Assessment of drought tolerance in mung bean cultivars/lines as depicted by the activities of germination enzymes,seedling’s antioxidative potential and nutrient acquisition

Drought stress hampers firm crop stand establishment and yield in arid and semiarid regions. The present study was conducted to examine the drought tolerance of various mung bean cultivars/lines based on the seed germination characteristics in relation with the seedling’s antioxidative potential and nutrient uptake. Activities of germination enzymes, seed germination attributes, seedling biomass production and nutrient uptake of studied cultivars/lines were adversely affected due to PEG-induced drought but the total soluble proteins (TSP) and malondialdehyde (MDA) contents were increased. The activities of catalse (CAT) and ascorbate peroxidase (APX) increased in all cultivars/lines being the maximum in cv./line NM-2006 and 8005. The activities of superoxide dismutase (SOD) and peroxidase (POD) were increased in cv./line NM-2006 and 8005 under drought condition. The ascorbic acid (AsA) and total phenolic content (TPC) decreased and total flavonoid content (TFC) increased in all cultivars/lines due to drought. Significant reduction in N, P, K, Ca and Mg was found in all cvs./lines but Fe remain unchanged. In conclusion, cultivars/lines NM-2006, 8005 were recommended as drought tolerant and 97,006 and 97,001 as drought sensitive ones. The study outcomes will likely be helpful for the farmers growing mung bean in rain fed areas for the better productivity.     

大豆种子老化的转录组学分析

大豆种子储存过程易老化劣变,研究大豆种子老化分子机制有助于耐储藏大豆品种遗传改良。文章对不同耐储性大豆品种老化种子作转录组测序分析,结果表明,储存2~4年后,易老化大豆"JP16"和耐储型大豆"JP6"分别有1 683个和832个差异转录基因,皆以上调为主。基因功能注释显示,这些基因主要富集于碳水化合物合成、水分损失、线粒体机能改变及蛋白质降解等生物过程。另外,"JP16"响应蛋白质泛素化和脂肪酸氧化基因上调,花青素、木质素合成相关基因下调;而"JP6"响应原花青素、异黄酮合成及活性氧水平调控相关基因上调,蜡质代谢相关基因下调。大豆种子通常随储存时间延长,内部碳水化合物降解,蛋白变性,扰乱胞内水分正常代谢,加剧活性氧积累,种子老化加剧。耐储型大豆种子可通过积累蜡质、原花青素、异黄酮等保护性成分,增强对活性氧调控提高细胞壁强度和抗氧化能力,延缓老化。研究结果为利用分子手段提高大豆种子耐储性能提供参考。     

Congener-specific evaluation of biota-sediment accumulation factor model for HCHs and DDTs under small-scale in situ riverine condition

Purpose

The congener-specific biota-sediment accumulation factors (BSAFs) model for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) was evaluated for four different freshwater fish species (Orienus plagiostomus, Tor putitora, Glyptothorax punjabensis, and Cyprinus carpio) in in situ riverine conditions of Kabul River, Pakistan.

Materials and methods

The congeners of HCH and DDT were quantified using gas chromatograph (GC-ECD). The BSAF for each congener (HCHs and DDTs) was calculated from paired observation of congener’s measured concentrations in fish and sediment taken at the same site. Pearson’s correlation and linear regression analyses were performed to determine the influence of sediment organic carbon fraction (f _soc ) and organism lipid fraction (f _lipid ) on BSAF, and the relationship between BSAFs and logarithm of octanol-water partition coefficients (log K _ows) of HCH and DDT congeners, respectively.

Results and discussion

The BSAFs for total HCH (t-HCH) and total DDT (t-DDT) ranged from 0.6 to 1.5 and from 0.2 to 1.6, respectively. The model was significantly influenced by both fish (p = 0.004) and chemical types (p = 0.002) at 95 % confidence level. The sediment organic carbon fraction (f _soc ) and fish lipid fraction (f _lipid ) had not-too-weak effects on BSAF values for all fish species. The BSAF values were linearly fitted with logarithmic octanol-water partition coefficients (log K _ows) of HCH and DDT congeners, despite the different chemical structures, and different compound class significant negative correlations between log K _ows and BSAF values were found, indicating that hydrophobicity is one of the key factors influencing the bioaccumulation potential of the investigated compounds.

