Methylglyoxal metabolism is altered during defence response in pigeonpea (Cajanus cajan (L.) Millsp.) against the spotted pod borer (Maruca vitrata).

Pigeonpea (Cajanus cajan ) production can be affected by the spotted pod borer (Maruca vitrata ). Here, we identified biochemical changes in plant parts of pigeonpea after M. vitrata infestation. Two pigeonpea genotypes (AL 1747, moderately resistant; and MN 1, susceptible) were compared for glyoxalase and non-glyoxalase enzyme systems responsible for methylglyoxal (MG) detoxification, γ-glutamylcysteine synthetase (γ-GCS), glutathione-S-transferase (GST) and glutathione content in leaves, flowers and pods under control and insect-infested conditions. MN 1 had major damage due to M. vitrata infestation compared to AL 1747. Lower accumulation of MG in AL 1747 was due to higher activities of enzymes of GSH-dependent (glyoxylase I, glyoxylase II), GSH-independent (glyoxalase III) pathway, and enzyme of non-glyoxalase pathway (methylglyoxal reductase, MGR), which convert MG to lactate. Decreased glyoxylase enzymes and MGR activities in MN 1 resulted in higher accumulation of MG. Higher lactate dehydrogenase (LDH) activity in AL 1747 indicates utilisation of MG detoxification pathway. Higher glutathione content in AL 1747 genotype might be responsible for efficient working of MG detoxification pathway under insect infestation. Higher activity of γ-GCS in AL 1747 maintains the glutathione pool, necessary for the functioning of glyoxylase pathway to carry out the detoxification of MG. Higher activities of GST and GPX in AL 1747 might be responsible for detoxification of toxic products that accumulates following insect infestation, and elevated activities of glyoxylase and non-glyoxylase enzyme systems in AL 1747 after infestation might be responsible for reducing reactive cabanoyl stress. Our investigation will help the future development of resistant cultivars.

Understanding the influence of genotype and temperature on proteolytic activity in distinct barley genotypes.

This study aimed at investigating the effects of genotype and temperatures on the proteolytic activity in green malt of 48 barley genotypes, including 19 mutants, 15 hulled, 4 hulless, and 10 wild using enzyme assays based on casein, as substrate. During malting, insoluble barley protein must be hydrolyzed into soluble peptides and free amino acids to supply the brewing yeast with sufficient nutrients to grow rapidly and metabolize glucose and other sugars into alcohol through fermentation. However, the relatively hot temperatures employed during kilning usually denature the proteolytic enzymes due to their thermolabile nature. Even though the hydrolytic activity of most of the proteases is destroyed during the kilning process, the malt includes a small fraction of thermostable proteases that can further degrade protein in the subsequent mashing process. Considering the higher temperature range employed in industrial kilning and mashing, three temperatures (37, 50, and 70°C) were selected to identify the genotypes possessing high activity at the higher range of temperatures as well as thermostable variant of the enzyme. The proteolytic activity in all the genotypes declined after 50°C depicting its optimum temperature. Overall proteolytic activity was observed to be positively correlated with the amino acids and negatively correlated with protein content. Three mutant (BL2086, BL2091, and BL2079) and one wild (WS 237) genotypes possessing proteolytic activity in a higher range at all the studied temperatures have the potential to be exploited in the breeding programs for incorporating trait of thermostable proteolytic activity into low malting efficiency cultivars. PRACTICAL APPLICATION: The optimal hydrolytic activities of carbohydrases and proteases during mashing are essential for producing high-quality wort from malted barley to ensure that hydrolyzed molecules are available to brewers' yeast to support fermentative metabolism. In this study, several barley cultivars were grown under identical environmental conditions but assayed at different temperatures. As result, four genotypes had been obtained that possessed optimal proteolytic activities at a higher temperature range and can be of great interest to breeders and maltsters for altering wort amino acid profiles and better exposure of starch to mashing enzymes, thereby increasing the fermentable sugar yield from the malt.

Effect of herbicide stress on synchronization of carbon and nitrogen metabolism in lentil (Lens culinaris Medik.).

