Screening for Partial Physiological Resistance to White Mold in Dry Bean Using Excised Stems

Abstract

<jats:p>A laboratory procedure was tested to determine whether excised stems would allow a reliable indication of partial physiological resistance (PPR) to white mold <jats:italic>[Sclerotinia sclerotiorum</jats:italic> (Lib.) deBary] in dry bean <jats:italic>(Phaseolus vulgaris</jats:italic> L.). Excised stems from 11- and 28-day-old plants were inoculated with growing mycelium of <jats:italic>S. sclerotiorum,</jats:italic> incubated for 4 to 7 days (11- and 28-day assays, respectively), then assayed for lesion length (LL). A total of 15 bean genotypes were screened for PPR, as indicated by LL. Significant <jats:italic>(P</jats:italic> &lt; 0.05) differences among LL means of small- and medium-seeded bean genotypes were detected in the 28-day assay, whereas only LL means among medium-seeded genotypes. differed significantly <jats:italic>(P &lt; 0.05)</jats:italic> in the n-day assay. `Bunsi', `C-20', `Sierra', `Topaz', and snap bean breeding lines NY 5262, NY 5394, and NY 5403 had the highest PPR and `Upland', D76125, and `UI-114' the lowest. The results from both assays were repeatable. A moderately high correlation <jats:italic>(r =</jats:italic> 0.68, <jats:italic>P &lt;</jats:italic> 0.02) was observed between PPR and field resistance. The 28-day assay has potential for evaluating dry bean germplasm for PPR to white mold disease caused by S. <jats:italic>sclerotiorum.</jats:italic> A 28-day assay also was used to measure virulence of 18 isolates of S. <jats:italic>sclerotiorum.</jats:italic> The 18 isolates did not differ <jats:italic>(P &lt;</jats:italic> 0.05) for virulence when measured by LL. The lack of any genotype × isolate interaction for LL indicated lack of host-pathogen specificity.</jats:p>

Mapping of QTL for Resistance to White Mold Disease in Common Bean

“…Several techniques such as the juvenile stem inoculation test (Dickson et al, 1982), the limited‐term inoculation test (Hunter et al, 1982), the excised stem test (Miklas et al, 1992a), and the callus‐weight assay (Miklas et al, 1992b) have been utilized to screen bean germplasm for PPR to WM in the laboratory, growth chamber, greenhouse, or in vitro. However, these techniques have some limitations such as lack of uniformity, lack of precision, nonrepeatability and complexity, and do not always correlate with field conditions (Petzoldt and Dickson, 1996; Miklas et al, 1992a; Steadman et al, 1997). The straw test (Petzoldt and Dickson, 1996) was used in this study because it provides more consistent, repeatable, and uniform results than other tests (Hall and Phillips, 1997), and also many plants can be inoculated rapidly by one person.…”

QTL Conferring Resistance and Avoidance to White Mold in Common Bean

“…Two recombinant populations (BN, HN) were developed as described in Kolkman and Kelly (2002) The BN population consisted of 98 F 3 ‐derived families, from a cross between two navy bean cultivars, Bunsi (also known as Ex Rico 23) and Newport, that varied in resistance to white mold (Kolkman and Kelly, 2002). Bunsi has an indeterminate (Type II; Singh, 1982) growth habit and possesses both physiological resistance and a porous canopy for avoidance to white mold (Tu and Beversdorf, 1982; Schwartz et al, 1987; Kolkman and Kelly, 2000; Miklas et al, 1992; Miklas and Grafton, 1992), whereas Newport is a susceptible cultivar with a determinate (Type I) growth habit (Kelly et al, 1995; Kolkman and Kelly, 2000). The HN population consisted of 28 F 5 –derived RILs developed by single‐seed descent from a cross between ‘Huron’ and Newport.…”

Breeding Common Bean for Resistance to White Mold: A Review

“…For direct screening of live plants, researchers have used mycelial plug inoculation of cotyledons (Grau and Bissonnette, 1974;Kim et al, 2000;Kull et al, 2003), cut petiole (del Río et al, 2000), cut-stem or straw test (del Río et al, 2000;Petzoldt and Dickson, 1996;Terán et al, 2006;Vuong et al, 2004), mycelial-infected oat (Avena sativa L.) seed for stem inoculation (Adams et al, 1973;Terán and Singh, 2009b), mycelial-infected celery (Apium graveolens L.) for a 24-to 48-h limited-term stem inoculation (Hunter et al, 1981;Pennypacker and Hatley, 1995), mycelial-infected carrot (Daucus carota L.) for stem inoculation , mycelial inoculation of foliage (Wegulo et al, 1998), mycelial-infected flower for stem inoculation (Schwartz et al, 1978;Terán and Singh, 2009b), and ascospore inoculation of flowering plants (Abawi et al, 1978;Cline and Jacobsen, 1983;Schwartz et al, 1978). Direct inoculation of excised common bean plant parts has been performed on detached leaves or flowers and excised stems using spore or mycelium suspensions (Chun et al, 1987;Leone and Tonneijck, 1990;Miklas et al, 1992a;Olivier et al, 2008;Steadman et al, 1997). Indirect methods include the use of pathogen filtrate to detect physiological resistance (Miklas et al, 1992b), oxalic acid (H 2 C 2 O 4 ) diffusion test (Tu, 1985), modified oxalate test (Kolkman and Kelly, 2000), and soluble stem pigment production in oxalic acid (Wegulo et al, 1998).…”