Current Status of Brown Planthopper (BPH) Resistance and Genetics

Among the planthoppers of rice, the brown planthopper (BPH) is a major threat to rice production and causes significant yield loss annually. Host-plant resistance is an important strategy to reduce the damage caused by BPH and increase rice productivity. Twenty-one major genes for BPH resistance have been identified by using standard evaluation methods developed at the International Rice Research Institute (IRRI) to distinguish resistance or susceptibility of rice genotypes to BPH biotypes/populations. These genes are from diverse genetic resources such as land race cultivars and wild species of Oryza. Of the 21 resistance genes, 18 genes have been localized on specific region of six rice chromosomes using molecular genetic analysis and genomics tools. Some of these resistance genes are clustered together such as Bph1, bph2, Bph9, Bph10, Bph18, and Bph21 on the long arm of chromosome 12; Bph12, Bph15, Bph17 and Bph20 on the short arm of chromosome 4; bph11 and Bph14 on the long arm of chromosome 3 and Bph13(t) and bph19 on the short arm of chromosome 3. Six genes (Bph11, bph11, Bph12, bph12, Bph13 and Bph13) originated from wild Oryza species have either duplicate chromosome locations or wrong nomenclature. The discrepancy should be confirmed by allelism tests. Besides identification of major resistance genes, some quantitative trait loci (QTLs) associated with BPH resistance have also been identified on eight chromosomes. Most of the rice cultivars developed at IRRI possess one or two of the major resistance genes and the variety IR64 has many QTLs and confers strong resistance to BPH. More BPH resistance genes need to be identified from the wealth of gene pool available in the wild species of Oryza. Two BPH resistance genes (Bph14 and Bph18) have been cloned, and a snow drop lectin gene (GNA) has been identified and used in the development of BPH-resistant transgenic plants. Efficient introgression of resistance genes (Bph1, bph2, Bph3, Bph14, Bph15, Bph18, Bph20, and Bph21) into elite rice cultivars by marker-assisted selection together with strategic deployment of these genes can be an important approach to develop stable resistance to BPH and sustain rice production in the tropical and temperate rice growing regions.     

若干粳稻品种（系）抗褐稻虱特征评价

 就一些粳稻抗性品种对褐稻虱(BPH)Nilaparvata lueens抗性进行了评价，水稻品种秀水48作感性品种对照。结果表明：1)褐稻虱在感性品种上分泌的蜜露面积显著地大于抗性品种；饲养在不同品种上褐稻虱一生产卵量(粒／♀)： 秀水48为316．2，秀水620为191，嘉23为165.2，IR64为87.5；不同品种上褐稻虱若虫的存活率：秀水48为100%，秀水620为44%，嘉23为28.22%；相对取食量与抗性等级、田间累计虫量、若虫存活率及产卵量呈正相关。2)不同抗性品种上褐稻虱的种群增长率，秀水48为0.1221，秀水620为0.088，嘉23-2为0.083．3) 供试品种上逻辑斯蒂模型的K值,秀水48为81.58．秀水620为30.54。4)本试验各品种对褐稻虱的内禀控制率(%)秀水48为0，秀水620为78.79，嘉23为8494，IR64为0.8632。5)各品种对褐稻虱田间控制率（%）秀水48为0，秀水620为77.23，嘉23-2为76.68。     

水稻抗虫品种对褐飞虱和白背飞虱种群增长的影响

 利用实验种群生命表和Morris-Watt模式综台评价了5个已推广的水稻品种对褐飞虱 Nilaparvata lugens Stal和白背飞虱Sogatetla furcifera Horvath的抗性及品种对稻飞虱各虫态的抗性作用大小。IR36、汕优6号、协优10号、秀水620和丙664对褐飞虱种群增长有明显的抑制作用；而品种秀水620、丙664和协优10号对白背飞虱呈中抗水平。同时发现，品种对稻飞虱各虫态抗性作用在成虫产卵期最明显，对褐飞虱表现为：成虫产卵期>卵孵化期>高龄(3-5龄)若虫期>低龄(1-2龄)若虫期；对白背飞虱则为：成虫产卵期>低龄若虫期>高龄若虫期>卵孵化期。     

