Screening of cultivated and wild adzuki bean for resistance to race 3 of Cadophora gregata f. sp. adzukicola, cause of brown stem rot

Abstract

Two diseases of adzuki bean, brown stem rot (BSR, caused by Cadophora gregata f. sp. adzukicola) and adzuki bean Fusarium wilt (AFW, caused by Fusarium oxysporum f. sp. adzukicola), are serious problems in Hokkaido and have been controlled using cultivars with multiple resistance. However, because a new race of BSR, designated race 3, was identified, sources of parental adzuki bean for resistance to race 3 were needed. Therefore, we examined 67 cultivars and lines of cultivated and wild adzuki bean maintained at the Tokachi Agricultural Experiment Station using a root-dip inoculation method. Consequently, nine adzuki bean cultivars, one wild adzuki bean accession and 30 lines (including two lines resistant to all the three races of BSR and AFW) were confirmed to be resistant or tolerant to race 3 of BSR, and we found a cultivar Akamame as well as a wild adzuki bean Acc2515 to be a new source for a resistance gene to the race 3. This cultivar also holds promise as a source of resistance against other races of BSR and AFW

New Sources of Resistance to Cadophora gregata f. sp. adzukicola and Fusarium oxysporum f. sp. adzukicola in Vigna spp.

“…In all trials, the varieties of adzuki bean that were used as controls showed resistant or susceptible reactions to each pathogen (data not showti), as was demonstrated previously (16 (Tables I and 2): A, susceptible to all pathogens tested; B, susceptible to BSR race 2 but resistant to the other pathogens; C, susceptible to BSR race 3 but resistant to the other pathogens; D, resistant to all pathogens tested; E, resistant to AFW race 3 but susceptible to the other pathogens; F, susceptible to BSR races 2 and 3 but resistant to BSR race I and AFW race 3; G, susceptible to BSR race 2 and AFW race 3 but resistant to BSR races 1 and 3; and H, susceptible to AFW race 3 but resistant to the other pathogens. Of the eight groups, E, F, G, and H were newly recognized in the present study; groups A, B, C, and D were described previously (16).…”

“…These species are potential sources of multiple resistance genes ( 1 ), Crosses between adzuki bean and these species, with the exception of V. glabrescens (an allotetraploid derived from V; trinervia x V. minitna), are reported to produce fertile Fi hybrids (23), V. angularis var, nipponensis showed greater genetic diversity in resistance patterns compared with cultivated adzuki bean (16) and, within this species, three newly designated disease reaction groups (E, G, and H) were identified. Altogether, 29 accessions from five Vtgna spp.…”

“…The Vigtia spp. Four cultivars and lines of adzuki bean or wild adzuki bean conserved in the TAES ('Erimo-shozu', 'Kita-no-otome', Acc259, and Acc2515) were used as standards to represent disease reaction groups (16). In the collection, seven species (Table I, bold) in the section Angulares are cross-compatible with adzuki bean; therefore, a large number of accessions were tested for resistance.…”

“…The inoculations were carried out according to Kondo et al (16). The inoculations were carried out according to Kondo et al (16).…”

“…nipponensis; e.g., Acc2515) adzuki bean accessions resistant to both races I and 2 (3). However, only two accessions showed resistance to all three races of BSR and AFW (16): Akamame (cultivated accession) and Acc2515 (a wild accession collected in Ishikawa prefecture, Japan). As the number of designated races has increased in Hokkaido, the need to find additional sources of resistance and to incorporate multiple sources of resistance into commercial culti-vars has become essential.…”