Morphological and physiological responses of the potato stem transport tissues to dehydration stress

Ernest B Aliche,Alena Prusova-Bourke,C Gerard Van Der Linden,Edo Gerkema,Richard G F Visser,Mariam Ruiz-Sanchez,Henk Van As,Marian Oortwijn

doi:10.1007/s00425-019-03336-7

Ernest B Aliche, Alena Prusova-Bourke + Show 6 more

Open Access

https://doi.org/10.1007/s00425-019-03336-7

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Abstract

Main conclusionAdaptation of the xylem under dehydration to smaller sized vessels and the increase in xylem density per stem area facilitate water transport during water-limiting conditions, and this has implications for assimilate transport during drought.The potato stem is the communication and transport channel between the assimilate-exporting source leaves and the terminal sink tissues of the plant. During environmental stress conditions like water scarcity, which adversely affect the performance (canopy growth and tuber yield) of the potato plant, the response of stem tissues is essential, however, still understudied. In this study, we investigated the response of the stem tissues of cultivated potato grown in the greenhouse to dehydration using a multidisciplinary approach including physiological, biochemical, morphological, microscopic, and magnetic resonance imaging techniques. We observed the most significant effects of water limitation in the lower stem regions of plants. The light microscopy analysis of the potato stem sections revealed that plants exposed to this particular dehydration stress have higher total xylem density per unit area than control plants. This increase in the total xylem density was accompanied by an increase in the number of narrow-diameter xylem vessels and a decrease in the number of large-diameter xylem vessels. Our MRI approach revealed a diurnal rhythm of xylem flux between day and night, with a reduction in xylem flux that is linked to dehydration sensitivity. We also observed that sink strength was the main driver of assimilate transport through the stem in our data set. These findings may present potential breeding targets for drought tolerance in potato.

Highlights

Potato (Solanum tuberosum L.) is the world’s third most important food crop (Bradshaw 2010) with a total global cultivation land area of about 20 million hectares (Haverkort et al 2013)
We examined the dehydration responses of different regions of the potato stem in terms of their vascular tissue morphology and sap transport, and how dehydration stress affects the interaction between xylem transport and phloem transport
Our results indicate that morphological changes in xylem diameter and density under drought may be associated with xylem flux and dehydration tolerance in potato plants

Summary

Introduction

Potato (Solanum tuberosum L.) is the world’s third most important food crop (Bradshaw 2010) with a total global cultivation land area of about 20 million hectares (Haverkort et al 2013). Potato plant is drought sensitive (Obidiegwu et al 2015). Hijmans (2003) estimated that drought will reduce potato yield by up to 32% globally between the years 2040–2069. Drought is gaining global concern in view of climate change scenarios and its huge negative impacts on agriculture resulting from reduced rainfall and increased evaporation (Grayson 2013). Research efforts toward improving potato tuber yield under drought are increasing. The role of the potato stem in drought tolerance has hardly been studied, even though the stem plays vital and indispensable roles in the bidirectional transport of water,

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