抗稻瘟霉中草药活性筛选

目的从广西产中草药中筛选具有抗稻瘟霉活性的中草药。方法利用稻瘟霉模型筛选中草药。结果 12个科的 18种中草药呈现出较好的抗稻瘟霉活性。结论抗稻瘟霉模型是一个很好的活性筛选体系 。

分子标记辅助选择Pi9(t)基因培育杂交稻抗稻瘟病恢复系

水稻抗稻瘟病基因Pi9(t)抗谱广、抗性强。以携带抗稻瘟病基因Pi9(t)的小粒野生稻Oryza minuta为抗源,以优良杂交稻恢复系泸恢17和泸恢602为受体亲本,通过杂交和复交,在分离群体中利用与Pi9(t)紧密连锁的标记PB8进行分子标记辅助选择,结合农艺性状选择,获得5份目标基因纯合且农艺性状优良的恢复材料。以四川近年来具有代表性的32个菌株对这5份材料进行抗性鉴定,其抗性频率达81.25%～87.50%;并对这5份材料进行了耐高温鉴定及配合力测定,最终培育出抗性较强、耐热、配合力较高的优良恢复系R102、R105。

谈水稻育种高世代材料抗稻瘟性的鉴定

稻瘟病是世界上各稻区分布最广泛的严重病害之一.随着人们对优质米的重视和对日本品种的大量引进种植,稻瘟病在我省局部地区又有回升趋势,选用和培育抗病品种是综合治理该病的经济有效措施.现将稻瘟病抗性鉴定方法简报如下,旨在为水稻抗病育种提供科学依据,加速抗病育种进程.1

抗稻瘟病杂交水稻新组合裕优美占

裕优美占是广东鲜美种苗股份有限公司用野败型香稻不育系裕A和恢复系金美占配组育成的早、晚兼用抗稻瘟病籼型杂交水稻新组合,2016年3月通过广东省农作物品种审定委员会审定。

利用分子标记辅助筛选改良‘泸恢602’稻瘟病抗性的研究

水稻抗稻瘟病基因Pi9(t)抗谱广、抗性强。以携带抗稻瘟病基因Pi9(t)的小粒野生稻Oryza minuta为抗源,以优良杂交稻恢复系‘泸恢602’为轮回受体亲本,通过杂交及选择与受体亲本相似单株连续回交,直至BC3F1,令其自交。在分离群体中利用与Pi9(t)紧密连锁的标记PB8进行分子标记辅助选择,并结合株型、粒型、播抽期等农艺性状与‘泸恢602’相似株的选择,在BC3F4代,获得15份Pi9(t)基因纯合且农艺性状与‘泸恢602’相似的单株。用120对SSR引物进行背景选择,决选出6个单株,作为改良的‘泸恢602’。以四川近年来具有代表性的32个菌株对这6份材料进行抗性鉴定,其抗性频率75.00%～87.50%,表明抗性基因已成功导入‘泸恢602’中并表达。

高产抗稻瘟三系杂交水稻新组合广优7289

广优7289是信阳市农业科学院利用自育的品质优良恢复系R7289与三明市农业科学研究所选育的高抗稻瘟病不育系广抗13A配组育成的,集抗性强、品质优、丰产稳产性好为一体的三系杂交水稻新组合,2018年7月通过河南省农作物品种审定委员会审定。

抗真菌中草药的初步筛选

目的从具有抗稻瘟霉活性的中草药中筛选具有抗病原真菌活性的中草药。方法采用管碟法 ,以白色念珠菌、申克氏孢子丝菌、絮状表皮癣菌为指示菌 ,进行抗真菌活性的筛选。结果筛选出 5种对絮状表皮癣菌有较好抑制活性的中药提取物。结论抗稻瘟霉模型与抗病原真菌活性具有较好的相关性 ,是一种很好的初筛模型。

利用分子标记辅助选择改良春恢350稻瘟病抗性

水稻抗稻瘟病基因Pigm（t）抗谱广、抗性强。春恢350是超级早稻春光1号的恢复系，该恢复系配合力强，丰产性好，但不抗稻瘟病。本研究以携带抗稻瘟病基因Pigm的谷梅4号为抗源，以春恢350为轮回受体亲本，在回交选育过程中，通过表形筛选与分子标记辅助选择相结合，将Pigm（t）基因导入到春恢350中，获得3个带有目标基因的改良恢复系纯合株系。以江西近年来具有代表性的20个菌株对这3份材料进行抗性鉴定，其抗性频率为85%~100%，而原始对照春恢350的抗性频率仅为5%，表明抗性基因已成功导入春恢350中并表达；并用不育系江农早4号A与改良的春恢350测配，其杂种一代田间表现优势强，抗性强。