Conclusions

The present study confirmed the applicability of the BSAF model as a screening tool for predicting bioaccumulation of sediment-associated HCH and DDT congeners in investigated fish species under small-scale in situ riverine conditions of Kabul River and suite the model for benthic fish (G. punjabensis) on the basis of the 25th and 75th percentiles of congener-specific BSAF values.

     

Current research status, databases and application of single nucleotide polymorphism

Single Nucleotide Polymorphisms (SNPs) are the most frequent form of DNA variation in the genome. SNPs are genetic markers which are bi-allelic in nature and grow at a very fast rate. Current genomic databases contain information on several million SNPs. More than 6 million SNPs have been identified and the information is publicly available through the efforts of the SNP Consortium and others data bases. The NCBI plays a major role in facillating the identification and cataloging of SNPs through creation and maintenance of the public SNP database (dbSNP) by the biomedical community worldwide and stimulate many areas of biological research including the identification of the genetic components of disease. In this review article, we are compiling the existing SNP databases, research status and their application.     

Breeding for drought tolerance in wheat (Triticum aestivum L.): constraints and future prospects

This review article is based on different aspects of wheat breeding for drought tolerance. Drought is regarded as one of the most serious threats to agriculture in Pakistan. Therefore, breeding for drought tolerance must be given top priority. Here, we try to study various options available to wheat breeders exploring the underlying mechanisms of drought tolerance. The progress made in conventional and non-conventional (molecular) based approaches with potential findings and constraints are reviewed in this article. Equipped with such information, it will be possible for breeders to further explore the mysteries of drought tolerance and to select genotypes with an improved yield under water-deficit conditions.     

Genetic diversity studies of coarse and fine rice using RAPD markers

The availability of a genetically diverse gene pool is vitally important in varietal development. Molecular markers are being extensively utilized to explore the genetic diversity among native and exotic germplasm. This study was designed to reveal the genetic diversity and patterns of relationships among the 20 accessions/genotypes representative of basmati and non-basmati rice from the existing rice gene pool using RAPD markers. Employing RAPD, 17 decamer oligonucleotide primers directed the amplification of 116 fragments, out of which 101 were polymorphic (87.06%) while 15 fragments were monomorphic (12.93%). Similarity coefficients had ranged from 0.47 to 0.90. The average genetic similarity was calculated 0.68 (68%). In this study, the coarse rice genotypes showed more polymorphism (85.84%) than the fine rice genotypes (61.76%). Genotypes were clustered into 8 distinct groups: A, B, C, D, E, F, G, and H but two genotypes, i.e., Shadab and Kangni-27 showed divergence from all the genotypes of the groups. Therefore, these diverse genotypes may be included in future breeding programmes.     

Seed priming improves early seedling vigor,growth and productivity of spring maize

Potential of seed priming treatments in improving the performance of early planted maize was evaluated against timely planting. Seeds of maize hybrid FH-810 were soaked in water(hydropriming), Ca Cl2(2.2%, osmopriming), moringa leaf extracts(MLE 3.3%, osmopriming) and salicylic acid(SA, 50 mg L–1, hormonal priming) each for 18 h. Untreated and hydroprimed seeds were taken as control. Seeds primed with SA took less time in emergence and had high vigor in early planted maize. Amongst treatments, hormonal priming, reduced the electrical conductivity, increased the leaf relative and chlorophyll contents followed by osmopriming with Ca Cl2 at seedling stage. Likewise, plant height, grain rows and 1 000-grain weight, grain and biological yield and harvest index were also improved by seed priming; however hormonal priming and osmopriming with MLE were more effective in this regard. Improved yield performance by hormonal priming or osmopriming with MLE in early planting primarily owed to increased leaf area index, crop growth and net assimilation rates, and maintenance of green leaf area at maturity. In conclusion, osmopriming with MLE and hormonal priming with SA were the most economical treatments in improving productivity of early planted spring maize through stimulation of early seedling growth at low temperature.     

