Mapping of QTL for resistance to first and second generation of European corn borer using an integrated SNP and SSR linkage map

The European corn borer (ECB, Ostrinia nubilalis Hübner) is a major pest of maize (Zea mays L.) in North America and Europe. In this study, we mapped and characterized QTL affecting the resistance to the first (ECB1) and second generation (ECB2) of ECB and plant height with the aid of 164 SNP and 88 SSR markers. A total of 144 testcross (TC) progenies of double haploid (DH) lines developed from a cross of two parental lines from the Stiff Stalk germplasm pool were tested at six different locations in the USA under both natural and artificial infestation with ECB larvae. Resistance to ECB1 and ECB2 was assessed by measuring leaf feeding and stalk breakage, respectively, using a visual rating scale from 1 (severe damage) to 9 (no damage). Genotypic variance among the TC progenies was significant for all traits. Heritabilities were moderately high (0.69) for stalk breakage and plant height (0.75), but only moderate for leaf feeding (0.43). For stalk breakage, three QTL were detected that together explained 36% of the genetic variance, whereas for leaf feeding only one QTL was mapped, which explained 25% of the genotypic variance. For plant height, two QTL were identified, explaining 20% of the genotypic variance. The QTL for leaf feeding and stalk breakage mapped by us were located in chromosomal regions adjacent to those reported for other maize germplasm and therefore might be suitable candidates for marker-assisted selection (MAS) during line development.     

Concentration of moniliformin produced by Fusarium species in grains of transgenic Bt maize hybrids compared to their isogenic counterparts and commercial varieties under European corn borer pressure

The European corn borer (ECB), Ostrinia nubilalis Hb., is a major pest of maize in Central Europe and is suspected to promote infection of maize with Fusarium species. The objectives of this study were to (1) determine moniliformin (MON) concentration in early maturing European Bt maize hybrids, their isogenic counterparts, commercial cultivars and experimental hybrids, (2) evaluate the association between MON concentration and ECB resistance and (3) correlate MON concentration with concentrations of other mycotoxins determined from the same plant materials. The field experiments were performed at five locations in Germany. MON concentration was significantly higher with manual infestation of ECB larvae (296 μg/kg) than under insecticide protection (66 μg/kg). Bt hybrids showed significantly lower MON concentrations and higher grain yields under manual ECB infestation than their corresponding isogenic counterparts, as well as commercial and experimental hybrids. All ECB resistance traits and grain yield under ECB infestation were significantly correlated with MON concentration. Correlations between concentrations of MON and other Fusarium mycotoxins were not significant. The use of Bt maize hybrids or insecticides to control ECB reduces the contamination of maize grains with MON in Central Europe. The presence of resistance genes against Fusarium species in the current elite maize germplasm was indicated by ECB susceptible non‐Bt hybrids with low‐MON concentrations.     

Selection efficiency of tunnel length and stalk breakage to obtain maize inbred lines resistant to stem borer attack

There is not any conclusive result about the most suitable trait for performing pedigree selection for improving maize performance against corn borer attack: tunnel length or stalk breakage. We have used simultaneously both selection traits in the same genetic backgrounds and the objective of the present work has been to compare the suitability of pedigree selection for tunnel length and stalk breakage in order to obtain inbred lines that per se and in hybrid combination show lower stem damage and good agronomic performance. Tunnel length is better as selection criteria for increasing resistance to corn borers, but, in some genetic backgrounds, genetic linkage between yield and stalk tunneling by stem borers could make that selection for reduced tunnel length resulted in significant yield reductions.     

Evaluation of early-maturing European maize inbreds for resistance to the European corn borer

The European corn borer (ECB) has become a serious pest for maize cultivation in Central and Western Europe. This study was conducted to evaluate resistance against ECB in a cross section of the European maize germplasm. A total of 115 flint and dent inbreds were evaluated for resistance under protected and artificial infestation conditions at two German sites in 1993. Resistance to ECB was assessed by damage rating before harvest, tunnel length in dissected stalks, and relative yield under infestation compared to protected control plots. Means for damage rating of stalks were significantly higher in flint lines than in dent lines. Artificial infestation reduced grain yield by 31% in flint lines and 20% in dent lines. Significant genotypic variances among lines and high genetic ratios (GR) were found in both flint and dent lines for all agronomic and ECB resistance traits. Exceptions were relative yield of stover in both germplasm groups and tunnel length in flint lines. Phenotypic correlations between agronomic and resistance traits were moderate to low. Damage rating was negatively correlated with days to silking and dry matter yield of stover in both germplasm groups. In vitro digestibility of stover was not associated with ECB resistance. Correlations of relative grain yield with tunnel length below the ear and damage rating were significantly negative, even though their magnitude was low. Our results indicate substantial genetic variation among European inbred lines for resistance to the univoltine ECB. Among all resistance traits measured, damage rating of stalks is best suited for assessment of ECB resistance in breeding programs because of its easy recording and high genetic ratio. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic variation among European maize inbreds for resistance to the European corn borer and relation to agronomic traits

