Title: Enhanced salt tolerance and photosynthetic performance: Implication of ɤ-amino butyric acid application in salt-exposed lettuce (Lactuca sativa L.) plants (original) (raw)
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Biostimulants-Based Amino Acids Augment Physio-Biochemical Responses and Promote Salinity Tolerance of Lettuce Plants (Lactuca sativa L.), 2023
Abstract: Studying the biostimulation effect of amino acids indicated their possible role in salt stress mitigation. In this investigation, six exogenous amino acids (alanine (Ala), arginine (Arg), glutamine (Glu), glycine (Gly), methionine (Met), and proline (Pro)) at 0.5 g/L were sprayed to evaluate their impact on lettuce plants cultivated under simulated salt stress conditions. Photosynthetic pigments, ion absorption, endogenous amino acids contents, catalase (CAT), and peroxidase (POD) enzyme activities were determined. A significant alleviation of salt stress was noticed when EAAs were used in the stress-induced plants, and applying Gly, Met, and Pro improved the plant status under salt stress conditions. The highest electric conductivity (568 μS/g) was testified from the control treatment (50 mM NaCl), while applying exogenous amino acids reduced electrical conductivity (EC), and the result was located between 469 and 558 μS/g. AAs alleviated Cl- anions in the lettuce leaves by 25% in comparison to control plants. Na+ cations were alleviated when the stress-induced plants were sprayed with amino acids. In contrast, applying amino acids promoted K+ uptake, and Arg presented the highest contents (3226 μg/g). AAs promoted chlorophyll (chl a and chl b) concentrations compared to the control treatment, and Met produced the maximum chl a content, while the carotene (car) contents significantly augmented when Gly, Met, and Pro were applied. AAs were highly generated in non-stressed treatment (Std) compared to the control. Under simulated salinity stress, Met and Pro application enhanced proteinogenic amino acids expression. Compared to Ctl treatment, peroxidase enzyme activities significantly diminished in the other treatments, which fell by over 40% when Gly, Met, and Pro were sprayed.
Turkish Journal of Agriculture and Forestry
Salinity is affecting more than 6 million hectares of cultivated area in Pakistan. The use of amino acids offers a pragmatic solution for minimizing the adverse effects of salinity on Spinacia oleracea L. (spinach). The present study evaluated the possible potential of amino acids in enhancing the salinity tolerance in spinach and identified the probable underlying mechanisms. The experiment comprised of two factors viz. amino acids with total of seven treatments; control, salinity (sal) 100 mM, Methionine + sal, Phenylalanine + sal, Proline + sal, Tyrosine + sal, Combined amino acids + sal, and two spinach cultivars (Desi Palak and VRI-2019). Salinity stress decreased the morpho-physiological attributes of both spinach cultivars, nevertheless, the application of combined amino acids effectively improved the tolerance against salinity stress. Compared with control, all applications of amino acids increased the root and shoot length, fresh and dry weight, number of leaves, and plant yield per plant of both spinach cultivars. However, the maximum was noted by the application of combined amino acids. Combined amino acids triggered the activities of antioxidants (catalase, superoxide dismutase, peroxidase), increased the contents of free proline, phenolics, flavonoids, chlorophyll a, b, carotenoids, calcium, and potassium in root and shoot while decreasing the reactive oxygen species (hydrogen peroxide) and sodium contents in both spinach cultivars under saline conditions. Overall, the VRI-2019 performed better than Desi Palak. The vigorous growth along with higher salinity tolerance because of amino acid treatments was linked to better chlorophyll contents, higher accumulation of osmolytes, maintenance of ionic balance, and an improved antioxidant defense system in Spinacia oleracea.
Open Agriculture
This study aimed to explore the changes in morphological, physiological and biochemical characteristics of lettuce (Lactuca sativa L.) in response to salt stress when grown using hydroponic techniques. The seedlings were subjected to five different concentrations (0 mM, 50 mM, 100 mM, 150 mM, and 200 mM) of NaCl for three weeks. During the salt stress, morphological properties (shoot length, root length, total plant weight, leaf number) were measured in every week. After 21 days of salt stress, physiological properties (water content and relative water content) and biochemical properties (proline, protein, phenol, reducing and non-reducing sugar content) were measured. Morphological and physiological properties were found decreased gradually with increasing salt concentrations. Biochemical properties such as proline and protein content increased remarkably, and total phenol content decreased gradually with increasing salt concentrations. Reducing sugar accumulation was higher in all...
