Brassica Juncea Cultivars Research Articles

Aphid‐induced phytochemicals in Brassica juncea (L.) Czern & Coss. afflicting host preference and bionomics of Lipaphis erysimi (Kaltenbach)

AbstractBionomics of an insect and metabolic flux of the host plant are important tools to decipher the status of plant resistance against insect species. This study illuminates vital information on aphid‐induced levels of phytochemicals in the siliquae of Brassica juncea cultivars and their effect on host selection and population growth parameters of Lipaphis erysimi. The current study unveiled that the siliquae preference, intrinsic rate of increase (r), finite rate of increase (λ), gross reproductive rate (GRR) and net reproductive rate (R0) were significantly lower on Pusa Mustard 27, DRMR 150‐35, RLC 3, NRCHB 101, Pusa Mustard 26 and Pusa Mustard 25. However, the mean generation time (T) and doubling time (DT) of L. erysimi were significantly longer (p < 0.001) in these genotypes. These cultivars were also found with elevated levels of aphid‐induced phytochemicals and their associated enzymes, except in a few cases. Total antioxidants, ferric ion reducing antioxidant power, chlorophyll A, total chlorophyll, ascorbate oxidase (AO), catalase, phenylalanine ammonia lyase (PAL) and myrosinase were found to contribute 49.18–85.30% variation for siliquae preference and bionomics of L. erysimi on the test B. juncea cultivars. The study revealed that phenols, antioxidants, chlorophyll A, chlorophyll B, total carotenoids, AO, ascorbate peroxidase, PAL, tyrosine ammonia lyase and myrosinase had significant and negative direct consequences on the siliquae preference and bionomics, thus can be exploited as biochemical markers to identify sources of resistance against L. erysimi. Furthermore, DRMR 150‐35, NRCHB 101, RLC 3, Pusa mustard 26, RH 749 and Pusa Mustard 27 were found with greater aphid‐induced defence phytochemicals and detrimental effects on the host selection and bionomics of L. erysimi, thus can be deployed in Brassica improvement program.

Tolerance in <i>Brassica juncea</i> Cultivars Vis-a-Vis Population Buildup of Mustard Aphid <i>Lipaphis erysimi</i> (Kalt.)

Current investigation deciphered the differential level of tolerance in diverse Brassica juncea cultivars, and variations in the preference and population buildup of Mustard aphid, Lipaphis erysimi. Cultivars RLC 3, NRCHB 101 and Pusa Mustard 27 were least preferred by L. erysimi. Further, total number of aphids and aphid resistance index under natural infestation condition were significantly lower on RLC 3, NRCHB 101, RH 725 and Pusa Mustard 27. However, under artificial conditions, total number of aphids, aphid resistance index and multiplication rates were significantly lower on DRMR 150-35, RH 0406, NRCHB 101, Pusa Mustard 27 and RLC 3. The cultivars DRMR 150-35, RH 0406, NRCHB 101, RLC 3, RH 725 and Pusa Mustard 27 were found with least preference, lower aphid resistance index, establishment, population buildup of L. erysimi under natural and/or artificial infestation conditions, thus can be used in Brassica improvement program.

Phytochemicals in Brassica juncea distressing developmental and reproductive biology of mustard aphid (Lipaphis erysimi)

The present study was carried out to decipher the variation in plant phytochemicals, and their effect on developmental, reproduction and survival of Lipaphis erysimi (Kalt.) on diverse Brassica juncea cultivars. These studies revealed significant differences in total nymphal, reproductive and developmental periods, fecundity and offspring survival of L. erysimi on the test B. juncea cultivars. Development period was significantly longer on DRMR 150-35, PM 26, RLC 3 and PM 25, while fecundity and survival were lower on PM 27, RLC 3, NRCHB 101, RH 749, Pusa Tarak, RH 0406 and PM 30, except in a few cases. Total proteins, antioxidants, tannins, phenols and FRAP were significantly higher, and sugars lower in DRMR 150-35, RLC 3, PM 26 and NRCHB 101 as compared to other B. juncea cultivars. Total proteins, total tannins and antioxidants exhibited a significant and positive, while total sugars showed negative correlation, and explained 86.1% variability in total developmental period of L. erysimi. Total sugars revealed a significantly positive and FRAP negative correlation, explaining 35.5% variability in fecundity of L. erysimi. Furthermore, total proteins and total antioxidants also showed significant and negative correlation with offspring survival, and total phenols and antioxidants explained 28.9% variability in offspring survival of L. erysimi on the test B. juncea genotypes. Present study suggests that DRMR 150-35, RLC 3, NRCHB 101 and PM 26 have greater amounts of antinutritional plant defense compounds which adversely affect the developmental and reproductive biology of L. erysimi, and thus could be used in Brassica improvement programme for sustainable crop production.

Interactive Effect of Elevated CO2 and Drought Stress on Leaf Anatomy in Brassica Species

The aim of present study was to understand how the ultrastructure of the leaf mesophyll cells in Brassica leaf can be altered under elevated CO2 by interactive effect of elevated CO2 on leaf anatomy and ultra structure of Brassica species under moisture stress conditions. Results of the experiment revealed that the crop genotypes differ greatly in response to elevated CO2 and moisture stress conditions. Elevated CO2 brought about an increase in cell and chloroplast expansion in Brassica genotypes. Elevated CO2 also increased the thickness of epidermis, size ofmesophyll cells, accumulation of starch and size and number of starch granules per chloroplast in Brassica juncea and Brassica juncea cultivars. These alterations in the ultra structure of cells in plants might help to plant adjustment to changing climate in the future.

Comparative Analysis of the Nutritional Components and Antioxidant Activities of Different Brassica juncea Cultivars.

The purpose of this study was to compare the nutritional components and antioxidant activities of two different cultivars of Brassica juncea (Dolsan, Yeosu, Korea (BJD) and (Jeongseon, Gangwon, Korea (BJJ)). We investigated the proximate composition (moisture, crude ash, crude protein and crude lipid), antioxidant activities (2,2-Diphenyl-2-picrylhydrazil (DPPH) scavenging activity and ferric reducing antioxidant power (FRAP)), total phenol content, total flavonoid content and sinigrin content by high-performance liquid chromatography analysis. Our results show that the proximate compositions of BJD and BJJ were not significantly different. However, both the DPPH radical scavenging and FRAP activities of the BJJ extracts were higher than those of the BJD extracts. The total phenol contents of the BJD and BJJ extracts were 6.56 and 9.80 mg gallic acid equivalent/g, respectively. The total flavonoids content of the BJD and BJJ extracts were 20.92 and 34.81 mg rutin equivalent/g, respectively, whereas the sinigrin contents, one of the major compounds in BJD and BJJ extracts, were 16.16 mg/g and 11.73 mg/g, respectively. In this study, we confirmed that, by comparing BJJ and BJD, the sinigrin content of BJD was higher than that of BJJ, but the antioxidant activity and phenol content of BJD were superior to that of BJJ.

Effects of Red Mud Addition in Soil Fertilized with Cowdung Manure on Growth Performance and Metal Accumulations in Brassica juncea Cultivars Kranti and Pusa Bold

ABSTRACTRed mud (RM) with organic manure may offer suitable substratum to support plant growth. The present study was conducted to evaluate the effects of 0, 5, 10 and 15% (w/w) RM additions in soil fertilized with cowdung manure (soil: manure: 2:1 w/w) on available metal contents, growth performance and metal accumulation in Brassica juncea cultivars Kranti and Pusa Bold. Increasing RM concentrations in manure-amended soil caused a significant increase in total metal contents but their phytoavailable contents decreased. A significant increase in plant growth performance and seed yield was observed up to 10% RM treatment compared to the control (without RM and manure). Maximum increase in seed yield (140.5%) of Pusa Bold and Kranti (120.3%) was found under 10% RM treatment. Metal contents in seeds were within the FAO/WHO safe limits. The study suggests utilization of 10% (w/w) RM in soil fertilized with cowdung manure for cultivation of Kranti and Pusa Bold. Based on plant performance, the study encourages the cultivation of Pusa Bold.

Differential antioxidative and biochemical responses to aluminium stress in Brassica juncea cultivars

Aluminium (Al) toxicity in acidic soils limits crop production worldwide. We evaluated eleven genotypes of Brassica juncea (Mustard) under Al stress on basis of their growth and shortlisted two best among them for further comparative analysis. Our objective was to elucidate individual and differential oxidative damage and defence response elicited by Al treatment in selected mustard genotypes, ‘Pusa Tarak’ and ‘Pusa Vijay’. Thirty-day-old plants of both genotypes were subjected to Al stress for a period of 24 h and 72 h. Concentration of superoxides was visible much higher in leaves of ‘Pusa Vijay’ both at 24 h and 72 h, also confirmed by oxidative stress marker thiobarbituric acid reactive substances (TBARS). The activities of the enzymatic antioxidants superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST), and catalase (CAT) were significantly higher in ‘Pusa Tarak’ compared to control and ‘Pusa Vijay’ at both time stages. Levels of non-enzymatic antioxidants glutathiones and ascorbates were already higher in ‘Pusa Vijay’; however, Al treatment increased their levels in both genotypes with non-significant changes on inter-genotypes basis. More and significant decline by Al in chlorophylls was observed in ‘Pusa Vijay’. Interestingly, increase in proline content by Al was much prominent in ‘Pusa Tarak’ compared to ‘Pusa Vijay’. The in vitro antioxidant capacity estimation of mustard genotypes, evaluated by measuring 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and hydroxyl radical scavenging (HRSA) activities proved that extract of ‘Pusa Tarak’ can detoxify more radicals than ‘Pusa Vijay’. We conclude that ‘Pusa Tarak’ can upregulate cellular antioxidants and osmoregulation, and quench more radicals compared to ‘Pusa Vijay’. The results will contribute for selection of better Brassica genus to be grown in Al rich acidic soils, and help in designing strategies for crop breeding and cultivation.

Transcriptome and Co-Expression Network Analyses Identify Key Genes Regulating Nitrogen Use Efficiency in Brassica juncea L.

Nitrate is the main source of inorganic nitrogen for plants, which also act as signaling molecule. Present study was aimed to understand nitrate regulatory mechanism in Brassica juncea cultivars, with contrasting nitrogen-use-efficiency (NUE) viz. Pusa Bold (PB, high-NUE) and Pusa Jai Kisan (PJK, low-NUE), employing RNA-seq approach. A total of 4031, 3874 and 3667 genes in PB and 2982, 2481 and 2843 genes in PJK were differentially expressed in response to early, low (0.25 mM KNO3), medium (2 mM KNO3) and high (4 mM KNO3) nitrate treatments, respectively, as compared to control (0 mM KNO3). Genes of N-uptake (NRT1.1, NRT1.8, and NRT2.1), assimilation (NR1, NR2, NiR, GS1.3, and Fd-GOGAT) and remobilization (GDH2, ASN2–3 and ALaT) were highly-upregulated in PB than in PJK in response to early nitrate treatments. We have also identified transcription factors and protein kinases that were rapidly induced in response to nitrate, suggesting their involvement in nitrate-mediated signaling. Co-expression network analysis revealed four nitrate specific modules in PB, enriched with GO terms like, “Phenylpropanoid pathway”, “Nitrogen compound metabolic process” and “Carbohydrate metabolism”. The network analysis also identified HUB transcription factors like mTERF, FHA, Orphan, bZip and FAR1, which may be the key regulators of nitrate-mediated response in B. juncea.

Aluminium Fluoride induced changes in chlorophyll a fluorescence, antioxidants and psb A gene expression of Brassica juncea cultivars

ABSTRACTIn present study, the effects of combined Aluminium and Fluoride (AlF) stress on chlorophyll a fluorescence, photosynthetic pigments, antioxidant system and psb A gene expression are first time reported in four Brassica juncea cultivars (CS-14, Pusa-Tarak, Bio-902 and Laxmi). Each cultivar was exposed to soil supplemented with AlF (0, 50 + 25, 100 + 50 and 150 + 75 mgkg−1). Lowest decline in the chlorophyll content, saturating photosynthetically active photon flux density, maximum apparent electron transport rate and effective quantum yield (PSII) under AlF was observed in Pusa-Tarak followed by CS-14, Bio-902 and Laxmi. The improved performance of the cultivar Pusa-Tarak under AlF stress was accompanied by an increase in proline level and enzymes activity of catalase and ascorbate peroxidase. However, significant increase in superoxide dismutase activity was observed in cultivar Laxmi. We also observed that AlF inhibits psb A gene expression to a lesser extent in tolerant cultivar Pusa-Tarak in comparison to susceptible cultivar Laxmi.

Differential response of Brassica juncea cultivars to Al; consequences for chlorophyll a fluorescence, antioxidants and psb A gene

ABSTRACTThe present study was undertaken to identify the aluminum (Al) tolerant cultivar of Brassica juncea. We examined the changes in antioxidant enzymes, proline level, chlorophyll a fluorescence and psb A gene expression at vegetative and reproductive growth stages of B. juncea cultivars (Bio-902, CS-14, Pusa-Tarak and Laxmi). The selected cultivars were exposed to soil (pH 5.2) supplemented with Al (0, 50, 100 and 150 mg kg−1). We observed the lowest decline in photosynthetic efficiency (ΔF/Fm′), ETR, PPFD values and psb A expression to Al stress in the cultivar Bio-902 (tolerant cultivar) followed by CS-14 and Pusa-Tarak whereas the highest decline was observed in the cultivar Laxmi (sensitive cultivar). The improved performance of the cultivar Bio-902 under Al stress was accompanied by an increase in proline level, CAT and APX activities but without any increase in SOD activity. However, significant increase in SOD activity was observed in Laxmi.

Arsenic affects the production of glucosinolate, thiol and phytochemical compounds: A comparison of two Brassica cultivars

Arsenic (As), a non-essential metalloid, severely affects the normal functioning of plants, animals and humans. Plants play a crucial role in metabolic, physiological and numerous detoxification mechanisms to cope up with As induced stress. This study aimed to examine the differential response in two Brassica juncea cultivars, Varuna and Pusa Jagannath (PJn) exposed to different doses of As (50, 150, 300 μM) for 48 h duration. Change in morphological traits, concentration of individual as well as total GSL, sulfur related thiol proteins, sulfur content, and phytochemicals were analyzed in both cultivars. Accumulation pattern of As showed dose dependent accumulation in both the cultivars, being more in PJn. Our finding revealed that both cultivars were tolerant at low concentrations of As, while at higher concentration Varuna excelled over PJn. The increased tolerance of Varuna cultivar exposed to 150 and 300 μM concentration of As, correlated with its increased thiol related proteins, sulfur content and phytochemicals, which serves as defence strategy in the plant against oxidative stress. Differential pattern of total as well as individual GSLs content was observed in both Varuna and PJn cultivars. Varuna cultivar showed higher level of total and aliphatic GSLs, which serves as defence compound with other detoxification machineries to combat As stress. Our findings provide foundation for developing metalloid tolerant crops by analyzing the role of different genes involved in GSL mechanism and signaling pathways in different organs of plant.

Is foliar spray of proline sufficient for mitigation of salt stress in Brassica juncea cultivars?

The effects of foliar application of proline (20mM) on growth, physio-biochemical, and yield parameters were assessed in two Brassica juncea (L.) Czern & Coss cultivars, namely, Varuna and RH-30, at different levels (2.8, 4.2, or 5.6dsm(-1)) of NaCl in soil. At 29days after sowing (DAS), plants were sprayed with either 20mM proline or water in the presence or absence of NaCl stress. The NaCl negatively affected parameters related to growth, photosynthesis, and yield in both varieties but more in RH-30 than in Varuna. Exogenous application of proline counteracted the effects of salt stress in Varuna only, by increasing the antioxidative capacity of the plants. Moreover, proline was not effective in alleviating the detrimental effects of higher salt concentrations on the studied parameters. Proline application to unstressed plants increased growth, photosynthesis, and yield parameters in both varieties; however, the effects were more prominent in Varuna than in RH-30.

Pathogenic and Genetic Characterization of Xanthomonas campestris Pv. campestris Races Based on Rep-PCR and Multilocus Sequence Analysis

Xanthomonas campestris pv. campestris (Pammel) Dowson (Xcc) is the causal agent of black rot disease of crucifers worldwide. Seventy five isolates of Xcc were collected from 12 agro-climatic regions of India to determine the distribution pattern of races and diversity of the population. Based on pathogenic reaction on seven standard differential crucifers, race 1, 4 & 6 were found to be prevalent. For assessing the pathogenic diversity, forty one cultivars of crucifers comprising seven Brassica and coeno species were inoculated artificially under field conditions. Brassica juncea cultivars (Pusa Bold, Varuna, Pusa Vijay, Pusa Mustard 21 and Pusa Mustard 25) showed resistance against all the strains of Xcc, whereas the Brassica olerecea cultivar Pusa Ageti was found to be resistant to races 1 and 4. Genetic characterization of these 75 strains of Xcc was carried out using rep-PCR (ERIC, REP and BOXPCRs) followed by phylogenetic analysis. The strains of Xcc clustered into 6 groups at 50% similarity coefficient and among these groups, 28 strains of Xcc belonging to races 1, 4 & 6 were clustered together under Group 5. Sequences of the 16S rRNA, hrpF and efP genes of five strains representing the races 1, 4 and 6 were used for multilocus sequence analysis. Based on sequence analysis of 16S rRNA and hrpF genes, the Indian strains were found to be very closely related to the strain Xcc ATCC 33913 (race 3, UK), whereas based on efP sequences, they were found to be closely related to strains race 1 Xcc B100 (Italy) and race 9 Xcc 8004 (UK).

Sodium and boron exclusion in two Brassica juncea cultivars exposed to the combined treatments of salinity and boron at moderate alkalinity

Salinity and high boron (B) concentrations are important co-limitations to crop production on naturally occurring alkaline soils in low rainfall regions of the world. Although the interactive effects of salinity and B toxicity on Brassica juncea growth have been reported in slightly acidic soils, very little is known about the interactive effects in alkaline soils. In the current study, a moderately tolerant (Vaibhav) and sensitive (Xinyou5) variety, were grown hydroponically for four weeks to assess mild salinity (50 mM NaCl) with or without high B (1 mM B) at moderate alkalinity (pH 8.5/5 mM NaHCO3). The growth of the two varieties was more affected under the combined treatment than either salinity or high B alone. Although growth rate reduction was similar among the varieties, Vaibhav maintained a lower sodium (Na) and B and a higher potassium (K) concentration in the leaves than Xinyou5. In response to salinity, Vaibhav demonstrated essential tolerance mechanisms of partial exclusion and presumably compartmentalization of Na, leading to greater biomass than Xinyou5. Despite being able to better exclude B, Xinyou5 suffered a greater growth penalty, indicating higher B sensitivity than Vaibhav. In conclusion, screening for individual stresses is not necessarily the best strategy because plant responses to a single stress either salinity or high B may not always be the same as observed when both stresses are present together. Therefore, Brassica germplasm screening is essential for stresses in combination but not separately.

An avirulence gene, AvrLmJ1, from the blackleg fungus, Leptosphaeria maculans, confers avirulence to Brassica juncea cultivars

The fungus Leptosphaeria maculans causes blackleg of Brassica species. Here, we report the mapping and subsequent cloning of an avirulence gene from L. maculans. This gene, termed AvrLmJ1, confers avirulence towards all three Brassica juncea cultivars tested. Analysis of RNA-seq data showed that AvrLmJ1 is housed in a region of the L. maculans genome which contains only one gene that is highly expressed in planta. The closest genes are 57 and 33 kb away and, like other avirulence genes of L. maculans, AvrLmJ1 is located within an AT-rich, gene-poor region of the genome. The encoded protein is 141 amino acids, has a predicted signal peptide and is cysteine rich. Two virulent isolates contain a premature stop codon in AvrLmJ1. Complementation of an isolate that forms cotyledonary lesions on B. juncea with the wild-type allele of AvrLmJ1 confers avirulence towards all three B. juncea cultivars tested, suggesting that the gene may confer species-specific avirulence activity.

Microscopic study of Alternaria brassicae infection processes in Brassica juncea cultivars by drop plus agarose method

Alternaria blight caused by Alternaria brassicae (Berk) Sacc. is one of the most serious diseases of Indian mustard [Brassica juncea (L.) Czern and Coss.] grown as edible oilseed crop in India. Poorly characterized tolerance mechanisms against this pathogen further confirm the strategies that can be undertaken to design durable resistance or effective disease control measures. The host-pathogen interaction was studied and showed that the initial infection processes involving conidium germination and mode of penetration were similar in both cultivars, although considerably late in ‘PAB 9511’ evidently due to tolerance. However, apparent differences between the two cultivars were noticeable by 1 dpi. At the plant surface, impeded fungal growth, less proliferation of spores and active suppression of the dense hyphal moulds are the factors involved in the expression of tolerance against A. brassicae in cultivar PAB 9511. Our findings have notably advanced our understanding of the mechanism of tolerance in this patho-system. Key words: Artificial inoculation, Brassica juncea, Alternaria brassicae, pathogenicity,plant-pathogen interaction.

Cadmium Induced Physio-Biochemical and Molecular Response in Brassica Juncea

Cadmium is a hazardous heavy metal; its presence in the agricultural soil constrains the crop productivity and restricts crop plants from reaching their full genetic potential. In the present study, two Brassica juncea cultivars (Pusa Bold and Pusa Jaikisan), were exposed to different concentrations of cadmium (Cd) as cadmium chloride (CdCl2) (50 μM, 100 μM, 150 μM, and 200 μM). The effect of cadmium on seed germination ratio, changes in the root and shoot length, plant dry weight, moisture content, metal tolerance index, antioxidant enzyme activity and lipid peroxidation were studied. The consequence of cadmium stress at the molecular level was studied using a key gene Phytochelatin Synthase (PCS). The results of our study suggested that, exposure of cadmium affected the seed germination, growth rate, biomass content and antioxidant enzyme activities in the root, shoot and leaves of both the cultivars. Transcript expression of PCS was increased with increasing CdCl2 concentration in both the cultivars. Based on the results, it was concluded that, Brassica juncea Cv Pusa Jaikisan is more tolerant to cadmium toxicity than the Pusa Bold. These findings could be used to develop heavy metal stress tolerant plants and more importantly, detoxification of heavy metals in the soil.

Salt-induced stress responses of Brassica (Brassica juncea L.) genotypes

The effects of salt stress were evaluated in two Brassica juncea cultivars, Varuna and TM2, in relation to growth, osmolyte accumulation and antioxidant enzymes at 50, 100 and 200 mmol l−1 NaCl concentration. In general, significant reduction in shoot and root growth and relative water content was observed under salt stress.Among the varieties, extent of reduction for these parameters was more pronounced and significant in the case of Varuna than TM2. Significant accumulation of glycine betaine was observed in Varuna and TM2 in 100 and 200 mmol l−1 salt stress treatments than control but the magnitude of increase was significantly higher in TM2. In general, salt stress led to increased activities of Superoxid dismutase, Catalase and Guaiacol peroxidase. The SOD activity was significantly higher in Varuna than TM2. Catalase activity showed an increase up to 100 mmol l−1 NaCl concentration whereas it decreased at 200 mmol l−1 in both the cultivars. Based on the results, TM2 appears to have higher salt tolerance than Varuna. It is also suggestive that osmotic adjustment and antioxidant enzymes play an important role in contributing to salinity tolerance in Brassica juncea L.

Activated charcoal induced high frequency microspore embryogenesis and efficient doubled haploid production in Brassica juncea

Three Indian Brassica juncea cultivars were studied for embryogenic response of microspores, microspore embryo regeneration, ploidy assessment of microspore-derived plants and their diploidization. Genotype dependence for microspore totipotency was observed and a significant effect of genotype by bud size selection was established. The addition of activated charcoal in NLN medium containing 13% (w/v) sucrose and 10 μM silver nitrate resulted in a fourfold increase in microspore embryogenesis, ranging from 100 to 405 embryos per Petri dish corresponding to 2,700–10,935 embryos per 100 buds. Conversion/germination of embryos produced in presence or absence of activated charcoal was similar but air-drying of microspore embryos was essential. Incubation of microspore embryos at 4 ± 1°C for 10 days in dark resulted in 82.3% conversion. The majority of plants produced from these embryos was haploid. Treating microspore-derived plants at the 3–4 leaf growth stage with 0.34% colchicine for 2–3 h resulted in greatest survival (70%) and chromosome doubling (75%) frequencies. Doubled haploid plants were self-pollinated and grown to maturity under field conditions.

Proline Metabolism Under Water Stress in the Leaves and Roots of Brassica juncea Cultivars Differing in Drought Tolerance

Plant water relations, proline content and activities of pyrroline-5-carboxylate synthetase (P5CS) and proline oxidase (PO) were studied in five Brassica juncea genotypes differing in drought response. Under water stress, drought tolerant cv Varuna showed maximum osmotic adjustment value (1/b) of 3.21. In this variety, proline content increased from 8.4 and 5.3 μmol g−1 dry weight under normal conditions to 128.2 and 44.5 μmol g−1 dry weight under stress conditions in the leaves and roots respectively. The increase in proline content in less drought tolerant variety Prakash was from 7.0 and 1.8 μmol g−1 dry weight In the absence of stress to 62.9 and 13.4 μmol g−1 dry weight in the presence of stress in leaves and roots respectively. Compared to the respective controls, increase in the activity of proline biosynthetic enzyme P5CS of roots and leaves under water stress was maximum (∼ 94%) in Varuna and minimum in Prakash (∼16%). Reduction in the activity of proline degrading enzyme PO due to stress was also maximum in the leaves (75%) and roots (87%) of Varuna. These results showed genotype dependent effect of water stress on plant water relations and proline metabolism.