The univoltine European corn borer (ECB) has become a major limiting factor for maize (Zea mays L.) production in central Europe. The objective of this study was to survey the genetic variation for ECB resistance in European elite maize germplasm. Eighteen flint and 23 dent inbreds were screened under artificial ECB infestation at two locations in 1993 and 1994. Resistance was assessed by damage rating of broken plants, measurement of tunnel length in dissected stalks, and yield reduction in infested plots relative to insecticide-protected control plots. Flint lines showed significantly greater means for damage rating than dent lines with grain yield reduction of 35% and 24%, respectively. Significant genotypic variances among lines and high heritabilities were found for agronomic traits and damage rating. Heritabilities were intermediate for tunnel length and relative grain yield. Significant associations of days to silking, ear dry matter content, and dry matter yield of the whole plant with damage rating and tunnel length suggested a better resistance in late-maturing, high-yielding inbreds. Genotypic correlations of relative grain yield with tunnel length and damage rating ranged between ?0.46 and ?0.72. Partial correlations, eliminating the effect of flowering time, confirmed these associations. Damage rating of stalks is the most suitable trait for evaluation of ECB damage owing to its high heritability and easy recording. Tunnel length below the primary ear is a useful trait for assessing antibiosis because it is not correlated with days to silking. Inbreds with extreme resistance and susceptibility were identified which can be used as parents for establishing breeding and QTL mapping populations.     

Comparison of Bt maize hybrids with their non-transgenic counterparts and commercial varieties for resistance to European corn borer and for agronomic traits

The European corn borer (ECB), Ostrinia nubilalis (Hübner), is a major pest of maize (Zea mays L.) in Central Europe. In order to compare transgenic Bt maize hybrids with their non‐transgenic counterparts and commercial hybrids, field trials and a laboratory bioassay were conducted. The field experiments were performed at four locations with natural and manual infestation of ECB larvae in 1998 and 1999. Transgenic Bt hybrids showed significantly lower means than their corresponding non‐transgenic counterparts and commercial hybrids for all resistance traits (damage rating of stalks, number of larvae per plant, and percentage of damaged plants or ears under infestation). Bt hybrids containing the CryIA(b) gene under the control of green tissue and pollen‐specific promoters (event 176) showed a significantly higher percentage of damaged ears than Bt hybrids carrying the CryIA(b) gene under the control of a constitutive promoter (Mon810). Bt and non‐Bt hybrids showed no significant differences for all agronomic traits, except for plant height under insecticide protection and grain yield reduction under infestation, whereas Bt hybrids had significantly lower means than their non‐transgenic counterparts and other commercial hybrids. All resistance traits were significantly correlated with grain yield reduction. The laboratory bioassay confirmed the level of antibiosis of Bt hybrids against neonate ECB larvae. Bt hybrids showed the highest level of ECB resistance and therefore are an attractive method of preventing ECB damage within an integrated pest‐management system.     

Relationship between European corn borer resistance and concentration of mycotoxins produced by Fusarium spp. in grains of transgenic Bt maize hybrids, their isogenic counterparts, and commercial varieties

The European corn borer (ECB), Ostrinia nubilalis Hb., is a major pest of maize in central Europe and promotes the infection of maize with Fusarium spp. In this study, transgenic Bt maize hybrids were compared with their isogenic counterparts, and with commercial hybrids from the recommended list with regard to their level of ECB resistance and their concentration of deoxynivalenol (DON), its 15‐acetyl (15‐A‐DON) and 3‐acetyl (3‐A‐DON) derivatives, nivalenol (NIV), fusarenon‐X (FUS‐X), fumonisins (FUM), and zearalenon (ZEN) in harvested grains. The field experiments were performed in Germany at four locations in 1999 and at five locations in 2000. Transgenic Bt hybrids showed significantly lower means than their corresponding isogenic counterparts and than commercial hybrids for all resistance traits: damage rating of stalks, number of larvae per plant, number of larvae per ear, and percentage of damaged plants or ears under infestation. Among all mycotoxins analysed, DON consistently showed the highest concentration across all year × location combinations. Mycotoxin concentrations varied significantly between locations, years and genotypes, whereas mycotoxin concentrations were not significantly different between infested and protected plots. Associations between ECB resistance traits and mycotoxin concentrations were not consistent across years. It is concluded that under central European conditions, the use of Bt maize hybrids will only slightly reduce the contamination of maize kernels with mycotoxins produced by Fusarium spp.     

Taxonomy of Mexican landraces of maize,Zea mays,based on their resistance to European corn borer,Ostrinia nubilalis

Summary The resistance to the European corn borer, Ostrinia nubilalis (Hubner), of thirty-seven indigenous landraces of Mexican maize was examined. The relationship of resistance and existing taxonomy of maize according to Wellhausen et al., (1952), was subjected to numerical analyses. Variables examined were: seedling DIM-BOA content, the extent of leaf feeding damage by early instar larvae both in the field and in the laboratory, the extent of plant breakage and stalk tunneling by late instar larvae, plant height, and the extent of fungal damage by Gibberella zeae and Ustilago maydis. Significant differences in resistance among the major taxonomic groupings were reflected in the existing taxonomy of maize (Wellhausen et al., 1952). The most resistant landrace grouping was Wellhausen et al.'s Prehistoric Mestizos. Eighty-five percent of a series of modern inbred lines, pools, and Argentine landraces were found to have affinities with one of the more susceptible groupings, the Ancient Indigenous Races, based upon analysis of the resistance data.     

Flavonoids as Flower Pigments: The Formation of the Natural Spectrum and its Extension by Genetic Engineering

Preharvest aflatoxin contamination of maize (Lea mays L.) gram by Aspergillns spp. is a concern to both producers and consumers of maize. Aflatoxms are carcinogenic to animals and have been linked to liver cancer in humans. The most desirable solution for eliminating or reducing aflatoxin contamination is to identify and/or develop sources of resistance. However, only a few genetic studies, which utilized a limited amount of genetic material, have been conducted. A thorough review and consolidation of information from these studies was deemed necessary. The purpose of this paper is to present a current, critical review on aspects of infection by Aspergillus, role of insects, inoculation techniques, and sources and genetics of resistance as they relate to aflatoxin production in maize. Damage to maize kernels by insects, especially the European corn borer (Ostrinia nubilalis Hübner), fall armyworm (Spodoptera frugiperda J. E. Smith), and corn ear-worm (Helicoverpa zea Boddie), has been associated with high aflatoxin levels. Artificial inoculation techniques that damage maize kernels generally result in the highest and most consistent aflatoxin levels. Although, a relatively large amount of maize germplasm has been screened for resistance and varying levels of resistance have been identified, additional germplasm needs to be systematically evaluated. To date, there are no known genotypes with complete resistance. Results from the few genetic studies indicated that additive genetic effects controlled resist-Preharvest aflatoxin contamination of maize (Zea mays L.) gram by Aspergillns spp. is a concern to both producers and consumers of maize. Aflatoxms are carcinogenic to animals and have been linked to liver cancer in humans. The most desirable solution for eliminating or reducing aflatoxin contamination is to identify and/or develop sources of resistance. However, only a few genetic studies, which utilized a limited amount of genetic material, have been conducted. A thorough review and consolidation of information from these studies was deemed necessary. The purpose of this paper is to present a current, critical review on aspects of infection by Aspergillus, role of insects, inoculation techniques, and sources and genetics of resistance as they relate to aflatoxin production in maize. Damage to maize kernels by insects, especially the European corn borer (Ostrinia nubilalis Hübner), fall armyworm (Spodoptera frugiperda J. E. Smith), and corn ear-worm (Helicoverpa Zea Boddie), has been associated with high aflatoxin levels. Artificial inoculation techniques that damage maize kernels generally result in the highest and most consistent aflatoxin levels. Although, a relatively large amount of maize germ-plasm has been screened for resistance and varying levels of resistance have been identified, additional germplasm needs to be systematically evaluated. To date, there are no known genotypes with complete resistance. Results from the few genetic studies indicated that additive genetic effects controlled resistance to aflatoxin contamination in maize. Aflatoxin production on maize grain appeared to be greatly influence by the environment. Further genetic studies, utilizing additional germplasm, are warranted for a better understanding of the nature of resistance to asflatoxin contamination in maize. Future research needs and plans relative to resistance to aflatoxin contaminaton in maize are presented.     

