玉米抗镰孢菌穗、茎腐病育种研究进展

随着玉米产量的提高,穗腐病和茎腐病在我国发生日益严重,而这与镰孢菌引起的穗腐病和茎腐病的病原学关系密切,通常认为禾谷镰孢菌和串珠镰孢菌是两种病害的共同病原菌,穗腐病的发生又与茎腐病发生有一定关系,两种病害防治难度均较大,所以选育和种植抗病品种是最有效的防治措施.     

具有纹枯病相似症状的小麦茎基病害初步研究

为明确具有纹枯病相似症状的小麦茎基病害的病原组成、筛选高效药剂,为设计药剂防治方案提供理论依据,采用常规组织分离法,对60份具有小麦纹枯病相似症状的病样进行病菌分离。分别选择从不同地区病样上分离到的丝核菌(Rhizoctonia)、镰孢菌(Fusarium)、蠕孢菌(Bipolaris)菌株,进行致病性测定;采用菌丝生长速率法,测定了氟唑环菌胺(sedaxane)等4种杀菌剂对禾谷丝核菌(Rhizootonia cerealis)、亚细亚镰孢菌(Fusarium asiaticum)的室内生物活性,并进行了田间防效验证试验。结果表明,丝核菌、镰孢菌、蠕孢菌等均可侵染小麦,在茎基部表现典型或近似小麦纹枯病症状;氟唑环菌胺对丝核菌有极高的室内生物活性、但对镰孢菌室内生物活性很差,其EC50分别是0.099 mg/L、126.974 mg/L;氟唑环菌胺单剂对小麦纹枯病的防效远低于其与咯菌腈等混剂防效。具有纹枯病相似症状的小麦茎基病害,是由丝核菌、镰孢菌、蠕孢菌等多病原混合侵染的病害,防治时应考虑药剂对丝核菌、镰孢菌、蠕孢菌等的综合作用效果。     

甘肃省张掖市玉米黑髓病病原的分离与鉴定

为明确引起甘肃省张掖市玉米黑髓病的病原菌种类,于2021年9月,在甘肃省张掖市采集具有典型病害症状标本,利用组织分离法进行分离纯化,并通过柯赫氏法则验证致病性;利用形态学特征和分子生物学方法进行鉴定。结果表明,于病样中共获得39株分离物,能引起与田间症状相一致的病原菌30株,表现症状为根茎腐烂型、根腐型和茎腐型3类。根据形态特征将30株病原物均鉴定为镰孢霉属真菌,结合分子生物学方法将30个致病镰孢霉菌分别鉴定为拟轮枝镰刀菌(Fusarium verticillioides)、尖孢镰刀菌(F.oxysporum)、层出镰刀菌(F.proliferatum)、茄病镰刀菌(F.solani)、变红镰刀菌(F.incarnatum)和柔毛镰刀菌(F.flocciferum),其分离频率依次为50.00%、20.00%、16.67%、6.67%、3.33%和3.33%,其中拟轮枝镰刀菌为张掖市玉米黑髓病的优势致病菌,首次报道柔毛镰刀菌可以侵染玉米。该研究结果为玉米黑髓病的诊断和防治提供了依据。     

东北地区小麦赤霉病镰孢菌种群及其致病性测定

为了明确东北地区小麦赤霉病镰孢菌的种群组成及分布,分别从辽宁省沈阳市、黑龙江省哈尔滨市和密山市、内蒙古自治区扎兰屯市、呼伦贝尔市和通辽市等地区采集小麦赤霉病病样,经单孢分离纯化共得到118株镰孢菌,传统形态学鉴定的基础上,采用基因组DNA的EF-1α序列分析技术进行了镰孢菌种类的辅助鉴定,确定属于7个种:禾谷镰孢菌为优势种,分离频率为64.41%,藤仓镰孢菌为次优势种,分离频率为18.64%;燕麦镰孢菌、尖孢镰孢菌、木贼镰孢菌、锐顶镰孢菌和轮枝镰孢菌的分离频率分别为5.08%,3.39%,3.39%,3.39%,1.70%。同时,在玉米成株期进行了致病性测定,结果表明,小麦赤霉病镰孢菌可以侵染玉米,较玉米茎腐镰孢菌的致病力低。     

