ZmGA3ox2, a candidate gene for a major QTL,qPH3.1, for plant height in maize

Maize plant height is closely associated with biomass, lodging resistance and grain yield. Determining the genetic basis of plant height by characterizing and cloning plant height genes will guide the genetic improvement of crops. In this study, a quantitative trait locus (QTL) for plant height, qPH3.1, was identified on chromosome 3 using populations derived from a cross between Zong3 and its chromosome segment substitution line, SL15. The plant height of the two lines was obviously different, and application of exogenous gibberellin A₃ removed this difference. QTL mapping placed qPH3.1 within a 4.0 cM interval, explaining 32.3% of the phenotypic variance. Furthermore, eight homozygous segmental isolines (SILs) developed from two larger F₂ populations further narrowed down qPH3.1 to within a 12.6 kb interval. ZmGA3ox2, an ortholog of OsGA3ox2, which encodes a GA3 β‐hydroxylase, was positionally cloned. Association mapping identified two polymorphisms in ZmGA3ox2 that were significantly associated with plant height across two experiments. Quantitative RT‐PCR showed that SL15 had higher ZmGA3ox2 expression relative to Zong3. The resultant higher GA₁ accumulation led to longer internodes in SL15 because of increased cell lengths. Moreover, a large deletion in the coding region of ZmGA3ox2 is responsible for the dwarf mutant d1‐6016. The successfully isolated qPH3.1 enriches our knowledge on the genetic basis of plant height in maize, and provides an opportunity for improvement of plant architecture in maize breeding.     

CO2浓度和磷对不同种植方式玉米大豆生长效应研究

通过顶置光源植物生长室控制380和760 μmol·mol-1 2个CO2浓度水平,研究了磷缺乏与正常供磷条件下,CO2浓度升高对玉米/大豆间作、玉米单作和大豆单作3种种植模式下作物株高、茎粗、叶面积及干物质积累的影响.结果表明:(1)CO2浓度升高能显著增加单/间作玉米、大豆的株高、茎粗、叶面积、根干重、地上部干重及总干重.(2)CO2浓度升高对供磷水平下单、间作玉米大豆的株高、茎粗、叶面积及干物质积累量增加的正效应均大于缺磷处理.(3)两种CO2浓度下,间作大豆与单作大豆生长差异不显著,而间作玉米较单作玉米有明显的生长优势,且供磷和CO2浓度的升高均能够促进这种优势.     

干旱高温复合胁迫下sHSPs基因在不同耐旱性玉米中的表达差异及其对ABA和H2O2的响应

以4个玉米(Zea mays L.)品种——‘郑单958’(耐干旱)、‘浚单20’(耐高温)、‘隆玉602’(耐干旱高温复合胁迫)和‘驻玉309’(对3种胁迫均敏感)为实验材料,分别采用脱落酸(ABA)及其抑制剂氟定酮(F)、H2O2及其清除剂碘化钾(I)和丙酮酸钠(P)预处理,探讨干旱高温复合胁迫下小热休克蛋白(sHSPs)在不同耐旱性玉米品种中的表达以及ABA和H2O2对其表达的影响。结果显示:(1)高温、干旱高温复合胁迫诱导的sHSP16.9、sHSP17.2、sHSP17.4、sHSP17.5、sHSP22和sHSP26等6个sHSPs基因表达增加量明显高于干旱和对照。(2)在6个sHSPs中,sHSP17.2基因仅在‘郑单958’中表达;sHSP16.9、sHSP17.4和sHSP26基因在‘隆玉602’中表达增加量最高,在‘驻玉309’中表达增量最低;sHSP17.5和sHSP22基因在‘郑单958’中表达增加量最高,在‘驻玉309’中最低。(3)ABA、F、I和P预处理后,对干旱高温复合胁迫诱导的6个sHSPs基因表达增加量仅有略微影响,但显著影响了sHSP26的蛋白表达。研究表明,sHSPs在不同耐旱性玉米品种中的表达存在显著差异,ABA和H2O2仅稍微提高了sHSPs基因表达,但显著提高了sHSP26蛋白表达,这些结果为进一步研究植物在多胁迫条件下耐逆机理奠定了基础。     

光照强度对大花旋蒴苣苔叶形态和生理指标的影响

以复苏植物大花旋蒴苣苔(Boea clarkeana)为盆栽实验材料,通过梯度遮光处理,研究不同光照强度(100%、80%、60%、40%和20%透光率)和不同处理时间(30、60、90、120和150d)对大花旋蒴苣苔叶生长指标和生理指标的影响。结果表明:随着光照强度的减弱,大花旋蒴苣苔叶的各生长指标(叶片长、叶片宽、叶柄长、叶柄直径以及叶面积)呈现先增大后减小的趋势,透光率为60%时达到最大值;全光照(100%透光率)时,大花旋蒴苣苔表现出明显的外伤症状,透光率为80%和20%时,分别表现出中度伤害和轻度伤害,透光率为40%和60%时,未出现明显的外伤症状;过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和过氧化物酶(POD)3种抗氧化酶活性均较低且随着光强减弱呈现先降低后升高的趋势,随着处理时间的延长呈先上升后下降的趋势,全光照时抗氧化酶的活性最大,透光率60%处理下酶活性相对较低;丙二醛(MDA)含量、脯氨酸(Pro)含量和质膜透性随着光强减弱呈先降低后升高的趋势,随着处理时间的延长显著升高;叶绿素含量随着光强减弱呈逐渐上升的趋势,随着处理时间的延长先降低后升高。分析表明,40%～60%的透光率有利于大花旋蒴苣苔的生长,强光和弱光对大花旋蒴苣苔的生长均不利。     

