Sisou Dana, Tadmor Yaakov, Plakhine Dina, Ziadna Hammam, Hübner Sariel, Eizenberg Hanan
Department of Phytopathology and Weed Research, Agricultural Research Organization, Newe Ya'ar Research Center, Ramat Yishay 30095, Israel.
Department of Vegetable and Field Crops, Agricultural Research Organization, Newe Ya'ar Research Center, Ramat Yishay 30095, Israel.
Plants (Basel). 2021 Aug 30;10(9):1810. doi: 10.3390/plants10091810.
Infestations with sunflower broomrape ( Wallr.), an obligatory root parasite, constitute a major limitation to sunflower production in many regions around the world. Breeding for resistance is the most effective approach to reduce sunflower broomrape infestation, yet resistance mechanisms are often broken by new races of the pathogen. Elucidating the mechanisms controlling resistance to broomrape at the molecular level is, thus, a desirable way to obtain long-lasting resistance. In this study, we investigated broomrape resistance in a confectionery sunflower cultivar with a robust and long-lasting resistance to sunflower broomrape. Visual screening and histological examination of sunflower roots revealed that penetration of the broomrape haustorium into the sunflower roots was blocked at the cortex, indicating a pre-haustorial mechanism of resistance. A comparative RNA sequencing between broomrape-resistant and -susceptible accessions allowed the identification of genes that were significantly differentially expressed upon broomrape infestation. Among these genes were β-1,3-endoglucanase, β-glucanase, and ethylene-responsive transcription factor 4 (ERF4). These genes were previously reported to be pathogenesis-related in other plant species. This transcriptomic investigation, together with the histological examinations, led us to conclude that the resistance mechanism involves the identification of the broomrape and the consequent formation of a physical barrier that prevents the establishment of the broomrape into the sunflower roots.
向日葵列当（Wallr.）是一种专性根寄生植物，其侵染是全球许多地区向日葵生产的主要限制因素。培育抗性品种是减少向日葵列当侵染最有效的方法，然而抗性机制常常会被病原菌的新小种打破。因此，在分子水平上阐明控制对列当抗性的机制是获得持久抗性的理想途径。在本研究中，我们调查了一个对向日葵列当具有强大且持久抗性的食用向日葵品种的列当抗性。对向日葵根系进行目视筛选和组织学检查发现，列当吸器侵入向日葵根系在皮层处受阻，这表明存在一种吸器前抗性机制。通过对列当抗性和感病材料进行比较RNA测序，能够鉴定出在列当侵染后显著差异表达的基因。这些基因包括β-1,3-内切葡聚糖酶、β-葡聚糖酶和乙烯响应转录因子4（ERF4）。这些基因先前在其他植物物种中被报道与病程相关。这项转录组学研究与组织学检查一起，使我们得出结论，抗性机制涉及对列当的识别以及随后形成物理屏障，从而阻止列当在向日葵根系中定殖。