山东省玉米穗腐病病原菌的分离鉴定及优势种的系统发育分析

旨在明确山东省玉米穗腐病病原菌组成及优势病原菌的流行趋势。对2015-2017年在山东省采集的138份玉米穗腐病样品进行了病原菌的分离,采用形态学和分子生物学方法对分离物进行鉴定,并对优势病原菌进行系统发育分析,明确其发生发展规律。分离鉴定结果表明,分离到的真菌共有18种,其中镰孢属的拟轮枝镰孢菌分离频率为67.39%,为山东省优势病原菌;其次为层出镰孢菌,分离频率为10.87%;禾谷镰孢复合种、木贼镰孢菌和尖孢镰孢菌的分离频率分别为7.97%,5.80%,0.72%;木霉属的哈茨木霉分离频率为7.91%;青霉属的草酸青霉分离频率为6.52%;曲霉属黄曲霉和黑曲霉的分离频率分别为2.17%和5.07%。基于EF-1α基因序列构建了山东省2015-2017年拟轮枝镰孢菌的系统发育树,并分析了山东省菌株与河北省菌株的遗传进化关系。系统发育分析结果发现,89个拟轮枝镰孢菌菌株可以分为2个大群,其遗传距离较小,为0.002～0.016,表明山东省2015-2017年的菌株之间遗传关系较近;河北省和山东省拟轮枝镰孢菌菌株的遗传距离较小,相似性较高,亲缘关系较近,存在较为频繁的基因交流。研究结果为深入开展拟轮枝镰孢菌穗腐病的抗性育种、发生发展规律以及综合防治提供科学依据。     

尖镰孢菌致病机理研究进展

香（大）蕉是世界重要的水果和粮食作物,但世界香蕉产业的发展正遭受到由古巴尖镰孢菌侵染引起的枯萎病的严重威胁,目前还没有有效的防治方法,而且其致病机理尚未明晰。笔者综述尖镰孢菌与寄主的互作关系,包括侵入前期寄主根的分泌物对尖镰孢菌生长的影响和尖镰孢菌侵染寄主的过程;致病毒素,包括尖镰孢菌所产毒素的成分和毒素的作用机制和致病相关基因等方面的研究进展,为全面、深入地揭示香蕉枯萎病的致病机理和开拓新的防治途径提供研究方向和思路。     

油菜素内酯有增强玉米抗禾谷镰孢侵染能力

<正>茎(基)腐病是造成玉米倒伏减产的主要病害,禾谷镰孢菌是引起茎(基)腐病的主要病原真菌。为明确油菜素内酯(BR)增强玉米抗禾谷镰孢侵染的作用及机制,河北农业大学生命科学学院研究人员以玉米郑单958为试验材料,分设喷施BR和未喷施BR的处理,在玉米喷施BR 10天后,接种禾谷镰孢菌,调查比较喷施BR后玉米感染禾谷镰孢菌的发     

2005—2007年辽宁省玉米区试品种抗病性分析

就2005-2007年辽宁省玉米区试参试品种对大斑病、弯孢菌叶斑病、灰斑病、茎腐病和丝黑穗病的抗病性情况进行了统计分析,结果表明,参试品种对弯孢菌叶斑病和茎腐病表现为中抗以上水平的数量逐年略有下降,对灰斑病和大斑病表现为抗性水平的品种数量逐年提高,对丝黑穗病表现为抗性水平的品种数量保持稳定.     

