Host-driven morphological variability in Orobanche crenata (Orobanchaceae)

Abstract

Studies on interactions between Orobanche species and their hosts are mainly focused on resistance, radical interactions, andhaustorium development. The influence of the host plant on morphology of the parasite under environmental controlled conditions isnot reported in the literature. With the aim of filling this gap, the results of cultivation experiments of Orobanche crenata on Vicia faba,V. sativa, Pisum sativum, Cicer arietinum, and Lathyrus clymenum are presented. The tested population of O. crenata infected all thestudied hosts but showed preferences toward Vicia and Pisum and, in particular, toward a foreign V. sativa cv. The higher resistance ofthe evaluated local cv. could be due to coevolution between host and parasite. There was little variation in times of emergence: about 110days on V. faba, while around 125 on P. sativum, C. arietinum, and V. sativa. The shape and size of flowers of O. crenata were influencedby its hosts. The more flourishing the host, the more vigorous the parasite with respect to overall size, number of flowers, and density ofthe inflorescence. However, significant variations were also observed in the shape of the calyx and the colour of the corolla and stigma.These observations suggest that other taxa of Orobanche that grow in the wild, which are considered to be different species, could bemorphotypes of the same taxon, although a process of speciation may be in progress.