Molecular characterization of the incitant of cowpea bacterial blight and pustule, Xanthomonas campestris pv. vignicola

Strains of Xanthomonas campestris pv. vignicola (Xcv), isolated from cowpea leaves with blight or minute pustules and collected from various geographic areas, were selected on the basis of pathological and physiological features. All strains were analyzed for genotypic markers by two methods: ribotyping with EcoRI endonuclease, and RFLP analysis with a plasmid probe (pthB) containing a gene required for pathogenicity from Xanthomonas campestris pv. manihotis. Ribotyping revealed a unique pattern for all the strains that corresponded to the previously described ribotype rRNA7. Based on polymorphism detected by pthB among Xcv strains, nine haplotypes were defined. The observed genetic variation was independent of the geographic origin of the strains and of pathogenic variation. Some haplotypes were widely distributed, whereas others were localized. In some cases, we could differentiate strains isolated from blight symptoms and pustules according to haplotypic composition. However, in most cases, no significant differences were observed. Our results and the previous pathogenic and biochemical characterizations suggest that the strains isolated from leaves with blight symptoms or minute pustules belong to the same pathovar. We provide information on pathogen diversity that can be used to identify and characterize resistant germplasm.     

The acquisition of cadmium by Lupinus albus L., Lupinus angustifolius L., and Lolium multiflorum Lam.

Das Cadmiumaneignungsvermögen von Lupinus albus L., Lupinus angustifolius L. und Lolium multiflorum Lam. Mehrere Pflanzenarten mobilisieren Bodenphosphate (P) und Kationen wie Fe und Al durch die Exsudation organischer Anionen und Protonen. Deshalb untersuchten wir das Cd‐Aneignungsver‐mögen von P‐, Fe‐, Al‐mobilisierenden Arten (Lupinus albus L., Lupinus angustifolius L.) im Vergleich zu einer nicht mobili‐sierenden Pflanzenart (Lolium multiflorum Lam.). Die Pflanzen wuchsen in zwei stark unterschiedlichen Böden (saurer Humuspodsol, karbonathaltiger Lössunterboden). Die Cd‐Aufnahme in die Sprosse war bei Weidelgras 5 bis 10 mal höher als bei Blauen bzw. Weißen Lupinen. Dieses Ergebnis hat mehrere Ursachen: 1. Das Wurzellängen/Sprossmasseverhältnis des Weidelgrases ist 2—3 mal größer als das der Lupinenpflanzen. 2. Bei Weidelgras wird ein größerer Teil des aufgenommenen Cd in die Sprosse verlagert. 3. Die Cd‐Aufnahme bei Lupinen ist im sauren Boden (Podsol) und bei P‐Mangel auch im Kalkboden niedriger als bei Weidelgras. Während im Podsol die Cd‐Konzentration der Bodenlösung unter Lupine geringer war als in der Kontrolle (Gefäße ohne Pflanzen), war sie im Kalkboden höher. Bei den Lupinen war der Efflux organischer Säureanionen, vor allem Citrat und Malat, um den Faktor 10—100 höher als bei Weidelgras. Diese Exsudation kann zu einer hohen Cd‐Komplexierung, insbesondere durch Citrat, in der Rhizosphärenbodenlösung führen (˜ 85%). Diese Ergebenisse deuten darauf hin, dass das komplexierte Cd von den Wurzeln schlechter aufgenommen wird als das freie Cd.     

Ralstonia solanacearum as a potato pathogen in Serbia: Characterization of strains and influence on peroxidase activity in tubers

Since 2011, the outbreaks of brown rot caused by Ralstonia solanacearum race 3, biovar 2, phylotype IIB-1 (R3/B2/PIIB-1) have significantly compromised potato production in Serbia. During 6 years of monitoring (2013–2018) among 3,524 potato tuber samples, 344 were found positive for brown rot disease. R. solanacearum R3/B2/PIIB-1 was isolated from seven cultivars among 12 monitored, and in five localities among 17 monitored. Cultivar Lady Claire was found to have the highest disease frequency (31.98%). A total of 78 isolates were identified by R. solanacearum-specific primer pairs (PS-1/PS-2 and OLI-1/Y-2), as well as the following tests: restriction fragment length polymorphism analysis, biovar determination, immunofluorescence, biochemical analysis, and pathogenicity. The genetic composition of 36 selected isolates assessed using multilocus sequence analysis with seven genes (adk, gapA, gdhA, gyrB, ppsA, hrpB, and fliC) showed that all isolates originating from Serbian potato were homogeneous. By using the TCS algorithm of concatenated sequences to get insight into the phylogeography of isolates and other R. solanacearum strains deposited in the NCBI database, we showed that their origin is undetermined. Peroxidase (POD) activity was measured in brown rotted potato tubers. A positive correlation was found between POD activity and disease severity rated on the analysed tubers. In general, POD activity increased by 2–22 times in vascular necrotic tissues compared to non-necrotic ones, and depended on disease severity but not on cultivar. Native polyacrylamide gel electrophoresis analysis of POD profiles resulted in a total of 10 distinct POD isoforms, of which PODs 3–5 were highly intensified in response to R. solanacearum.     