The role of amino acids in improvement in salt tolerance of crop plants
Journal of Stress Physiology & …, 2010
The present work has been performed to study the growth and metabolic activities of maize and broad bean plants which are shown to have a degree of sensitivity to salinity and to determine the role of amino acids proline or phenylalanine in increasing the salt tolerance of theses plants. Dry mass, water content, leaf area and photosynthetic pigment of maize and broad bean plants decreased with increasing salinity. These changes were accompanied with a drop in the contents of soluble sugars, soluble proteins and amino acids. This was accompanied by a marked increase in the proline content. When maize and broad bean plants sprayed with proline or phenylalanine the opposite effect was occurred, saccharides as well as proteins progressively increased at all sanitization levels and proline concentration significantly declined. Salinity significantly increased the sodium content in both shoots and roots of maize and broad bean plants, while a decline in the accumulation of K + , Ca ++ , Mg ++ and P was observed. Amino acids treatments markedly altered the selectivity of Na + , K + , Ca ++ and P in both maize and broad bean plants. Spraying with any of either proline or phenylalanine restricted Na + uptake and enhanced the uptake of K + , K + /Na + ratio, Ca ++ and P selectivity in maize and broad bean plants.
Acta Botanica Gallica Bulletin De La Societe Botanique De France, 2010
Tomato seedlings (Solanum lycopersicon) were exposed to 100 mM NaCl during 10 days. NaCl stress led to about 40% and 20% decrease in leaf and root biomass, respectively. Accumulation of Na + and Clions was concomitant with NH 4 + contents increase in stressed leaves and roots. While total amino acids contents rapidly increased by salt in both organs, they recovered control value in the leaves at the end of treatment. In leaves, NaCl stress increased proline (Pro) and serine (Ser) contents, lately associated with accumulation of γ-aminobutyric (GABA) and asparagine (Asn). Slat-treated roots showed 2-fold higher contents of serine (Ser), glycine (Gly), glutamine (Gln) and GABA. Asparagine became the most abundant amino acid, accounting for 26% of total amino acids in the treated roots. These disturbances in the amino acids composition reflect a new distribution of internal nitrogen compounds, building up an amino acid pool with high N to C ratio (GABA, Pro, Asn, Gln) and avoiding thus an ammoniacal intoxication. Proline, Asn and GABA highly accumulated in the leaves and roots are useful for nitrogen transport to developing tissues and protect against osmotic and oxidative stresses during salt stress.
Journal of Plant Physiology, 2012
Plants accumulate high levels of Gamma amino butyric acid (GABA) in response to different environmental stresses and GABA metabolism has different functions such as osmotic and pH regulation, bypass of tricarboxylic acid cycle, and C:N balance. The cytoplasmic male sterile (CMS) II mutant of Nicotiana sylvestris has a deletion in the mitochondrial gene nad7 which encodes the NAD7 subunit of complex I which causes increased leaf respiration, impaired photosynthesis, slower growth and increased amino acid levels. In this study we aimed to elucidate the role of GABA and GABA metabolism in different genotypes of the same plant system under salt stress (100 mM NaCl) in short (24 h) and long (7, 14 and 21 days) terms. We have investigated the differences in leaf fresh and dry weights, relative water content, photosynthetic efficiency (F v /F m ), glutamate dehydrogenase (GDH, EC 1.4.1.4) and glutamate decarboxylase (GAD, EC 4.1.1.15) enzyme activities, GABA content and GAD gene expression profiles. GDH activity showed variations in CMSII and wild type (WT) plants in the first 24 h. GAD gene expression profiles were in good agreement with the GAD enzyme activity levels in CMSII and WT plants after 24 h. In long-term salinity, GAD activities increased in WT but, decreased in CMSII. GABA accumulation in WT and CMSII plants in short and long term was induced by salt stress. Variations in GDH and GAD activities in relation to GABA levels were discussed and GABA metabolism has been proposed to be involved in better performance of CMSII plants under long term salinity.
