Differentially expressed galactinol synthase(s) in chickpea are implicated in seed vigor and longevity by limiting the age induced ROS accumulation.

Prafull Salvi,Harmeet Kaur,Bhanu Prakash Petla,Venkateswara Rao,Manoj Majee,Pooja Verma,Nitin Uttam Kamble,Saurabh Chandra Saxena,Shraboni Ghosh

doi:10.1038/srep35088

Prafull Salvi, Harmeet Kaur + Show 7 more

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https://doi.org/10.1038/srep35088

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Journal: Scientific Reports	Publication Date: Oct 11, 2016
Citations: 77	License type: CC BY 4.0

Affiliation: National Institute of Plant Genome Research

Abstract

Galactinol synthase (GolS) catalyzes the first and rate limiting step of Raffinose Family Oligosaccharide (RFO) biosynthetic pathway, which is a highly specialized metabolic event in plants. Increased accumulation of galactinol and RFOs in seeds have been reported in few plant species, however their precise role in seed vigor and longevity remain elusive. In present study, we have shown that galactinol synthase activity as well as galactinol and raffinose content progressively increase as seed development proceeds and become highly abundant in pod and mature dry seeds, which gradually decline as seed germination progresses in chickpea (Cicer arietinum). Furthermore, artificial aging also stimulates galactinol synthase activity and consequent galactinol and raffinose accumulation in seed. Molecular analysis revealed that GolS in chickpea are encoded by two divergent genes (CaGolS1 and CaGolS2) which potentially encode five CaGolS isoforms through alternative splicing. Biochemical analysis showed that only two isoforms (CaGolS1 and CaGolS2) are biochemically active with similar yet distinct biochemical properties. CaGolS1 and CaGolS2 are differentially regulated in different organs, during seed development and germination however exhibit similar subcellular localization. Furthermore, seed-specific overexpression of CaGolS1 and CaGolS2 in Arabidopsis results improved seed vigor and longevity through limiting the age induced excess ROS and consequent lipid peroxidation.

Highlights

Galactinol synthase (GolS) catalyzes the first and rate limiting step of Raffinose Family Oligosaccharide (RFO) biosynthetic pathway, which is a highly specialized metabolic event in plants
We clearly demonstrated that galactinol synthase, the rate limiting enzyme of RFO biosynthesis, plays an important role in seed vigor and longevity
The pattern of galactinol synthase (GolS) activity along with galactinol and raffinose accumulation reflects that galactinol is mostly utilized for raffinose synthesis during the very late stage of seed maturation, as galactinol content reduces and raffinose content increases towards the end of seed maturation

Summary

Introduction

Galactinol synthase (GolS) catalyzes the first and rate limiting step of Raffinose Family Oligosaccharide (RFO) biosynthetic pathway, which is a highly specialized metabolic event in plants. Synthesis of Raffinose Family of Oligosaccharides (RFOs) is a highly specialized metabolic event in higher plants where galactinol synthase (GolS; EC: 2.4.1.123) catalyzes the key step in RFO biosynthesis These RFOs participate in many physiological processes like translocation of photoassimilates, abiotic stress tolerance, seed desiccation tolerance etc.[1,2,3,4]. Accumulation of galactinol and RFOs during late maturation stages in few plant species in legumes suggests their potential role in seed desiccation tolerance and longevity in dry state[3,9,19]. Implication of these isoforms in seed vigor and longevity has been investigated through seed specific overexpression in Arabidopsis thaliana

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