Fabian Matthew L, Nguyen Hien P, Stommel John R, Clarke Christopher R
Genetic Improvement for Fruits and Vegetables Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture-Agricultural Research Service, Beltsville, MD, United States.
Front Plant Sci. 2025 Aug 18;16:1641317. doi: 10.3389/fpls.2025.1641317. eCollection 2025.
Foliar application of low-dose 2,4-dichlorophenoxyacetic acid (2,4-D) has been demonstrated to reduce potato common scab disease caused by phytopathogenic . Foliar-applied 2,4-D is translocated to the tubers but does not cause direct toxicity against the pathogen. The efficacy of 2,4-D treatment for common scab disease management is inconsistent among field trials in the literature, and the exact mode of action is unknown. Here, we identified transcriptomic responses of potato to low-dose 2,4-D treatment in the presence and absence of the pathogen and in tuber periderm and foliar tissue. Pathogen infection primarily altered transcriptomic responses in tuber periderm tissue, while foliar 2,4-D application caused larger shifts in gene expression in leaf tissue, as expected. Gene ontology (GO) terms associated with pathogen defense, stress responses, and enzymatic inhibitors were significantly enriched among differentially expressed genes in the tuber response to the pathogen. There were more differentially expressed genes and enriched GO terms in response to the pathogen when plants were treated with 2,4-D than in the non-2,4-D-treated plants, including differentially expressed genes and GO terms related to lipases, jasmonic acid signaling, and transport. Fewer differentially expressed genes were identified in tuber tissue than in leaf tissue following foliar 2,4-D treatment, but GO terms related to sucrose transport were enriched in tuber RNA samples from 2,4-D-treated, non-inoculated plants. Altered glucose and fructose, but not sucrose, levels in tuber medulla and periderm tissue, the site of common scab infection, were observed in 2,4-D-treated plants. Utilizing multiple factors, i.e., mock or 2,4-D treatments in both the presence and absence of the pathogen, in parallel transcriptional profiling experiments enabled the identification of pathways that directly respond to 2,4-D treatment in both foliar and tuber tissue and pathways with altered response in the context of pathogen infection. Identifying tools to more consistently induce these changes may enable more robust disease management than indirect foliar 2,4-D treatments.
已证明叶面喷施低剂量的2,4-二氯苯氧乙酸（2,4-D）可减少由植物病原体引起的马铃薯普通疮痂病。叶面喷施的2,4-D会转移至块茎，但对病原体无直接毒性。在文献中的田间试验里，2,4-D处理对普通疮痂病防治的效果并不一致，其确切作用方式尚不清楚。在此，我们确定了在有或没有病原体的情况下，以及在块茎周皮和叶片组织中，马铃薯对低剂量2,4-D处理的转录组反应。正如预期的那样，病原体感染主要改变了块茎周皮组织中的转录组反应，而叶面喷施2,4-D则导致叶片组织中的基因表达发生更大变化。与病原体防御、应激反应和酶抑制剂相关的基因本体（GO）术语在块茎对病原体反应的差异表达基因中显著富集。与未用2,4-D处理的植物相比，用2,4-D处理的植物在对病原体的反应中有更多差异表达基因和富集的GO术语，包括与脂肪酶、茉莉酸信号传导和转运相关的差异表达基因和GO术语。叶面喷施2,4-D处理后，在块茎组织中鉴定出的差异表达基因比在叶片组织中少，但与蔗糖转运相关的GO术语在来自2,4-D处理的未接种植物的块茎RNA样本中富集。在2,4-D处理的植物中，观察到普通疮痂感染部位的块茎髓和周皮组织中的葡萄糖和果糖水平发生了变化，但蔗糖水平未变。在平行转录谱实验中利用多种因素，即在有或没有病原体的情况下进行模拟或2,4-D处理，能够鉴定出在叶片和块茎组织中直接响应2,4-D处理的途径，以及在病原体感染背景下反应发生改变的途径。识别能够更一致地诱导这些变化的工具可能比间接叶面喷施2,4-D处理实现更有效的病害防治。
