Effects of Phosphate Shortage on Root Growth and Hormone Content of Barley Depend on Capacity of the Roots to Accumulate ABA.

Lidiya Vysotskaya,Alla Korobova,Guzel Akhiyarova,Ian Dodd,Zarina Akhtyamova,Arina Feoktistova,Igor Ivanov,Bulat Kuluev,Guzel Kudoyarova

doi:10.3390/plants9121722

Lidiya Vysotskaya, Alla Korobova + Show 7 more

Open Access

https://doi.org/10.3390/plants9121722

Copy DOI

Abstract

Although changes in root architecture in response to the environment can optimize mineral and water nutrient uptake, mechanisms regulating these changes are not well-understood. We investigated whether P deprivation effects on root development are mediated by abscisic acid (ABA) and its interactions with other hormones. The ABA-deficient barley mutant Az34 and its wild-type (WT) were grown in P-deprived and P-replete conditions, and hormones were measured in whole roots and root tips. Although P deprivation decreased growth in shoot mass similarly in both genotypes, only the WT increased primary root length and number of lateral roots. The effect was accompanied by ABA accumulation in root tips, a response not seen in Az34. Increased ABA in P-deprived WT was accompanied by decreased concentrations of cytokinin, an inhibitor of root extension. Furthermore, P-deficiency in the WT increased auxin concentration in whole root systems in association with increased root branching. In the ABA-deficient mutant, P-starvation failed to stimulate root elongation or promote branching, and there was no decline in cytokinin and no increase in auxin. The results demonstrate ABA’s ability to mediate in root growth responses to P starvation in barley, an effect linked to its effects on cytokinin and auxin concentrations.

Highlights

Deficiencies in mineral nutrients reduce plant growth and crop yields
Pstarvation decreased shoot mass in both WT and abscisic acid (ABA) deficient mutant plants (Figure 1), indicating that ABA was not involved in regulating shoot growth responses to P starvation
Shoot CK concentrations decreased in P-starved WT plants (Figure 8), they did not change in Az34, while P starvation decreased both genotypes’ shoot growth

Summary

Introduction

Deficiencies in mineral nutrients reduce plant growth and crop yields. Changes in root architecture are an important adaptation to acquire scarce nutrient resources from the soil solution [1]. Rapid root elongation allows foraging for water and ions in the soil, while active root branching at sites of locally high nutrient concentrations enhances nutrient uptake [2]. Despite sustained interest in root architecture regulation (the rate of root elongation and branching), many mechanisms are still not fully understood. Increased biomass allocation to root growth is another common response to nitrogen (N) and phosphorus (P) deficits [3,4], with each element inducing some specific changes in root architecture. While low N primarily stimulates root elongation [5], P deficit increased root branching [6–9]. Effects of Plants 2020, 9, 1722; doi:10.3390/plants9121722 www.mdpi.com/journal/plants

Objectives

Results

Discussion

Conclusion