6.37 and 4.06 respectively. Through quantitative analysis of the candidate genes related to leaf length, leaf width and leaf area in these QTL regions, it was found that LOC_Os02g52040, LOC_Os03g46610, LOC_Os04g52230, LOC_Os04g42230, LOC_Os04g44150, LOC_Os04g52479, LOC_Os09g37400 and LOC_Os12g42020 were significantly different in expression levels between the parents. Combined with the data of leaf length, leaf width and leaf area of the parents, we speculated that The high expressions of LOC_Os04g52230, LOC_Os04g44150, LOC_Os09g37400 and LOC_Os12g42020 may promote the growth of leaf width and leaf area, while the high expressions of LOC_Os02g52040, LOC_Os03g46610 and LOC_Os04g52479 may inhibit the growth of rice flag leaves. Through the analysis of QTL in this study, QTL regulating leaf length, leaf width and leaf area of rice flag leaf were excavated, which provided a reference for cultivating new rice varieties with excellent plant type.

水稻（Oryzasativa）是全世界重要的经济作物之一,稻田镉（Cd）污染和镉积累问题严重威胁世界水稻的产量和品质以及人类健康,如何降低水稻中镉积累已成为热点问题。以籼稻品种华占（HZ）为父本、粳稻品种热研2号（Nekken2）为母本,连续自交多代后得到120个重组自交系群体,对其镉积累进行检测和分析,同时利用遗传图谱进行QTL作图。结果共检测到7个QTLs,分别位于水稻第2、3、9和12号染色体上,其中1个LOD值高达4.97。对这些QTL区间内与耐金属离子胁迫相关的候选基因进行定量分析,发现LOC O s02g50240、LOC O s02g52780、LOC O s09g31200、LOC O s09g35030和LOC O s09g37949这5个基因在双亲间的表达量差异显著,结合亲本对不同金属离子的浓度积累数据,推测LOC O s02g50240、LOC O s09g31200及LOC O s09g35030的高表达可能极大地提高了水稻对镉离子的吸收和胁迫耐受能力。通过QTL挖掘和分析,发现这些基因与水稻籽粒的镉积累有关,可能影响水稻耐镉胁迫的能力。研究结果为进一步筛选和培育耐镉胁迫的水稻品种创造了条件,为阐明水稻镉积累的分子调控机制奠定了基础。

The tea green leafhopper (Empoasca onukii Matsuda) is a severe pest for the tea plant (Camellia sinensis (L.) O. Ktze), which significantly reduces the tea yields and quality. Herbivore feeding events lead to the emission of herbivore-induced plant volatiles (HIPVs) to elicit plant defense. To examine the volatile release profiles of tea shoots infested by leafhoppers, gas chromatography-mass spectrometry (GC–MS) analysis was performed. 23 volatiles were emitted in healthy tea shoots whereas 29 volatiles were identified from infested ones. The relative contents of volatiles were significantly increased during infestation. The volatile profiles from healthy and infested tea shoots could be well clustered into two groups by unsupervised clustering analysis and principal component analysis (PCA). Furthermore, a partial least square discriminant analysis (PLS-DA) model can differentiate volatile profiles between healthy and infested tea shoots with a predictive power of 91.8%. From the variable importance for the projection (VIP), eight critical volatiles were identified. Collectively, we have identified a novel volatile release profile after leafhopper infestation in tea plant and provide clues for defensive strategies against herbivores.

为探究叶片水势（LWP）相关基因在水稻（Oryzasativa）抗旱中的作用及其遗传机制,以热研2号（Nekken2）和华占（HZ）为亲本以及构建的120个重组自交系（RILs）群体为实验材料,对水稻分蘖期叶片水势进行检测,并利用前期基于高通量测序构建的分子遗传连锁图谱进行数量性状基因座（QTL）分析。结果表明,共检测到5个与水稻分蘖期叶片水势相关的QTLs,分别位于第2、 3、 4、 11和12号染色体上,LOD值均达2.5以上,其中位于4号染色体物理距离24 066 261–30 847 136 bp内QTL的LOD值高达5.15。对这些QTL区间内与水势相关的候选基因进行定量分析,发现LOC O s02g56630、LOC O s02g57720、LOC O s02g57580、LOC O s04g43730、LOC O s04g46490、LOC O s04g44570和LOC O s04g44060这7个基因在双亲间表达量差异显著。位于4号染色体QTL区间内LOC O s04g46490基因的表达在两亲本间存在显著差异。对基因LOC O s04g46490进行测序分析,发现该基因在两亲本间共存在6处差异,从而导致氨基酸序列的改变。通过QTL挖掘及相关基因表达分析,发现这些基因与水稻叶片水势调控相关,可能间接影响水稻的抗旱性。检测到的QTL位点对水势相关基因精细定位和克隆具有重要参考价值,有助于进一步理解水稻叶片水势的遗传基础,并为培育耐旱水稻新品种提供有利的基因资源。

Premature leaf senescence negatively affects rice yield and quality. Identifying premature senescence mutants and examining their gene functions are important for the genetic improvement of crops. In this study, a leaf senescence mutant dls-1 was obtained from japonica Yundao by ethyl methane sulfonate mutagenesis, which showed the phenotypes of premature leaf senescence, reduced plant height and decreased yield-associated traits including panicle length, seed setting rate, and 1000-grain weight. Biochemical analysis revealed the accumulation of reactive oxygen species in dls-1 leading to increased apoptosis rates, stomata length extension, higher water loss, and a decline in leaf silicification. Transcriptomic data showed that pathogen resistance-related genes were down-regulated in dls-1, causing increased sensitivity to bacterial-induced blight. Genetic analysis indicated that the mutant trait of dls-1 was controlled by a single recessive nuclear gene, and the gene was fine-mapped to a 159 kb region on rice chromosome 1 using map-based cloning strategy. A total of 23 open reading frames were found in the interval, and no similar phenotypic genes have been reported. However, all candidate coding genes and promoter regions were sequenced, and no mutation sites were found. RNA-seq analysis and qRT-PCR showed that the candidate gene LOC_Os01g71670, encodes a rice endo-1,3-β-glucanase, showed significantly different expression levels in dls-1 compared to the wild-type. LOC_Os01g71670 is highly homologous with GII in barley, and Gns4 and glu1 in rice, which participates in the hormone response pathway affecting plant growth and development, and also involve in the regulation of PR2 expression. Taken together with the phenotypes of dls-1, we conclude that LOC_Os01g71670 may be the candidate gene, causing the premature senescence of the leaf tip and loss of pathogen resistance.