夏玉米常见病虫害防治技术

研完了夏玉米蚜虫、粗缩病、玉米螟、茎腐病等几种常见病虫害的发生规律及危害症状,并提出针对性的防治措施。     

甘薯茎基部腐烂病调查及病原鉴定

2012年以来浙江省台州市及其周边市县甘薯产区发生了大面积的甘薯茎基部腐烂病,导致当地甘薯种植面积大幅度下滑。为明确浙江省甘薯茎基部腐烂病的发生情况、病原组成及种类,本团队于2015年至2018年对浙江省11个县市区进行了田间调查并采集127份病样分离鉴定病原菌,结果表明浙江省甘薯茎基部腐烂病主要存在4种主要症状,根据病菌的致病性、形态特征、ITS和16S rDNA序列分析鉴定,主要鉴定到达旦提狄克氏菌(Dickeya dadantii)、齐整小核菌(Sclerotium rolfsii)、拟轮枝镰孢菌(Fusarium verticillioides )、腐皮镰刀菌(F. solani)、尖镰刀菌(F. oxysporum)、甘薯间座壳菌(Diaporthe batatas)、毁坏性拟茎点霉(Phomopsis destruens)和爪哇镰孢(F. javanicumS)等8种致病病菌,各地区病原菌组成分布均有所不同,采集的样品普遍为多种致病菌复合侵染危害。     

西瓜枯萎病菌的鉴定及申嗪霉素对其防效评价

由于重茬西瓜种植面积增多,西瓜枯萎病的发生面积逐步扩大,严重影响了西瓜生产。本研究用PDA培养基从中国农业科学院郑州果树研究所大棚温室萎蔫枯萎的西瓜上分离病原菌。形态学鉴定为尖孢镰刀菌;ITS序列分析表明其与西瓜枯萎病菌的序列一致性达到99%;发现该菌引起西瓜枯死严重,发病率达96.7%以上。因此,证实是西瓜枯萎病菌引起的。为了防治该病害,进行了温室和室内的申嗪霉素药效评价。室内抑菌实验和温室内药剂处理结果一致,1%申嗪霉素100倍防治效果最好,抑菌率达76.03%,灌根防治率达58.86%。因此,生产上建议在西瓜枯萎病发病早期使用1%申嗪霉素100倍连续3次灌根,每次间隔约8天左右,尽可能减少西瓜枯萎病菌对西瓜的影响。     

水稻草状矮化病毒侵染下水稻根发育相关基因的表达分析

水稻草状矮化病毒(Rice grassy stunt virus, RGSV)引起的水稻草矮病是热带和亚热带稻区的重要病害,RGSV侵染引起水稻植株根系严重发育不良。为解析RGSV侵染引致水稻根系发育不良的分子机制,以水稻品种‘汕优63’为材料,通过实时荧光定量RT-PCR技术分析水稻经RGSV侵染后根系发育相关基因OsPHR2、QHB、OsRR1、OsEXPB5、Crl-5和OsEXPA17等基因的mRNA表达量变化。结果表明,RGSV侵染引起OsPHR2和Crl-5基因表达下调,下调比率分别为2.18和4.86,而水稻病株QHB、OsRR1、OsEXPB5和OsEXPA17等基因的表达量与健株相比,各基因差异比率分别为1/1.49、1.01、1.39、1/1.37,表明RGSV侵染未引起这些基因的表达量发生变化。RGSV可能通过直接或间接调控根系发育相关基因表达水平而使根系发育异常。

     

Identification of dominant and recessive genes for resistance to Fusarium wilt in pigeonpea and their implication in breeding hybrids

Fusarium wilt is an important disease of pigeonpea [Cajanus cajan (L.) Millsp.] and it can cause severe yield losses. Chemical control of this disease is difficult and expensive; therefore, cultivation of resistant varieties/hybrids is the most efficient strategy for enhancing the production. In the present study, by using a wilt susceptible cytoplasmic-nuclear male-sterile line and four wilt resistant fertility restorers, one dominant and one recessive gene with dominant suppressive epistatic effects were found responsible for controlling resistance to Fusarium wilt. Considering the annual losses and wide spread nature of wilt diseases in pigeonpea, it is imperative that all the inbred and hybrid cultivars have high level of resistance to this disease. The presence of dominant gene for resistance will increase the efficiency of breeding wilt resistant cultivars because it will yield greater proportion of resistant genotypes in segregating generations. In hybrid breeding also, the presence of dominant gene for wilt resistance will be an advantage. The transfer of this gene in female hybrid parents will ease the breeding of wilt resistant hybrids because this will allow the use of both wilt resistant as well as susceptible restorers in generating wilt resistant hybrid combinations.     