Weed invasion causes significant yield losses in lentil. Imazethapyr (IM), a broad-spectrum herbicide inhibits the biosynthesis of branched chain amino acids necessary for plant growth. Plant growth depends upon translocation of photo-assimilates and their partitioning regulated by carbon and nitrogen metabolism. This study aimed to investigate the impact of imazethapyr spray on carbon and nitrogen metabolism in tolerant (LL1397 and LL1612) and susceptible (FLIP2004-7L and PL07) lentil genotypes during vegetative and reproductive development. Significantly higher activities of invertases and sucrose synthase (cleavage) in leaves and in podwall and seeds during early phase of development in tolerant genotypes were observed as compared to susceptible genotypes under herbicide stress that might be responsible for providing hexoses required for their growth. Activities of sucrose synthesizing enzymes, sucrose phosphate synthase and sucrose synthase (synthesis) increased significantly in podwalls and seeds of LL1397 and LL1612 genotypes during later phase of development towards maturity while the activities decreased in FLIP2004-7L and PL07 genotypes under herbicide stress. Activities of nitrate and nitrite reductase, glutamine 2-oxoglutarate aminotransferase, glutamine synthetase and glutamate dehydrogenase were increased in leaves, podwalls and seeds of LL1397 and LL1612 under herbicide stress. A proper synchronization of carbon and nitrogen metabolism in tolerant lentil genotypes during vegetative and reproductive phase might be one of the mechanisms for their recovery from herbicide stress. This first ever comprehensive information will provide a basis for future studies on the molecular mechanism of source sink relationship in lentil under herbicide stress and will be utilized in breeding programmes.

Induced defense responses in cultivated and wild chickpea genotypes against Helicoverpa armigera infestation.

Five desi (GL 12,021, GL 29,095, GL 29,078, H11 22 and CSJ 515) and three wild (GLW 22, GLW 58 and GLW 187) chickpea cultivars showed induced defense response against Helicoverpa armigera infestation as a result of enhanced activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione reductase, polyphenol oxidase, phenylalanine ammonia lyase, tyrosine ammonia lyase in leaves, pod walls and seeds. Catalase activity increased in leaves of GL 12,021, H11 22, GL 29,095, CSJ 515, GLW 22, and GL 29,078 after infestation compared to resistant check; catalase and peroxidase activities in GL 29,095 and GL 29,078; ascorbate peroxidase and glutathione reductase activities in leaves of GLW 58. The increased activity of superoxide dismutase in pod wall of H1122; catalase in pod wall of 29,078, GL 29,095 and GL 22; ascorbate peroxidase and glutathione reductase in pod wall of GLW 58; phenylalanine ammonia lyase and tyrosine ammonia lyase in pod wall of GLW 187, H11 22, GL 20,978, GLW 22 and GLW 58 after infestation as compared to resistant check might be responsible for mitigating infestation induced oxidative stress. MDA content decreased in leaves, pod wall and seeds of GLW 187 and GL 12,021 after infestation. Lower percent pod damage (9.58-12.44%) in GL 12,021, GLW 187, GL 29,095, H11 22, GL 29,078, GLW 22 and GLW 58 as compared to resistant (16.18%) and susceptible (21.50) checks might be attributed to differential induced defense mechanism in them. The identified desi and wild genotypes might be used in breeding program to develop cultivars with improved resistance to herbivore.

Impact of post-emergent imazethapyr on morpho-physiological and biochemical responses in lentil (Lens culinaris Medik.).

Yield reduction in lentil crop due to weed infestation is a key hindrance to its growth due to poor weed-crop competition. Imazethapyr (IM), a selective herbicide, target acetolactate synthase (ALS) which catalyzes the first reaction in biosynthesis of branched chain amino acids, required for plant growth and development. The objective of the present study was to investigate the impact of IM treatment on weeds, ALS enzyme activity, antioxidant capacity, osmolyte accumulation, growth and yield related parameters in lentil genotypes. Two IM tolerant (LL1397 and LL1612) and two susceptible (FLIP2004-7L and PL07) lentil genotypes were cultivated under weed free, weedy check and IM treatments. Weed control efficiency reached its peak at 21 days after spray (DAS). Imazethapyr treatment decreased chlorophyll and carotenoid content up to 28 DAS with higher reduction in susceptible genotypes. FLIP2004-7L and PL07 had reduced plant height and lower number of pods under IM treatment which resulted in decreased seed yield. Higher ALS activity in LL1397 and LL1612 at 21 DAS, higher antioxidant capacity and glycine betaine content both at 21 and 28 DAS and lower decrease in relative leaf water content might be mediating herbicide tolerance in these genotypes that led to higher seed yield. The identified IM tolerance mechanism can be used to impart herbicide resistance in lentil. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01244-x.

