Seminal roots of wild and cultivated barley differentially respond to osmotic stress in gene expression, suberization, and hydraulic conductivity.

Tino Kreszies,Lukas Schreiber,Victoria Kreszies,Nandhini Shellakkutti,Alina Osthoff,Kosala Ranathunge,Jutta A Baldauf,Stella Eggels,Viktoria V Zeisler‐Diehl,Frank Hochholdinger

doi:10.1111/pce.13675

Tino Kreszies, Lukas Schreiber + Show 8 more

Open Access

https://doi.org/10.1111/pce.13675

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Abstract

Wild barley, Hordeum vulgare spp. spontaneum, has a wider genetic diversity than its cultivated progeny, Hordeum vulgare spp. vulgare. Osmotic stress leads to a series of different responses in wild barley seminal roots, ranging from no changes in suberization to enhanced endodermal suberization of certain zones and the formation of a suberized exodermis, which was not observed in the modern cultivars studied so far. Further, as a response to osmotic stress, the hydraulic conductivity of roots was not affected in wild barley, but it was 2.5-fold reduced in cultivated barley. In both subspecies, osmotic adjustment by increasing proline concentration and decreasing osmotic potential in roots was observed. RNA-sequencing indicated that the regulation of suberin biosynthesis and water transport via aquaporins were different between wild and cultivated barley. These results indicate that wild barley uses different strategies to cope with osmotic stress compared with cultivated barley. Thus, it seems that wild barley is better adapted to cope with osmotic stress by maintaining a significantly higher hydraulic conductivity of roots during water deficit.

Highlights

In a recent study (Kreszies et al, 2019), we found that roots of the modern barley cultivar Scarlett, exposed to osmotic stress (−0.8 MPa), responded with an enhanced endodermal suberization and reduced hydraulic conductivity of the roots
Results indicated that in response to water deficit, the root apoplast was sealed with suberin and water uptake was exclusively possible via the cell‐to‐cell pathway, which ensures further water uptake into the plant and avoids water loss to the dry soil environment under drought conditions
We extended our investigations including three additional modern barley cultivars (Golden Promise, Morex, and Barke) and compared them with three wild barley accessions (Iran, Jordan, and Pakistan), which are the ancestors of the modern cultivars

Summary

| INTRODUCTION

As important as wheat, maize, and rice (Mascher et al, 2016; Mayer et al, 2012). because of its early domestication around. The increase of suberization of roots in response to abiotic stresses such as water deficit, salinity, or hypoxia has been shown in the past (Barberon et al, 2016; Enstone, Peterson, & Ma, 2002; Hose, Clarkson, Steudle, Schreiber, & Hartung, 2001; Kotula, Schreiber, Colmer, & Nakazono, 2017; Kreszies et al, 2019; Krishnamurthy et al, 2009; Ranathunge, Lin, Steudle, & Schreiber, 2011). Our findings indicate that the wild barley accessions use different strategies to cope with osmotic stress compared with the modern cultivated barley plants. All cultivated barley varieties showed a similar reaction towards osmotic stress, increasing the amount of suberin in roots as an adaptation to prevent uncontrolled passive water loss from the root to the surrounding environment. Water transport was significantly reduced in response to osmotic stress and suberization enhanced, in roots of wild barley, water uptake rates did not change at all and remained constant

| MATERIAL AND METHODS

| RESULTS

Findings

| DISCUSSION