Ascorbate deficient semi-dwarf asfL1 mutant of Lathyrus sativus exhibits alterations in antioxidant defense

Abstract

An ascorbate-deficient semi-dwarf mutant asfL-1 was detected in 250 Gy γ-ray treated grass pea (Lathyrus sativus L.) cv. BioR-231. The mutant contained only 42 % of leaf and 20 % of root ascorbate content of mother control (MC). I investigated the possible causes of ascorbate deficiency and its effect on growth and antioxidant defense in control and 150 mM NaCl-treated seedling after 60-d growth period. Ascorbate deficiency was due to significant reduction in activities of monodehydroascorbate reductase and dehydroascorbate reductase as well as increase in ascorbate oxidase, leading to considerable decrease in redox state. Despite low ascorbate pool and decrease in ascorbate peroxidase activity, shoot and root biomass production in asfL-1 mutant were similar to MC plants, even at NaCl treatment. High accumulation of glutathione (GSH) coupled with high activities of GSH reductase, catalase, GSH peroxidase and peroxidase in both tissues of the mutant permitted efficient recycling of GSH and scavenging of H 2 O 2 through well integrated catalase/peroxidase system, despite high superoxide dismutase activity under NaCl treatment. The collapse of this system led to inhibition of growth in NaCl-treated mother plants. Together, the results suggested that asfL-1 plants undertook a major reshuffle in its antioxidant defense machinery, which effectively counterbalanced the negative impact of ascorbate deficiency and remained unperturbed by NaCl treatment to maintain normal growth and biomass production.

Arsenic-induced oxidative stress in the common bean legume, Phaseolus vulgaris L. seedlings and its amelioration by exogenous nitric oxide

“…Obviously, low APX activity in the present material could not contain rising level of H 2 O 2 . Decreased activity of APX might be either due to low availability of reduced ascorbate, its co-factor, or inhibition of its isoform/s by excess H 2 O 2 or both (Hiner et al 2000;Talukdar 2012b). Furthermore, as arsenic treatment reduced both the GR and DHAR activity to a significant extent, regeneration of glutathione and ascorbate to their reduced forms might be severely hampered.…”

“…Significant increase in root POX level, as observed in this study, might be responsible for cell wall thickness in SNP + As-treated roots. POX is able to catalyze lignin synthesis and is induced in higher plants exposed to toxic metals or other stresses (Prasad 1996;Probst et al 2009;Talukdar 2012b).…”

Differential Response of Cysteine-deficient Lentil (<i>Lens culinaris</i> Medik.) Mutants Impaired in Foliar O-acetylserine(thiol)-lyase Expression

“…2.1 cysLc1 and cysLc2: two unique biochemical mutants isolated in lentil Induced mutagenic techniques have earlier been successfully used to isolate novel biochemical mutants exhibiting modulations in antioxidant defense components in edible legumes such as lentil, common beans, and grass pea (Talukdar, 2012a;2012b;Talukdar and Talukdar, 2013a;2013b). In present case, both the mutants are unique in legumes, containing very low seed cysteine level and deficiency in a major cysteine-synthesizing enzyme in photosynthetic organ.…”

“…Substantial reduction of GSH level with concomitant rise in GSSG level led to reduction in GSH-redox in the mutant lines. GSH is a multipurpose thiol peptide, and functions as an efficient thiol-buffer to maintain delicate redox balance in favor of plant growth and development (Noctor et al, 2011;Talukdar, 2012a;2012b). However, the peptide exclusively requires cysteine as one of its building blocks, and thus, it seems likely that apart of constant consumption by usual cellular processes low availability of cysteine also resulted in GSH-deficiency and concomitant fall in GSH-redox in both the mutants.…”

“…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).…”