苗期抗性不同的水稻品种成株期对褐飞虱的抗性

 在浙江富阳评价了汕优63（含Bph1）、IR42（含bph2）、IR56（含Bph3）和TN1(感虫对照)以及新近育成的杂交稻中浙优1号、国稻6号等苗期抗性不同的水稻品种成株期对褐飞虱的抗性。结果表明,苗期中抗（5级）以上的水稻品种在成株期均表现出明显的抗性;苗期高感(9级)的水稻品种成株期亦感虫,但田间虱烧出现时间和虱烧程度有所差异。苗期高感的中浙优1号田间“虱烧”发生时间比同样高感的TN1晚5 d,推测中浙优1号对褐飞虱有一定的耐受性,这是在苗期鉴定中不能体现的。因此,应重视对苗期感虫的优良水稻品种的成株期抗性鉴定。     

水稻品种(组合)对褐飞虱抗性的田间表现

在褐飞虱大发生的2007年单季稻期间,以TN1作为感虫对照,在浙江省金华市评价了48份水稻品种(组合)的田间成株期抗性表现。结果表明,16个品种(组合)表现为田间成株期感虫,其他32个品种(组合)具有中抗以上水平,其中丙04-123、Ⅱ优845、宜香845、中组14、嘉兴优04-1和IR36等品种(组合)达高抗水平。在持久抗性方面,除高抗品种外,秀水09、新嘉优99、嘉优22-5、秀优0969、宁04-81、丙04-103、丙04-08、丙04-123、R4101、丙04-132、丙05-129、丙05-227、浙粳23和浙粳22等品种(组合)具持抗性。试验表明,成株期田间褐飞虱抗性评价对生产实践具有更重要的意义。     

Understanding Brown Planthopper Resistance in Rice: Genetics,Biochemical and Molecular Breeding Approaches

Brown planthopper (BPH, Nilaparvata lugens Stål) is the most devastating pest of rice in Asia and causes significant yield loss annually. Around 37 BPH resistance genes have been identified so far in indica, African rice varieties along with wild germplasms such as Oryza officinalis, O. minuta, O. nivara, O. punctata, O. rufipogon and O. latifolia. Genes/QTLs involved in BPH resistance, including Bph1, bph2/BPH26, Bph3, Bph6, bph7, BPH9, Bph12, Bph14, Bph15, Bph17, BPH18, bph19, Bph20, Bph21(t), Bph27, Bph27(t), Bph28(t), BPH29, QBph3, QBph4, QBph4.2, Bph30, Bph32, Bph33, Bph35 and Bph36, have been fine-mapped by different researchers across the globe. The majority of genes/QTLs are located on rice chromosomes 1, 3, 4, 6, 11 and 12. Rice plants respond to BPH attack by releasing various endogenous metabolites like proteinase inhibitors, callose, secondary metabolites (terpenes, alkaloids, flavonoid, etc.) and volatile compounds. Besides that, hormonal signal pathways mediating (antagonistic/synergistic) resistance responses in rice have been well studied. Marker-assisted breeding and genome editing techniques can also be adopted for improving resistance to novel BPH biotypes.     

Mechanism Analysis of Rice Resistance Protein OsRRK1 Against the Brown Planthopper

