Quantitative trait loci for resistance to stripe rust of wheat revealed using global field nurseries and opportunities for stacking resistance genes

Key message

Quantitative trait loci controlling stripe rust resistance were identified in adapted Canadian spring wheat cultivars providing opportunity for breeders to stack loci using marker-assisted breeding.

Abstract

Stripe rust or yellow rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss., is a devastating disease of common wheat (Triticum aestivum L.) in many regions of the world. The objectives of this research were to identify and map quantitative trait loci (QTL) associated with stripe rust resistance in adapted Canadian spring wheat cultivars that are effective globally, and investigate opportunities for stacking resistance. Doubled haploid (DH) populations from the crosses Vesper/Lillian, Vesper/Stettler, Carberry/Vesper, Stettler/Red Fife and Carberry/AC Cadillac were phenotyped for stripe rust severity and infection response in field nurseries in Canada (Lethbridge and Swift Current), New Zealand (Lincoln), Mexico (Toluca) and Kenya (Njoro), and genotyped with SNP markers. Six QTL for stripe rust resistance in the population of Vesper/Lillian, five in Vesper/Stettler, seven in Stettler/Red Fife, four in Carberry/Vesper and nine in Carberry/AC Cadillac were identified. Lillian contributed stripe rust resistance QTL on chromosomes 4B, 5A, 6B and 7D, AC Cadillac on 2A, 2B, 3B and 5B, Carberry on 1A, 1B, 4A, 4B, 7A and 7D, Stettler on 1A, 2A, 3D, 4A, 5B and 6A, Red Fife on 2D, 3B and 4B, and Vesper on 1B, 2B and 7A. QTL on 1A, 1B, 2A, 2B, 3B, 4A, 4B, 5B, 7A and 7D were observed in multiple parents. The populations are compelling sources of recombination of many stripe rust resistance QTL for stacking disease resistance. Gene pyramiding should be possible with little chance of linkage drag of detrimental genes as the source parents were mostly adapted cultivars widely grown in Canada.

     

Alpha-synuclein overexpression and aggregation exacerbates impairment of mitochondrial functions by augmenting oxidative stress in human neuroblastoma cells

Overexpression of alpha-synuclein and oxidative stress has been implicated in the neuronal cell death in Parkinson's disease. Alpha-synuclein associates with mitochondria and excessive accumulation of alpha-synuclein causes impairment of mitochondrial functions. However, the mechanism of mitochondrial impairment caused by alpha-synuclein is not fully understood. We recently reported that alpha-synuclein associates with mitochondria and that overexpression of alpha-synuclein causes nitration of mitochondrial proteins and release of cytochrome c from the mitochondria [Parihar M.S., Parihar A., Fujita M., Hashimoto M., Ghafourifar P. Mitochondrial association of alpha-synuclein causes oxidative stress. Cell Mol Life Sci. 2008a;65:1272–1284]. The present study shows that overexpression of alpha-synuclein A53T or A30P mutants or wild-type in human neuroblastoma cells augmented aggregation of alpha-synuclein. Immunoblotting and immuno-gold electron transmission microscopy show localization of alpha-synuclein aggregates within the mitochondria of overexpressing cells. Overexpressing cells show increased mitochondrial reactive oxygen species, increased protein tyrosine nitration, decreased mitochondrial transmembrane potential, and hampered cellular respiration. These findings suggest an important role for mitochondria in cellular responses to alpha-synuclein.     

