伴生细菌在入侵种桉树枝瘿姬小蜂克服桉树抗性中的作用

【目的】桉树枝瘿姬小蜂是我国近年来发现的一种主要危害桉属树种的外来有害生物。本研究旨在通过探究中国桉树枝瘿姬小蜂主要伴生细菌在桉树枝瘿姬小蜂成功定殖中的作用。【方法】测定不同抗性品系桉树的次生代谢物质黄酮和单宁的含量以及易感品系桉树在枝瘿姬小蜂危害前后的含量变化。通过体外抑菌和化学物质降解实验,探究桉树枝瘿姬小蜂主要伴生细菌对抗虫性物质黄酮和单宁的耐受性及降解能力。【结果】抗性品系桉树的黄酮和单宁的含量明显高于易感品系,易感品系在桉树枝瘿姬小蜂危害后黄酮和单宁的含量显著提高;高浓度的黄酮和单宁会抑制桉树枝瘿姬小蜂伴生细菌的生长,在中低浓度黄酮和单宁的条件下,主要伴生细菌能够适应,并继续繁殖;桉树枝瘿姬小蜂伴生细菌具有一定的降解黄酮和单宁的能力,其中细菌Staphylococcus cohnii降解黄酮的能力比Pseudomonas geniculate稍强,而Bacillus wiedannii、Serratia macescens对单宁具有较强的降解能力。【结论】桉树枝瘿姬小蜂侵染桉树后,可以诱导桉树产生抗性,桉树产生大量的次生代谢物质来抵御桉树枝瘿姬小蜂的危害,而桉树枝瘿姬小蜂部分伴生细菌可降解桉树次生代谢物质来帮助小蜂克服植物抗性完成定殖。

The associated bacteria of Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) facilitate their host to overcome eucalyptus chemical defense

[Aim] Leptocybe invasa is an emerging invasive pest, which causes galls and reduces seedling growth of Eucalyptus spp. The purpose of this study was to investigate the role of associated bacteria in the adaptation of L. invasa to its host plant.[Method] First, we measured the content of flavonoids and tannins of eucalyptus in response to damage by L. invasa. Furthermore, the inhibition of flavonoids and tannins on the growth of the main L. invasa-associated bacteria and the ability of bacteria to degrade flavonoids and tannins were studied.[Result] Flavonoid and tannin content in the resistant eucalyptus species was significantly higher than in susceptible ones. Staphylococcus cohnii and Peseudomonas geniculate were resistant to higher concentrations of flavonoids, whereas Bacillus wiedannii, Serratia macescens and Klebsiella quasipneumoniae were more resistant to tannins. Correspondingly, all of these resistant bacteria were able to degrade these allelochemicals. Base on that, Staphylococcus cohnii had a stronger ability to degrade flavonoids than Pseudomonas geniculate, and B. wiedannii and Serratia macescens had stronger abilities to degrade tannins than Klebsiella quasipneumoniae.[Conclusion] Flavonoids and tannins are the key allelochemicals ineucalyptus in response to the infection by L. invasa. Furthermore, the associated bacteria might contribute to the adaptation of L. invasa to its host, by degrading these allelochemicals.