【Objective】 OsRRK1 (Rop-interacting receptor-like kinase 1) protein in rice is the first RLCK VI family protein in rice that has been studied. It plays an important role in regulating the curling of rice leaves and the defense against brown planthoppers. However, the mechanism of its regulation of resistance to the brown planthopper remains unclear. We attempt to further explore the mechanism of OsRRK1 gene resistance to the brown planthoppers. 【Method】The interaction between OsRRK1 protein and OsLecRK (lectin-like receptor kinase), OsLecRK1, OsLecRK2 and OsLecRK3 was analyzed by yeast two-hybrid method. OsLecRK is a candidate gene for BPH15 range of anti-brown planthopper, and is an important member of rice innate immune system. OsLecRK is involved in not only rice innate immune response, including resistance to brown planthoppers, white leaf blight and rice blast, but also the development of rice. The gene clusters of OsLecRK1, OsLecRK2 and OsLecRK3 constitute the anti-brown planthopper gene BPH3. Rice containing the BPH3 gene has a broad spectrum and lasting insect resistance. Meanwhile, DNAMAN software was used to analyze the homology of OsLecRK with OsLecRK1, OsLecRK2 and OsLecRK3. 【Result】The analysis results of DNAMAN showed that OsLecRK has high homology with OsLecRK1, OsLecRK2 and OsLecRK3, and the proteins shared more than 50% identity. The results of yeast two-hybrid analysis showed that OsRRK1 interacted with OsLecRK, OsLecRK2 and OsLecRK3.【Conclusion】OsRRK1 participates in the process of resistance to the brown planthoppers through interacting with BPH15 and BPH3 candidate genes.     

田间发生与室内驯化的褐飞虱生物型2的特性比较

比较研究了采自菲律宾国际水稻研究所室内长期用水稻抗性品种Mudgo驯化的褐飞虱生物型2和从广西田间褐飞虱种群中分离获得的田间生物型2的致害性、在不同抗性品种上的生长发育和生殖等特性。结果表明室内和田间生物型2对Mudgo和IR26的致害能力相同,即两者均能成功地致害含[WTBX][STBX]Bph1[WTBZ][STBZ]基因的水稻品种,但田间生物型2对ASD7和IR36的致害性明显比室内生物型2强,说明两者在具有抗性[WTBX][STBX]bph2[WTBZ][STBZ]的水稻品种上的致害性有差异。取食不同抗性品种时,田间生物型2的若虫历期均比取食相同品种的室内生物型2短,两个生物型2在取食ASD7时的若虫历期最长、存活率最低、雌成虫体重最轻、产卵量和蜜露量最少、种群增长指数和营养指数最低。取食IR26的田间生物型2的若虫存活指数和种群增长指数均明显高于取食IR26的室内生物型2的指数,同时也显著高于取食Mudgo的生物型2。建议在进行褐飞虱致害性监测和水稻品种抗性评价时以选用IR26为宜。     

温度对水稻抗褐飞虱特性的影响

 为研究温度对水稻抗褐飞虱特性的影响,于2007年和2008年应用苗期集团筛选法（SSST）在杭州地区的自然条件下测定了抗性水稻品种IR26和IR36对田间褐飞虱的抗性,同时比较了不同温度（22℃、25℃、28℃、31℃和34℃）下IR26和IR36对褐飞虱的抗性、可溶性糖和草酸含量的变化。自然条件下,IR26已完全失去对杭州种群褐飞虱的抗性,而IR36仍具中等抗性。在25℃到34℃的范围内随着温度升高,IR26对褐飞虱抗性减弱,但22℃条件下抗性比25℃更弱。IR36在温度升高的条件下对褐飞虱的抗性总体呈降低趋势,在31℃和34℃下也已完全失去对褐飞虱的抗性。在22~25℃条件下,IR26和IR36的持抗期均在25℃下最长,分别为9 d和11 d。3个品种稻株中的可溶性糖含量均随温度升高而增加,而草酸含量则随温度升高先增加后下降,在25℃时为最大值。不同温度下及不同水稻品种之间稻株内可溶性糖和草酸的含量均有显著差异。     

褐飞虱的再迁飞能力

 通过室内模拟试验研究了褐飞虱经过一次远迁降落、取食不同食料后的再迁飞能力。根据吊飞试验测得的飞行能力可将褐飞虱种群分为居留型（小于20 min）、迁飞型（20 min以上）、强迁飞型（160 min以上）和再迁飞型（二次吊飞飞行20 min以上）。不同营养条件对褐飞虱的飞行能力和迁飞型的分化有显著影响，早期营养条件好（取食穗期感性水稻品种）的迁飞型比率较低，但迁飞型个体的飞行能力和再迁飞能力均较强。未交配能显著提高再迁飞型比率。自然种群中褐飞虱再迁飞型比率仅占0.84%，吊飞一次后的迁飞型个体再次吊飞时的再迁飞型比率为4.9%，且强迁飞型个体具有较强的再迁飞能力。     

