Satvir Kaur

Effect of osmo- and hydropriming of chickpea seeds on seedling growth and carbohydrate metabolism under water deficit stress

Seven-day-old seedlings obtained from seeds primed with mannitol (4%)and water showed three to four fold more growth with respect to root and shootlength in comparison with seedlings obtained from non-primed seeds. Seedlingswere grown under water deficit stress conditions created by 15% polyethyleneglycol (PEG) 6000 in the medium. Priming of chickpea seeds with NaCl and PEGwasnot effective in increasing seedling growth under these water deficit stressconditions. The activities of amylase, invertases (acid and alkaline), sucrosesynthase (SS) and sucrose phosphate synthase (SPS) were higher in shoots ofprimed seedlings. An increase in the activities of SS, and both the acid andalkaline invertases was also observed in roots of primed seedlings. The twofoldincrease in specific activity of sucrose phosphate synthase was observed incotyledons of primed seedlings. The higher amylase activity in shoots of primedseedlings enhanced the rapid hydrolysis of transitory starch of the shootleading to more availability of glucose for shoot growth and this was confirmedby the low level of starch in shoots of primed seedlings.

Effect of GA3, kinetin and indole acetic acid on carbohydrate metabolism in chickpea seedlings germinating under water stress

Enhanced amylase activity was observed during a 7-day-growth period in the cotyledons of PEG imposed water stressed chickpea seedlings grown in the presence of GA3 and kinetin, when compared with stressed seedlings. During the first 5 days of seedling growth, the seedlings growing under water deficit conditions as well as those growing in the presence of PGRs had a higher amylase activity in shoots than that of control seedlings. Neither GA3 nor kinetin increased the amylase activity of roots whereas IAA reduced root amylase activity. Activity of acid and alkaline invertases was maximum in shoots and at a minimum in cotyledons. Compared with alkaline invertase, acid invertase activity was higher in all the tissues. The reduced acid and alkaline invertase activities in shoots of stressed seedlings were enhanced by GA3 and kinetin. Roots of stressed seedlings had higher alkaline invertase activity and GA3 and IAA helped in bringing the level near to those in the controls. GA3 and kinetin increased the sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities in cotyledons of stressed seedlings, whereas they brought the elevated level of SPS of stressed roots to near normal level. The higher level of reducing sugars in the shoots of GA3 and kinetin treated stressed seedlings could be due to the high acid invertase activity observed in the shoots, and the high level of bound fructose in the cotyledons of stressed seedlings could be due to the high activity of SPS in this tissue.

Gibberellin A3 reverses the effect of salt stress in chickpea (Cicer arietinum l.) seedlings by enhancing amylase activity and mobilization of starch in cotyledons

The percentage germination of chickpea seeds (Cicer arietinum L.cv. PBG-1) gradually decreased with increasing concentration of NaCl in the growth medium and was completely inhibited with 200 mM NaCl. In the presence of 75 mM NaCl, only 51% of the seeds germinated. Gibberellic acid (GA3) and kinetin at 6 µM concentration induced the maximum increase in % germination and seedling growth under salt stress. However, IAA further inhibited both the germination and growth of stressed seedlings. The reduction in amylase activity in cotyledons of stressed seedlings was partially reversed with GA3 and kinetin whereas IAA did not show any positive effect. GA3 was more effective than kinetin in enhancing the reduced germination and seedling growth of chickpea seeds along with amylase activity in cotyledons under NaCl induced saline conditions. The reduced uptake of radiolabelled 14C sucrose by cotyledons and its reduced distribution in the shoots and roots of stressed seedlings was increased with addition of GA3 in the medium. Cotyledonary amylase was separated into amylase 1 and amylase 2 by sephadex G 150 column chromatography. The reduced activities of both amylase 1 and amylase 2 in cotyledons under salt stress was returned to near normal levels with GA3 and there was also an increase in starch utilization, resulting in its lower concentration in cotyledons of GA3-supplemented stressed cotyledons.

