The transcriptome of potato tuber phellogen reveals cellular functions of cork cambium and genes involved in periderm formation and maturation

Vijaya K R Vulavala,Idit Ginzberg,Oded Shoseyov,Adi Faigenboim,Edna Fogelman

doi:10.1038/s41598-019-46681-z

Vijaya K R Vulavala, Idit Ginzberg + Show 3 more

Open Access

https://doi.org/10.1038/s41598-019-46681-z

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Abstract

The periderm is a protective corky tissue that is formed through the cambial activity of phellogen cells, when the outer epidermis is damaged. Timely periderm formation is critical to prevent pathogen invasion and water loss. The outer layers of the potato periderm, the tuber skin, serves as a model to study cork development. Early in tuber development the phellogen becomes active and produces the skin. During tuber maturation it becomes inactive and the skin adheres to the tuber flesh. The characterization of potato phellogen may contribute to the management of costly agricultural problems related to incomplete skin-set and the resulting skinning injuries, and provide us with new knowledge regarding cork development in planta. A transcriptome of potato tuber phellogen isolated by laser capture microdissection indicated similarity to vascular cambium and the cork from trees. Highly expressed genes and transcription factors indicated that phellogen activation involves cytokinesis and gene reprograming for the establishment of a dedifferentiation state; whereas inactivation is characterized by activity of genes that direct organ identity in meristem and cell-wall modifications. The expression of selected genes was analyzed using qPCR in native and wound periderm at distinct developmental stages. This allowed the identification of genes involved in periderm formation and maturation.

Highlights

Potato tubers are covered with a protective corky tissue called the periderm
To visualize the phellogen in developing periderm, cultures of in vitro-induced microtubers were prepared from transgenic plants carrying constructs with the cell cycle marker CycB123 (Fig. 1a) and the cytokinin-responsive element ARR524 (Fig. 1b), both fused to GUS reporter gene
Phellogen characteristics and its shared functions with cork and vascular cambium. Despite their importance in planta, there is lack of information regarding the characteristics of phellogen cells with respect to their initiation, proliferative activity and their inactivation following the completion of periderm development

Summary

Introduction

Potato tubers are covered with a protective corky tissue called the periderm. The periderm is made up of three types of cells[1]. The original epidermis is replaced by the protective periderm; subepidermal cells undergo dedifferentiation to initiate the phellogen cells that sequentially initiate skin formation. It has been suggested that cytological events that lead to potato phellogen initiation and periderm development may follow a transient increase in auxin and lipid hydroxyperoxide levels, both peaking at 20 to 30 min after the wounding of a potato tuber[13]. This is followed by mitotic activity of cells competent to produce periderm, starting from 120 min post-wounding[13]. It was further suggested that the factor might act through the modulation of cytokinin homeostasis[17]

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