Satish K. Munshi

Biochemical changes in sunflower plants due to seed treatment/spray application with biocontrol agents

The application ofTrichoderma harzianum andPseudomonas fluorescens led to increases in dry matter content, starch, total soluble sugars (TSS) and reducing sugar contents in leaves of sunflower (Helianthus annuus) when done as seed treatment or coupled with spray. There was a significant increase in TSS and reducing sugars in stem tissue after treatment with biocontrol agents. The content of total phenols in leaves increased after treatment at 30 and 60 days after sowing (DAS) and at 30 DAS in stem tissues. Biocontrol agents increased the activities of phenylalanine ammonia lyase (PAL) in leaves and stem tissue after 30 DAS and significantly reduced total phenolic content and PAL activity in the stem at 60 DAS. Following treatment with biocontrol agents, seed lipid content increased, the proportion of linoleic acid increased and that of oleic acid decreased. Application of biocontrol agents to sunflower plants initiated certain biochemical changes, which can be considered to be part of the plant’s defense response.

Accumulation of glucosinolates in developing mustard (Brassica juncea L.) seeds in response to sulphur application

Abstract Changes in glucosinolate content and its relationship with oil content and erucic acid were determined in mustard (Brassica juncea L.) seeds in response to application of sulphur to sulphur deficient soil. Glucosinolates were accumulated actively in the seeds from 40 days after fertilization (DAF) up to maturity. Total glucosinolate content showed a positive correlation with oil content and erucic acid content and the addition of sulphur did not bring about change in the oveall attern of their accumulation. Gluconapin predominated followed by sinigrin, glucobrassicanapin, progoitrin and gluconapoleiferin. The amount of all other glucosinolates except gluconapoleiferin increased in response to addition of sulphur to the soil; a ten fold increase was recorded in progoitrin content.

The influence of zinc and sulphur deficiency on oil-filling in peanut (Arachis hypogaea L.) kernels

In the developing peanut (Arachis hypogaea L.) kernels, the period between 15 and 35 days after podding (DAP) was identified as the active period of oil-filling. The period of active oil-filling was associated with a decrease in the starch, soluble sugars and proteins so as to make available the energy and carbon skeleton for the synthesis of oil. The oil content in the mature kernels decreased by 11, 12 and 25 per cent with Zn, S and Zn+S deficiency, respectively. In addition, proteins and starch content decreased significantly while that of soluble sugars increased slightly. The activity of malate dehydrogenase and glucose-6-phosphate dehydrogenase also decreased due to Zn as well as S deficiency. The deficiency treatments resulted in a decrease in phospholipids, free fatty acids and triacylglycerols in mature kernels. Further the proportion of 16∶0 and 18∶2 decreased while that of 18∶1 increased in developing kernels.

Changes in biochemical components of wheat and rapeseed grown on selenium-contaminated soil

To study changes in some biochemical parameters in relation to selenium accumulation in wheat and rapeseed, plant samples at different growth stages of the crops were collected from the normal and selenium-contaminated region of Punjab. Plants grown in seleniferous soils accumulated 220–242 folds Se in wheat (Triticum aestivum L.var PBW 343) and 51–67 folds in rapeseed (Brassica napus L.var GSL-1) leaves; and 16–17 folds in grains of both the crops. Due to selenium accumulation, lipid and protein contents remained significantly low in leaves at both the stages of growth as well as grains of both the crops. Distinct differences were noticed in both the crops with respect to changes in total soluble sugars, reducing sugars and starch contents. In seleniferous soils, wheat leaves at stage I (55-day-growth) contained significantly higher amounts of total soluble sugars, reducing sugars and starch and thereafter these parameters recorded significantly low values in leaves at stage II (ear initiation) as well as in grains. On the other hand, a significant decrease in total soluble sugars and reducing sugars was recorded due to Se accumulation in rapeseed leaves at both growth stages. Quality of rapeseed grains harvested from seleniferous soil was not affected by Se accumulation except decrease in lipid content. Se accumulation did not influence the proportion of different lipid classes like phospholipids, glycolipids and sterols but reduced the proportion of unsaturated fatty acids.

Influence of systemic insecticides on lipid biosynthesis in seeds of Indian mustard (Brassica juncea L.)