一株抑菌活性粘细菌Myxococcus fulvus N11的分离、筛选和鉴定

本论文从土壤中分离出16株粘细菌,并对其进行了多种细菌和真菌的抑菌活性分析,筛选出一株活性较高的粘细菌N11,随后根据菌落、子实体形态及16S rDNA序列分析鉴定粘细菌N11为黄色粘球菌(Myxococcus fulvus),抑菌试验结果表明,M.fulvus N11粗产物对多种病原真菌和细菌都有不同程度的抑制作用,在低浓度下对稻瘟霉的菌丝有明显的致畸作用,具有一定的抗肿瘤药物开发潜力。

Improvement of Resistance to Rice Blast in Zhenshan 97 by Molecular Marker-aided Selection

Fungi blast is one of the most serious diseases of rice worldwide. Breeding resistant varieties have been proved to be the most effective and economical means to control the disease. This paper describes the molecular marker-assisted selection (MAS) procedure for a broad-spectrum blast resistant gene Pi1 integrated into an elite hybrid maintainer line, Zhenshan 97. A simple sequence repeat (SSR) based on molecular marker-aided selection system for Pi1 segment was established. Using a backcross population and a blast isolate F1829, Pi1 gene was mapped on the top of chromosome 11 between markers RZ536 and RM144, with a distance of 9.7 cM and 6.8 cM, respectively. Seventeen families derived from the recurrent parent Zhenshan 97 were obtained with homozygous Pi1 gene. The background of the 17 families was identified with inter simple sequence repeat (ISSR) amplification, the highest recovery of the Zhenshan 97 genetic background was 97.01% after the assay of 167 polymorphic bands.

Effects of β-Amino Butyric Acid Induced Rice Blast Resistance on Reactive Oxygen Metabolism

[Objective] This study was to understand the effects of β-Amino butyric acid(abbreviated as BABA) induced rice blast resistance on reactive oxygen metabolism. [Method] Using the cultivar Chaochan 2 that is highly susceptible to disease as experimental material, the changes of catalase(CAT), and superoxide dismutase(SOD) and MDA activities in rice treated by BABA were investigated. [Result] In rice plants treated by BABA, the activities of CAT and SOD increased, meanwhile the MDA content also rose to some extent, resulting in the disease resistance to rice blast. [Conclusion] By influencing reactive oxygen metabolism, BABA endows rice plants with resistance to rice blast. BABA is safe to environment and has highly resistance-inducing capacity, it could be generalized in production.

Genotypic Analysis of Rice Blast Resistance Genes Pi-ta and Pi-b in Japonica Rice Varieties and Lines in Jiangsu Province

Pi-ta and Pi-b, the first cloned rice blast resistant genes, have been wide- ly used in rice blast resistance breeding for their lasting and stable resistance. To define the distribution of Pi-ta and Pi-b in japonica rice in Jiangsu, the genotypes of resistance genes Pi-ta and Pi-b in 40 varieties and 665 new lines were detected using functional markers of Pi-ta/pi-ta and Pi-b^pi-b alleles. The results showed that the resistance alleles of Pi-ta and Pi-b were widely spread in japonica rice varieties, and the distribution frequency of Pi-b was higher than that of Pi-ta. Most of the Lianjing serial varieties didn＇t carry the two resistance genes, but the two resistance genes were widely distributed in Wujing serial varieties. There was no significant dif- ference in distribution frequency of Pi-ta between new lines and commercial vari- eties. However, the distribution frequency of Pi-b in new lines was higher than that in commercial varieties. It was indicated that artificial selection was conducive to the improvement of distribution frequency of Pi-b in rice varieties. Among the 4 genotypes, the distribution frequency of pi-taJPi-b was highest （60.0%）, followed by Pi-ta/ Pi-b （33.5%） and pi-ta/pi-b （3.9%）. The frequency of Pi-taJpi-b was lowest, account- ing for only 2.6%. In terms of source of resistance genes in the four combinations, the resistant allele Pi-ta might be from parents of Wuxiangjing14, Wujing15 or Nanjing44, and Pi-b might come from parents of Wujing13, Wuxiangjing14, Wujing15 or Nanjing44. The analysis on the genotypic frequencies in offspring of the rice vari- eties showed that the resistance genotype of Pi-ta/Pi-b had the highest frequency in the cross combination of Nanjing44//Wujing13/Kantou194.

