Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto, 606-8585, Japan.
The Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Matsugasaki Sakyo-ku, Kyoto, 606-8585, Japan.
Planta. 2021 Jan 19;253(2):37. doi: 10.1007/s00425-020-03530-y.
Genes of the PLAT protein family, including PLAT and ATS3 subfamilies of higher plants and homologs of liverwort, are involved in plant defense against insects. Laticifer cells in plants contain large amounts of anti-microbe or anti-insect proteins and are involved in plant defense against biotic stresses. We previously found that PLAT proteins accumulate in laticifers of fig tree (Ficus carica) at comparable levels to those of chitinases, and the transcript level of ATS3, another PLAT domain-containing protein, is highest in the transcriptome of laticifers of Euphorbia tirucalli. In this study, we investigated whether the PLAT domain-containing proteins are involved in defense against insects. Larvae of the lepidopteran Spodoptera litura showed retarded growth when fed with Nicotiana benthamiana leaves expressing F. carica PLAT or E. tirucalli ATS3 genes, introduced by agroinfiltration using expression vector pBYR2HS. Transcriptome analysis of these leaves indicated that ethylene and jasmonate signaling were activated, leading to increased expression of genes for PR-1, β-1,3-glucanase, PR5 and trypsin inhibitors, suggesting an indirect mechanism of PLAT- and ATS3-induced resistance in the host plant. Direct cytotoxicity of PLAT and ATS3 to insects was also possible because heterologous expression of the corresponding genes in Drosophila melanogaster caused apoptosis-mediated cell death in this insect. Larval growth retardation of S. litura occurred when they were fed radish sprouts, a good host for agroinfiltration, expressing any of nine homologous genes of dicotyledon Arabidopsis thaliana, monocotyledon Brachypodium distachyon, conifer Picea sitchensis and liverwort Marchantia polymorpha. Of these nine genes, the heterologous expression of A. thaliana AT5G62200 and AT5G62210 caused significant increases in larval death. These results indicated that the PLAT protein family has largely conserved anti-insect activity in the plant kingdom (249 words).
PLAT 蛋白家族的基因，包括高等植物的 PLAT 和 ATS3 亚家族以及苔藓的同源物，参与植物对昆虫的防御。植物中的乳管细胞含有大量的抗微生物或抗昆虫蛋白，并参与植物对生物胁迫的防御。我们之前发现，PLAT 蛋白在榕属（Ficus carica）的乳管细胞中的积累水平与几丁质酶相当，另一种含有 PLAT 结构域的蛋白 ATS3 的转录本水平在大戟属（Euphorbia tirucalli）乳管细胞的转录组中最高。在这项研究中，我们研究了是否 PLAT 结构域蛋白参与了对昆虫的防御。鳞翅目夜蛾（Spodoptera litura）幼虫在喂食农杆菌介导的表达载体 pBYR2HS 转染的表达 F. carica PLAT 或 E. tirucalli ATS3 基因的菸草叶片时生长迟缓。这些叶片的转录组分析表明，乙烯和茉莉酸信号被激活，导致 PR-1、β-1,3-葡聚糖酶、PR5 和胰蛋白酶抑制剂的基因表达增加，表明 PLAT 和 ATS3 诱导的宿主植物抗性的间接机制。PLAT 和 ATS3 对昆虫的直接细胞毒性也是可能的，因为在果蝇（Drosophila melanogaster）中异源表达相应的基因会导致这种昆虫的细胞凋亡介导的细胞死亡。当它们以萝卜芽为食时，萝卜芽是农杆菌浸润的良好宿主，表达拟南芥（Arabidopsis thaliana）、单子叶植物柳枝稷（Brachypodium distachyon）、针叶树黑云杉（Picea sitchensis）和苔藓（Marchantia polymorpha）的 9 个同源基因中的任何一个时，斜纹夜蛾幼虫的生长迟缓。在这 9 个基因中，拟南芥 AT5G62200 和 AT5G62210 的异源表达导致幼虫死亡率显著增加。这些结果表明，PLAT 蛋白家族在植物界中具有广泛保守的抗昆虫活性（249 个单词）。