水稻新品种（系）对褐飞虱抗性的筛选及评价

 采用改进的苗期集团筛选法，测定了1999 ~2002年国家和浙江省水稻育种攻关项目的769个水稻新品种（系）对褐飞虱的抗性反应。结果表明，在769个品种中筛选出抗级为0~5级的品种93个，其中长持抗期（LD）、中持抗期（MD）和短持抗期（SD）级的品种分别有3、13、77个。同时对1999~2000年和部分2001年苗期抗级为0~5级的47个水稻品种进行成株期持抗期鉴定，发现苗期与成株期LD、MD、SD相一致的品种分别有3、3、15个；苗期为SD、成株期为MD的品种有3个，成株期无持抗期的品种有21个；苗期为MD、成株期为SD的品种有3个。试验进一步表明，利用水稻苗期和成株期的受害级别（5级）和持抗期长短（MD~LD）来评价耐褐飞虱水稻品种是一种比较可行的方法。     

不同水稻品种对褐飞虱为害的耐性和补偿作用评价

利用采自云南高原粳稻区病叶分离的17份水稻白叶枯病菌株,在30份水稻品种上接种进行致病型初步鉴定。研究表明可以将17个菌株分为7个致病型（Ⅰ~Ⅶ）,其中Ⅴ型菌为云南高原粳稻区的优势菌群。初步构建了一套包含7个品种（黄玉、毫糯扬、TN1、珍珠矮、IR26、南粳33、金南风）的高原粳稻白叶枯病菌的鉴别品种,明确了7个致病型在这套鉴别品种上的反应型。早生爱国3号(Xa-3)、IR1545-339(xa-5)、IRBB21（Xa-21）、扎昌龙（Xa-22t,Xa-24t）对所接种菌均表现抗病,在云南高原粳稻育种中具有较好的利用前景。     

经除草剂处理的水稻对褐飞虱体内几种酶及水稻受褐飞虱为害程度的影响

褐飞虱５龄若虫在不同除草剂不同剂量处理的水稻上短期取食(取食１ h)和长期取食（３龄若虫取食至５龄,约７ d）,然后测定其体内代谢酶、保护酶的变化。褐飞虱取食除草剂处理的水稻后其体内羧酸酯酶活性不论是短期取食还是长期取食均极显著高于对照（未施用除草剂）;乙酰胆碱酯酶活性明显高于对照;稻乐思、苯达松低剂量、丁草胺高剂量处理短期取食后超氧化物歧化酶活性显著低于对照,所有处理长期取食明显高于对照;过氧化物酶活性除了稻乐思300 mL/hm2和苯达松1500 mL/hm2处理短期取食低于对照外（但没有达显著差异）,也不同程度地高于对照。褐飞虱在除草剂处理的水稻上蜜露排泄量显著增加,水稻受害程度与对照相比极显著加重。除草剂处理后的水稻游离氨基酸的含量增加而蔗糖含量下降,由此表明除草剂施用后对水稻和褐飞虱具有双向效应     