Using Gene Silencing Technology to Create Blast Resistant Rice Resources

Rice blast disease is one of the most devastating diseases in rice production,which severely affects the high and stable yield of rice.The formation of appressorium plays a key role in the pathogenesis of Magnaporthe grisea in rice.It has been confirmed that a P-type ATPase （P-ATPase） is involved in the formation of appressorium.A number of small molecular substances are able to enter the pathogen from the host during the interactions between pathogens and hosts,thus resisting the infection of pathogens.In this study,a 232 bp DNA sequence with good specificity from the first exon of P-ATPase gene MgAPT2 was used as an interference fragment and was inserted into interference vector forward and reversely.The interfering vector was then transformed into rice blast-susceptible rice variety Nipponbare via Agrobacterium-mediated transformation.Identification of rice plants inoculated with M.grisea at the seedling stage and detection of the expression level of P-ATPase gene MgAPT2 showed that the expression level of MgAPT2 gene in transgenic plants was reduced and the rice blast resistance was improved.This study provided a new way for the innovation of rice germplasm resources resistant to rice blast disease.

Application of Broad-spectrum Blast Resistance Gene Pi40 in Breeding of Japonica Rice in Yunnan Plateau

The resistance of a newly bred line 4163 containing the rice blast resistance gene P/40 and another 11 monogenic lines to rice blast in natural disease nurseries was identified. The results showed that 4163 was resistant to rice blast isolates from Yunnan, and the leaf blast resistance levels were at grades 0, 0 and 4 in Baoshan City, Yiliang City and Yuxi City respectively, while the ear blast resistance was at level 3. Meanwhile, the resistance spectrum of Pi40 to 49 representative rice blast isolates from Yunnan Province was studied by indoor inoculation and was compared with another 25 resistance genes. The results revealed that the resistance frequency of Pi40 to the 49 typical isolates reached 87.8%, showing a broader resistance spectrum, so it could be used as a new source of resistance genes in breeding of japonica rice in Yunnan plateau in the future.

Establishment and Application of a Multiplex PCR System for the Detection of Blast Resistance Genes Pi-ta and Pi-b in Rice

Rice blast is one of the important diseases in major rice producing areas of China. The main blast resistance genes Pi-ta and Pi-b showed broad-spectrum and durable resistance to rice blast in many rice growing areas of China, which have been widely utilized in rice breeding and commercial production. In this study, on the basis of detection and verification of the genotypes of 22 rice varieties har- boring known blast resistance genes （Pi-ta and Pi-b） and blast susceptibility genes （pi-ta and pi-b）, two multiple PCR systems for these genes were established by us- ing the functional markers of blast resistance genes Pi-ta and Pi-b as well as blast susceptibility genes pi-ta and pi-b, respectively. Specifically, multiple PCR system I could simultaneously detect blast resistance genes Pi-ta and Pi-b, while system II could detect simultaneously blast susceptibility genes pi-ta and pi-b. In addition, the genotypes of 336 high generation breeding materials were detected with these two multiple PCR systems. The results were highly consistent with those of conventional single mark detection, indicating that these two multiplex PCR systems were stable, reliable and time-saving. The established multiplex PCR systems may serve as a rapid and efficient method to identify and screen rice germplasm resources and can be applied in marker-assisted selection to polymerize multiple genes for blast resis- tance in rice breeding.

Resistance Evaluation of Part of Leading Rice Varieties to Rice Blast in Guangxi Province

In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.

