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PLANT GENE & TRAIT
2014, Vol. 5, No.5, 33-39
http://pgt.biopublisher.ca
Research Report
Open Access
Differential Response of Cysteine-deficient Lentil (
Lens culinaris
Medik.)
Mutants Impaired in Foliar
O
-acetylserine(thiol)-lyase Expression
Dibyendu Talukdar
Department of Botany, R.P.M. College (University of Calcutta), Uttarpara, Hooghly 712258, West Bengal, India
Correspondings author, dibyendutalukdar9@gmail.com;
Authors
Plant Gene and Trait, 2014, Vol.5, No.5 doi: 10.5376/pgt.2014.05.0005
Copyright
© 2014 Talukdar, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Lentil is a cool-season pulse crop, rich in protein but deficient in two sulphur-containing amino acids cysteine and
methionine. Due to low genetic variability in existing germplasm, induced mutagenic technique has been adopted in lentil, and two
mutant lines exhibiting poor growth and low dry weight were isolated in M
2
-mutagenized (0.10% and 0.15% EMS, 6 h) population
of variety L 414. Further analysis revealed that plants from both mutant lines were highly deficient in seed cysteine (Cys) content,
and thus, were tentatively designated as
cysLc1
and
cysLc2
mutants. Mutant plants were advanced to M
3
generation. Biochemical
analysis through cysteine synthesizing pathway in leaves revealed that activity of serine acetyl transferase (SAT) was normal in both
the mutant progenies but both were highly deficient in foliar
O
-acetylserine(thiol)-lyase (OAS-TL) activity. Transcriptomic analysis
by qRT-PCR confirmed normal expression of SAT in both mutants but revealed differential expressions of two OAS-TL isoforms;
OAS-TL 1 isoform was not detectable in
cysLc1
mutant while expression of OAS-TL 2 isoform was totally repressed in leaves of
cysLc2
mutant. Genetic studies and test of allelism pointed out that both the mutants were recessive and were complementing with
each other to produce normal in F
1
and normal along with mutant plants in F
2
progeny. The progeny plants exhibiting normal
phenotype showed normal mRNA transcripts of both OAS-TL isoforms. Being stable and self-fertile, the mutants will give vital clues
in genetic basis of thiol-metabolic network of lentil crops.
Keywords
EMS-Mutagenesis; Gene expression analysis; Glutathione; Lentil; OAS-TL isoforms
Background
Mutational strategy provides a powerful tool to study
the genetic, physiological and molecular mechanisms
of plant metabolism. This technique has been
successfully used to develop cytogenetic and breeding
tools in different legume crops including lentil (Fazal
Ali et al., 2010; Talukdar, 2009; 2013), the potential of
which is now being exploited to ascertain the intrinsic
metabolic events in grain legumes (Talukdar,
2012a;
2012b; Tsyganov et al., 2013). Lentil is a cool-season
edible pulse crop grown widely in the Indian
subcontinent, West Asia, North Africa and parts of
Europe, Oceania and North America (Erskine et al.,
2011) and has tremendous health benefits (Erskine et
al., 2011; Talukdar, 2012c). Despite a protein rich
pulse crop with high nutritional values, improvement
of this crop has not reached its desirable peak due to
low genetic variability.
Sulphur metabolism is fundamental to agricultural
productivity and quality of grain in legume crops
(Wirtz and Hell,
2006; Tabe et al., 2010; Khan and
Mazid,
2011; Liao et al., 2012). Plants generally take
sulphur from soil as sulphate. After reduction of
sulphate to sulphide, the sulphide combined with
O
-acetylserine (OAS) forms cysteine in a reaction
catalyzed by
O
-acetylserine (thiol) lyase (OAS-TL)
either in free active homodimer or in association with
serine acetyl transferase (SAT) as an inactive subunit
of the cysteine synthase (CS) complex (Takahashi
et
al., 2011). Cysteine is the first committed molecule in
plant metabolism that contains both sulphur and
nitrogen, and, thus, the regulation of its biosynthesis is
of utmost importance for the synthesis of a number of
essential metabolites in plant pathways (Wirtz and
Hell, 2006). Cysteine is incorporated into proteins and
glutathione (GSH) directly (Wirtz and Hell,
2006).
Several studies including mutants of
Arabidopsis
indicate that decreased activity of CS ultimately
compromise cysteine level and GSH synthesis in
PLANT GENE AND TRAIT
Preferred citation for this article:
Talukdar, 2014, Differential Response of Cysteine-deficient Lentil (
Lens culinaris
Medik.) Mutants Impaired in Foliar
O
-acetylserine(thiol)-lyase Expression,
Plant Gene and Trait, Vol.5, No.5 33-39 (doi: 10.5376/pgt.2014.05.0005)
Received: 17 Mar., 2014
|
Accepted: 25 Mar., 2014
|
Published: 28 Mar., 2014