Atmospheric H2S and SO2 as sulfur source for Brassica juncea and Brassica rapa: impact on the glucosinolate composition.

Tahereh Aghajanzadeh,Stanislav Kopriva,Stanislav Kopriva,Luit J De Kok,Malcolm J Hawkesford,Anna Koprivova

doi:10.3389/fpls.2015.00924

Abstract

The impact of sulfate deprivation and atmospheric H2S and SO2 nutrition on the content and composition of glucosinolates was studied in Brassica juncea and B. rapa. Both species contained a number of aliphatic, aromatic and indolic glucosinolates. The total glucosinolate content was more than 5.5-fold higher in B. juncea than in B. rapa, which could solely be attributed to the presence of high levels of sinigrin, which was absent in the latter species. Sulfate deprivation resulted in a strong decrease in the content and an altered composition of the glucosinolates of both species. Despite the differences in patterns in foliarly uptake and metabolism, their exposure hardly affected the glucosinolate composition of the shoot, both at sulfate-sufficient and sulfate-deprived conditions. This indicated that the glucosinolate composition in the shoot was hardly affected by differences in sulfur source (viz., sulfate, sulfite and sulfide). Upon sulfate deprivation, where foliarly absorbed H2S and SO2 were the sole sulfur source for growth, the glucosinolate composition of roots differed from sulfate-sufficient B. juncea and B. rapa, notably the fraction of the indolic glucosinolates was lower than that observed in sulfur-sufficient roots.

Highlights

Brassicaceae are nutritionally important crops containing relatively high levels of sulfurcontaining secondary metabolites, viz., glucosinolates, which are responsible for the flavor of these species and may be of great significance as phytopharmaceuticals considering their potential anti-carcinogenic properties (Fahey et al, 2001; Wittstock and Halkier, 2002; Jahangir et al, 2009)
Sulfate-deprivation resulted in strongly decreased glucosinolate content, both in shoots and roots of B. juncea and B. rapa (Aghajanzadeh et al, 2014; Figure 1)
The glucosinolate content of both shoot and root of sulfate-deprived plants was substantially enhanced upon H2S or SO2 exposure, was still lower than that observed in sulfate-sufficient plants (Aghajanzadeh et al, 2014; Figure 1)

Summary

Introduction

Brassicaceae are nutritionally important crops containing relatively high levels of sulfurcontaining secondary metabolites, viz., glucosinolates, which are responsible for the flavor of these species and may be of great significance as phytopharmaceuticals considering their potential anti-carcinogenic properties (Fahey et al, 2001; Wittstock and Halkier, 2002; Jahangir et al, 2009). 3 -phosphoadenosine 5 -phosphosulfate (PAPS), which is Sulfur nutrition and glucosinolate composition synthetized from adenosine 5 -phosphosulfate (APS), the first intermediate in the sulfate reduction pathway by APS kinase, is essential for the synthesis of the sulfated moiety of glucosinolates (Schnug, 1990, 1993; Halkier and Gershenzon, 2006; Falk et al, 2007; Kopriva et al, 2012). Brassica species contain a wide variety of glucosinolates, which on the basis of amino acid precursors, side chain elongation and further modification are classified in aliphatic, indolic, and aromatic glucosinolates (Wittstock and Halkier, 2002; Halkier and Gershenzon, 2006)

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Conclusion