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

Yelena Guttman,Nirmal Khadka,Zunzheng Wei,Zohar Kerem,Noam Reznik,Janak Raj Joshi,Maya Kleiman,Iris Yedidia,Nofar Chriker

doi:10.1038/s41438-020-00446-2

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.

Highlights

Zantedeschia, commonly known as calla lily, is one of the world’s most iconic ornamental plants
POD and polyphenol oxidases (PPOs) analysis in both Zantedeschia groups revealed higher basal levels of POD activity in Captain Romance” (CR), as compared with ZA (Supplementary Fig. S1); following infection with P. brasiliense (Pb), POD activity was downregulated in CR, while in ZA, similar activity levels were observed in both treated and control samples
The genus Zantedeschia is divided into two botanical sections: the section Zantedeschia with Z. aethiopica, being relatively tolerant to bacterial soft rot, and section Aestivae being highly susceptible[2,17]

Summary

Introduction

Zantedeschia, commonly known as calla lily, is one of the world’s most iconic ornamental plants. P. brasiliense (Pb) is an emerging pathogen in the family Pectobacteriaceae that has been reported in a wide range of hosts, including ornamental plants and vegetables such as Solanum tuberosum (potato), S. lycopersicum (tomato), and Cucumis sativus (cucumber)[8]. Humidity, and pH are suitable, the bacteria proliferate up to a critical number and start producing and secreting large amounts of PCWDEs that macerate the plant tissue[15]. They attack aboveground plants or underground storage organs, both in the field and in the warehouse, causing severe losses[16]

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Conclusion