Methylglyoxal detoxification pathway - Explored first time for imazethapyr tolerance in lentil (Lens culinaris L.).

Lentil is an important pulses crop but it's short stature and slow growth rate make it vulnerable to weed competition, limiting crop productivity. There is need to identify herbicide tolerant genotypes and their tolerance mechanism. The present investigation was conducted to understand the effect of imazethapyr (IM) treatment on accumulation of methylglyoxal (MG) and its detoxification mechanism in IM-tolerant (LL1397 and LL1612) susceptible (FLIP2004-7L and PL07) genotypes sown under control (weed free), weedy check (weeds were growing with crop) and sprayed with imazethapyr. The enzymes of glyoxalase pathway (glyoxalase I, II and III) and non glyoxalase pathway (methylglyoxal reductase), lactate dehydrogenase (LDH), glutathione content, gamma-glutamyl-cysteine synthetase (γ-GCS) were estimated in lentil genotypes at different days after spray. Higher activities of glyoxalase I, II and III and MGR along with the increased glutathione content (GSH) content in LL1397 and LL1612 under IM treatment as compared to FLIP2004-7L and PL07 might be responsible for lowering MG accumulation and increasing lactate content, which is end product of these pathways. Enhanced LDH activity in LL1397 and LL1612 might be responsible for energy production via TCA cycle that might be responsible for growth and recovery of tolerant genotypes after IM treatment. Higher γ-GCS activity in tolerant genotypes led to increased glutathione content required for glyoxalase pathway. However, decreased activities of glyoxalase enzymes and MGR in susceptible genotypes result in MG accumulation which limit plant growth. This is the first ever study elucidating the role of MG detoxification pathway conferring IM tolerance in lentil.

Drought stress-induced changes in redox metabolism of barley (Hordeum vulgare L.).

In the present investigation, influence of water stress on redox metabolism was evaluated in the flag leaf and grains of four barley (Hordeum vulgare L.) genotypes viz DWRB 101, 432 ICARDA, Jyoti and 430 ICARDA at 10th, 20th and 30th days after anthesis (DAA). Relative water content, electrolyte leakage, antioxidative enzymes and their related metabolites were studied during drought stress. Relative water content was well maintained in both the tissues of DWRB 101 and 432 ICARDA. The upregulation of catalase at 20th DAA while ascorbate peroxidase, glutathione reductase and dehydro reductase at 30th DAA in the flag leaf and grains of DWRB 101 and 432 ICARDA may be responsible for lesser increase in H2O2 content as compared to other genotypes. Moreover, the downregulation of superoxide dismutase was comparatively higher in Jyoti and 430 ICARDA. The redox homeostasis was well established during the stress in DWRB 101 and 432 ICARDA by maintaining comparatively higher ratios of ascorbate/dehydroascorbate and reduced/oxidized glutathione. Therefore, scrutiny of data indicated that DWRB 101 and 432 ICARDA may perform better under drought stress in comparison with Jyoti and 430 ICARDA.

Quality attributes for barley malt: "The backbone of beer".

Malting is the process of preparing barley for brewing through partial germination followed by drying. This process softens the grain cell wall and stimulates the production of diastatic enzymes, which convert starch into malt extract. The suitability of a barley grain for malt production depends upon a large number of quality parameters that are crucial for the identification and release of high-quality malt varieties. Maintaining tight control of these quality attributes is essential to ensure high processing efficiency and final product quality in brewery and malt house. Therefore, we have summarized the basic malting process and various physiological and biochemical quality parameters that are desirable for better malt quality. This study may provide an understanding of the process, problems faced, and opportunities to maltsters and researchers to improve the malt efficiency by altering the malting process or malt varieties.

Hydrogen peroxide regulates antioxidant responses and redox related proteins in drought stressed wheat seedlings.