Acta Physiologiae Plantarum, 2011
Salt stress perturbs a multitude of physiological processes such as photosynthesis and growth. To understand the biochemical changes associated with physiological and cellular adaptations to salinity, two lettuce varieties (Verte and Romaine) were grown in a hydroponics culture system supplemented with 0, 100 or 200 mM NaCl. Verte displayed better growth under 100 mM NaCl compared to Romaine, but both genotypes registered relatively similar reductions in growth under 200 mM NaCl treatment. Both varieties showed differences in net photosynthetic activity in the absence of salt and 8 days after salt treatment. These differences diminished subsequently under prolonged salt stress (14 days). Verte showed enhanced leaf proline and restricted total cations especially Na ? , lesser malondialdehyde (MDA) formation and lignification in the roots under 100 mM NaCl salinity. Membrane damage estimated by electrolyte leakage increased with elevated salt concentrations in roots of both varieties, but Verte had significantly lower electrolyte leakage relative to Romaine under 100 mM NaCl. Moreover, Verte also accumulated greater levels of carotenoids under increasing NaCl concentrations compared to Romaine. Taken together, these findings suggest that the greater tolerance of Verte to 100 mM NaCl is related to the more restricted accumulation of total cations and toxic Na ? in the roots and enhanced levels of antioxidative metabolites in root and leaf tissue.
Journal of Agricultural and Food Chemistry, 2010
Salinity inhibits plant growth due to osmotic and ionic effects. However, little is known about the impact of genotype and salinity on biochemical and molecular processes in the leafy vegetable lettuce. We report here evaluations of two lettuce types, Verte (NaCl tolerant) and Romaine (NaCl sensitive), under iso-osmotic 100 mM NaCl and 77 mM Na 2 SO 4 treatments. As compared to Romaine, NaCl-treated Verte displayed better growth, contained lower levels of inorganic cations in leaves, and possessed superior antioxidative capacity due to enhanced carotenoid and phenolics biosynthesis and more active antioxidative enzymes resulting in reduced membrane damage. Both genotypes had relatively similar growth patterns under Na 2 SO 4 treatment, but Romaine showed enhanced root lignification, greater malondialdehyde formation, and suppressed Fe-superoxide dismutase expression in roots as compared with Verte.
Effect of Salinity on Germination, Seedling Growth and Acid Phosphatase Activity in Lettuce
American Journal of Plant Sciences, 2015
The impact of salt stress (NaCl 100 mM) on two lettuce varieties Romaine and Vista was conducted at germination and early seedling stages. The seeds of lettuce varieties were provided by the Seed Laboratory of Tunisian Ministry of Agriculture. The seeds were germinated in Petri dishes with double filter paper in distilled water (control) or NaCl solution (100 mM) for 5 days. The result showed that salinity significantly affected percentage and rate of germination in Vista variety but 100% of germination was found in Romaine. Length and fresh weight of root and shoot were reduced significantly with salt treatment in two lettuce varieties. Regarding biochemical analysis, acid phosphatase activity in root increased in Romaine and decreased in Vista. In shoot, this activity showed no difference with the control in the two varieties. However in cotyledons, and during 24 hours after germination, salinity decreased acid phosphatase activity in both varieties whereas in the later hours (48-96 h) this activity reached the value of the control in Romaine and Vista.
2020
Salinity is a serious environmental hazard which limits world agricultural production by adversely affects plant physiology and biochemistry. Hence increase tolerance against salt stress is very important. In this study, we explored the function of β-aminobutyric acid (BABA) in enhancing salt stress tolerance in rapeseed (Brassica napus L.). After pretreatment with BABA, seedlings were exposed to NaCl (100 mM and 150 mM) for 2 days. Salt stress increased Na content and decreased K content in shoot and root. It disrupted the antioxidant defense system by producing reactive oxygen species (ROS; H2O2 and O2•−), methylglyoxal (MG) content and causing oxidative stress. It also reduced the growth and photosynthetic pigments of seedlings but increased proline (Pro) content. However, BABA pretreatment in salt-stressed seedlings increased ascorbate (AsA) and glutathione (GSH) contents; GSH/GSSG ratio; and the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), d...