Partial resistance to a Fusarium root disease in Egyptian white lupin landraces

A Fusarium sp. root pathogen of lupin is the causal agent of the most important disease that affects the cultivation of white lupin (Lupinus albus L.) in Egypt. The aim of our research was to investigate whether host resistance to Fusariumroot disease was available in Egyptian landraces ofLupinus albus. Five Fusarium isolates collected from white lupin samples in Egypt were tested with an Egyptian landrace and a French cultivar. The most aggressive isolate was used to screen an additional 15 Egyptian landraces, two cultivars released in Egypt after selection among landraces, one Polish cultivar, and two French cultivars. The assessment of host response to Fusarium was performed in a field, and under controlled conditions in a greenhouse pot experiment. Most landraces and the two Egyptian cultivars showed better resistance with good accordance between field and pot experiment. This experiment showed that Egyptian genetic resources of white lupin possess partial resistance to Fusarium root rot. Egyptian germplasm may be an alternative genetic source for incorporating partial resistance to Fusarium root rot into the breeding pools. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of resistance to spotted stem borer, Chilo partellus, in sorghum, Sorghum bicolor

The spotted stem borer, Chilo partellus, is one of the most important pests of sorghum, and host plant resistance is an important component for the management of this pest. Most of the sorghum hybrids currently under cultivation are based on cytoplasmic male-sterility (CMS). In order to develop a strategy for resistance to stem borer, we studied the traits associated with resistance, and their nature of gene action in F₁ hybrids derived from resistant, moderately resistant, and susceptible CMS and restorer lines. The hybrids based on stem borer-resistant, moderately resistant, or susceptible CMS and restorer lines were equally resistant or susceptible as the parents for leaf feeding [Damage rating (DR) 5.8 to 6.6 vs. 5.9 to 6.6], and had significant and decreasing trend in deadheart formation (resistant CMS × resistant restorer lines < moderately resistant CMS × moderately resistant restorer lines < susceptible CMS × susceptible restorer lines), respectively. Proportional contributions of restorer lines were greater than those of the CMS lines for leaf feeding, deadhearts, recovery and overall resistance, stalk length, nodes per plant, stem borer holes per plant, and peduncle tunneling. The general (GCA) and specific combining ability (SCA) estimates suggested that leaf feeding score, number of nodes, overall resistance score, panicle initiation, recovery score, and stalk length (dominance type of gene action) have been found to be associated with resistance to spotted stem borer, governed by additive type of gene action, their correlation and direct effects in the same direction, and explained 65.3% of the variation in deadhearts, and thus could be used as marker traits to select and breed for resistance to C. partellus in sorghum. The parents having significant SCA effects for two or more resistance traits for either or more parents have also been discussed for their use in the stem borer resistance breeding.     

Molecular markers for improving control of soil-borne pathogen <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> in sugar beet

Fusarium spp. cause severe damage in many agricultural crops, including sugar beet, with Fusarium oxysporum historically being considered as the most damaging of all species. Sugar beet needs to be protected from this class of soil-borne pathogens in order to ensure an optimal sugar yield in the field. Genetic control of the disease is crucial in managing these pathogens. Identification of single nucleotide polymorphism (SNP) markers linked to resistance can be a powerful tool for the introgression of valuable genes needed to develop Fusarium-resistant varieties. A candidate gene approach was carried out to identify SNP markers linked to putative Fusarium resistance sources in sugar beet. Five resistant analogue genes (RGAs) were screened by means of high resolution melting (HRM) analysis in a set of sugar beet lines, considered as resistant and susceptible to Fusarium oxysporum. HRM polymorphisms were observed in 80% of amplicons. Two HRM polymorphisms were significantly associated with Fusarium resistance (P < 0.05). The amplicons that showed association were sequenced and two SNPs were identified. The association was further validated on 96 susceptible and 96 resistant plants using competitive allele-specific PCR (KASPar) technology. The selected SNPs could be used for marker-assisted breeding of Fusarium resistance in sugar beet.     

