Introduction

Brown planthopper (BPH) is the most destructive insect pest for rice, causing major reductions in rice yield and large economic losses. More than 31 BPH-resistance genes have been located, and several of them have been isolated. Nevertheless, the metabolic mechanism related to BPH-resistance genes remain uncharacterized.

Objectives

To elucidate the resistance mechanism of the BPH-resistance gene Bph6 at the metabolic level, a Bph6-transgenic line R6 (BPH-resistant) and the wild-type Nipponbare (BPH-susceptible) were used to investigate their lipid profiles under control and BPH treatments.

Methods

In conjunction with multivariate statistical analysis and quantitative real-time PCR, BPH-induced lipid changes in leaf blade and leaf sheath were investigated by GC–MS-based lipidomics.

Results

Forty-five lipids were identified in leaf sheath extracts. Leaf sheath lipidomics analysis results show that BPH infestation induces significant differences in the lipid profiles of Nipponbare and R6. The levels of hexadecanoic acid, methyl ester, linoleic acid, methyl ester, linolenic acid, methyl ester, glycidyl palmitate, eicosanoic acid, methyl ester, docosanoic acid, methyl ester, beta-monolinolein, campesterol, beta-sitosterol, cycloartenol, phytol and phytyl acetate had undergone enormous changes after BPH feeding. These results illustrate that BPH feeding enhances sterol biosynthetic pathway in Nipponbare plants, and strengthens wax biosynthesis and phytol metabolism in R6 plants. The results of quantitative real-time PCR of 5 relevant genes were consistent with the changes in metabolic level. Forty-five lipids were identified in the leaf blade extracts. BPH infestation induces distinct changes in the lipid profiles of the leaf blade samples of Nipponbare and R6. Although the lipid changes in Nipponbare are more drastic, the changes within the two varieties are similar. Lipid profiles in leaf sheath brought out significant differences than in leaf blade within Nipponbare and R6. We propose that Bph6 mainly affects the levels of lipids in leaf sheath, and mediates resistance by deploying metabolic re-programming during BPH feeding.

Conclusion

The results indicate that wax biosynthesis, sterol biosynthetic pathway and phytol metabolism play vital roles in rice response to BPH infestation. This finding demonstrated that the combination of lipidomics and quantitative real-time PCR is an effective approach to elucidating the interactions between brown planthopper and rice mediated by resistance genes.

中文翻译：

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脂质谱揭示了对易受害虫和抗性的水稻植物对褐飞虱侵扰的不同反应

介绍

褐飞虱是稻米中最具破坏力的害虫，可导致稻米减产和巨大的经济损失。已经找到了超过31种抗BPH的基因，其中一些已经被分离出来。然而，与BPH抗性基因相关的代谢机制仍然未知。

目标

为了阐明BPH抗性基因Bph6在代谢水平上的抗性机制，使用了Bph6-转基因系R6（BPH-抗性）和野生型日本晴（BPH-易感）来研究其在对照和BPH下的脂质谱治疗。

方法

结合多元统计分析和定量实时PCR，通过基于GC-MS的脂质组学研究了BPH诱导的叶片和叶鞘脂质变化。

结果

在叶鞘提取物中鉴定出四十五种脂质。叶鞘脂质组学分析结果表明，BPH侵染引起了日本晴和R6脂质谱的显着差异。十六烷酸，甲酯，亚油酸，甲酯，亚麻酸，甲酯，棕榈酸缩水甘油酯，二十烷酸，甲酯，二十二烷酸，甲酯，β-单油菜籽油，菜油甾醇，β-谷甾醇，环戊烯醇，植醇和BPH喂食后乙酸植酸酯发生了巨大变化。这些结果说明BPH进食增强了日本晴植物中的固醇生物合成途径，并增强了R6植物中的蜡生物合成和植醇代谢。5个相关基因的实时定量PCR结果与代谢水平的变化一致。在叶片提取物中鉴定出四十五种脂质。BPH侵染会导致日本晴和R6叶片样品的脂质谱发生明显变化。尽管日本晴中的脂质变化更为剧烈，但两个品种中的变化相似。在日本晴和R6中，叶片鞘中的脂质分布与叶片相比具有显着差异。我们建议Bph6主要影响叶鞘中脂质的水平，并通过在BPH进食过程中进行代谢重编程来介导抗性。

结论

结果表明，蜡的生物合成，固醇的生物合成途径和植醇代谢在水稻对BPH侵害的响应中起着至关重要的作用。这一发现表明，脂质组学和定量实时PCR的结合是阐明抗性基因介导的褐飞虱与水稻之间相互作用的有效方法。