An SSR-SNP Linkage Map of the Parasitic Weed Orobanche cumana Wallr. Including a Gene for Plant Pigmentation

Abstract

Sunflower broomrape ( Orobanche cumana Wallr.) is a holoparasitic plant that causes major yield losses to sunflower crops in the Old World. Efforts to understand how this parasitic weed recognizes and interacts with sunflowers are important for developing long-term genetic resistance strategies. However, such studies are hampered by the lack of genetic tools for O. cumana . The objectives of this research were to construct a genetic linkage map of this species using SSR and SNP markers, and mapping the P g locus that is involved in plant pigmentation. The genetic map was developed from the progenies of a cross between the O. cumana inbred lines EK-12 and EK-A1, which originated from populations belonging to two distant and geographically separated gene pools identified in Spain. The inbred lines also differed in plant pigmentation, with EK-A1 lacking anthocyanin pigmentation ( p g p g genotype). A genetic map comprising 26 SSR and 701 SNP markers was constructed, which displayed 19 linkage groups (LGs), corresponding to the 19 chromosome pairs of O. cumana . The total length of the map was 1795.7 cM, with an average distance between two adjacent positions of 2.5 cM and a maximum map distance of 41.9 cM. The P g locus mapped to LG19 between the SNP markers OS02468 and OS01653 at 7.5 and 3.4 cM, respectively. This study constitutes the first linkage map and trait mapping study in Orobanche spp., laying a key foundation for further genome characterization and providing a basis for mapping additional traits such as those having a key role in parasitism.

Genetic and Genomic Tools in Sunflower Breeding for Broomrape Resistance

“…Determination and mapping of races revealed a high level of divergence along with a common trend of virulence increase. Broomrape attack on previously resistant sunflower genotypes results in labelling parasite populations with the same letter, indicating the need for comparative studies of populations in different countries [36]. Better understanding of processes which condition the emergence of new virulence biotypes and their comparison is therefore needed, together with fundamental research at the cellular level of the interaction between the host and parasite in the early developmental stages [37].…”

The Effect of Virulence and Resistance Mechanisms on the Interactions between Parasitic Plants and Their Hosts

“…Genetic studies related to the virulence/race of O. cumana have been poorly described. However, an avirulence gene interacting with Or5 resistance gene in sunflower (see below) was characterized [93] and was mapped [94]. The O. cumana genome sequence will help to identify the avirulence genes [95].…”

A new race of sunflower broomrape (Orobanche cumana) with a wider host range due to changes in seed response to strigolactones

“…Differences in the response of O. cumana populations in Israel to sunflower root exudates have been shown by Joel et al (2011), and a new virulent race of O. cumana has also been reported in this country (Eizenberg et al 2004), suggesting a polymorphic nature for O. cumana. Genetically distant gene pools of O. cumana, derived from separate introduction events, are known in almost all sunflower-growing countries (Calderón-González et al 2019;Fernández-Martínes et al 2008;Martín-Sanz et al 2016;Molinero-Ruiz et al 2014;Pineda-Martos et al 2013;Román 2013). Increased virulence of O. cumana, due to changes in seed responsiveness to stimulants, may result from admixtures of O. cumana populations (Martín-Sanz et al 2016;Román 2013).…”

“…The difference in seed responsiveness to stimulants may be due to a mutation in a structural gene or controlling element, alternative splicing, or epigenetic methylation (Bruce and Gressel 2013;Conn et al 2015;Joel et al 2011). A single O. cumana plant that carries such a genetic change or genetic recombination is sufficient for the development of a seedbank of similar plants that are able to parasitize tomato, because a single Orobanche plant produces copious amounts of miniscule seeds.…”