The site of water stress governs the pattern of ABA synthesis and transport in peanut.

Bo Hu,Kui Ge,Jiajia Cao,Ling Li

doi:10.1038/srep32143

Abstract

Abscisic acid (ABA) is one of the most important phytohormones involved in stress responses in plants. However, knowledge of the effect on ABA distribution and transport of water stress at different sites on the plant is limited. In this study, water stress imposed on peanut leaves or roots by treatment with PEG 6000 is termed “leaf stress” or “root stress”, respectively. Immunoenzyme localization technolony was first used to detect ABA distribution in peanut. Under root stress, ABA biosynthesis and distribution level were all more pronounced in root than in leaf. However, ABA transport and the ability to induce stomatal closure were still better in leaf than in root during root stress; However, ABA biosynthesis initially increased in leaf, then rapidly accumulated in the vascular cambium of leaves and induced stomatal closure under leaf stress; ABA produced in root tissues was also transported to leaf tissues to maintain stomatal closure. The vascular system was involved in the coordination and integration of this complex regulatory mechanism for ABA signal accumulation. Water stress subject to root or leaf results in different of ABA biosynthesis and transport ability that trigger stoma close in peanut.

Highlights

abscisic acid (ABA) synthesized in root tissues is thought to be transported to the apoplastic space of the leaf tissue by long distance transport, after which it enters the cytoplasm of leaf cells by simple diffusion without specific transporters[15]
25–30% of the ABA in xylem sap might come from shoots due to recirculation of basipetally transported ABA in the phloem[16], root ABA concentration increases in response to soil drying due to an increase in ABA biosynthesis by roots and ABA recirculation from shoots via phloem transport[17]
We found that biosynthesis of ABA in peanut plants subject to water deficiency may be dependent on developmental stage, with the roots being the initial site of ABA biosynthesis during the seedling stage, whereas during the fruiting stage ABA biosynthesis occurs initially in the leaf

Summary

Introduction

AJ574819) and immunostaining has been used to show that both AhNCED1 and ABA levels increase rapidly in the vascular parenchyma of plants subjected to water stress; AhNCED1 distribution reflects that of ABA14. These results provide insights into AhNCED1-mediated ABA biosynthesis and distribution in peanut, and its importance for a rapid response to water stress. We previously suggested that the regional distribution patterns of ABA biosynthesis in seedling-stage peanut plants in response to water stress were root-stem-leaf[12]. This study aimed to assess how ABA biosynthesis and transport, and their influence on stomatal closure, depend on the site of imposition of water stress in peanut

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