A Novel Lens orientalis Resistance Source to the Recently Evolved Highly Aggressive Australian Ascochyta lentis Isolates

Abstract

Substantial yield losses and poor seed quality are frequently associated with Ascochyta blight infection of lentil caused by Ascochyta lentis. Recently reported changes in aggressiveness of A. lentis have led to decreased resistance within cultivars, such as Northfield and Nipper in Australia. Furthermore, the narrow genetic base of the current breeding program remains a risk for further selective pathogen evolution to overcome other currently used resistances. Therefore, incorporation of potentially novel and diverse resistance genes into the advanced lines will aid to improve cultivar stability. To identify these, 30 genotypes sourced from five wild species (Lens orientalis, L. odomensis, L. ervoides, L. nigricans and L. lamottei), including eight previously reported resistance sources, were screened for disease reaction to two recently isolated and highly aggressive isolates. Subsequently, two L. orientalis accessions were found highly resistant and a further six L. nigricans, one L. odomensis, one L. ervoides, one L. lamottei, and one L. orientalis accessions were moderately resistant. Several of these were more resistant than the currently deployed resistance source, ILL 7537. Furthermore, L. orientalis accession ILWL 180 was consistently resistant against other highly aggressive isolates recovered from diverse geographical lentil growing regions and host genotypes, suggesting stability and potential for future use of this accession in the Australian lentil breeding program.

Determination of the Key Resistance Gene Analogs Involved in Ascochyta rabiei Recognition in Chickpea

“…The timing of RGA expression is thus crucial for a plant to be able to recognize a pathogen fast enough to incite effective defense responses. In this study, we found that a cluster of RGAs (Cluster 2), was up-regulated by 2–6 h following inoculation with a highly aggressive A. rabiei isolate and that this was consistent with the timing of spore growth (germ tube elongation) and penetration (appressoria development) (Sambasivam et al, 2008). If a plant can recognize and initiate defense responses faster, it may be able to contain the fungus long enough for more systemic resistance responses to occur, including hormone signaling, structural rearrangement and production of pathogenesis proteins.…”

Evidence of early defence to Ascochyta lentis within the recently identified Lens orientalis resistance source ILWL180

“…Single spore cultures of one aggressive isolate (FT13037) and one non-aggressive isolate (F13082) were supplied by the South Australian Research and Development Institute (SARDI), South Australia. Aggressiveness of isolate FT13037 was previously identified by Dadu et al (2017) and isolate F13082 was identified as non-aggressive on a set of host differentials in a controlled bioassay (Davidson, SARDI, Adelaide, personal communication).…”

“…Spore suspensions were prepared from 14-day-old fungal cultures as described previously (Dadu et al, 2017).…”

Species Diversity of the Vir Collection of Grain Legume Genetic Resources and Its Use in Domestic Breeding

“…Изучение диких родичей чечевицы показало, что они имеют ряд ценных признаков, утерянных культурным видом в процессе доместикации и селекции. Выявлены образцы L. nigricans, устойчивые к фузариозу, мучнистой росе и ржавчине (Gupta, Sharma, 2006;Sing et al, 2014); L. ervoides, устойчивые к антракнозу и аскохитозу (Tullu et al., 2006;; образец L. orientalis, устойчивый к агрессивным австралийским изолятам Ascochyta lentis Vassiljevsky (Dadu et al, 2017). Показано, что в семенах диких видов содержание ингибиторов протеаз не выше, чем у сортов L. culinaris (Benken, Boluzneva, 1977;Suvorova et al, 2004).…”