Pre-haustorial resistance to broomrape (Orobanche cumana) in sunflower (Helianthus annuus): cytochemical studies

• Published in: Journal of experimental botany 2006, Vol.57 (15), p.4189-4200
• Main Authors: Echevarría-Zomeño, Sira, Pérez-de-Luque, Alejandro, Jorrín, Jesús, Maldonado, Ana M
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Breeding; Cell walls; Confocal laser microscopy; defence responses; Fluorescence; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Genotype; Genotypes; Helianthus - anatomy & histology; Helianthus - genetics; Helianthus - parasitology; Helianthus annuus; histology; Host parasite relationships; Host-Parasite Interactions; Immunity, Innate - genetics; Infections; Microscopy, Confocal; Orobanche - physiology; Orobanche cumana; Parasite hosts; Parasites; parasitic plants; Parasitism; Parasitism and symbiosis; Pest resistance; phenolics; Plant pathogens; Plant physiology and development; Plant roots; Plant Roots - anatomy & histology; Plant Roots - parasitology; Plant Roots - physiology; Plants; protein cross-linking; Research Papers; resistance; suberization; Sunflowers; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erl195

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.