Novel QTL associated with Rhizoctonia solani Kühn resistance identified in two table beet × sugar beet F_2:3 populations using a new table beet reference genome

Abstract

The necrotrophic fungus Rhizoctonia solani Kühn is a major concern for table beet (Beta vulgaris L. ssp. vulgaris) producers across the United States causing upward of 75% losses in severe instances. Thus far, there have been minimal efforts to incorporate host resistance to R. solani in table beet germplasm. To investigate the genetic control of R. solani resistance in table beet, we developed two mapping populations. Parents of the two populations were a Rhizoctonia‐susceptible table beet inbred W357A and a resistant sugar beet germplasm FC709‐2 (sugar beet resistance population, SBRP) and a Rhizoctonia‐resistant table beet inbred W364B and a susceptible sugar beet inbred FC901/C817 (table beet resistance population, TBRP). In Spring 2020, F2:3 families were evaluated for response to artificial inoculation with R. solani AG 2‐2 IIIB isolate R1 in replicated greenhouse experiments. This work also represents the first use of the W357B table beet reference genome, utilized here to align genotyping‐by‐sequencing reads to identify polymorphic markers. Using interval linkage mapping, we identified one quantitative trait locus (QTL) in each of the two populations, each accounting for 30% of the phenotypic variation. The QTL in both the SBRP and TBRP were found on chromosome 2 and contained several putative resistance genes in annotations of the Beta vulgaris and Arabidopsis thaliana genomes. This is the first report of a QTL on chromosome 2 for resistance to R. solani in B. vulgaris ssp. vulgaris and the first identification of QTL for disease resistance in table beet. The newly developed table beet reference genome and markers identified in this study may be of value for marker‐assisted selection in breeding for resistance to R. solani in both sugar beet and table beet breeding programs.

Determination of Disease Severity of Rhizoctonia solani Kühn (Telemorph: Thanatephorus cucumeris (Frank) Donk) Isolates from Bean, Sugar Beet and Potato Planting Areas in Konya

“…In many studies, it has been reported that high levels of AG 2-2 are found in isolations made from sugar beet plants and especially AG 2-2 is highly virulent in more mature tubers. In another study, it was determined that the most common group was AG 2-2 IIIB (Herr and Roberts 1980;Windels et al 1989;Çebi Kılıçoğlu 2009;Strausbaugh et al 2011;Stojsin et al 2011;Avan 2020;Wigg 2021). In our research, the most virulent isolates in sugar beet, coded ŞP 2.2, ŞP 7.2 and ŞP 11.1, were isolated by taking samples in the more mature stages of beet and anastomosis groups were determined as AG 2-2, similar to other studies.…”

A fully phased, chromosome-scale genome of sugar beet line FC309 enables the discovery of Fusarium Yellows resistance QTL

“…vulgaris L.) genome has served as a powerful tool for global research and for breeding programs in both the public and private sectors (Dohm et al, 2014; McGrath et al, 2023). Both the RefBeet and EL10 assemblies have enabled the sugar beet research community to identify genetic loci linked to important traits underlying important agronomic, biotic, and abiotic stress tolerance traits (Dally et al, 2014; Galewski et al, 2022; Holmquist et al, 2021; Pfeiffer, 2016; Pfeiffer et al, 2017; Ravi et al, 2021a; Sielemann et al, 2023; Wigg et al, 2023). The rapid advancement in sequencing technologies has resulted in a moving target of benchmarks that represent ‘gold standard’ genome assembly and annotations for many species.…”