Improved phosphorus efficiency of three new wheat genotypes from CIMMYT in comparison with an older Mexican variety

In a field trial in Northwest Mexico, the phosphorus efficiency of three advanced bread wheat lines (Triticum aestivum L.) from CIMMYT were compared with an older Mexican variety Curinda, under irrigation, on an alkaline clay soil (3.7 mg Olsen-P kg^—1 soil) without (P-0) and with P-fertilisation (P-35; 35 kg P ha^—1). Dry matter, P-content, P-uptake of above ground biomass and root growth (root length densities in different soil depths) were measured at different growth stages, and the net P-uptake rates per unit root length calculated. All four genotypes responded positively to P-fertilisation. The three new genotypes showed significantly higher grain yields compared with the old variety Curinda, on the average, 54% and 42% higher at P-0 and P-35, respectively. The higher grain yield was mainly due to a larger number of kernels per ear, higher thousand kernel weight as well as a higher harvest index. The old variety Curinda had the same (P-0) or greater (P-35) number of spikes m^—2 than the new genotypes. In conclusion of this experiment, the three new genotypes could be classified as more P-efficient. The P-uptake at harvest averaged 35% and 24% more than the old variety Curinda at the P-0 and P-35 level, respectively. The improved P-efficiency was mainly due to a more efficient P-uptake. However, there were only small differences in P-utilisation efficiency (kg grain per kg P in shoots) between old and new varieties (8—11%). The differences in the root systems were more decisive in the P-0 treatment than with P-fertilisation. At low P, the improved P-uptake per ha of the advanced lines was due to a higher root length density especially after flowering, while at high P, a higher P-influx rate per unit root length played a more important role than the root length density. The superiority of the new genotypes at both P levels is obviously due to the good adaptation of their root system (root length density, uptake rate per unit root) to variable P availability in soil.     

Efficacy of feeding tiger puffer Takifugu rubripes on moon jellyfish with respect to nutritional composition and behavioural traits

Although jellyfish blooms are serious nuisances for fisheries and other industries, the utilization and nutritional value of by‐catch jellyfish has drawn public attention. Here, we evaluated the efficacy of feeding tiger puffer Takifugu rubripes with moon jellyfish Aurelia sp. using 20‐day rearing experiments. Feeding on jellyfish had no positive effect on growth performance, although it significantly reduced neutral lipids and increased proportions of polar lipids, n?3 and n?6 highly unsaturated fatty acids (HUFAs), especially arachidonic and docosahexaenoic acids, and taurine. Supplemental feeding on jellyfish plus pellets elevated activity and responsiveness in the fish, with no effect on burst swimming speed or prevention of aggressive biting by siblings. The present research suggests that feeding on jellyfish improves body composition and some behaviours in tiger puffers. As cultured fish tend to accumulate excessive amounts of lipids from lipid‐rich pellets that can induce an unhealthy condition, and behavioural deficits of hatchery‐reared fish reduce survival after release in the wild, we propose the use of jellyfish as a supplemental diet in the nursery production of tiger puffer. Moreover, feeding on jellyfish can overcome deficiencies in alternative soy‐material feeds by supplying phospholipid, HUFAs, or taurine.     

Improvement of Rice Production under Drought Conditions in West Africa: Application of QTLs in Breeding for Drought Resistance

Rice plays a paramount role in food and nutrition security in many West African countries. Despite the doubling of production during the last decade, rice consumption has grown faster, creating a deficit between the demand and supply. Although the West African sub-region remains the main rice-producing centre on the continent, production is severely hampered by biotic and abiotic stresses. Drought is one of the factors that most severely reduce grain yields of rice. Systems of production need to be established in order to mitigate yield loss as a result of drought. This review discusses the effects of drought on rice production in West Africa and its mitigation with an emphasis on the improvement of tolerance to drought stress. Yield stability can be achieved by developing drought-tolerant varieties through several processes encompassing profiling of known QTLs and identification of new ones, marker-assisted selection, genomic selection, and extensive multi-locational yield trials. We suggest a comprehensive strategy for breeding drought-tolerant rice varieties in West Africa.