Ecological adaptations influence the susceptibility of plants in the genus Zantedeschia to soft rot Pectobacterium spp.

Abstract

Soft rot disease caused by Pectobacterium spp. is responsible for severe agricultural losses in potato, vegetables, and ornamentals. The genus Zantedeschia includes two botanical groups of tuberous ornamental flowers that are highly susceptible to the disease. Previous studies revealed that Z. aethiopica, a member of the section Zantedeschia, is significantly more resistant to Pectobacterium spp. than members of the same genus that belong to the section Aestivae. During early infection, we found different patterns of bacterial colonization on leaves of hosts belonging to the different sections. Similar patterns of bacterial colonization were observed on polydimethylsiloxane (PDMS) artificial inert replicas of leaf surfaces. The replicas confirmed the physical effect of leaf texture, in addition to a biochemical plant–bacterium interaction. The differential patterns may be associated with the greater roughness of the abaxial leaf surfaces of Aestivae group that have evolutionarily adapted to mountainous environments, as compared to Zantedeschia group species that have adapted to warm, marshy environments. Transverse leaf sections also revealed compact aerenchyma and reduced the total volume of leaf tissue air spaces in Aestivae members. Finally, an analysis of defense marker genes revealed differential expression patterns in response to infection, with significantly higher levels of lipoxygenase 2 (lox2) and phenylalanine ammonia lyase (pal) observed in the more resistant Z. aethiopica, suggesting greater activation of induced systemic resistance (ISR) mechanisms in this group. The use of Zantedeschia as a model plant sheds light on how natural ecological adaptations may underlay resistance to bacterial soft rot in cultivated agricultural environments.

Phylogenetic and phenotypic analyses on Dickeya spp. isolated from different host plants in Taiwan

“…), differential susceptibility to Pectobacterium spp. between white and coloured species/hybrids has been suggested to be contributed by differences in plant morphological features (Guttman et al., 2021). Further analyses on multiple combinations of Dickeya and plant species may help elucidate if these factors and mechanisms could also determine the interactions between Dickeya species and their hosts.…”

Use of X-Ray Mutagenesis to Increase Genetic Diversity of <em>Zantedeschia aethiopica</em> for Early Flowering, Improved Tolerance to Bacterial Soft Rot and Higher Yield

“…Here, we have created 319 individual mutant lines (CaX), from which we have selected and further propagated 20 lines that exhibit some of the desired traits that we defined: higher flower yield, early flowering time, large flowers with the desired shape, and tolerance to soft rot caused by Pectobacterium [8,[22][23][24]. Most of the selected varieties had more than one of these traits (i.e., two to six of these traits), resulting in greater potential for commercialization.…”

“…Letty [4] grouped the species into two informal sections: Zantedeschia, containing two species of the evergreen Z. aethiopica and the summer dormant Z. odorata, both with a white spathe and a rhizomatous storage organ; and Aestivae, containing six winter-dormant species with a colored spathe and a tuberous storage organ [4,5]. One of the major threats to Z. aethiopica crops around the world is the soft-rot disease caused by Pectobacterium spp., although Z. aethiopica is more resilient than the colorful Zantedeschia hybrids (Aestivae) group [6][7][8]. A major factor enabling commercial development of high-value cultivars is the species' breeding potential, but unlike members of the Aestivae group, which can be easily crossed through conventional interspecific hybridization, members of the Zantedeschia group may only be crossed with other members of their own species [9].…”

“…Israeli growers use a single variety, namely Z. aethiopica var. Israeli (ZAI), which naturally blooms during the late winter (weeks [6][7][8][9][10][11][12][13][14][15][16][17][18]. This variety has never been registered as a commercial cultivar and is derived from several genetic resources of South African origin that have been vegetatively propagated by flower growers over the last decades [12].…”

Use of X-ray Mutagenesis to Increase Genetic Diversity of Zantedeschia aethiopica for Early Flowering, Improved Tolerance to Bacterial Soft Rot, and Higher Yield

“…Letty [4,5] grouped the species into two informal sections: Zantedeschia, containing two species of the evergreen Z. aethiopica and the summer dormant Z. odorata, both with white spathes and rhizomatous storage organs; and Aestivae, containing six winter-dormant species with colored spathes and tuberous storage organs [4,5]. One of the major threats to Z. aethiopica crops around the world is the soft-rot disease caused by Pectobacterium spp., although Z. aethiopica is more resilient than the colorful Zantedeschia hybrid (Aestivae) group [6][7][8]. A major factor enabling commercial development of high-value cultivars is the species' breeding potential, but unlike members of the Aestivae group, which can be easily crossed through conventional interspecific hybridization, members of the Zantedeschia group can only be crossed with other members of their own species [9].…”