Efficacy Assessment of Different Screening Methods for Detecting Resistance against Erwinia carotovora in Calla Lily

Abstract

Bacterial soft rot is one of the major disease of Zantedeschia species (Calla lily) caused by Erwinia carotovora. The objectives of this study were i) to screen the most efficient method to determine resistance level against E. carotovora and ii) to evaluate the genetic variability in Zantedeschia genotypes by inoculation of Ecc NHRI-3 and PD 1784 isolates. Four screening tests i.e. leaf disk, petiole, tuber and tuber slice tests were used to determine the resistance level in calla lily. Eleven genotypes from section Zantedeschia were used for variation studies against E. carotovora by using the leaf disk test. It was observed that all genotypes showed variation in resistance level and could be categorized in 3 groups on the basis of their resistance level. Four of the genotypes were resistant against this pathogen whereas, 6 genotypes were moderately resistant and only one genotype was found susceptible. Within section Aestivae, ‘Galaxy’, ‘Florex Gold’, ‘Treasure’ and ‘Mango’ were found very susceptible cultivars, whereas ‘Coral Sunset’, ‘Hazel Marie’ and ‘Neroli’ were less susceptible genotypes. Most of the cultivars from section Aestivae were susceptible to bacterial soft rot and the cultivar ‘Florex Gold’ was identified as susceptible control. It is suggested to perform pre-screening through leaf disk method which proved to a non-destructive test. The pre-screening evaluation can discriminate susceptible cultivar and resistant cultivar. Tuber slice test is more useful in screening subsequent genotypes at a later growth stage in any breeding program.