United States Department of Agriculture - Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Palier, CA 93648, USA.
Phytopathology. 2012 Sep;102(9):816-26. doi: 10.1094/PHYTO-04-12-0074-R.
Pierce's disease of grapevine (PD), caused by the bacterial pathogen Xylella fastidiosa, remains a serious problem for grape production in California and elsewhere. This research examined induction of phenolic compounds in grapevines ('Thompson Seedless') infected with X. fastidiosa over a 6-month period. Two months postinoculation with X. fastidiosa, catechin, digalloylquinic acid, and astringin were found at greater levels in xylem sap; multiple catechins, procyanidins, and stilbenoids were found at greater levels in xylem tissues; and precursors to lignin and condensed tannins were found at greater levels in xylem cell walls. However, such large-scale inductions of phenolic compounds were not observed 4 months after inoculation. Six months after inoculation, infected plants had significantly reduced phenolic levels in xylem sap and tissues when compared with control plants, including lowered levels of lignin and condensed tannins. At 6 months, PD symptoms were severe in infected plants and most photosynthetic tissue was abscised. These results suggest that, even though grapevine hosts may initially respond to X. fastidiosa infections with increased production of phenolic compounds, ultimately, PD causes grapevines to enter a state of decline whereby diseased hosts no longer have the resources to support secondary metabolite production, including defense-associated phenolic compounds.
葡萄皮尔氏病（PD）由细菌病原体韧皮部难养菌（Xylella fastidiosa）引起，仍是加利福尼亚州和其他地区葡萄生产的严重问题。本研究在 6 个月的时间内调查了感染 X. fastidiosa 的葡萄（‘Thompson Seedless’）中酚类化合物的诱导。在接种 X. fastidiosa 2 个月后，木质部汁液中发现了表儿茶素、二没食子酰奎宁酸和鞣花酸含量增加；木质部组织中发现了多种儿茶素、原花青素和芪类含量增加；木质部细胞壁中发现了木质素和缩合单宁的前体含量增加。然而，在接种后 4 个月并未观察到如此大规模的酚类化合物诱导。接种后 6 个月，与对照植物相比，感染植物木质部汁液和组织中的酚类化合物水平显著降低，包括木质素和缩合单宁水平降低。在 6 个月时，感染植物的 PD 症状严重，大多数光合组织脱落。这些结果表明，尽管葡萄宿主可能最初会对 X. fastidiosa 感染产生酚类化合物产量增加的反应，但最终 PD 会导致葡萄进入衰退状态，患病宿主不再有资源支持次生代谢产物的产生，包括与防御相关的酚类化合物。
