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Molecular detection of pathogenic Fusarium species in roots and stalks of maize plants with or without transgenic resistance to corn rootworm

机译：对玉米根虫有或没有转基因抗性的玉米植物根和茎中病原性镰刀菌属物种的分子检测

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摘要

Fusarium species are among most common fungal pathogens of maize, causing root rot, stalk rot, stalk lodging and ear rot. Fusarium verticillioides and F. graminearum are two of the most prevalent stalk rot fungi in Nebraska and Iowa. Corn root worms (CRW) are the most costly pests of maize plants, causing damage to both above- and below-ground parts of the plant. CRW feeding on roots creates good invading sites for different fungal species. The goal of this research was to determine whether use of transgenic CRW-resistant maize hybrids will have reduced levels of Fusarium colonization of roots and stalks compared to their near-isogenic susceptible hybrids. Experiments were conducted at two locations each in 2007 and 2008 in fields with high populations of Western corn root worms, (Diabrotica virgifera LeConte): Bruner farm near Ames, IA (2007), ISU Southeast Research Farm near Crawfordsville, IA (2007-2008), and Agricultural Research and Development Center, Univ. of NE near Mead, Nebraska (2007-2008). Commercially available hybrids with CRW-resistance transgenes along with their near-isogenic CRW-susceptible hybrids were planted. The CRW events include DAS-59122 (HerculexRTM Xtra), MON863 (Yieldgard PlusRTM), MON88107 (Yieldgard VT TripleRTM) and MIR604 (AgrisureRTM RW/CB/LL). In 2008, insecticidal seed treatment also was tested for its effect on CRW feeding and subsequent Fusarium colonization. Sampling was done on roots in mid-July and stalks in mid-September in 2007 and in 2008 mid-September roots were also sampled. Root colonization was assessed by dilution plating of dried ground tissue, and by real-time polymerase chain reaction (PCR). Primers and fluorogenic probes, specific to mycotoxin biosynthesis genes in F. verticillioides and F. graminearum were used to quantify root and stalk colonization. Standard calibration curves of both species showed linear correlation (r2=0.99) between the fungal genomic DNA and the threshold cycle values. There were highly significant differences in colonization between resistant and near isogenic susceptible hybrids for events MON 88017 and MIR 604 in Nebraska July roots in 2007. F. verticillioides was at high levels in Nebraska whereas F. graminearum was more common in Iowa. Stalks from both locations were highly colonized with F. graminearum. The PCR results were compared to a microbiological dilution plating method. In 2007 the results of the two methods correlated well but in 2008 they did not follow the same pattern. In dilution plating results we could consistently see significantly lower Fusarium CFU/g tissue in hybrids with CRW resistance than in near-isogenic CRW susceptible hybrids. Insecticidal seed treatment did not have a significant effect on level of colonization of fungal species measured by PCR or dilution plating results. CRW feeding on maize roots sometimes enhanced the infection of roots by Fusarium species and transgenic CRW resistant hybrids suffered less colonization than susceptible hybrids in CRW infested fields. However, the interaction between Fusarium spp and CRW varied in their degree among Fusarium species. Known maize pathogens F. verticillioides and F. graminearum were not consistently affected by CRW resistance as much as the total Fusarium population. The impact of this interaction on stalk rots is not clearly demonstrated.
机译：镰刀菌种是玉米中最常见的真菌病原体，可引起根腐，茎腐，茎倒伏和穗腐。镰刀菌和禾谷镰刀菌是内布拉斯加州和爱荷华州最常见的两种腐烂真菌。玉米根蠕虫（CRW）是玉米植物中最昂贵的害虫，对植物的地面和地下部分均造成损害。以根为食的CRW会为不同的真菌物种创造良好的入侵位点。这项研究的目的是确定使用转基因抗CRW的玉米杂交种与近等基因易感杂交种相比，其根和茎的镰孢菌定殖水平是否降低。在2007年和2008年分别在两个西部玉米根虫种群的两个地点分别进行了实验（Diabrotica virgifera LeConte）：爱荷华州埃姆斯附近的布鲁纳农场（2007），爱荷华州克劳福德斯维尔附近的ISU东南研究农场（2007-2008） ）和大学农业研究与发展中心。内布拉斯加州米德附近的东北角（2007-2008）。种植了具有CRW抗性转基​​因的可商购杂种以及它们的近等基因CRW易感杂种。 CRW事件包括DAS-59122（HerculexRTM Xtra），MON863（Yieldgard PlusRTM），MON88107（Yieldgard VT TripleRTM）和MIR604（AgrisureRTM RW / CB / LL）。 2008年，还测试了杀虫种子处理对CRW饲喂和随后的镰刀菌定植的影响。在7月中旬对根进行了采样，2007年9月中旬对茎进行了采样，2008年9月中旬还对根进行了采样。通过干燥地面组织的稀释平板和实时聚合酶链反应（PCR）评估根定植。特异于F. verticillioides和F. graminearum中霉菌毒素生物合成基因的引物和荧光探针用于定量根和茎定殖。两种物种的标准校准曲线均显示出真菌基因组DNA与阈值循环值之间的线性相关性（r2 = 0.99）。在2007年7月的内布拉斯加州根源MON 88017和MIR 604事件中，抗药性和近等基因敏感性杂种的定植之间存在高度差异。内布拉斯加州的黄萎病菌水平较高，而衣阿华州的禾本科病菌更为常见。来自两个位置的秸秆都高度被禾本科镰刀菌定殖。将PCR结果与微生物稀释平板法进行比较。在2007年，这两种方法的结果相关性很好，但是在2008年，它们没有遵循相同的模式。在稀释接种结果中，我们可以始终观察到具有CRW抗性的杂种中镰刀菌的CFU / g组织显着低于近等基因CRW易感杂种。杀虫种子处理对通过PCR或稀释平板检测法测得的真菌物种定殖水平没有显着影响。以玉米根为食的CRW有时会增加镰刀菌属对根的感染，在CRW侵染的田地中，转基因抗CRW杂种的定植率比易感杂种少。然而，镰刀菌属物种和CRW之间的相互作用在镰刀菌物种之间的程度不同。已知的玉米病原菌F. verticillioides和F. graminearum不受CRW耐药性的影响一直像总镰刀菌种群一样多。这种相互作用对秸秆腐烂的影响尚未明确证实。

著录项

  • 作者

    Muppa, Saritha.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Plant biology.;Genetics.;Molecular biology.
  • 学位 M.S.
  • 年度 2009
  • 页码 66 p.
  • 总页数 66
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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