Identification of Major Locus Bph35 Resistance to Brown Planthopper in Rice

An introgression line RBPH660, derived from wild rice Oryza rufipogon, showed stable resistance to brown planthopper(BPH). Segregation analysis indicated BPH resistance of RBPH660 was controlled by multiple genes/QTLs. By using the bulked segregant analysis(BSA)-seq method, two genomic regions harboring QTLs resistance to BPH were identified from 1.20 to 16.70 Mb on chromosome 4 and from 10.20 to 12.60 Mb on chromosome 9 in RBPH660, respectively. A major resistance locus, designated as Bph35 accounting for 51.27% of the phenotypic variation with a LOD score of 42.51, was mapped to the candidate region of chromosome 4 between In Del(insertion-deletion) markers PSM16 and R4 M13. For fine mapping of Bph35, one simple sequence repeat and three newly developed In Del markers were used to screen the recombinants. Finally, the Bph35 locus was delimited in the region from 6.28 to 6.93 Mb and there were 18 predicted protein-encoding genes with a total of 114 non-synonymous single nucleotide polymorphism(SNP) variant sites between the resistant and susceptible parents. Out of these genes, Os04 g0193950, encoding a putative NB-ARC(nucleotidebinding adaptor shared by APAF-1, R proteins and CED-4) and LRR(leucine-rich repeat) domain protein with nine non-synonymous SNP substitutions in its coding sequence regions, might be the candidate gene for Bph35. These findings would facilitate the map-based cloning of the Bph35 gene and development of resistant varieties against BPH in rice.     

水稻飞虱对十三种杀虫剂的抗性监测

1987～1991年选用有机磷、有机氯和拟除虫菊酯类十三种杀虫剂对白背飞虱和褐飞虱用国际统一标准毒力测定点滴法进行抗药性监涮。结果表明：1)白背飞虱和褐飞虱对呋喃丹最为敏感。对马拉硫磷敏感度最低,LD50值相差上百倍。因两种飞虱均属迁飞性害虫,年度间的测定结果稍有波动;2) 白背飞虱抗药性发展比褐飞虱快,在测定方法和供试昆虫条件基本相同的情况下, 将1990年所测几种药剂的LD50与Nagata (1967)测定的数据进行比较。浙江省白背飞虱种群对马拉硫磷的抗性差异高达1lO．56倍, 对杀螟松为48.90倍;褐飞虱种群对马拉硫磷、杀螟松的抗性分别相差11.61倍和6．11倍。3)褐飞虱种群对药剂的敏感度与当地用药水平呈负相关。4) 有机磷类不同品种杀虫剂对两种飞虱的毒力差异较大。毒力较高的久效磷的LD50值与毒力较低的马拉硫磷的LD50值相差数十倍。     

Comprehensive Characteristics of MicroRNA Expression Profile Conferring to Rhizoctonia solani in Rice

MicroRNAs(miRNAs) are about 22 nucleotides regulatory non-coding RNAs that play versatile roles in reprogramming plant responses to biotic and abiotic stresses. However, it remains unknown whether miRNAs confer the resistance to necrotrophic fungus Rhizoctonia solani in rice. To investigate whether miRNAs regulate the resistance to R. solani, we constructed 12 small RNA libraries from susceptible and resistant rice cultivars treated with water/pathogen at 5 h post inoculation(hpi), 10 hpi and 20 hpi, respectively. By taking the advantage of next-generation sequencing, we totally collected 400–450 known mi RNAs and 450–620 novel miRNAs from the libraries. Expression analysis of mi RNAs demonstrated different patterns for known and novel miRNAs upon R. solani challenge. Thirty-four mi RNA families were identified to be expressed specifically in rice, and most of them were involved in plant disease resistance. A particular Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway analysis result revealed that a great majority of target genes of regulated miRNAs belonged to the pathway of plant-pathogen interaction. Moreover, miR444 b.2, miR531 a, mir1861 i, novel_miR1956 and novel_miR135 conferred response to R. solani infection confirmed by Northern blot. Our global understanding of miRNA profiling revealed that the regulation of mi RNAs may be implicated in the control of rice immunity to R. solani. Analysis of the expression of miRNAs will offer the community with a direction to generate appropriate strategies for controlling rice sheath blight disease.     