Genetic variation in testcrosses of European maize inbreds for resistance to the European corn borer and relations to line per se performance

The European com borer (ECB) Ostrinia nubilalis H. is a major pest in World maize Zea mays L. production. Objectives of this study were to (1) investigate the genotypic variance and covariance in testcrosses of European flint and dent inbreds for ECB resistance and agronomic traits, and (2) estimate the correlation between line per se and testcross performance for ECB resistance traits. A total of 16 flint and 24 dent inbreds and their testcrosses with two testers from the opposite germplasm pool were evaluated in four and three German environments, respectively. Using artificial infestation with ECB larvae, resistance was assessed by damage rating of stalks, tunnel length in dissected stalks, and relative yield of infested plots compared with protected plots. Yield losses due to ECB damage in testcross hybrids amounted to 40%. Significant genotypic variances between flint and dent lines and high heritabilities were found for damage rating of stalks for both line per se and testcross performance. Heritabilities were low or intermediate for tunnel length and relative grain yield. Correlations between line per se and testcross performance were tight for the damage rating of stalks and moderate for tunnel length and relative yield in both flint and dent germplasm. For damage rating of stalks, per se performance of lines tested in a few environments can be used to predict their testcross performance. In contrast, assessment of testcross performance for tunnel length and relative yield requires evaluating testcrosses with several testers in multi-environment trials.     

Rind puncture resistance in maize: inheritance and relationship with resistance to pink stem borer attack

The main pest of maize in north‐western Spain is the pink stem borer, Sesamia nonagrioides, and stem lodging is one of the consequences of attack. Since rind puncture resistance is related to stem lodging resistance, the objectives of this work were to estimate the genetic effects involved in the inheritance of rind puncture resistance and to determine the phenotypic correlation coefficients between rind puncture resistance and pink stem borer damage. Six generations from the crosses ‘CM109’בEP31’ and ‘CM109’בEP42’ and a 10‐inbred line diallel were evaluated in Pontevedra, Spain, in 1995 and 1996. The inheritance of rind puncture resistance had two significant components, one additive and one dominant. Non‐allelic and genotype × environment interactions were not significant. Improvement for internode rind puncture resistance to increase stem strength and stalk lodging resistance could have some positive influence on resistance to pink stem borer. However, its use as an estimator of pink stem borer resistance cannot be generalized and so must be restricted to programmes that involve materials exhibiting physical resistance to pink stem borer attack.     

Genetic and statistical models for estimating genetic parameters of maize seedling resistance to Fusarium graminearum Schwabe root rot

Root lodging is an important problem in corn fields. Fungi recovered from roots include seedling blight and stalk rot pathogens. The objective of this work was to study the inheritance of maize seedling resistance to pathogens causing maize lodging. The Fusarium graminearum strain, 241 Fr1, was isolated from maize lodged plants and identified as the most pathogenic isolate for root rotting. Nine inbred lines of maize and their diallel F₁ crosses plus control genotypes were studied. Seedlings were inoculated at the stage of four-leaves. Disease severity was measured as percentage of the root rotted area. Highly significant differences between inoculated and non-inoculated genotypes were found. Four genetic models and two statistical approaches—the mixed model for the best linear unbiased prediction (BLUP) and the general linear model (GLM)—were used for the analysis. Favorable heterosis of resistance of hybrids over inbreds was the most important effect detected. The general combining ability (GCA) effects were significant for all genetic models and statistical methods studied, and a good agreement existed among the GCA estimates by the different methods. The type of gene action, either additive or dominance, showed a large variation among the parental inbreds and hybrids. Selection of additive effects based exclusively on inbred lines is not sufficient to confer resistance to hybrids, additional selection should be practiced on hybrids to look for favorable dominance effects. This revised version was published online in July 2006 with corrections to the Cover Date.     