Induced polyploidy in inter‐subspecific maize hybrids to reduce heterosis breakdown and restore reproductive fertility

The aim of this study was to reduce the breakdown of hybrid vigour by crossing maize × teosinte subspecies through induced tetraploidy and to improve the biomass and reproductive fertility of the induced tetraploids. To achieve this, seeds of maize breeding lines selected from an open‐pollinated population ‘Sargodha‐2002’ and a maize × teosinte cross were germinated in colchicine solution (0·25, 0·5 or 1·0%) until they had a thick radical and protruded plumule. Colchicine at 0·5% induced the highest number of tetraploids with the lowest number of chimeric plants. The induced tetraploids of maize and maize × teosinte crosses showed a significant (P ≤ 0·05) increase in leaf area (5 and 14%), total soluble solids (20 and 18%), leaf oil percentage (42 and 12%) and leaf crude protein contents (10 and 14%) in leaves relative to the diploid subspecies. Moreover, induced tetraploidy also arrested hybrid vigour by slowing down the decay of heterosis in progenies (4x) for plant height, leaf biomass and leaf oil percentage. Induced maize × teosinte hybrid tetraploids selected for frequent bivalent chromosome pairing resulted in higher seed setting cob^?1 (increased 58%), pollen fertility (increased 59%) and seed setting percentage (increased 100%) than the quadrivalent variant.     

Hatchery seed production of giant freshwater prawn,Macrobrachium rosenbergii using inland ground saline water in India

The suitability of inland saline water (ISW) from the Lahli‐Baniyani Fish Farm, Rohtak was investigated for the larval rearing of giant freshwater prawn (GFP), Macrobrachium rosenbergii. Six experiments were conducted. In Experiment‐I, 54% of the larvae metamorphosed to postlarvae (PL) in constituted seawater (CSW) whereas total mortality occurred at larval stages (LS)‐II and LS‐III in ISW with salinity of 12 g L^?1. Larvae survived to LS‐IV in Experiment‐II, when ISW was supplemented with K⁺~ SW. In Experiment‐III, total hardness in ISW was reduced serially, but K⁺ ~ SW was supplemented. The larvae did not survive beyond LS‐V. In Experiment‐IV, ISW was amended with different ratios of Mg²⁺/Ca²⁺ and K⁺ ~ SW. The larvae successfully metamorphosed to postlarvae with highest survival of 51.6% in Mg²⁺/Ca²⁺ ratio of 2.5. In Experiment‐V, eight larval cycles were run with water quality used in Experiment V, where all the cycles produced PL's with a survival rate of 20–67%. In Experiment VI, the larvae were reared in Mg²⁺/Ca²⁺ ratio of 2.5 and different levels of K⁺ to optimize its requirement. The ISW amended with K⁺ 80% ~ SW and Mg²⁺/Ca²⁺ ratio of 2.5 was found to be commercially suitable for the seed production of GFP.     

Mutagenic induction of double-podding trait in different genotypes of chickpea and their characterization by STMS marker

A gene that confers double-podding in chickpea is considered to be important for breeding higher yielding cultivars. Double-podded mutants were produced from five desi- and four kabuli-type chickpea genotypes through induced mutations and stabilty was checked up to M₁₃ generation. Desi-type produced higher number of mutants as compared with kabuli-type. The inheritance studies in induced mutants of six genotypes showed that the double-podded trait was governed by single recessive gene. Different genotypes and their double-podded mutants were also characterized through sequence-tagged microsatellite site marker, TA-80. Allelic variations were found in single-podded genotypes and eight different alleles were identified, while for double-poddedness no allelic variants were found in all the analysed mutants. Addition of bases in the double-podded mutants showed that there might be involvement of transposable elements in the production of double-podded mutants through mutagens.