Effects of Nitrogen Rate on Blast Resistance and Grain Yield of Super Early Hybrid Rice Luliangyou 996

Super early hybrid rice Luliangyou 996 was the materials for this experiment. This paper focused on the influences of different nitrogen rates on blast resistance and grain yield. Studies suggested that with the increase of nitrogen rate,there were no distinct changes in the sick grain rate and sickness index, but the fifth grade of panicle blast rate rose gradually. When the nitrogen was too much（270 kg/hm^2）, the sick grain rate and sickness index were the highest. The yield rose along with the addition of nitrogen if the amount of applied nitrogen was within the range of 0 to 180 kg/hm^2, and the yield would decrease with the addition of nitrogen if the amount of applied nitrogen was over 180 kg/hm^2. Considering the sickness, output and economic benefit of rice, it is better to applied 90 to 135 kg/hm^2 of nitrogen for Luliangyou 996.

Molecular Cloning of Early-expressed cDNAs from Rice in Response to Infection by Rice Blast Fungus Magnaporthe grisea

Compatible and incompatible reactions in rice plants ( Oryza sativa L. cv. Shenxianggen No.4) were resulted from inoculation with two different virulent races of rice blast fungus ( Magnaporthe grisea (Hebert) Barr), and thus an effective infecting system was established between rice plants and the rice blast pathogen. Two cDNA clones that showed induced and temporal patterns in expression in the very early stage in response to infection of the fungus were obtained from the plants by use of differential display. Of the two cDNA clones, Fastresp_a was induced to express in both compatible and incompatible interactions although it was expressed earlier in the former reaction. The second one, Fastresp_b , was only expressed in incompatible interaction. Southern blot analysis of the rice genomic DNA indicated that both of the two clones were from genome of the plant. No significant homology to the two genes was found from the rice gene database. This suggested that they were novel genes in rice and may play important roles in rice resistant response to infection of rice blast fungus.

Improvement of Rice Blast Resistance of High-Quality Rice Variety Xiangwanxian 13 by Molecular Marker-Assisted Selection

At present, most of high-quality rice varieties are susceptible to blast diseases. In this study, Gumei 2, a rice variety carrying broad-spectrum resistant Pi25 gene, was used as the donor, with Xiangwanxian 13 taken as the receptor and recurrent parent which is also of good quality but highly susceptible to rice blast, to improve the rice blast resistance of Xiangwanxian 13 by crossing and backcrossing based on molecular marker-assisted selection. The results showed that the resistance of the improved strains （i.e. Xiang C72, Xiang C76 and Xiang C77） to blast diseases had been enhanced signifcantly through feld resistance identifcation, equaling the resistance level of Gumei 2, and the main agronomic and quality-related traits of these improved strains had been restored to the level of Xiangwanxian 13, except the chalkiness and cooking-related traits, which suggested similar genomic loci of Xiang C72, Xiang C76 and Xiang C77 to those of Xiangwanxian 13. These three improved strains （i.e. Xiang C72, Xiang C76 and Xiang C77） can provide good intermediate materials for breeding elite varieties with high grain yields and superior blast resistance.

Characterization and fine mapping of the rice blast resistance gene Pia

Blast, caused by Magnaporthe oryzae, is one of the most widespread and destructive diseases of rice. Breeding durable resistant cultivars （cvs） can be achieved by pyramiding of various resistance （R） genes. Pia, carded by cv. Aichi Asahi, was evaluated against 612 isolates of M. oryzae collected from 10 Chinese provinces. The Pia gene expresses weak resistance in all the provinces except for Jiangsu. Genomic position-ready marker-based linkage analysis was carded out in a mapping population consisting of 800 F2 plants derived from a cross of Aichi Asahi×Kasalath. The locus was defined in an interval of approximately 90 kb, flanked by markers A16 and A21. Four candidate genes （Pia-1, Pia-2, Pia-3, and Pia-4）, all having the R gene conserved structure, were predicted in the interval using the cv. Nipponbare genomic sequence. Four candidate resistance gene （CRG） markers （A17, A25, A26, and A27）, derived from the four candidates, were subjected to genotyping with the recombinants detected at the flanking markers. The first three markers completely co-segregated with the Pia locus, and the fourth was absent in the Aichi Asahi genome and disordered with the Pia locus and its flanking markers, indicating that the fourth candidate gene, Pia-4, could be excluded. Co-segregation marker-based genotyping of the three sets of differentials with known R gene genotypes revealed that the genotype of A26 （Pia-3） perfectly matched the R gene genotype of Pia, indicating that Pia-3 is the strongest candidate gene for Pia.