Department of Arctic and Marine Biology, University of Tromsø, N-9037, Tromsø, Norway.
Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA.
Physiol Plant. 2018 Feb;162(2):205-218. doi: 10.1111/ppl.12660. Epub 2017 Dec 8.
The parasitic flowering plant genus Cuscuta (dodder) is a parasitic weed that infects many important crops. Once it winds around the shoots of potential host plants and initiates the development of penetration organs, called haustoria, only a few plant species have been shown to deploy effective defense mechanisms to ward off Cuscuta parasitization. However, a notable exception is Solanum lycopersicum (tomato), which exhibits a local hypersensitive reaction when attacked by giant dodder (Cuscuta reflexa). Interestingly, the closely related wild desert tomato, Solanum pennellii, is unable to stop the penetration of its tissue by the C. reflexa haustoria. In this study, we observed that grafting a S. pennellii scion onto the rootstock of the resistant S. lycopersicum did not change the susceptibility phenotype of S. pennellii. This suggests that hormones, or other mobile substances, produced by S. lycopersicum do not induce a defense reaction in the susceptible tissue. Screening of a population of introgression lines harboring chromosome fragments from S. pennellii in the genome of the recurrent parent S. lycopersicum, revealed that most lines exhibit the same defense reaction as shown by the S. lycopersicum parental line. However, several lines showed different responses and exhibited either susceptibility, or cell death that extended considerably beyond the infection site. These lines will be valuable for the future identification of key loci involved in the perception of, and resistance to, C. reflexa and for developing strategies to enhance resistance to infection in crop species.
寄生性开花植物菟丝子（菟丝子）是一种寄生杂草，感染许多重要作物。一旦它缠绕在潜在宿主植物的芽上，并开始发育穿透器官，称为吸器，只有少数几种植物被证明能够部署有效的防御机制来抵御菟丝子寄生。然而，一个显著的例外是番茄（番茄），当受到巨型菟丝子（菟丝子 reflexa）的攻击时，它会表现出局部过敏反应。有趣的是，亲缘关系密切的野生沙漠番茄，Solanum pennellii，无法阻止 C. reflexa 吸器穿透其组织。在这项研究中，我们观察到将 S. pennellii 的接穗嫁接到抗 S. lycopersicum 的根砧上并没有改变 S. pennellii 的易感性表型。这表明 S. lycopersicum 产生的激素或其他可移动物质不会在易感组织中诱导防御反应。对含有 S. pennellii 染色体片段的渐渗系群体进行筛选，发现这些渐渗系中的大多数都表现出与 S. lycopersicum 亲本系相同的防御反应。然而，有几条线表现出不同的反应，表现出易感性，或细胞死亡，大大超出了感染部位。这些系将有助于未来鉴定参与 C. reflexa 感知和抗性的关键基因座，并开发增强作物物种感染抗性的策略。