Hydrogen peroxide plays pivotal role as a potent regulator in signalling pathways when the plant is under stress. The current study appraised the potential of hydrogen peroxide through seed pre-treatment on the seedling growth and defense responses of three wheat cultivars i.e. PBW 644 (tolerant), PBW 621 and HD 2967 (sensitive) grown under drought stress. Imposition of drought stress reduced seedling growth of all the three wheat cultivars. Pre-treatment of seeds with 60 mM H2O2 alleviated water stress induced growth inhibition in all the three wheat cultivars. Further, it enhanced the drought tolerance of PBW 644 by upregulating SOD, POX, APX and GR enzymes accompanied by an increase in total phenols and ascorbate content. H2O2 treatment also protected the sensitive cultivars from drought stress by increasing CAT, POX, APX, MDHAR and GR enzymes. The contents of osmolytes were comparable or slightly higher as compared to stressed seedlings. The levels of MDA content were reduced in the treated seedlings of all the cultivars which further revealed the role of H2O2 pre-treatment in alleviating membrane damage. The comprehensive scrutiny of proteins differentially expressed in control, stressed and H2O2 primed stressed seedlings revealed that drought stress enhanced the expression of proteins involved in photosynthesis, protein biosynthesis and degradation, carbohydrate metabolism, fatty acid metabolism, nucleic acid metabolism, phytohormone response, defense and regulation, whereas H2O2 pre-treatment led to over expression of proteins which had functions in processes such as defense, redox homeostasis and photosynthesis. SUPPLEMENTARY INFORMATION: The online version of this article (10.1007/s12298-021-00937-z).

Browning and quality management of pear fruit by salicylic acid treatment during low temperature storage.

BACKGROUND: 'Patharnakh' pear, a dominant cultivar in the Punjab province of India, has a shorter storage life as it matures during the hot and humid weather. Studies have reported that postharvest chemical treatments have a major role in improving the storage life of the fruit. In this study, the efficacy of different concentrations (1, 2, and 3 mmol L-1 ) of salicylic acid (SA), a well-known signaling molecule, was explored to overcome browning and maintain the postharvest quality of the Patharnakh pear during cold storage. RESULTS: SA treated pears were better than the untreated fruits in all of the studied parameters. SA application alleviated the rate of weight loss and respiration, and lowered the decay percentage. The efficacy of SA in the reduction of polyphenol oxidase (PPO) activity, which correlates negatively with the total phenolic content, was quite noticeable. The SA treated fruits exhibited a slower oxidation of the total phenol content by inhibiting the action of PPO and retaining the total phenolic content, leading to lower incidence of browning. SA effectively maintained the ascorbic acid content and superoxide dismutase activity. Total soluble solids, titratable acidity, ascorbic acid, and pH of the pears were highest with the SA treatment. CONCLUSION: The 2 mmol L-1 SA treatment exhibited the best result of reducing fruit decay and tissue browning, and maintaining the postharvest quality parameters of pear up to 60 days of cold storage. © 2020 Society of Chemical Industry.

Metabolic adjustments during compatible interaction between barley genotypes and stripe rust pathogen.

Stripe rust is a fungal disease that has devastated the barley production for a long time. The present study focused on the role of ß-glucan, PR proteins, diamine oxidase (DAO), polyamine oxidase (PAO), key enzymes and metabolites of phenol and proline metabolism in the stripe rust resistance of barley. RD2901 with resistant behavior against stripe rust showed increased levels of PR proteins, phenylalanine ammonia lyase (PAL), tyrosine ammonia lyase (TAL) along with the accumulation of ß-glucan and lignin which strengthen the plant cell wall during plant-pathogen interaction. It also depicted the enhanced activities of glutamate dehydrogenase (GDH) and ornithine aminotransferase (OAT) coupled with the increased amounts of proline, glycine betaine and choline after infection with M-race of P. striiformis f. sp. hordei. On the contrary, the sensitive genotype Jyoti was unable to enhance the activities of most of these enzymes except PAL and OAT so that it showed an increase in lignin and choline contents only. Secondly, the increase in lignin content was less as compared to the tolerant genotype. Hence, it can be inferred that these key metabolites and enzymes of various metabolic pathways may contribute to the resistance of barley against stripe rust pathogen. This study suggested that these key enzymes and their metabolites could serve as markers for the characterization of plant defensive state that is essential for crop protection.

