Differential responses of oat cultivars to phospha

Authors: Ewa Żebrowska Elżbieta Bujnowska Iwona Ciereszko

Publish Date: 2011/12/24

Volume: 34, Issue: 4, Pages: 1251-1260

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Abstract

The effect of phosphate starvation on growth and acid phosphatases APases localization and activity in oat tissues was investigated Oat cultivars Avena sativa L—Arab Polar Szakal were grown for 1–3 weeks in complete nutrient medium +P and without phosphate −P Pi concentration in plant tissues decreased strongly after culturing on −P medium Pi deficit reduced shoot growth stimulated root elongation and increased ratio of root/shoot in all oat cultivars Pi deficit had a greater impact on growth of oat cv Polar than other varieties A decrease in the internal Pi status led to an increase of acid phosphatase activities in extracts from shoots and roots and in root exudates The highest activity of secreted APases was observed for oat cv Arab during the third week of growth under Pideficient conditions The activity of extracellular APase was high in young growing zones of roots of −P plants Histochemical visualization indicated high activity of APases in the epidermis and vascular tissues of −P plants Pi deficiency increased intracellular APase activity in shoot mainly in oat cv Polar whereas APase activity in roots was the highest in oat cv Szakal Protein extracts from roots and shoots were run on native discontinuous PAGE to determine which isoforms may be affected by Pi deficiency Three major APase isoforms were detected in all oat plants one was strongly induced by Pi deficit The studied oat cultivars differed in terms of acclimation to deficiency of phosphate—used various pools of APases to acquire Pi from external or internal sourcesPhosphorus plays an important role in various processes such as organic compounds biosynthesis photosynthesis respiration and energy transfer regulation of enzymes activity and gene expression or signal transduction Maleszewski et al 2004 Ciereszko et al 2005 Ciereszko and Kleczkowski 2005 Rychter and Rao 2005 Yang and Finnegan 2010 Yao et al 2011 Availability of phosphorus determines the plant growth development reproduction and crop yield Marschner 1995 Plants absorb only inorganic phosphate Pi but most soil phosphorus exists as insoluble complexes eg aluminum and ferrous phosphates or inaccessible to plants organic forms Marschner 1995 Vance et al 2003 Phosphorus is frequently the most limiting element for cultivated plants Application of phosphorusrich fertilizers is recommended in agriculture for enhancing Pi availability and stimulating crop yield However the inexpensive rock phosphate reserves may be soon depleted Vance et al 2003 Cordell et al 2009 As the inorganic phosphorus sources are nonrenewable further investigations and selection of cultivars tolerant to Pi depletion are very important in order to sustain or improve crop productivity Shenoy and Kalagudi 2005 Cordell et al 2009

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