Identification of Vicia ervilia Germplasm Resistant to Orobanche crenata

Abstract

Bitter vetch (Vicia ervilia L.) is an ancient grain legume used as animal feed in the Mediterranean basin. This legume has a large economical potential because of its high yield under low inputs and good protein content, as well as resistance to cold and drought. Nevertheless, its growth and production area are affected in the presence of the broomrape weed species Orobanche crenata. Due to the small bitter vetch size, infection by as few as two or three O. crenata per vetch plant can be devastating. There are no efficient methods of selectively controlling O. crenata in this crop, for which reason the development of varieties resistant and tolerant to O. crenata infection is needed. Phytogenetic resources are valuable reserves for species survival. They represent important genetic variability and allow the possibility of finding characters of interest, such as new resistance sources. A large-scale field screening of a collection of 102 bitter vetch accessions indicated that most bitter vetch accessions were susceptible but allowed us to select 16 accessions with low levels of O. crenata infection. Next, we used a combination of field and rhizotron experiments to investigate the resistant response of selected bitter vetch genotypes in detail by studying the performance and resistance mechanisms. These experiments led to the identification of three different mechanisms that block O. crenata parasitism. A pre-attachment mechanism of low induction of O.crenata germination was identified in two bitter vetch accession Ve.055 and Ve.155. In addition, a post-attachment mechanism of resistance to O. crenata penetration was identified inthe accession Ve.125. In addition, the field-resistant accession Ve.123 showed susceptible response in rhizotron, indicating that a late mechanism acting after vascular connection, most probably related with bitter vetch of escape due to fructification precocity was acting against O. crenata development.

Resistance against Orobanche crenata in Bitter Vetch (Vicia ervilia) Germplasm Based on Reduced Induction of Orobanche Germination

“…With the aim of validating the results obtained in the rhizotron experiment, two consecutive field experiments were carried out during the seasons of 2016–2017 and 2017–2018. Weather conditions ( Figure 1 ) were conducive for O. crenata infection and its emergence [ 7 ], as it was indicated by the O. crenata emergence on the susceptible faba bean checked (average of 2.85 ± 0.18 and of 7.05 ± 0.49 emerged O. crenata per faba bean plant during 2016–2017 and 2017–2018 seasons, respectively).…”

“…In addition, 10 lines including the susceptible accession Ve.38 with the highest stimulating activity of O. crenata germination and a higher number of tubercles were included as susceptible controls. As a resistant bitter vetch control, the cultivar Jabegote was selected due to its previously characterized incomplete resistance, but high productivity under O. crenata infestation [ 7 ] was used.…”

“…An important feature in bitter vetch sources of parasitic weed resistance is the ability to be productive in soils highly infested by O. crenata infection [ 7 ]. In some legume species, accessions with levels of resistance are not able to yield to their potential when they are infected by a reduced number of O. crenata plants due to the strong competition for nutrients created by the parasite even at low levels of infection [ 10 ].…”

“…The main constrain for bitter vetch cultivation in Mediterranean rainfed cropping systems is the crenata broomrape ( Orobanche crenata Forsk.) [ 7 ]. O. crenata is a parasitic broomrape weed species that infects roots of different crops, mainly legume species as well as other crops including carrot or celery [ 8 , 9 ], causing severe yield damage [ 10 ].…”

“…Low germination-inducers genotypes have been described previously in faba bean [ 22 , 23 , 24 ], tomato [ 25 , 26 ], pea [ 27 ], rice [ 28 ], sorghum [ 29 ], and sunflower [ 30 , 31 ]. Despite the severe damage inflicted by O. crenata in bitter vetch plants, few resistant genotypes have been identified so far [ 7 ]. The aim of this study was to identify differences in induction activity of O. crenata germination in a collection of 39 bitter vetch accessions using a combination of field, rhizotron, and in vitro experiments.…”