Genetic structure of Phaeosphaeria nodorum populations in the north-central and midwestern United States

Stagonospora nodorum blotch, caused by Phaeosphaeria nodorum, is considered one of the most destructive foliar diseases of wheat in the United States. However, relatively little is known about the population biology of this fungus in the major wheat-growing regions of the central United States. To rectify this situation, 308 single-spore isolates of P. nodorum were analyzed from 12 populations, five from hard red spring wheat cultivars in Minnesota and North Dakota and seven from soft red winter wheat in Indiana and Ohio. The genetic structure of the sampled populations was determined by analyzing polymorphisms at five microsatellite or simple-sequence repeat (SSR) loci and the mating type locus. Although a few clones were identified, most P. nodorum populations had high levels of gene (H(S) = 0.175 to 0.519) and genotype (D = 0.600 to 0.972) diversity. Gene diversity was higher among isolates collected from spring wheat cultivars in North Dakota and Minnesota (mean H(S) = 0.503) than in those from winter wheat cultivars in Indiana and Ohio (H(S) = 0.269). Analyses of clone-corrected data sets showed equal frequencies of both mating types in both regional and local populations, indicating that sexual recombination may occur regularly. However, significant gametic disequilibrium occurred in three of the four populations from North Dakota, and there was genetic differentiation both within and among locations. Genetic differentiation between the hard red spring and soft red winter wheat production regions was moderate (F(ST) = 0.168), but whether this is due to differences in wheat production or to geographical variation cannot be determined. These results suggest that sexual reproduction occurs in P. nodorum populations in the major wheat-growing regions of the central United States, and that geographically separated populations can be genetically differentiated, reflecting either restrictions on gene flow or selection.     

On-Farm Diversity Assessment and Participatory Varietal Evaluation of Cold-Tolerant Rice in Mid-Hills of Nepal

Journal of Crop Science and Biotechnology - Drawing upon consequentially growing food insecurity in mid-hills attributed to poor adoption levels inter alia inflicted by narrow range of locally...     

Resistance to multiple leaf spot diseases in wheat

Tan spot (TS), Stagonospora nodorum blotch (SNB), and Septoria tritici blotch (STB) are three major leaf spot diseases of wheat worldwide. Host plant resistance (HPR) is one of the main components in the management of these diseases in wheat. The objective of this study was to identify new sources of resistance to TS (races 1 and 5), SNB, and STB. A total of 164 wheat genotypes developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico were individually evaluated for TS, SNB and STB in spring and fall of 2006 in the greenhouse. Two experiments were conducted in a randomized complete block design with three replicates. Each replicate consisted of 164 wheat genotypes planted in cones with three seedlings/genotype in each cone and disease reaction was assessed for each race or pathogen at the two- to three-leaf stage. Based on the disease reactions, three wheat genotypes were resistant to both TS and SNB, while 13 genotypes were resistant to TS and STB. Similarly, 13 genotypes were resistant to both SNB and STB. In addition, four wheat genotypes were highly resistant to TS, SNB, and STB. These results suggest that the resistant genotypes identified in this study possess high levels of resistance to multiple leaf spot diseases and could be valuable sources for wheat improvement programs.     

Growth performance,nutrient digestibility and digestive enzyme activity in Asian seabass,Lates calcarifer juveniles fed diets supplemented with cellulolytic and amylolytic gut bacteria isolated from brackishwater fish

Asian seabass, Lates calcarifer juveniles were fed for 30 days to evaluate the efficacy of cellulolytic (Bacillus sp. DDKRC1.) and amylolytic (Bacillus subtilis DDKRC5.) bacteria supplemented diets. Four experimental groups were maintained in triplicate of which group I was the control group and received no bacterial supplementation. Groups II, III and IV were fed diet supplemented with B. subtilis DDKRC5. (14.25 × 10⁷ CFU/mL), Bacillus sp. DDKRC1. (2.94 × 10⁷ CFU/mL) and mixture of both the microbes (1:1 ratio), respectively, @ 1% (v/w). After 30 days of feeding, fish reared as group IV showed significantly higher (P < 0.01) weight gain (141.42%), survival (91.50%), protein efficiency ratio (1.18) and significantly lower (P < 0.01) FCR (2.15) than that of other groups. Nutrient digestibility parameters were significantly (P < 0.01) higher in group IV followed by groups III, II and I. Digestive cellulase, amylase and protease activities in the gastrointestinal tract were also significantly (P < 0.01) higher in group IV. Amylolytic and cellulolytic microbial count in the gastrointestinal (GI) tract were significantly (P < 0.01) higher in groups II, III and IV as compared with that of control. It can be concluded that feed supplemented with mixture of B. subtilis DDKRC5. and Bacillus sp. DDKRC1. showed better performance in Asian seabass juveniles.     

Policosanol content and composition in perilla seeds

Policosanols, long-chain alcohols, have many beneficial physiological activities. Contents and compositions in perilla seeds (Perilla frutescens) produced in Korea and China were determined. Waxy materials were extracted from perilla seeds using hot hexane. Yield of the waxy materials from perilla seeds was 72.1 mg/100 g of dry weight. Contents and compositions of the waxy materials and policosanols were identified and quantified by TLC, HPLC, and GC. Major components of the waxy materials from Korean and Chinese perilla seeds were policosanols (25.5 and 34.8%, respectively), hydrocarbons (18.8 and 10.5%), wax esters, steryl esters and aldehydes (53.0 and 49.8%), acids (1.7 and 2.1%), and triacylglycerols (1.0 and 2.9%), determined by HPLC. For comparison, waxy materials of sesame seeds were also analyzed. Yield of the waxy materials from sesame seeds were 8.6 mg/100 g. Less than 5% policosanols were detected in the waxy materials extracted from sesame seeds produced in Korea and China. Wax esters or steryl esters accounted for 93-95% of the sesame waxy materials. Policosanols in the perilla seeds were composed of 67-68% octacosanol, 16-17% hexacosanol, 6-9% triacontanol, and others.     

