Deciphering Phosphate Deficiency-Mediated Temporal Effects on Different Root Traits in Rice Grown in a Modified Hydroponic System.

Manisha Negi,Vandna Rai,Ajay Jain,Raghavendrarao Sanagala

doi:10.3389/fpls.2016.00550

Manisha Negi, Vandna Rai + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2016.00550

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Abstract

Phosphate (Pi), an essential macronutrient for growth and development of plant, is often limiting in soils. Plants have evolved an array of adaptive strategies including modulation of root system architecture (RSA) for optimal acquisition of Pi. In rice, a major staple food, RSA is complex and comprises embryonically developed primary and seminal roots and post-embryonically developed adventitious and lateral roots. Earlier studies have used variant hydroponic systems for documenting the effects of Pi deficiency largely on primary root growth. Here, we report the temporal effects of Pi deficiency in rice genotype MI48 on 15 ontogenetically distinct root traits by using easy-to-assemble and economically viable modified hydroponic system. Effects of Pi deprivation became evident after 4 days- and 7 days-treatments on two and eight different root traits, respectively. The effects of Pi deprivation for 7 days were also evident on different root traits of rice genotype Nagina 22 (N22). There were genotypic differences in the responses of primary root growth along with lateral roots on it and the number and length of seminal and adventitious roots. Notably though, there were attenuating effects of Pi deficiency on the lateral roots on seminal and adventitious roots and total root length in both these genotypes. The study thus revealed both differential and comparable effects of Pi deficiency on different root traits in these genotypes. Pi deficiency also triggered reduction in Pi content and induction of several Pi starvation-responsive (PSR) genes in roots of MI48. Together, the analyses validated the fidelity of this modified hydroponic system for documenting Pi deficiency-mediated effects not only on different traits of RSA but also on physiological and molecular responses.

Highlights

Rice, a major staple food in Asia, is grown largely under rain-fed ecosystem on soils that are naturally low in phosphorus (P) (Gamuyao et al, 2012)
The modified hydroponic system was amenable for detailed analysis of the temporal effects of Pi deprivation on the developmental responses of primary, seminal and adventitious roots and of the lateral roots on each of them of rice genotypes MI48 and Nagina 22 (N22)
The data generated on Pi deficiencymediated effects on different root traits could be employed for mathematical simulation and modeling

Summary

Introduction

A major staple food in Asia, is grown largely under rain-fed ecosystem on soils that are naturally low in phosphorus (P) (Gamuyao et al, 2012). Root system plays a key role in acquisition of inorganic phosphate (Pi); a readily bioavailable source of P in rhizosphere. Phosphate Deficiency-Mediated Effects on Root (Marschner, 1995). Soil exploration by roots is critically important for optimal acquisition of Pi (Lynch, 2015). Arabidopsis thaliana, a favored model plant species, has been extensively used for elucidation of Pi deficiency-mediated responses of root system architecture (RSA; Sánchez-Calderón et al, 2005; Gruber et al, 2013; Kellermeier et al, 2014). Pi deficiency induces inhibitory effects on the developmental responses of both embryonically and postembryonically developed primary and lateral roots, respectively (Sánchez-Calderón et al, 2005; Jain et al, 2007)

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