Epigeic spiders are not affected by the genetically modified maize MON 88017

The genetically modified (GM) maize MON 88017 facilitates weed management owing to its tolerance to glyphosate, and resists western corn rootworm (WCR), Diabrotica virgifera virgifera, owing to the expression of Cry3Bb1 toxin. MON 88017 could therefore contribute to the solution of two major problems of European agriculture: continuous WCR spreading and high use of herbicides. To assess possible unwanted environmental impacts of MON 88017, we compared communities of spiders in plots planted in three successive years with this maize, its near isogenic non‐GM cultivar treated or not treated with an insecticide and two unrelated maize cultivars. Each of the five treatments was applied on five 0.5 ha plots in a 14 ha field. Spiders were collected in five pitfall traps per plot five times per year. Upon reaching the waxy ripening stage, all plants of first‐year cultivation were shredded to small pieces and ploughed into the soil in the respective plot, whereas in the 2nd and 3rd year the harvest was used for biogas production and only digestate was returned to the field. Out of 79 spider species, Pardosa agrestis, Pachygnatha degeeri and Oedothorax apicatus made up 28%, 25% and 23% of the total spider count in the 1st year of study; 2%, 8% and 84% in the 2nd; and 40%, 8% and 35% in the 3rd year. Statistical analysis did not reveal any influence of GM maize on the spider abundance and biodiversity. The abundance, and in two years also the species diversity, was insignificantly higher on the plots with GM maize than on plots with the insecticide‐treated non‐GM maize. The composition and size of spider community varied year to year, probably reflecting weather conditions and differences in field fertilization with organic matter.     

A Phytotoxin,Betaenone C,and Its Related Metabolites of Phoma betae Fr

For rough quantitative analysis of genetically modified maize contents, rapid methods for measurement of the copy numbers of the cauliflower mosaic virus 35S promoter region (P35S) and MON810 construct-specific gene (MON810) using a combination of a capillary-type real-time PCR system with a plasmid DNA were established. To reduce the characteristic differences between the plasmid DNA and genomic DNA, we showed that pretreatment of the extracted genomic DNA by a combination of sonication and restriction endonuclease digestion before measurement is effective. The accuracy and reproducibility of this method for MON810 content (%) at a level of 5.0% MON810 mixed samples were within a range from 4.26 to 5.11% in the P35S copy number quantification. These methods should prove to be a useful tool to roughly quantify GM maize content.     

Hoverflies (Diptera: Syrphidae) benefit from a cultivation of the bioenergy crop Silphium perfoliatum L. (Asteraceae) depending on larval feeding type,landscape composition and crop management

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Joint‐linkage mapping and GWAS reveal extensive genetic loci that regulate male inflorescence size in maize

Both insufficient and excessive male inflorescence size leads to a reduction in maize yield. Knowledge of the genetic architecture of male inflorescence is essential to achieve the optimum inflorescence size for maize breeding. In this study, we used approximately eight thousand inbreds, including both linkage populations and association populations, to dissect the genetic architecture of male inflorescence. The linkage populations include 25 families developed in the U.S. and 11 families developed in China. Each family contains approximately 200 recombinant inbred lines (RILs). The association populations include approximately 1000 diverse lines from the U.S. and China. All inbreds were genotyped by either sequencing or microarray. Inflorescence size was measured as the tassel primary branch number (TBN) and tassel length (TL). A total of 125 quantitative trait loci (QTLs) were identified (63 for TBN, 62 for TL) through linkage analyses. In addition, 965 quantitative trait nucleotides (QTNs) were identified through genomewide study (GWAS) at a bootstrap posterior probability (BPP) above a 5% threshold. These QTLs/QTNs include 24 known genes that were cloned using mutants, for example Ramosa3 (ra3), Thick tassel dwarf1 (td1), tasselseed2 (ts2), liguleless2 (lg2), ramosa1 (ra1), barren stalk1 (ba1), branch silkless1 (bd1) and tasselseed6 (ts6). The newly identified genes encode a zinc transporter (e.g. GRMZM5G838098 and GRMZM2G047762), the adapt in terminal region protein (e.g. GRMZM5G885628), O‐methyl‐transferase (e.g. GRMZM2G147491), helix‐loop‐helix (HLH) DNA‐binding proteins (e.g. GRMZM2G414252 and GRMZM2G042895) and an SBP‐box protein (e.g. GRMZM2G058588). These results provide extensive genetic information to dissect the genetic architecture of inflorescence size for the improvement of maize yield.