Abstract The systemic insecticides namely phorate (Thimet 10 G) oxydemeton methyl (metasystox 25 EC) and dimethoate (Rogor 30 EC) decreased oil content in the developing seeds of Indian mustard ( Brassica juncea L.) but showed an increase in the mature seeds. The inhibitory effect in the developing seed was accompanied by an increase in soluble sugars and a corresponding decrease in malate dehydrogenase and G6P dehydrogenase activity. The relative proportion of triacylglycerols and glycolipids decreased significantly while that of phospholipids and free fatty acids increased in the developing seeds. In the mature seeds, the proportion of triacylglycerols did not change appreciably from that in control. The erucic acid synthesis which was less at 10 and 20 days after fertilization (DAF) increased at 30 DAF with oxydemeton methyl and dimethoate; phorate was ineffective. In mature seeds, the proportion of erucic acid increased at the cost of linoleic and linolenic acids. All the insecticides appreciably decreased the rate of [1- 14 C]acetate incorporation into lipids both in vivo and in vitro experiments. In the in vivo experiment, the synthesis of polar lipids was enhanced at 10 and 20 DAF, and the higher doses of oxydemeton methyl and dimethoate at 30 DAF. On the other hand, the 14 C-incorporation into triacylglycerols showed an opposite trend to that of polar lipids. In the in vitro experiment, oxydemeton methyl and dimethoate enhanced the synthesis of polar lipids at 10 and 20 DAF while these inhibited it at 30 DAF. The synthesis of triacylglycerols was inhibited by the use of these insecticides.

Effects of biocontrol agents on lipid and protein composition of Indian mustard seeds from plants infected with Alternaria species

Field experiments were carried out with Indian mustard (Brassica juncea L. Cv RLM 1359) to investigate the influence of biocontrol agents on seeds from plants infected with Alternaria blight. The biocontrol agents viz, Trichoderma harzianum, Pseudomonas fluorescens and Bacillus subtilis were applied as seed treatment/seed treatment coupled with spray on 30 and 60 days after sowing of seeds in experimental fields. The plants treated with different biocontrol agents were more developed than non-treated plants throughout the experiment. Biochemical analysis revealed that application of biocontrol agents resulted in increase in lipid and protein content in seeds from treated plants. The proportion of various lipidic fractions i.e. phospholipids, glycolipids and sterol content in seeds increased with a corresponding decrease in total glycerides. The proportion of 18:3, 20:1 and 22:1 fatty acids increased while that of 18:1 and 18:2 fatty acids decreased in seeds with application of biocontrol agents. There were both qualitative and quantitative differences in the banding patterns of albumin and globulin proteins after application of biocontrol agents. The data suggested that biochemical alterations in the host induced by treatment with biocontrol agents could be associated with defence mechanisms and enhanced growth of the plant.

Biochemical changes associated with application of biocontrol agents on Indian mustard leaves from plants infected with Alternaria blight

The present investigation reports the biochemical changes associated with application of biocontrol agents on Indian mustard (Brassica juncea L Cv RLM 1359) leaves from plants infected with Alternaria blight. Indian mustard seeds were treated separately with three biocontrol agents, viz. Trichoderma harzianum, Pseudomonas fluorescens and Bacillus subtilis and grown in experimental fields; followed by spraying on 30 and 60 days after sowing (DAS). The use of biocontrol agents showed enhanced growth in comparison to control, decreased disease index on the leaves as well as the pod wall of Indian mustard. These biocontrol agents enhanced the content of dry matter, total phenol, ortho-dihydroxyphenols, starch, total soluble sugars, reducing sugars, total lipids and different membrane lipids in the leaves. The total protein content decreased after treatment with biocontrol agents at 30 and 60 days after sowing. The data suggested that treatment with biocontrol agents initiated in the plants a number of biochemical changes which can be considered to be a part of plant defense response.

A hypocotyl-derived somatic embryogenic system in Brassica juncea Czern & Coss and its manipulation for enhanced storage lipid accumulation

A simple and reproducible protocol for induction, growth and development of somatic embryos from hypocotyl explants of Indian mustard (Brassica juncea L. Czern & Coss) var. RLM 198 is reported. The HDSE (Hypocotyl-derived somatic embryos) were fleshy globular to torpedo structures that were maintained by regular subculturing every three weeks. These embryos developed non-synchronously into the heart shaped-stage while some were matured into a green cotyledon-stage bearing embryos in the same medium. The HDSE accumulated as much as 50.2% lipid content on a dry weight basis at 14 DAC (days after culture) using a culture medium supplemented with 10% PEG (Polyethylene glycol 6000) in comparison to less than 15% lipid content in 2% sucrose (control) or 20 μM ABA (abscisic acid). An increase in total soluble sugar content was observed with 2.5% PEG and increasing PEG concentration caused a decrease in their contents in HDSE. The activities of invertase, acetyl CoA carboxylase and 1-14C-acetate incorporation into lipids in HDSE were enhanced significantly in the culture medium containing 10% PEG. The content of triacylglycerols in HDSE was maximum with 10% PEG supplemented culture medium. The wax content in HDSE increased progressively with an increase of PEG concentration in the culture medium. The ABA and PEG supplementation increased the content of membrane lipids when the data was expressed on a 100 g dry weight basis. The proportion of palmitate and erucate decreased and that of oleate, linoleate and linolenate increased at 14 DAC in HDSE in 10% PEG supplemented culture medium. Thus, the manipulation of culture conditions significantly altered total lipid content, membrane lipid composition and the quality of storage lipids.