Gibberellic acid and kinetin partially reverse the effect of water stress on germination and seedling growth in chickpea

The percent germination and seedling growth of chickpea (Cicer arietinum L. cv. PBG-1) decreased with increasing concentrations of exogenous polyethylene glycol 6000 (PEG). With 15% PEG in the growth medium germination was only 33% while with 10% PEG it was 58% as compared to 93% in control. Addition of gibberellic acid (GA3) and kinetin to medium containing 10% PEG increased the germination and seedling growth and the effect was maximum with 6 µM GA3 which was a better inducer of growth and germination under reduced water potential than kinetin. However, indole acetic acid (IAA) inhibited germination and growth of stressed seedlings. The activity of amylase in cotyledons under stress was significantly increased with GA3 while kinetin and IAA were less effective. Gibberellic acid also enhanced the mobilization of starch from cotyledons of stressed seedlings resulting in low starch levels in cotyledons compared with stressed seedlings.

Effect of kinetin on starch and sucrose metabolising enzymes in salt stressed chickpea seedlings

Higher amylase activity in cotyledons of kinetin treated salt stressed (75 mM NaCl) chickpea (Cicer arietinum L. cv. PBG-1) seedlings, as compared to salt stressed seedlings was observed during a growth period of 7 d. The activities of acid and alkaline invertases were maximum in shoots and minimum in cotyledons under all conditions. The reduced shoot invertase activities under salt stress were enhanced by kinetin with a simultaneous increase in reducing sugar content. Kinetin increased the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in both the cotyledons and shoots of stressed seedlings. Kinetin appears to increase the turnover of sucrose in the shoots of stressed seedlings.

Indole acetic acid mimics the effect of salt stress in relation to enzymes of carbohydrate metabolism in chickpea seedlings

The effect of addition of indole acetic acid (3 μM) andNaCl (75 mM) on growth and enzymes of carbohydrate metabolism inchickpea seedlings was compared. In comparison with control seedlings, theseedlings growing in the presence of indole acetic acid (IAA) had reducedamylase activity in cotyledons and enhanced sucrose synthase (SS) and sucrosephosphate synthase (SPS) activities in cotyledons and shoots at all days ofseedling growth. Compared with control seedlings, sucrose content was higher incotyledons, shoots and roots and reducing sugar content was lower in shoots ofIAA treated seedlings. A low invertase (acid and alkaline) activity in shoots ofIAA treated seedlings could lead to reduced sink strength and hence decreasedgrowth of seedlings. Effects of NaCl stress on growth and activities of amylase,SS and SPS in cotyledons and invertase, SS and SPS in shoots were similar tothose observed with addition of IAA.

Exploration of biochemical and molecular diversity in chickpea seeds to categorize cold stress-tolerant and susceptible genotypes

Chickpea (Cicer arietinum L.) genotypes are sensitive to low temperature (<10°C) during its reproductive stage suffer from abortion of flowers, infertile pods and small shriveled seeds that resulted in a significant decrease in crop yield. In the present investigation seeds of a number of cold stress-tolerant and susceptible genotypes were evaluated for biochemical and molecular diversity with the purpose to categorize them. The activities of various antioxidative enzymes (superoxide dismutase, glutathione reductase, ascorbate peroxidase and catalase), content of H2O2 and malondialdehyde, enzymes involved in phosphate metabolism (acid and alkaline phosphatases), and content of phytic acid and proline were determined in seeds of 20 cold stress tolerant and seven cold stress susceptible genotypes. Higher activities of superoxide dismutase, ascorbate peroxidase, catalase and acid phosphatase and low content of malondialdehyde and phytic acid were observed in cold stress-tolerant genotypes as compared to cold stress susceptible genotypes. Seventeen chickpea genotypes comprising both cold stress-tolerant and susceptible ones were evaluated through 20 randomly amplified polymorphic DNA (RAPD) primers. The results of cluster analysis revealed two major groups. In the first group five tolerant (group 1a) and six susceptible genotypes (group 1b) clustered together whereas in second group all the tolerant genotypes clustered together (group 2). Out of 20 RAPD primers, 4 primers (Opa-13, Opa-14, Opa-15 and Opa-16) have been identified as markers for cold stress tolerance. In general high SOD activity, and H2O2 content and low MDA and phytic acid content are related with cold stress tolerance. The status of these markers was more pronounced in genotypes clustered in group 2 after RAPD analysis than in group 1a of cold stress-tolerant genotypes as compared to susceptible genotypes. The observed biochemical and molecular diversity could be useful for identifying and developing cold stress-tolerant genotypes of chickpea.