Characterization of Zinc Oxide Nano Particles and Their Effect on Growth of Maize (Zea mays L.) Plant

In the current literature, the impact of nano-particles (NPs) on growth of higher plants has scantly been reported. An investigation was carried out to study the effect of zinc oxide nano-particles (<100 nm) on growth of maize (Zea mays L.) plant, as one of the major agricultural crops, in a solution culture system. Various concentrations of zinc (Zn) were applied through nano-zinc oxide (ZnO) particles (<100 nm) in suspension form and in ionic form through zinc sulfate (ZnSO₄) salt in Hoagland solution culture. Experimental results showed that nano zinc oxide particles could enhance and maintain the growth of maize plant as well as conventional Zn fertilizer (as ZnSO₄). The plant parameters like plant height, root length, root volume, and dry matter weight were all improved due to application of zinc oxide nano-particle. These findings indicate that plant roots might have the unique mechanism of assimilating nano-Zn and using for its growth and development. Different enzymatic activities were also studied and experimental results revealed that nano-ZnO particles (<100 nm) also governed the enzymatic activity of maize plant. A separate laboratory experiment was also carried out to characterize the zinc oxide nano particle for its size, zeta potential, etc.     

Microalgae Schizochytrium sp. as a source of docosahexaenoic acid (DHA): Effects on diet digestibility,oxidation and palatability and on immunity and inflammatory indices in dogs

The objective of this study was to evaluate the effects of the microalgae Schizochytrium sp., as a dietary source of docosahexaenoic acid (DHA), on diet palatability, coefficients of total tract apparent digestibility (CTTAD) of nutrients and metabolizable energy (ME), blood variables and indicators of immunity in dogs. We also evaluated oxidative stability. Two diets containing 0 and 0.4% of microalgae Schizochytrium sp. were evaluated in three experiments. On Experiment I the palatability of diets containing 0% versus 0.4% microalgae was compared. In Experiment II test diets were offered for 30 days to determine digestibility, fecal characteristics, and blood parameters. In Experiment III, the oxidative stability of diets containing microalgae versus anchovy oil was evaluated. There was a higher intake ratio of the diet containing microalgae (p < .05). The ME and CTTAD of nutrients increased (p < .05), except for ether extract after acid hydrolysis, with the inclusion of the microalgae in diet. The amount of monocytes and phagocytic granulocytes was higher (p < .05) in dogs fed 0.4% microalgae. There was greater oxidative stability for the sample containing microalgae. The addition of 0.4% microalgae presented high palatability, increased phagocytic cell numbers, and demonstrated oxidative stability superior to anchovy oil.     

Influence of mesoscale physical forcing on trophic pathways and fish larvae retention in the central Cantabrian Sea

This study was carried out over the central Cantabrian shelf during a post‐bloom phase in May. Late phases of the spring phytoplankton bloom, which are characterized by high crustacean mesozooplankton biomass, have been proposed to be a particular case for high‐energy flow towards large metazoans. The overall objective of the study is to analyse the influence of mesoscale physical forcing on primary production patterns, its implications on food web pathways, and on larval fish distribution during a period of intense spawning of Sardina pilchardus and Scomber scombrus. Physical and biological variables of different trophic levels show coupled cross‐shelf and along‐shelf heterogeneity. Quasi‐geostrophic analysis and other indirect approaches, such as the depth of the slope salinity maximum, reveal predictable patterns of vertical instabilities associated with mesoscale physical forcing that enhance production of large‐size phytoplankton. The latter is expected to enhance the energy flow towards higher trophic levels at a time of high mesozooplankton biomass. Distributions of S. pilchardus and S. scombrus eggs and larvae indicate retention related to the coastal salinity front and the overall eastward circulation pattern. The observed mesoscale physical processes may favour survival of early stages of fish by their influence on the energy flow of primary production towards higher trophic levels and larval retention at the coast.     

Effects of temperature on infection and subsequent development of clubroot under controlled conditions

Controlled‐environment studies were conducted on two Brassica crops (canola, Brassica napus; and Shanghai pak choi, B. rapa subsp. chinensis var. communis) to examine the effects of temperature on infection and subsequent development of clubroot caused by Plasmodiophora brassicae. In the first experiment, canola seedlings were grown in infested soil for 3 weeks at 14–26°C to assess the impact on primary and secondary infection and transferred to 20°C for 3 weeks to assess symptom development under uniform conditions, or started at 20°C for 3 weeks and then placed at the treatment temperatures for the final 3 weeks to assess the impact of temperature on symptom development. A second experiment examined a wider range of temperatures (10–30°C). Similar experiments were also conducted on Shanghai pak choi. The studies demonstrated that clubroot severity was affected by temperature during both infection and vegetative development of the crop. Both early and late in crop development, little or no clubroot developed at temperatures at or below 17°C, and development was slower above 26°C than at 23–26°C for both crops throughout the study. In canola, the high levels of inoculum used in the study resulted in a high incidence of clubroot irrespective of temperature, but in pak choi incidence showed the same pattern as severity. This is the first study to demonstrate under controlled conditions that temperature during vegetative growth of the crop affects symptom development of clubroot.