Development and Evaluation of Sustained Release Gastroretentive Minimatrices for Effective Treatment of H. pylori Infection

In the present work, sustained release gastroretentive minimatrices of amoxicillin have been designed and optimized using central composite design. Effect of amount of xanthan gum, rate controlling polymers (HPMC K100M CR/PEO coagulant (1:1)), carbopol 974P, and gas generating couple (sodium bicarbonate/citric acid (3:1)) was studied on dependent (response) variables, i.e., buoyancy lag time, drug release at 1 h, time required for 95% drug release, swelling index, and bioadhesive strength. Minimatrices were prepared by non aqueous granulation method using solution of PVP K30 in isopropyl alcohol. All the formulations were found to contain 99.2% to 100.9% of amoxicillin per minimatrix. Optimum formulation (Formulation number AGT09) containing high level of the independent variables was having buoyancy lag time of 7 min and drug release at 1 h was 32.5%. It required 9.39 h for 95% drug release while swelling index and bioadhesive strength were 341 and 17.9 dyn/cm², respectively. This formulation was said to be optimum because it has minimum buoyancy lag time, requires maximum time for 95% drug release, and has higher bioadhesive capabilities. In vitro results of an optimized formulation indicate its sustained drug release and gastric retention capability, which may be very useful for effective treatment of H. pylori infection.     

A flexible bioreactor system for constructing in vitro tissue and organ models

To develop in vitro models of cells, tissues and organs we have designed and realized a series of cell culture chambers. Each chamber is purpose designed to simulate a particular feature of the in vivo environment. The bioreactor system is user friendly, and the chambers are easy to produce, sterilize and assemble. In addition they can be connected together to simulate inter-organ or tissue cross-talk. Here we discuss the design philosophy of the bioreactor system and then describe its construction. Preliminary results of validation tests obtained with hepatocytes and endothelial cells are also reported. The results show that endothelial cells are extremely sensitive to small levels of shear stress and that the presence of heterotypic signals from endothelial cells enhances the endogenous metabolic function of hepatocytes.     

Insecticidal and antifungal potentials of a proteinaceous extract of Cassia occidentalis (Linn.) seeds

Proteinaceous extract obtained from Cassia occidentalis seeds with purification fold of 3.91 and 82.7% of bovine trypsin inhibitory activity was assessed at different concentrations (25, 50, 100, 200, 400 and 800 μg/ml) against Spodoptera litura. Assay of larval feeding suggested proteinaceous extract to be toxic as prepupal (80.16%) and pupal mortalities (100%) along with growth deterrent effect with only 16.71% pupation was observed at 800 μg/ml. Fifty per cent mortality (LC₅₀) was observed at 132.91 μg/ml. Also the inhibitor affected fecundity, longevity and percentage of egg hatching. Nutritional indices were adversely affected as both efficiency of conversion of ingested and digested food decreased while approximate digestibility and metabolic cost increased. In vitro studies on proteolytic enzymes of S. litura revealed inhibition of trypsin and chymotrypsin in lumen and faecal matter at all tested concentrations. Also proteinaceous extract inhibited mycelial growth in Fusarium oxysporum, Alternaria brassicicola and Alternaria alternata at 100 μg/ml.     

Potential cow milk xanthine oxidase inhibitory and antioxidant activity of selected phenolic acid derivatives

Xanthine oxidase (XO) found in all mammals and excess activity leads to urolithiasis. The cow milk XO was purified to 305‐fold with a specific activity of 8.76 EU/mg and overall yield of 87% by using DEAE‐Sepharose chromatography. The phenolics showed potent XO inhibitory effect with K_i, P1 (0.412), P2 (0.632), P3 (0.585), P4 (0.886), P5 (1.633), P6 (0.503), P7 (2.882), P8 (3.761), P9 (4.487), and P10 (5.841) μM. The phenolics P9 and P10 exhibited uncompetitive inhibition; the phenolics P1, P2, P3, P4, and P6 showed competitive inhibition, and other phenolic acids showed noncompetitive inhibition. The studied phenolic compounds showed potent antioxidant activity and expressed as EC₅₀, ranged from, DPPH (4.2–25.8 μg mL^–1), ABTS (10.2–42.5 mmol TE 100 g^–1), and FRAP (6.3–36.8 mol Fe (II) 100 g^–1). The results obtained from this study might be utilized for design of XO inhibitors and as antigout agent.