Desi and kabuli chickpea cultivars had differential behaviour towards salinity stress tolerance.

Twenty chickpea cultivars were germinated under control and different levels of salt stress induced by sodium chloride and out of these, three desi (PDG 3, GL 12003, C 106) and two kabuli (FLIP-08-125-C and GLK 28127) cultivars were selected on the basis of embryonic axis growth, biomass, salinity stress tolerance index. Antioxidative enzymes, non-enzymatic antioxidants proline and proline metabolizing enzymes and free radical scavenging activities were estimated in embryonic axes of these selected cultivars under control and salt stressed conditions. Higher activities of catalase and Δ1-pyrroline-carboxylate synthetase (P5CS) and sustained activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in embryonic axis along with higher SOD and glutathione reductase and maintained APX in cotyledons might be mediating salt stress tolerance in kabuli cultivar FLIP-08-125-C. Higher proline content, enhanced P5CS activity and decreased proline dehydrogenase activity in embryonic axis along with higher free radical scavenging activities both in cotyledons and embryonic axis in desi cultivar PDG 3 might be mediating salt stress tolerance by maintaining osmotic balance and reducing oxidative damage.

Stripe rust induced defence mechanisms in the leaves of contrasting barley genotypes (Hordeum vulgare L.) at the seedling stage.

Puccinia striiformis f. sp. hordei, the causal organism of stripe rust in barley poses serious threats to its production. The present study examined the seedling response and changes in antioxidant defence system along with NADPH oxidase, hydrogen peroxide, and lipid peroxidation marker-malondialdehyde (MDA) in the four barley genotypes namely Jyoti, RD2900, RD2901, and RD2552 in response to M and G-races of stripe rust pathogen. Disease reaction showed Jyoti as susceptible genotype, RD2901 and RD2552 as resistant, whereas RD2900 behaved differentially to both the races. M-race which is predominant was found to be more virulent than G-race of barley stripe rust pathogen. RD2901 showed an increase in activities of NADPH oxidase, catalase, peroxidase, and enzymes of ascorbate-glutathione pathway along with ascorbate and glutathione pool on inoculation with M-race, which was accompanied by the decrease in hydrogen peroxide and MDA contents. Jyoti, on the other hand, showed an increase in peroxidase and glutathione-S-transferase activities only which were unable to maintain redox homeostasis. The scrutiny of data indicated an increase in ASA/DHA ratio on infection in all the genotypes irrespective of their behaviour towards the races. However, GSH/GSSG ratio significantly declined in Jyoti and increased or remained unaffected in the resistant genotypes which suggested that GSH/GSSG might be playing a vital role in imparting tolerance against stripe rust. Further, correlation studies also revealed that leaf damage was positively correlated with H2O2 and MDA contents.

Antioxidant potential of barley genotypes inoculated with five different pathotypes of Puccinia striiformis f. sp. hordei.

The stripe rust caused by the fungal pathogen, Puccinia striiformis f. sp. hordei in barley (Hordeum vulgare L.) is a global problem that threatens the production of barley. The present study examined the disease reaction, free radical scavenging potential, non-enzymatic antioxidants like total phenols, o-dihydroxy phenols, flavonoids along with total chlorophyll, chlorophyll a, chlorophyll b and total carotenoids of the four barley genotypes viz. Jyoti (susceptible), RD2900, RD2901 and RD2552 (resistant) infected with five different pathotypes (M, G, 57, Q and 24) of P. striiformis f. sp. hordei. The disease reaction showing RD2901 in the category of immune to very resistant genotype followed by RD2552 in immune to resistant and RD2900 as moderately resistant and Jyoti as susceptible, which was well correlated with biochemical studies. RD2901 possessed higher antioxidant potential in terms of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·) scavenging activity, ferric reducing antioxidant power, reducing power and nitric oxide scavenging activity under control conditions and were maintained sufficiently high on inoculation with different pathotypes (M, G, 57, Q and 24) of P. striiformis f. sp. hordei. Further, these free radical scavenging activities showed the positive correlation with total phenols, o-dihydroxy phenols, flavonoids which in turn might be contributing in tolerance behaviour of this genotype. However, Jyoti with sensitive behaviour towards M, G, and 24 pathotypes depicted minimum DPPH activity and reducing power under control conditions.