Echevarría-Zomeño Sira, Pérez-de-Luque Alejandro, Jorrín Jesús, Maldonado Ana M
Agricultural and Plant Biochemistry Research Group, Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Edificio Severo Ochoa, E-14071 Córdoba, Spain.
J Exp Bot. 2006;57(15):4189-200. doi: 10.1093/jxb/erl195. Epub 2006 Nov 9.
Sunflower broomrape (Orobanche cumana Wallr.) is a root holoparasitic angiosperm considered as one of the major constraints for sunflower production in Mediterranean areas. Breeding for resistance is regarded as the most effective, feasible, and environmentally friendly solution to control this parasite. However, the existing sources of genetic resistance are defeated by the continuous emergence of new more virulent races of the parasite. In this work, the interaction between sunflower and O. cumana has been analysed in order to gain insights into the mechanisms involved in resistance. Two sunflower genotypes were selected showing different behaviour against the new race F of O. cumana, HE-39998 (susceptible) and HE-39999 (resistant), and both compatible and incompatible interactions were compared. Pot and Petri dish bioassays revealed that only HE-39998 plants were severely affected, supporting a high number of successfully established broomrapes to mature flowering, whereas in HE-39999 root tubercles were never observed, resistance being associated with browning symptoms of both parasite and host tissues. Histological aspects of the resistance were further investigated. Suberization and protein cross-linking at the cell wall were seen in the resistant sunflower cells in contact with the parasite, preventing parasite penetration and connection to the host vascular system. In addition, fluorescence and confocal laser microscopy (CLM) observations revealed accumulation of phenolic compounds during the incompatible reaction, which is in agreement with these metabolites playing a defensive role during H. annuus-O. cumana interaction.
向日葵列当（Orobanche cumana Wallr.）是一种根部全寄生被子植物，被认为是地中海地区向日葵生产的主要限制因素之一。培育抗性品种被视为控制这种寄生虫最有效、可行且环保的解决方案。然而，现有的遗传抗性来源被该寄生虫新出现的更具毒性的小种所克服。在这项研究中，对向日葵与向日葵列当之间的相互作用进行了分析，以深入了解抗性相关机制。选择了两种对向日葵列当新小种F表现出不同抗性的向日葵基因型，HE - 39998（感病）和HE - 39999（抗病），并比较了亲和与非亲和相互作用。盆栽和培养皿生物测定表明，只有HE - 39998植株受到严重影响，支持大量成功寄生的列当发育到成熟开花，而在HE - 39999中从未观察到根瘤，抗性与寄生虫和宿主组织的褐变症状相关。进一步研究了抗性的组织学方面。在与寄生虫接触的抗病向日葵细胞中观察到细胞壁的栓质化和蛋白质交联，阻止了寄生虫的侵入以及与宿主维管系统的连接。此外，荧光和共聚焦激光显微镜（CLM）观察显示在非亲和反应过程中酚类化合物的积累，这与这些代谢产物在向日葵 - 向日葵列当相互作用中发挥防御作用一致。
