Towards developing resistance to chickpea chlorotic dwarf virus through CRISPR/Cas9-mediated gene editing using multiplexed gRNAs

Journal of Plant Diseases and Protection - Mastreviruses are an emerging group of viruses transmitted by leafhoppers and infect both monocot and dicot plants. Chickpea chlorotic dwarf virus...     

Genome-wide association analysis for stripe rust resistance in spring wheat(Triticum aestivum L.) germplasm

Stripe rust is a continuous threat to wheat crop all over the world. It causes considerable yield losses in wheat crop every year. Continuous deployment of adult plant resistance(APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease. Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm. An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs. Based on D' measure, linkage disequilibrium(LD) exhibited between loci distant up to 45 c M. Marker-trait associations(MTAs) were determined using mixed linear model(MLM). Total 31 quantitative trait loci(QTLs) were observed on all 21 wheat chromosomes. Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm. The major QTLs were QYr.uaf.2 AL and QYr.uaf.3 BS(PVE, 11.9%). Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop.     

Nitrogen management improves lodging resistance and production in maize (Zea mays L.) at a high plant density

Lodging in maize leads to yield losses worldwide. In this study, we determined the effects of traditional and optimized nitrogen management strategies on culm morphological characteristics, culm mechanical strength, lignin content,root growth, lodging percentage and production in maize at a high plant density. We compared a traditional nitrogen(N) application rate of 300 kg ha–1(R) and an optimized N application rate of 225 kg ha^–1(O) under four N application modes: 50% of N applied a...     

Phenotypic variations of wheat cultivars from the North China Plain in response to cadmium stress and associated single nucleotide polymorphisms identified by a genome-wide association study

Understanding the genetic mechanisms for cadmium(Cd) uptake and translocation in common wheat(Triticum aestivum) is of significance in food Cd contamination control. In this study, a diverse panel of 132 wheat cultivars was collected from the North China Plain. The cultivars were evaluated in terms of their phenotypic variations in response to Cd stress and subjected to a genome-wide association study(GWAS) to identify single nucleotide polymorphisms(SNPs) associated with the phenotypic variatio...     

Silicon-mediated genotoxic alterations in Brassica juncea under arsenic stress: A comparative study of biochemical and molecular markers

Arsenic (As), one of the most harmful toxicant at the global level, severely affects plant metabolism when taken up. Interestingly, the presence of silicon (Si) as a fertilizer in As-contaminated soil is an effective strategy to decrease As accumulation in plants. Brassica juncea (var. Varuna) were grown hydroponically to investigate the role of Si at biochemical and molecular levels under arsenite (As³⁺) stress. Seedlings of B. juncea were exposed to As³⁺, Si, and a combination of both elements. Our data demonstrated that seedlings exposed to As³⁺ showed an inhibition in shoot length, chlorophyll, carotenoid, and protein, while co-application of Si improved these growth parameters. Silicon supplementation reduced As accumulation in shoot. Increase/decrease was observed in stress-related parameters (cysteine and proline), antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, and catalase), and oxidative stress markers (malondialdehyde and H₂O₂), which were improved upon co-application of Si as compared to As³⁺ alone treatment. Random amplified polymorphic DNA (RAPD) is a suitable biomarker assay for plants for assessing the genotoxicity. Seven RAPD primers produced a total of 39 and 48 bands in the leaves of the untreated and treated seedlings, respectively. The RAPD band-profiles and genomic template stability were consistent with other growth and physiological parameters. In conclusion, the genotoxic alterations along with the biochemical parameters indicate that the exposure to Si mitigates As³⁺-induced oxidative stress by improving the stress-related parameters and antioxidant system in B. juncea.     

小麦品种的耐盐性变化：甜菜碱和乙烯的作用

Four wheat (Triticum aestivum L.) cultivars 711, PBW343, 3765 and WH542 were screened for studying variations in glycinebetaine (GB) content and plant dry mass under 100 mmol L-1 NaCl stress. A tolerance index was calculated using plant dry mass data to select salt-tolerant and salt-sensitive types and find association between tolerance index and GB content. Tolerance index has been used as a good criterion to select the tolerant types under high salinity stress. Further, physiological differences in salt-tolerant cultivar 711 and salt-sensitive cultivar WH542 were examined. The salt-tolerant cultivar exhibited greater GB content, which was found correlative with ethylene. The cultivar also showed higher nitrogen (N) content and nitrate reductase activity, reduced glutathione and higher redox state resulting in maximal protection of plant dry mass than the salt-sensitive type. Thus, the content of GB may be considered as important physiological criteria for selecting salt-tolerant wheat types.     

Effects of simulated acid rain and root-knot nematode on tomato

Effects were examined of simulated acid rain and of root-knot nematode, Meloidogyne incognita race 1, on plant growth, yield, photosynthetic pigments and leaf epidermal characters of tomato ( Lycopersicon esculentum cv. Pusa Ruby). Sequential inoculation exposures (pre-, post-, and concomitant with nematode inoculation) were carried out in a greenhouse. Intermittent treatments of simulated acid rain at pH 3.2 caused white-to-tan irregular lesions on both the upper and lower surfaces of tomato leaves. The foliar symptoms were more pronounced on nematode-infected plants. Simulated acid rain (pH 3.2) and/or nematode infection suppressed plant growth, yield and pigment synthesis, the effects being greatest in post-inoculation treatments compared with simulated acid rain at pH 6.8. The total weight of fruits per plant was greatly suppressed owing to simulated acid rain or nematode infection. Chlorophyll a was found to be more sensitive to simulated acid rain or nematode infection than other leaf pigments. Root penetration, galling, egg mass production, and fecundity (number of eggs per egg mass) of M. incognita were enhanced at pH 5.6 and suppressed at pH 3.2 compared with pH 6.8. Nematode infection or simulated acid rain at pH 3.2 suppressed stomata and trichome development (number and size). Simulated acid rain treatments at pH 5.6 had a positive effect on number and size of trichomes, but a negative effect on stomata. The apertures of stomata were wider on tomato leaves exposed to simulated acid rain, especially at pH 3.2, than at pH 6.8.     

Wheat Seed Presoaking for Improved Germination

Seed presoaking improves wheat germination under marginal moisture conditions. The duration of seed presoaking was studied at The University of Arid Agriculture, Rawalpindi, using 10 wheat varieties. Seed presoaking beyond 12 h does not improve germination further, and beyond 21 h, germination rate is drastically reduced.     

RNAi-mediated knockdown of INHBB increases apoptosis and inhibits steroidogenesis in mouse granulosa cells

Inhibins are members of the TGFβ superfamily and act as suppressors of follicle stimulating hormone (FSH) secretion from pituitary glands via a negative feedback mechanism to regulate folliculogenesis. In this study, the INHBB gene was knocked down by three RNAi-Ready pSIREN-RetroQ-ZsGreen vector- mediated recombinant plasmids to explore the effects of INHBB silencing on granulosa cell (GC) cell cycle, apoptosis and steroid production in vitro. Quantitative real-time polymerase chain reaction, Western blot, flow cytometry and ELISA were performed to evaluate the role of INHBB in the mouse GC cell cycle, apoptosis and steroid production in vitro. The results showed that the relative mRNA and protein expression of INHBB in mouse GCs can be significantly reduced by RNAi with pshRNA-B1, pshRNA-B2 and pshRNA-B3 plasmids, with pshRNA-B3 having the best knockdown efficiency. Downregulation of the expression of INHBB significantly arrests cells in the G1 phase of the cell cycle and increases the apoptosis rate in GCs. This was further confirmed by downregulation of the protein expressions of Cyclin D1, Cyclin E and Bcl2, while the protein expression of Bax was upregulated. In addition, specific downregulation of INHBB markedly decreased the concentration of estradiol and progesterone, which was further validated by the decrease in the mRNA levels of CYP19A1and CYP11A1. These findings suggest that inhibin βB is important in the regulation of apoptosis and cell cycle progression in granulosa cells. Furthermore, the inhibin βB subunit has a role in the regulation of steroid hormone biosynthesis. Evidence is accumulating to support the concept that inhibin βB is physiologically essential for early folliculogenesis in the mouse.