转Bt基因玉米对亚洲玉米螟的抗性评价

转Bt基因抗虫玉米为诺华公司含Bt11转化系的杂交种NX4777,能全株表达Cry1Ab杀虫蛋白,以其非转基因受体玉米品种NX4906为对照。在玉米生长至心叶中期(50~60cm高)、抽雄前期和抽丝散粉期分别进行人工接亚洲玉米螟[Ostrinia furnacalis (Guenée)]初孵幼虫40~60头。以食叶级别、存活幼虫数、蛀孔数、隧道长度和雌穗被害级别等,分别作为评价玉米心叶期和穗期的抗性标准。结果表明,Bt玉米食叶级别仅为1级,显著低于对照的7级。Bt玉米平均每株存活幼虫0.04~0.20头、蛀孔0.11~0.15个、隧道长度0.13~0.41cm,雌穗被害级别为0,植株折茎率为0,而对照玉米平均每株存活幼虫6.19~12.41头、蛀孔4.48~7.05个、隧道长度12.41~24.09cm,雌穗被害级别为5.9,植株折茎率高达73.6%~95.5%。室内生测结果亦表明,取食Bt玉米心叶、雄穗的初孵幼虫3d全部死亡,取食花丝7d死亡率达到99%,相比之下取食常规玉米的存活率在88.7%以上。表明表达Cry1Ab杀虫蛋白的Bt对亚洲玉米螟具有很高的抗虫性,能够保护玉米全生育期免受玉米螟的危害。     

Damage assessment for selection of resistance to the spotted stalk borer and genetic correlations for resistance and yield components in sugarcane

We conducted an assessment of the stalk damage of the spotted borer, Chilo sacchariphagus (Bojer), on 65 cultivars and elite clones under natural infestation conditions in Réunion Island, with the objectives (i) of comparing seven damage measures on the basis of their quantitative genetic parameters and (ii) of studying the relationships between borer resistance and sugarcane yield components. The heritabilities of the damage measures related to counts of borer exit holes were low, whereas the heritabilities of the damage measures related to bored stalks or internodes were high and similar amongst them. The percentage of bored stalks exhibited high phenotypic and genotypic correlations with the other damage measures, and appeared as the best cost effective damage measure. Genetic correlations revealed a negative relationship between resistance to borer and cane yield, due to a relationship of stalk damage with stalk length and (in a lesser extent) with stalk number. No significant genetic relationship between resistance and sugar content parameters was observed.     

Comparing the resistance of mid‐maturing maize varieties to European corn borer (Ostrinia nubilalis Hbn.)—results from the Polish VCU registration field trials

European corn borer is a major pest in the United States and Europe. This pest causes grain yield losses worth billions of Dollars. One of the best methods to control this pest making damages is cultivation of resistant varieties. In the present work, using the generalized linear mixed model methodology, we identified maize varieties with improved resistance to European corn borer from a Polish VCU series of field trials performed in the two consecutive years 2014 and 2015.     

外源MeJA诱导玉米抗性对亚洲玉米螟生物学特性的影响

为明确茉莉酸甲酯(methyl jasmonate,MeJA)诱导玉米幼苗产生抗性对亚洲玉米螟(Ostrinia furnacalis)生物学特性的影响,测定了玉米幼苗在4种浓度的外源MeJA处理后对亚洲玉米螟幼虫生长发育和成虫繁殖情况,并利用生命表方法研究了饲喂MeJA处理后的玉米幼苗对次代亚洲玉米螟实验种群的影响。结果表明：取食外源MeJA诱导的玉米幼苗后,亚洲玉米螟幼虫死亡率增加,发育历期延长,成虫寿命缩短、产卵量下降,除了100 μmol/L MeJA处理组蛹重高于对照外,其他处理亚洲玉米螟体重与蛹重均降低,影响程度与MeJA的浓度有关。225 μmol/L MeJA诱导处理后的玉米幼苗对亚洲玉米螟生长发育影响最大,与对照组相比,幼虫历期长了5.41天,成虫寿命减少1.33天,产卵量减少3.6头。MeJA的诱导抗性显著影响了亚洲玉米螟幼虫对玉米幼苗的取食,100 μmol/L和225 μmol/L MeJA处理组与对照组虫体体重相差3.29~6.86 mg,达到统计学差异,生长抑制率达28.34%~59.09%。对次代种群的影响表现在净生殖率(R0)、周限增长率(λ)降低,内禀增长率(rm)由0.0725降至0.0502,平均世代周期(T)和种群加倍时间(Dt)较对照显著延长。这些结果表明MeJA处理玉米幼苗能够降低亚洲玉米螟的发育速率,这将对亚洲玉米螟的综合防治具有重要的指导意义。     

