Endogenous abscisic acid promotes hypocotyl growth and affects endoreduplication during dark-induced growth in tomato (Solanum lycopersicum L.).

Jan F Humplík,Michaela Jandová,Ondřej Tomanec,Martin Fellner,Véronique Bergougnoux,Ondřej Novák,Jan Šimura,Jakub Rolčík,Aleš Pěnčík,Ricardo Aroca

doi:10.1371/journal.pone.0117793

Abstract

Dark-induced growth (skotomorphogenesis) is primarily characterized by rapid elongation of the hypocotyl. We have studied the role of abscisic acid (ABA) during the development of young tomato (Solanum lycopersicum L.) seedlings. We observed that ABA deficiency caused a reduction in hypocotyl growth at the level of cell elongation and that the growth in ABA-deficient plants could be improved by treatment with exogenous ABA, through which the plants show a concentration dependent response. In addition, ABA accumulated in dark-grown tomato seedlings that grew rapidly, whereas seedlings grown under blue light exhibited low growth rates and accumulated less ABA. We demonstrated that ABA promotes DNA endoreduplication by enhancing the expression of the genes encoding inhibitors of cyclin-dependent kinases SlKRP1 and SlKRP3 and by reducing cytokinin levels. These data were supported by the expression analysis of the genes which encode enzymes involved in ABA and CK metabolism. Our results show that ABA is essential for the process of hypocotyl elongation and that appropriate control of the endogenous level of ABA is required in order to drive the growth of etiolated seedlings.

Highlights

Abscisic acid (ABA) is very often regarded as an inhibitor of shoot growth e. g. [1], [2], [3]
The effects of abscisic acid (ABA) deficiency on hypocotyl growth and expansion of hypocotyl cells The tomato sit mutant, which is defective in the last step of ABA biosynthesis, was used as the main tool to investigate the role of ABA in hypocotyl growth
The not seedlings were significantly inhibited in the hypocotyl growth compared to the WT, but the treatment with 50 nM ABA led to the improvement of the mutant

Summary

Introduction

Abscisic acid (ABA) is very often regarded as an inhibitor of shoot growth e. g. [1], [2], [3]. Abscisic acid (ABA) is very often regarded as an inhibitor of shoot growth e. G. [1], [2], [3] This is based on the fact that i) ABA accumulates at high concentrations in water stressed plants, correlating with growth inhibition [4], [5], [6] and ii) treatment with exogenous ABA at μM concentrations inhibits shoot growth [7], [5], [8]. ABA deficient mutants are PLOS ONE | DOI:10.1371/journal.pone.0117793. ABA Promotes Hypocotyl Growth in Tomato (IGA-PrF-2013-003; IGA-PrF-2014001). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion