Pusa Sugandh Research Articles

Climate–resilient strategy for shortening the crop cycle in rice and the host influenced rhizosphere microbiome

We present the field rapid generation advancement procedure for shortening the crop cycle in rice. The practical protocol developed by us using different maturity groups of rice showed promising early flower induction. We observed a shortening of crop cycle to about 35–40 days depending on the variety. The spacing between the plants was the major influencer for flower induction compared to other interventions tested viz., clipping, potassium di-hydrogen phosphate and paclobutrazol spray. Our raised bed direct seeding strategy completely avoided the transplantation. The work flow for flower induction can be a reference to increase generations of rice breeding. The rhizosphere bacterial dynamics using 16srRNA gene amplicon sequencing showed the Acinetobacter population abundance as a key mediator and marker for flowering time. The alpha diversity at flowered and unflowered stage showed the species richness as Control < Pusa Sugandh 5 < BPT-5204. The rice rhizosphere of this ecosystem had an abundance of Methylotrophs that utilize methane as a carbon source suggesting that the developed method is a green technique suitable for generation advancement that can be replaced for flooded condition assisted breeding in rice. Selective enrichment of functional abundance between varieties suggested the host - influenced microbiome for early flowering in rice. This protocol is expected to greatly accelerate the process of new variety breeding and the construction of mapping populations.

A novelmicronutrients and methyl jasmonate cocktail of elicitors via seed priming improves drought tolerance by mitigating oxidative stress in rice (Oryza sativaL.).

Drought is a major limiting factor for rice (Oryza sativa L.) production globally, and a cost-effective seed priming technique using bio-elicitors has been found to have stress mitigating effects. Till date, mostly phytohormones have been preferred as bio-elicitors, but the present study is a novel attempt to demonstrate the favorable role of micronutrients-phytohormone cocktail, i.e., iron (Fe), zinc (Zn), and methyl jasmonate (MJ) via seed priming method in mitigating the deleterious impacts of drought stress through physio-biochemical and molecular manifestations. The effect of cocktail/priming was studied on the relative water content, chlorophyll a/b and carotenoid contents, proline content, abscisic acid (ABA) content, and on the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), NADPH oxidase (Nox), and catalase (CAT). The expressions of drought-responsive genes OsZn-SOD, OsFe-SOD, and Nox1 were found to be modulated under drought stress in contrasting rice genotypes -N-22 (Nagina-22, drought-tolerant) and PS-5 (Pusa Sugandh-5, drought-sensitive). A progressive rise in carotenoids (10-19%), ABA (18-50%), proline (60-80%), activities of SOD (27-62%), APX (46-61%), CAT (50-80%), Nox (16-30%), and upregulated (0.9-1.6-fold) expressions of OsZn-SOD, OsFe-SOD, and Nox1 genes were found in the primed plants under drought condition. This cocktail would serve as a potential supplement in modern agricultural practices utilizing seed priming technique to mitigate drought stress-induced oxidative burst in food crops.

Overexpression of a DUF740 family gene (LOC_Os04g59420) imparts enhanced climate resilience through multiple stress tolerance in rice.

Functional characterization of stress-responsive genes through the analysis of transgenic plants is a standard approach to comprehend their role in climate resilience and subsequently exploit them for sustainable crop improvement. In this study, we investigated the function of LOC_Os04g59420, a gene of DUF740 family (OsSRDP-Oryza sativa Stress Responsive DUF740 Protein) from rice, which showed upregulation in response to abiotic stress in the available global expression data, but is yet to be functionally characterized. Transgenic plants of the rice OsSRDP gene, driven by a stress-inducible promoter AtRd29A, were developed in the background of cv. Pusa Sugandh 2 (PS2) and their transgene integration and copy number were confirmed by molecular analysis. The three independent homozygous transgenic plants (AtRd29A::OsSRDP rice transformants) showed better resilience to drought, salinity, and cold stresses, but not heat stress, as compared to the non-transformed PS2, which corresponded with their respective relative transcript abundance for OsSRDP. Transgenic plants maintained higher RWC, photosynthetic pigments, and proline accumulation under drought and salinity stresses. Furthermore, they exhibited less accumulation of reactive oxygen species (ROS) than PS2 under drought stress, as seen from the transcript abundance studies of the ROS genes. Under cold stress, OsSRDP transgenic lines illustrated minimal cell membrane injury compared to PS2. Additionally, the transgenic plants showed resistance to a virulent strain of rice blast fungus, Magnaporthe oryzae (M. oryzae). The promoter analysis of the gene in N22 and PS2 revealed the presence of multiple abiotic and biotic stress-specific motif elements supporting our observation on multiple stress tolerance. Based on bioinformatics studies, we identified four potential candidate interaction partners for LOC_Os04g59420, of which two genes (LOC_Os05g09640 and LOC_Os06g50370) showed co-expression under biotic and drought stress along with OsSRDP. Altogether, our findings established that stress-inducible expression of OsSRDP can significantly enhance tolerance to multiple abiotic stresses and a biotic stress.

CRY2 gene of rice (Oryza sativa subsp. indica) encodes a blue light sensory receptor involved in regulating flowering, plant height and partial photomorphogenesis in dark.

OsiCRY2 is involved in light-regulated plant development and plays a role in regulating photomorphogenesis, plant height, flowering and most strikingly partial photomorphogenesis in dark. Cryptochrome 2 (CRY2), the blue/UV-A light photoreceptor in plants, has been reported to regulate photoperiod-dependent flowering and seedling photomorphogenesis (under low-intensity light). Among monocots, CRY2 has been reported from japonica rice, wheat, sorghum and barley. The two sub-species of rice, indica and japonica, exhibit a high degree of genetic variation and morphological and physiological differences. This article describes the characterization of CRY2 of indica rice (OsiCRY2). While the transcript levels of OsiCRY2 did not change significantly under blue light, its protein levels were found to decline with increased time duration under blue light. For phenotypic characterization, OsiCRY2 over-expression (OX) transgenics were generated in Oryza sativa Pusa Sugandh 2 (PS2) cultivar, a highly scented Basmati cultivar. The OsiCRY2OX transgenics displayed shorter coleoptiles and dwarfism than wild-type under blue light, white, and far-red light. Interestingly, even the dark-grown transgenics were shorter, concomitant with higher OsiCRY2 protein levels in transgenics than wild-type. Histological analysis revealed that the decrease in the length of the seedlings was due to a decrease in the length of the epidermal cells. The fully mature rice transgenics were shorter than the untransformed plants but flowered at the same time as wild-type. However, the OsiCRY2 Arabidopsis over-expressors exhibited early flowering by 10-15days, indicating the potential and conservation of function of OsiCRY2. The whole-genome transcriptome profiling of rice transgenics revealed the differential up-regulation of several light-regulated genes in dark-grown coleoptiles. These data provide evidence that OsiCRY2 regulates photomorphogenesis, plant height, and flowering in indica rice.

Expression profiling of flavonoid biosynthesis genes in association with accumulation of flavonoid compounds in rice under water deficit stress

Aim: To investigate whether the phenolic and flavonoid contents have any direct relation with the water deficit stress tolerance in rice. If so, then, which genes in the flavonoid biosynthesis pathway are involved in the tolerance mechanism was explored by comparing a well-known water deficit tolerant cv. Nagina 22 (N22) as experiment material along with a sensitive cv. Pusa Sugandh 2 (PS2). Methodology: Water deficit stress was imposed on N22 (drought tolerant) and PS2 (drought sensitive) cultivars at the seedling stage by withholding water for 7days. Further, the expression level of flavonoid biosynthesis genes (OsCHS, OsCHI, OsF3H, OsF3’H, OsDFR, and OsANS) and the accumulation of total contents of phenolics and flavonoids in rice leaves of N22 and PS2 under water deficit stress were also investigated. Results: Quantitative RT-PCR analysis revealed enhanced expression of six major genes of the flavonoid biosynthesis pathway, namely OsCHS, OsCHI, OsF3H, OsF3’H, OsDFR, and OsANS in the drought tolerant cv. N22 compared to the drought sensitive cv. PS2 under water deficit stress. Accumulation of total phenolics and flavonoids compounds increased during water deficit stress in both the genotypes, but, it was significantly higher in N22 as compared to PS2. Interpretation: Our findings conclude that enhanced drought tolerance is positively correlated with an enhanced transcription of flavonoid biosynthesis genes and higher flavonoid content, suggesting that there could be differences in the genetic control of flavonoid metabolism in rice for drought stress response that, the enhanced expression and accumulation of flavonoids is promising strategy for rice improvement.

Stress-inducible expression of chalcone isomerase2 gene improves accumulation of flavonoids and imparts enhanced abiotic stress tolerance to rice

Analysis of rice microarray data indicated that a gene encoding for chalcone isomerase2 (OsCHI2) showed upregulation in response to abiotic stress. Hence, we isolated OsCHI2 from a popular drought tolerant upland rice variety Nagina22 and developed transgenic plants of a drought stress sensitive rice cv. Pusa Sugandh 2 expressing OsCHI2 under the control of stress inducible promoter AtRd29A and further studied their response to different abiotic stresses. Stable chromosomal integration of transgene was confirmed in the transgenic plants through PCR, Southern hybridization and expression analysis. Physio-biochemical studies revealed that the Rd29A::OsCHI2 transgenic rice plants upheld higher relative water content, more photosynthetic pigments and proline with lower relative electrolyte leakage and less malondialdehyde content as compared to WT plants under abiotic stresses. Quantitative RT-PCR analysis demonstrated that the expression level of the transgene in the OsCHI2 transgenic lines was higher than WT plants under stress conditions. Stress-inducible expression of OsCHI2 also enhanced transcript abundance of structural genes of flavonoids biosynthesis pathway leading to higher production of flavonoids under abiotic stresses in the transgenic plants. In brief, our results demonstrated that OsCHI2 is not only capable of modulating flavonoid metabolism but also can impart enhanced adaptation to different abiotic stresses other than heat stress.

Adaptability and AMMI biplot analysis for yield and agronomical traits in scented rice genotypes under diverse production environments

The crucial aspect of the identification of the genotypes adaptable to different production environments (systems) for the thirty-six popular scented rice varieties was countered via adaptability and AMMI biplot analysis. The varieties were evaluated for several agronomical traits (twelve) under four production environments namely, direct-seeded rice (DSR), the system of rice intensification (SRI), chemical-free cultivation (CFC) and transplanted rice (TPR). Among different production environments, SRI was found on the top followed by TPR, CFC and DSR. Genotype × environment interactions were significant for all of the traits. Based on the AMMI biplot technique, Pusa Sugandh 3, HKR -11-509 and Pusa Sugandh 5 were found suitable for grain yield per plant and general adaptation to all the environments.

Expression dynamics of genes encoding nitrate and ammonium assimilation enzymes in rice genotypes exposed to reproductive stage salinity stress

Understanding the reproductive stage salinity stress tolerance is a key target for breeding stress tolerant rice genotypes. Nitrate and ammonium are equally important nitrogen forms utilized by rice. We evaluated nitrate and ammonium assimilation during reproductive stage in control and salinity (10dSm−1 using NaCl) stressed rice plants. Osmotic stress tolerant rice genotype Shabhagidhan (SD) and high yielding yet osmotic and salinity stress sensitive genotype Pusa sugandh-5 (PS5) were evaluated. Salinity stress was given to plants during panicle emergence and flag leaves was collected after 1d, 3d 5d, 7d, 9d,12d and 15d after anthesis. Reproductive stage salinity stress resulted in decrease of membrane stability, relative water content and osmotic potential of rice plants. Reproductive stage salinity stress decreased the expression of nitrate reductase (OsNIA), nitrite reductase (OsNiR), Glutamine synthetase (OsGLN1.1, OsGLN1.2, OsGLN2) and glutamate synthase/GOGAT (OsFd-GOGAT, OsNADH-GOGAT) in flag leaves. In response to stress, SD showed better stress tolerance than PS5 in terms of higher yield stability. Variety SD showed higher leaf nitrate and ammonium content and maintained comparatively higher nitrate and ammonia metabolism enzyme activity than PS5. Salinity stress upregulated the activity of glutamate dehydrogenase enzyme and indirectly contributed to the higher proline content and maintenance of favourable osmotic potential in SD. Expression of GS2 which has role in photo respiratory ammonia assimilation was upregulated by salinity stress in PS5 in comparison to SD. Rice genotype showing better induction of nitrogen assimilatory genes will be more tolerant to reproductive stage salinity stress.

Plant growth regulator induced mitigation of oxidative burst helps in the management of drought stress in rice (Oryza sativa L.)

Drought is a major yield-limiting factor for rice production. Present study is a first of its own kind to show the promising role of plant growth regulators (PGRs) [methyl jasmonate (MJ), salicylic acid (SA), paclobutrazol (PBZ)] to mitigate drought induced notable variations in physio-biochemical parameters-relative water content (RWC), total antioxidant activity (TAO), total phenolic content (TPC), lipid peroxidation (LP), protein oxidation (PO), abscisic acid content (ABA) and NADPH oxidase (Nox) activity in contrasting rice genotypes-Nagina-22 (N-22, drought-tolerant) and Pusa Sugandh-5 (PS-5, drought-sensitive). It also revealed the changes in expressions of drought responsive genes (RD1, RD2) of AP2/ERF family and Nox family (Nox1, Nox5). A progressive increase in TPC (21–50 %), ABA content, (17–45 %), Nox (6–40 %), TAO (12–25 %) activity, while decrease in RWC (90−55 %), LP (64−25 %), PO (25−9 %) level, and expressions of RD1 and RD2 genes were found upregulated (∼1.4−1.8 fold) in primed samples under drought stress. Cloning, sequencing and characterization of Nox1 gene (accession number- MT771724) revealed its role in regulating oxidative burst during drought stress. Overall, seed-priming with MJ was identified to be highly effective to mitigate the deleterious effects of drought stress which could be further used to enhance drought tolerance in rice for improved yield under dry-land and rain-fed conditions.

In vitro Callus Induction and Regeneration of Popular Indica Rice Genotypes

Five rice cultivars viz., ASD 16, White Ponni, Pusa Basmati 1, Pusa Sugandh 4 and Pusa Sugandh 5 belonging to subspecies indica were compared for its ability in callus formation and regeneration. In this experiment, the different parameters viz., the effect of hormones (2,4-D and kinetin), organic supplement (coconut milk O1-CM 100 mll-1, O2-CM 75 mll-1, O3-CM 50 mll-1), explants (seed and immature embryo), media (MS and N6), carbon source (sucrose and maltose) using five genotypes on callus response was studied. The effect of hardening methods was also assessed. Results showed that for enhanced callus induction was with MS medium supplemented with 2.0 mgl-1 2, 4-D + 0.5 mgl-1 kinetin + 30 gl-1 maltose irrespective of explants used. Addition of 100 ml l-1 coconut milk was found have improvement in callus response. The performance of immature embryo was better than seed for callus induction, emrbyogenic callus formation, rhizogenic callus formation and regeneration. MS media provided superiority over N6. Among the genotypes Pusa Basmati 1 rendered outstanding performance in callus behavior. The treatment combination MS + 2.5 mgl-1 BAP + 0.5 mgl-1 NAA + 1.0 mgl-1 KN gave the highest organogenesis response and regeneration of plantlets. Hardening in mist chamber was recognized as the best method to give the highest per cent of regenerated plant lets.

The abscisic acid receptor OsPYL6 confers drought tolerance to indica rice through dehydration avoidance and tolerance mechanisms.

Abscisic acid (ABA) is a key regulator of plant development and stress tolerance. Here we report functional validation of the ABA receptor OsPYL6 by constitutive and stress-inducible overexpression and RNAi silencing, in an indica rice cultivar 'Pusa Sugandh 2'. Overexpression of OsPYL6 conferred ABA hypersensitivity during germination and promoted total root length. Overexpression and RNAi silencing of OsPYL6 resulted in enhanced accumulation of ABA in seedlings under non-stress conditions, at least, in part through up-regulation of different 9-cis epoxycarotenoid dioxygenase (NCED )genes. This suggests that PYL6 expression is crucial for ABA homeostasis. Analysis of drought tolerance of OsPYL6 transgenic and wild type plants showed that OsPYL6 overexpression enhanced the expression of stress-responsive genes and dehydration tolerance. Transgenic rice plants overexpressing OsPYL6 with AtRD29A (Arabidopsis thaliana Responsive to Dehydration 29A) promoter also exhibited about 25% less whole plant transpiration, compared with wild type plants under drought, confirming its role in activation of dehydration avoidance mechanisms. However, overexpression of PYL6 reduced grain yield under non-stress conditions due to reduction in height, biomass, panicle branching and spikelet fertility. RNAi silencing of OsPYL6 also reduced grain yield under drought. These results showed that rice OsPYL6 is a key regulator of plant development and drought tolerance, and fine-tuning of its expression is critical for improving yield and stress tolerance.

Cloning and characterization of a gene encoding MIZ1, a domain of unknown function protein and its role in salt and drought stress in rice.

Dwindling fresh water resources and climate change poses serious threats to rice production. Roots play crucial role in sensing water gradient and directing growth of the plant towards water through a mechanism called hydrotropism. Since very little information is available on root hydrotropism in major food crops, this study was carried out to clone and characterize an ortholog of Arabidopsis MIZU-KUSSEI1 (MIZ1) from rice. Contrasting rice genotypes for drought and salt tolerance were selected based on phenotyping for root traits. Nagina 22 and CR-262-4 were identified as most tolerant and Pusa Sugandh 5 and Pusa Basmati 1121 were identified as most susceptible varieties for both drought and salt stresses. Allele mining of MIZ1 in these varieties identified a 12 bp Indel but did not show specific allelic association with stress tolerance. Analysis of allelic variation of OsMIZ1 in 3024 rice genotypes of 3K genome lines using Rice SNP-Seek database revealed 49 InDels. Alleles with the 12bp deletions were significantly prevalent in indica group as compared to that of japonica group. Real-time RT-PCR analysis revealed that OsMIZ1 expression levels were upregulated significantly in tolerant cv. Nagina 22 and CR-262-4 under osmotic stress, while under salt stress, it was significantly upregulated only in CR-262-4 but maintained in Nagina 22 under salt stress. However, in the roots of susceptible genotypes, OsMIZ1 expression decreased under both the stresses. These results highlight the possible involvement of OsMIZ1 in drought and salt stress tolerance in rice. Furthermore, expression studies using publically available resources showed that enhanced expression of OsMIZ1 is regulated in response to disease infections, mineral deficiency, and heavy metal stresses and is also expressed in reproductive tissues in addition to roots. These findings indicate potential involvement of MIZ1 in developmental and stress response processes in rice.

Cloning and abiotic stress responsive expression analysis of Arginine decarboxylase genes in contrasting rice genotypes

Arginine decarboxylase (ADC) is the first enzyme of polyamine biosynthesis in plants, an important mediator of abiotic stress tolerance. Two genes OsADC1 and OsADC2 were found to be differentially expressed under various abiotic stresses namely salinity, drought, low temperature and high temperature. Significant differences in gene expression were found among contrasting rice genotypes Nerica-L-44 (NL44; tolerant) and Pusa Sugandh 2 (PS2; sensitive). Among the homologs, OsADC2 was induced frequently in abiotic stresses with a higher transcript level than OsADC1. When the stress dependent gene expression was estimated relative to control conditions, PS2 showed a significant and higher level of induction. The estimation of relative gene expression between genotypes for each stress in all shoot tissues showed significantly higher level of expression in NL44 than PS2. In roots, the stress induced expression was higher in the sensitive genotype PS2. Construction of phylogenetic tree provided an insight on the evolution of OsADC gene from lower to higher organisms. The OsADC2 gene was found to be highly diverged from OsADC1 as well as from the counterparts of related and distant taxa. The analysis of amino acid sequence identified the conserved substrate binding, cofactor binding and dimerisation domains essential for enzyme activity.

Development of temperate basmati rice: a multi-year study on performance and adaptation under high altitude conditions of Northern Himalayas

AbstractIn the present study, an effective secondary selection of transgressive variants from a homozygous population of Pusa Sugandh 3 (PS3) has led to the development of basmati variant SKUA 494. SKUA 494 exhibited a grain yield (7.9 t/ha) with superiority of 21.5% over its progenitor (6.5 t/ha). Besides, the genotype revealed an earliness of about 13 and 15 days for flowering and maturity, respectively. Hulling, milling and head rice recovery traits of SKUA 494 were comparatively better over the controls PS3 and Pusa Basmati 1509. No significant differences in the cooking quality were observed in SKUA 494 over its parental line. Quality traits of SKUA 494 revealed an intermediate score for alkali spreading value, besides similar values for gel consistency and amylose content in comparison to PS3. On the basis of stability variables, stability index and overall mean for most of the traits, SKUA 494 depicted stable performance across the locations and over the years. Molecular analysis based on simple sequence repeat markers revealed polymorphism at locus flanking the quantitative trait loci for days to heading (Hd6) between SKUA 494 and its parent (PS3). Based on overall superiority in the performance and adaptability of SKUA 494, the variety has been recommended to farmers for general cultivation under temperate ecology.

Developing rice hybrids for temperate conditions using three line approach

Exploitation of heterosis in the form of hybrid rice is yet to be exploited at commercial level in the temperate regions of India. The present study is attempted to develop rice hybrids for the temperate conditions of Kashmir valley by utilizing the cytoplasmic genetic male sterility system (CGMS). Among the four CMS lines evaluated, the genotype SKUA-7A and SKUA-11A had desirable performances. The 24 test crosses developed involving these CMS lines were evaluated for spikelet fertility and pollen fertility. Moreover, the highest standard heterosis for grain yield and other yield attributes over the check varieties (Jehlum and Shalimar Rice-3) was recorded in the cross combination K15-34 followed by K15-31 and K15-40. Pollen parents of all the three test crosses on screening with RM-6100, DDRMRf3-10 and DRCG-Rf4-14 markers revealed presence of both Rf3 and Rf4 genes responsible for fertility restoration. Besides, 39 genotypes were screened for fertility restoration and the lines RL-2, RL-5, RL-6, RL-7, RL-10, Pusa Sugandh3 and Kohsar were identified to carry homozygous alleles at both Rf3 and Rf4 loci. These genotypes can thus be used as promising restores for the development of temperate rice hybrids.

Effect of different production systems on flowering and maturity duration of basmati rice genotypes

The study of G×E Interaction (GEI) is critical for evaluating the mean performance and stability of cultivars across wide range of environmental conditions. An experiment was conducted during kharif 2014–2015 for discriminating 22 basmati rice genotypes for days to 50% flowering and days to 75% maturity using AMMI and regression stability models under four different environments viz. direct (DSR-wet) and (DSR-dry) and indirect seeding transplanted rice (TPR) and system of rice intensification (SRI) conditions at CCS HAU farm, Kaul. Estimates of G×E interaction following Eberhart and Russell (1966) and AMMI biplot analysis as per Gauch and Zobel model (1989) were computed. For days to 50% flowering, genotypes like Pusa Basmati 6, Pusa Sugandh 3, Haryana Basmati-1 and Pusa RH 10 were identified under SRI; CSR-30 under DSR (dry) and DSR (wet) and HKR 98–476, Pusa Sugandh 2 and Pusa Sugandh 5 under TPR conditions. However, for days to 75% maturity Pusa Sugandh 3, Pusa Basmati 1121, Pusa Basmati 1 and HKR 06–434 were adapted best to SRI; Traori Basmati, Basmati-370, HKR 98–476 and HKR 06–443 to TPR and DSR (dry) and HKR 06–487 and Pusa RH 10 to DSR (wet).

Combining ability studies for yield and quality traits in aromatic genotypes of rice (Oryza Sativa. L.)

The present investigation was aimed to study the general combining ability of eight aromatic genotypes of rice and specific combining ability of all possible crosses for grain yield and quality traits in 28 F1’s obtained by 8x8 on way Diallel mating design. The estimates of SCA variance were revealed greater than GCA variance for all the characters except days to 50% flowering, days to maturity, plant height, effective tillers/plant and kernel length after cooking. It showed that both the additive as well as non-additive genetic variance exhibited importance for expression of the characters studied. The Parents, Pusa -2517-2-51-1and Pusa Sugandh-5 studied were identified as best general combiner for both yield and quality traits for most of the characters. Crosses, Pusa-2517-2-51-1×Type-3 showed non additive effects for yield traits only. However, the cross Ranbir Basmati x Pusa Basmati-1 showed non additive effects for quality traits. Cross combination viz., Pusa Sugandh-5 x Pusa Basmati-1, Ranbir Basmati x Kasturi Basmati, Kasturi Basmati × Pusa-2517-2-51-1 and Pusa Sugandh-3 x Type-3 showed non additive gene action for most of the yield as well as quality traits. For those traits which showed high performance were under the control of dominance and dominance × dominance gene effects, heterosis breeding would be most effective. Thus, present study aims to develop hybrids performing better for both yield as well as quality traits.

Genetic engineering of indica rice with AtDREB1A gene for enhanced abiotic stress tolerance

Drought and cold stresses are major abiotic stresses that affect rice productivity. Therefore, enhancing tolerance to these stresses is necessary for sustaining rice productivity. Overexpression of the AtDREB1A gene has been shown to confer tolerance to both drought and cold stresses in diverse plant species. Hence, we genetically engineered indica rice cv. Pusa Sugandh 2 with AtDREB1A gene under the transcriptional control of stress responsive AtRD29A promoter. The transformants were confirmed for the stable integration of transgene in the rice genome by using PCR, RT-PCR and Southern blot analyses. Two single copy transgenic events (T3) and non-transgenic (NT) plants grown in pots were subjected to drought and cold stresses for 14 days. Transgenic plants exhibited enhanced tolerance to both drought and cold stresses as compared with NT plants. Transgenic plants maintained significantly higher leaf relative water content (LRWC), chlorophyll content, total sugars and proteins, but lower canopy temperature as compared with NT plants. Microarray analysis of AtDREB1A transgenic rice line (TL4) subjected to drought stress at reproductive stage led to the identification of 256 differentially expressed genes (DEGs), of which 201 were upregulated under drought stress. Interestingly, ~ 38% of the up-regulated genes coded proteins for chloroplast structure and function, which is a unique finding of this study. About 47% of the DEGs were enriched with CRT/DRE cis-regulatory elements in their promoters. Of these CRT/DRE cis-element containing genes, 50% genes coded for chloroplast function suggesting that these genes might be the direct targets of DREB1A TF. Up-regulation of TFs ZFP179 and NF-YC1, which are positive regulators of stress tolerance and downregulated TFs HOX22 and OsNAP, which are negative regulators of stress tolerance might have contributed to the enhanced drought tolerance of AtDREB1A transgenic plants. In addition, AtDREB1A-mediated orchestration of genes for chloroplast function appeared to have played an important role in not only providing carbon requirements of plants for survival and growth, but also helped minimize photo-inhibition and ROS accumulation in chloroplast under drought stress. Thus, stress-inducible overexpression of AtDREB1A in rice is a useful strategy to enhance drought and cold tolerance in the major staple food crop of the world.

Impact of particulate matter on basmati rice varieties grown in Indo-Gangetic Plains of India: Growth, biochemical, physiological and yield attributes

The study presents the first experimental evidence of the effects of atmospheric particulate matter (PM) deposition on two basmati (scented) rice varieties [Pusa Basmati-1509 (PB-1509) and Pusa Sugandh-5 (PS-5)] grown in Indo-Gangetic Plains (IGP) of India. Atmospheric PM load at the experimental site during rice crop growth period (August–November) was in the range of 162–660 μgm−3. The rice varieties growth, biochemical, physiological and yield attributes were monitored under three levels of PM deposition namely - low levels of PM deposition (LPM), ambient levels of PM deposition (APM) and elevated levels of PM deposition (EPM). PM deposition and PM flux on the canopy of rice varieties were 400–574 μgcm−2 and 24–58 μgcm−2day−1, respectively. PM deposition was 4.5% higher on the PS-5 than PB-1509 and among growth stages; it was the highest during the reproductive growth stage. Significant reduction in chlorophyll, leaf water and carotenoid content were observed in both varieties under EPM compared to APM. The air pollution tolerance index (APTI) also declined significantly. PM deposition enhanced leaf temperature (1–6%) of rice varieties under EPM compared to APM. The reduction in photosynthesis, stomatal conductance and transpiration of rice varieties under EPM were in the range of 9–52%; 6–40% and 8–46%, respectively compared to APM. PM deposition effects on plant height, the number of tillers and recoverable root biomass were found non-significant. PS-5 and PB-1509 exhibited 4–7% enhancement and 7.5–14% reduction in grain yield under LPM and EPM compared to APM, respectively. The results of the study indicate that increasing atmospheric PM pollution in IGP may adversely affect productivity and economic gains from scented basmati varieties of rice.

AMMI biplot analysis for stability in basmati rice (Oryza sativa L.) in different production systems

The study of G×E Interaction (GEI) is critical for evaluating the mean performance and stability of cultivars across wide range of environmental conditions. An experiment was conducted during kharif 2014-2015 for discriminating 22 basmati rice genotypes for days to 50% flowering and days to 75% maturity using AMMI and GGE stability models under four different environments viz. direct (DSR-wet) and (DSR-dry) and indirect seeding transplanted rice (TPR) and system of rice intensification (SRI) conditions at CCS HAU farm, Kaul. Estimates of G×E interaction following Eberhart and Russell (1966) and AMMI biplot analysis as per Gauch and Zobel model (1989) were computed. For days to 50% flowering, genotypes like Pusa Basmati 6, Pusa Sugandh 3, Haryana Basmati-1 and Pusa RH 10 were identified under SRI, CSR-30 under DSR (dry) and DSR (wet) and HKR 98-476, Pusa Sugandh 2 and Pusa Sugandh 5 under TPR conditions. However, for days to 75% maturity, Pusa Sugandh 3, Pusa Basmati 1121, Pusa Basmati 1 and HKR 06-434 were adapted best to SRI, Traori Basmati, Basmati-370, HKR 98-476 and HKR 06-443 to TPR and DSR (dry) and HKR 06-487 and Pusa RH 10 to DSR (wet).