Impact of Nitrogen,Phosphorus and Potassium on Brown Planthopper and Tolerance of Its Host Rice Plants

The brown planthopper (BPH), Nilaparvata lugens (Stål), appeared as a devastating pest of rice in Asia. Experiments were conducted to study the effects of three nutrients, nitrogen (N), phosphorus (P) and potassium (K), on BPH and its host rice plants. Biochemical constituents of BPH and rice plants with varying nutrient levels at different growth stages, and changes in relative water content (RWC) of rice plants were determined in the laboratory. Feeding of BPH and the tolerance of rice plants to BPH with different nutrient levels were determined in the nethouse. Concentrations of N and P were found much higher in the BPH body than in its host rice plants, and this elemental mismatch is an inherent constraint on meeting nutritional requirements of BPH. Nitrogen was found as a more limiting element for BPH than other nutrients in rice plants. Application of N fertilizers to the rice plants increased the N concentrations both in rice plants and BPH while application of P and K fertilizers increased their concentrations in plant tissues only but not in BPH. Nitrogen application also increased the level of soluble proteins and decreased silicon content in rice plants, which resulted in increased feeding of BPH with sharp reduction of RWC in rice plants ultimately caused susceptible to the pest. P fertilization increased the concentration of P in rice plant tissues but not changed N, K, Si, free sugar and soluble protein contents, which indicated little importance of P to the feeding of BPH and tolerance of plant against BPH. K fertilization increased K content but reduced N, Si, free sugar and soluble protein contents in the plant tissues which resulted in the minimum reduction of RWC in rice plants after BPH feeding, thereby contributed to higher tolerance of rice plants to brown planthopper.     

Expression Analysis of Genes Related to Rice Resistance Against Brown Planthopper,Nilaparvata lugens

Brown planthopper(BPH) is an insect species that feeds on the vascular system of rice plants. To examine the defence mechanism of rice plants against BPH, the pathogenesis-related genes(PR1a, PR2, PR3, PR4, PR6, PR9, PR10a, PR13, PR15 and PRpha), signaling molecule synthesis genes(AOS, AXR, ACO and LOX), antioxidant-related genes(CAT, TRX, GST and SOD) and lignin biosynthesis-related genes(CHS, CHI and C4H) were investigated in a resistant rice variety. AOS, PR6,PR9 and PR15 genes showed significantly increased relative expression levels at 24.38-, 19.17-, 14.71-, and 12.74-fold compared to the control. Moderate increased relative expression levels of lignin biosynthesis-related gene(C4H), pathogenesis-related genes(PR4, PR10a and PRpha), and antioxidant-related gene(GST) were found, while CHI, LOX, SOD, TRX1 and AXR showed decreased relative expression levels. It was thus clearly shown that wound-induced response genes were activated in rice plants after BPH attacks through AOS activation. Jasmonic acid signaling molecule may activate PR6, PR15, GST and CAT subsequently increasing their expression for H_2O_2 detoxification. PR6 were expressed at the highest relative level among the PR genes. These genes therefore have also a considerable synergistic role with the other genes against BPH by interfered their digestion tract system.     

光照因素对水稻品种苗期褐稻虱抗性的影响

 在人工气候箱及温室自然条件下研究了光照对品种抗性、植株生势及耐害性和褐稻虱生存、发育的影响。光照不足造成品种苗期抗性减弱甚至丧失，其原因是由于植株的生势减弱导致受飞虱为害后的补偿能力下降。中抗品种耐害性丧失和抗级品种的拒虫性减弱。在短光照生长条件下和长光照条件下，飞虱取食高抗品种的植株，其吸食量若虫生存率和发育进度，均无显著差异，表明高抗品种的抗生性在短光照条件下仍能保持。短光照条件下．如果接虫前或后予以充足的光照条件，或将接虫秧龄提高到4片叶，品种的抗性水平则可保持。     

褐飞虱为害对水稻产量结构影响的研究

 采用标准虫态分期连续接虫方法，研究了褐飞虱为害对水稻产量结构的影响。结果表明，褐飞虱为害可造成水稻有效穗数和实粒数减少，千粒重下降，并皆最终导致产量降低。分蘖期是穗数减少的敏感生育朝；灌浆开始以后为影响千粒重的敏感生育期。褐飞虱为害早期需达到较大的虫口数量才能造成水稻有效穗数和实粒数显著减少。灌浆期水稻只要遭受一定虫量为害即可引起千粒重显著下降，相同虫量下不同起始受害时间及同生育期稻株不同虫量造成的损失均有显著差异，水稻被害时间越早、受害时间越长、虫量越多，造成的产量损失越大。