Sensitivities of Baseline Isolates and Boscalid-Resistant Mutants of Alternaria alternata from Pistachio to Fluopyram, Penthiopyrad, and Fluxapyroxad
Sensitivities of Baseline Isolates and Boscalid-Resistant Mutants of Alternaria alternata from Pistachio to Fluopyram, Penthiopyrad, and Fluxapyroxad
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DOI：
10.1094/pdis-04-13-0459-re
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发表时间：
2014-02-01
期刊：
影响因子：
4.5
通讯作者：
Michailides, T. J.
中科院分区：
文献类型：
--
作者：
Avenot, H. F.;van den Biggelaar, H.;Michailides, T. J.
互隔交链孢菌素是第一种标记在开心果上的琥珀酸脱氢酶抑制剂(SDHI)杀菌剂，对该杀菌剂的抗性已在加州开心果果园中普遍发生，并影响该杀菌剂的药效。在这项研究中，我们建立了互隔交链霉菌对新的SDHIS氟比兰、氟沙比沙和喷替吡格雷的基线敏感性，并评估了它们与博斯卡利特的交叉抗性模式。对50个基线菌株的有效杀菌剂浓度(EC50)的检测表明，大多数菌株对博斯卡利特、吡硫磷、氟比兰和氟喹诺酮敏感。对采自果园的117个互作木霉分离物的EC50值分析表明，分别有44个、3个、1个和69个分离物具有敏感、减敏、中抗和高抗的表现型。对已知SDH突变发生的分子研究表明，在69个对博斯卡利特高度抗性的菌株中，44个、2个、14个和1个菌株分别存在导致AaSDHB、AaSDHB、AaSDHC和AaSDHD亚基H277Y、H277R、H134R和H133R氨基酸替换的突变。一些SDHB或SDHC突变体对吡硫磷或氟沙培南表现出高度敏感、敏感或减敏的表型，而另一些突变体对这些杀菌剂表现出低、中或高水平的抗性。相反，所有SDHB突变体都对氟吡兰敏感，而10、5和1个SDHC突变体分别具有敏感、降低敏感性和中等抗性的氟吡兰表型。Sdhd突变体降低了对氟吡兰和吡硫磷的敏感性，但对氟沙培南具有高度抗性。SDHI之间交叉耐药模式的差异表明，它们在复合体II中的结合位置可能略有不同，可能涉及对这些化合物的其他抗性机制。最终，这项研究的发现应该会导致在链格孢菌晚疫病喷雾项目中合理和持续地部署新的SDHIs。
Resistance of Alternaria alternata to boscalid, the first succinate dehydrogenase inhibitor (SDHI) fungicide labeled on pistachio, has become a common occurrence in California pistachio orchards and affects the performance of this fungicide. In this study, we established the baseline sensitivities of A. alternata to the new SDHIs fluopyram, fluxapyroxad, and penthiopyrad and assessed their cross resistance patterns with boscalid. Examination of the effective fungicide concentration that inhibits mycelial growth to 50% relative to the control (EC50) for 50 baseline isolates revealed that the majority were sensitive to boscalid, penthiopyrad, fluopyram, and fluxapyroxad. Analysis of EC50 values for boscalid for 117 A. alternata isolates originating from boscalid-exposed orchards showed that 44, 3, 1, and 69 isolates had sensitive, reduced sensitivity, moderately resistant, and highly resistant boscalid phenotypes, respectively. Molecular investigation of the occurrence of known SDH mutations showed that, among the 69 isolates highly resistant to boscalid, 44, 2, 14, and 1 isolates possessed the mutations leading to the H277Y, H277R, H134R, and H133R amino acid substitutions in AaSDHB, AaSDHB, AaSDHC, and AaSDHD subunits, respectively. Some SDHB or SDHC mutants displayed highly sensitive, sensitive, or reduced sensitivity phenotypes toward penthiopyrad or fluxapyroxad, whereas other had low, moderate, or high levels of resistance to these fungicides. In contrast, all the SDHB mutants were sensitive to fluopyram, while 10, 5, and 1 SDHC mutants had sensitive, reduced sensitivity, and moderately resistant fluopyram phenotypes, respectively. The SDHD mutant had reduced sensitivity to fluopyram and penthiopyrad but was highly resistant to fluxapyroxad. The discrepancies of cross-resistance patterns between SDHIs suggest that their binding sites in complex II may differ slightly and that additional mechanisms of resistance to these compounds are likely involved. Ultimately, the findings of this study should lead to the rational and sustained deployment of new SDHIs in Alternaria late blight spray programs.