玉米种质资源大规模多年多点多病害的自然发病抗性鉴定

病害是影响玉米生产的重要因素。利用品种的抗性是控制玉米病害的经济、安全和有效措施。2016—2019年间,在黄淮海和东华北地区,首次对2000份来源广泛且遗传背景丰富的玉米种质资源进行了多年多点多病害的田间自然发生条件下抗病性鉴定,部分材料在西北地区也进行了田间鉴定,重点调查了小斑病、茎腐病、瘤黑粉病、弯孢叶斑病、南方锈病、粗缩病、大斑病、灰斑病和丝黑穗病的抗病性。综合4年共10个不同环境的自然发病下抗性鉴定数据表明,自然发病鉴定的结果受环境因素影响较大,表现为年度间和地域间的差异。在所有鉴定的病害中,小斑病在多个年份和多个鉴定点的发病均比较充分, 11份种质对该病害表现出稳定抗性;茎腐病、大斑病和灰斑病,在不同年份的部分鉴定点发病较为充分,对这3种病害表现抗病的种质分别为440、356和423份,综合抗性鉴定结果具有较大的参考价值;弯孢叶斑病、瘤黑粉病和粗缩病仅在1个鉴定点发病较为充分,南方锈病和丝黑穗病在所有鉴定点均发生较轻,鉴定结果有待进一步验证。本研究筛选出一批在不同环境条件下对多种病害均具有稳定抗性的材料,其中JN15、953、沈977、68122、K21、SC24-1、17...     

高产多抗玉米新品种隆玉五号的选育及栽培技术

陕西关中夏播玉米单产低而不稳,抗病性抗逆性降低,选育玉米新品种,应以多抗、广适、稳产、高产为育种目标。咸阳市农科所通过种质改良和系统选择,选育成功玉米杂交种隆玉五号。该品种夏播生育期95—98d。高抗大小斑病、穗粒腐病,抗茎腐病、弯孢叶斑病、黑粉病。籽粒含粗蛋白10.0%,淀粉71.0%,粗脂肪4.1%,赖氨酸0.258%,产量高、品质优良、抗病性好、抗倒伏、中早熟、适应性广,成熟时保绿性好。属于粮饲兼用型玉米杂交种。     

吉林省不同熟期玉米病虫害发生情况

在吉林省中部地区的梨树县,依据玉米病虫害对气候变化的敏感性,通过田间试验进行了不同熟期玉米病虫害发生种类、程度以及对玉米产量的影响。为了明确气候变化条件下,吉林省不同熟期玉米病虫害发生规律、特点,进而为气候变化条件下不同熟期玉米病虫害的预测、预报和防治提供理论依据,2013年在吉林省中部地区的梨树县,通过田间试验调查并分析了不同熟期玉米病虫害发生种类、程度及对玉米产量的影响。结果表明：不同熟期玉米粘虫的植株平均被率分别为中早熟组5.59%、中熟组3.23%、中晚熟组2.61%;不同熟期玉米螟的平均蛀茎率依次为中早熟组17.40%、中熟组16.51%、中晚熟组5.97%;不同熟期玉米叶斑病病级指数依次为中早熟组2.03%~10.07%、中熟组0.70%~2.73%、中晚熟组0.73%~3.09%。说明中早熟组玉米病虫害对气候变化的敏感性较强,抗病、抗虫性低于中熟组和中晚熟的玉米品种;同一熟期的不同品种之间由于遗传特性也表现出抗性差异。不同熟期玉米产量分别为中早熟组8732.8~10273.1 kg/hm²、中熟组11507.0~13724.0 kg/hm²、中晚熟组11684.5~12722.6 kg/hm²。产量表现以中熟组和中晚熟组明显高于中早熟组,说明在吉林省中部地区早春低温、高湿,生长季节高温、高湿的气候条件下,种植中早熟品种病虫害发生较重,不利于产量的提高。     

A genome‐wide association study for partial resistance to southern corn rust in tropical maize

Southern corn rust (SCR) is a fungal disease found on corn in several countries worldwide. In Brazil, the disease can result in productivity losses of 65%, especially in areas with a history of the disease. In this study, the genetic architecture and identification of genomic regions associated with SCR resistance was investigated by performing a genome‐wide association study. Genotyping‐by‐sequencing was performed to carry out the association between single nucleotide polymorphism (SNP) markers and phenotypic data from two environments on a panel of 164 maize inbred lines. Eight SNPs were identified as significant for SCR resistance. These SNPs were colocalized with QTL regions, some of which underlie candidate resistance genes with functions that play an important role in the stress response during pathogen recognition. These candidate genes, involved in plant defense pathways, could be associated with partial resistance to SCR and provide a partial comprehensive insight into the genetic architecture of this trait. After validation of the SNPs, they will be useful for marker–assisted selection and for a better understanding of maize resistance to SCR.