Inheritance of resistance to Fusarium oxysporum f. sp. cubense race 1 in bananas

Fusarium wilt of bananas (also known as Panama disease), caused by the soil-borne fungus Fusarium oxysporum f. sp cubense (Foc), is a serious problem to banana production worldwide. Genetic resistance offers the most promising means to the control of Fusarium wilt of bananas. In this study, the inheritance of resistance in Musa to Foc race 1 was investigated in three F₂ populations derived from a cross between ‘Sukali Ndizi’ and ‘TMB2X8075-7’. A total of 163 F₂ progenies were evaluated for their response to Fusarium wilt in a screen house experiment. One hundred and fifteen progenies were susceptible and 48 were resistant. Mendelian segregation analysis for susceptible versus resistant progenies fits the segregation ratio of 3:1 (χ² = 1.72, P = 0.81), suggesting that resistance to Fusarium wilt in Musa is conditioned by a single recessive gene. We propose panama disease 1 to be the name of the recessive gene conditioning resistance to Fusarium wilt in the diploid banana ‘TMB2X8075-7’.     

Screening for Fusarium resistance in seedling populations of Asiatic hybrid lily

A test to select Fusarium resistant seedlings of the Asiatic hybrid lily is described. Young seedlings of 28 populations, obtained from an incomplete diallel between eight parents with different levels of Fusarium resistance, were tested for resistance. Significant differences in Fusarium resistance between and within populations were detected. The average percentage of selected seedlings ranged from 34% in resistant × resistant crosses to 2% in susceptible × susceptible crosses. Although resistant descendants were obtained in susceptible × susceptible crosses, using at least one resistant parent produced higher percentages of resistant seedlings. The resistance level of the parents correlated highly with the general combining ability for Fusarium resistance based on the seedling test. For eight populations, seedlings selected for Fusarium resistance and non-tested (control) seedlings of the same cross were compared, after propagation, in a clonal test. Variation between and within populations, found at seedling level, was confirmed at clonal level. A positive selection response was found for all eight populations. In the seedling test, approximately 18% of the seedlings were selected as resistant of which 15% (2.7% of seedlings tested) appeared to be susceptible escapes. Comparison between selection at seedling level and at clonal level indicated that approximately 25% of the seedlings tested were missed (rejected resistant plants) in the seedling test. The practical use of a seedling test for Fusarium resistance in lily breeding programs is discussed.     

Fusarium resistance in Gladiolus: Selection in seedling populations

A test to select Fusarium resistant seedlings of Gladiolus is described. Seedlings of 37 populations, obtained from an incomplete diallel between eight parents with different levels of Fusarium resistance, were used. Significant differences in Fusarium infection between and within populations were detected. Most of the descendants selected had a resistant G. dalenii genotype as one of the parents. The resistance level of the parents was associated with the general combining ability for Fusarium resistance based on the seedling test. Implications for resistance breeding are discussed.     

Increasing resistance to Fusarium crown and root rot in asparagus by gametophyte selection

In garden asparagus, Fusarium crown and root rot is the main cause of crop decline. Since chemical treatments are inefficient, efforts should focus on the development of resistant cultivars to control the disease. Toxic culture filtrate (TCF) of F. oxysporum has affected asparagus pollen germination and tube growth. Consequently, gametophyte selection was evaluated to ascertain if the application of selective agents at this level could increase selection efficiency. Two susceptible pistillate plants and one tolerant and one susceptible staminate plants were used in controlled crosses. Before pollination, a drop of a germination vehicle with TCF or without it was applied to the stigmas. Some pollinated pistils were fixed and analyzed by fluorescence microscopy; the rest were left on the plant for seed production. Fifty to 200 seeds were obtained per treatment combination (staminate plant x pistillate plant x pollination vehicle). The derived plantlets were inoculated in vitroand evaluated for disease symptoms. The application of TCF to stigmas reduced pollen germination and tube growth compared with untreated controls,regardless of the genotypic combination. Pollen germination and tube growth was poorer for the tolerant staminate genotype than for the susceptible one. When the TCF was applied, the number of seeds per pollination in comparison with the controls diminished only when the susceptible genotype was the pollinator. The percentage of affected root area of the progenies obtained after applying the TCF was lower than in the controls only when the tolerant genotype was the pollinator. Increasing Fusarium resistance in asparagus by means of gametophyte selection seems feasible. This revised version was published online in August 2006 with corrections to the Cover Date.