Nodule metabolism in cold stress tolerant and susceptible chickpea cultivars

Early maturing short duration cold-tolerant chickpea cultivars are being introduced to avoid yield loss from spell faced by crops. However, the biochemical basis of the low temperature stress tolerance is not known. In the present study carbon and nitrogen metabolizing enzymes in nodules along with physiological indices were measured in early maturing short duration cold- tolerant chickpea cultivars (ICCV 93929 and ICCV 88503) and in normal cold - susceptible (PBG1 and GPF2) cultivars. The higher biomass in nodules of cold-tolerant cultivars might act as a greater sink for attracting photoassimilates to fuel N2-fixation. The simultaneous increase of sucrose synthase and alkaline invertase in nodules of ICCV 93929 and ICCV 88503 at the stage corresponding to lower temperature, ensures hexose supply for meeting the energy and reducing power demands for active nitrogen fixation. The greater activity of glutamine synthetase observed in nodules of cold tolerant cultivars at stages exposed to lower temperature indicates an efficient assimilation of the symbiotically fixed nitrogen into amino acids. The total protein and amino acid contents were also higher in cold tolerant cultivars. There was a greater and more rapid dry matter accumulation in ICCV 88503 and ICCV 93929 as compared to PBG1 and GPF2 in which biomass accumulation extended up to 70 DAS. Sustainable photosynthetic efficiency and activities of carbon and nitrogen metabolizing enzymes for a longer period in ICCV 93929 and ICCV 88503 even after flowering and during the onset of pod setting indicates that period of active nitrogen fixation is extended in cold tolerant chickpea cultivars due to allocation of photosynthates for longer period. This will lead to more transfer of reduced N as amino compounds towards the shoots which will lead to more nitrogen availability to seeds and ultimately better seed filling. The molecular diversity characterized by using RAPD primers and clustering method revealed a greater similarity between cold tolerant cultivars than between the cold susceptible cultivars.

Translocation of metabolites in pigeonpea (Cajanus cajan L.) under the influence of mineral nutrients

Mineral nutrient sources viz., CaCl2 (0.01% and 0.02%), KNO3 (0.5% and 1%), MgCl2 (0.1% and 0.2%) and urea (1% and 2%) were applied as foliar application to pigeonpea varieties (PAU 881 and AL 201) at green floral bud stage of inflorescence to study their effect on the level of various metabolites viz., total soluble sugars, total starch, total free amino acids and total soluble proteins in leaves and their subsequent accumulation in developing seeds. It was observed that mineral nutrients caused greater accumulation of different metabolites in developing seeds (sink) which may be attributed to enhanced translocation of these metabolites from source to sink tissues as evident from their decline in leaf tissues (source) thereby strengthening the source-sink relationship in pigeonpea. Urea application @ 2% increased accumulation of metabolites in mature seeds by 27.71 (PAU 881) and 25.25% (AL 201) in case of total soluble sugars, 11.19 (PAU 881) and 11.33%(AL 201) in case of total starch, 38.23 (PAU 881) and 39.41% (AL 201) total free amino acids and 10.72 (PAU 881) and 8.66% (AL 201) of total soluble proteins as compared to their respective controls.

Changes in the Activity of Carbon and Nitrogen Metabolising Enzymes in Nodules of Bold and Small Seeded Lentil Cultivars

Lentil (Lens culinaris L.) is one of the earliest cultivated crops and most nutritious rabi season food legumes as from plant-based food; lentil has the third highest level of protein (26%) after soybeans and hemp and is an important constituent of the diet in many parts of the world, especially in Indian subcontinent which have large vegetarian populations (Tyagi and Khan, 2010). Lentil seeds contain 25% protein, 0.7% fat, 2.1% mineral, 0.7% fibre and 59% carbohydrate (Bhatty and Christison, 1984). It is rich in phosphorus, calcium, iron, zinc and carotene. Due to presence of more protein, calcium and phosphorus it is preferred fodder for animals also as compared to wheat straw (Gupta et al., 2013). The seeds are consumed in North Africa, Middle East, West Asia and India as staple food as well as in vegetarian dishes worldwide providing essential nutrients such as proteins and micronutrients like iron and zinc. In developing countries, lentil straw is valued as animal feed (Erskine et al., 1990). It plays an important role in human, animal and soil health improvement occupying a unique position in cereal based cropping system International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 12 (2017) pp. 3311-3320 Journal homepage: http://www.ijcmas.com