Development of Single Nucleotide Polymorphism Markers for the Wheat Curl Mite Resistance Gene Cmc4

Wheat curl mite (Aceria tosichella Keifer) is an important wheat (Triticum aestivum L. em. Thell.) pest in many wheat-growing regions worldwide. Mite feeding damage not only directly affects wheat yield, but A. tosichella also transmits Wheat streak mosaic virus (WSMV). Wheat resistance to A. tosichella, therefore, helps control WSMV. OK05312 (PI 670019) is an advanced breeding line released from Oklahoma that shows a high level of A. tosichella resistance. To map the gene(s) conditioning wheat resistance to A. tosichella in OK05312, a genetic linkage map was constructed using single nucleotide polymorphism (SNP) markers derived from genotyping-by-sequencing (GBS) and a population of 186 recombinant inbred lines (RILs) from the cross ‘Jerry’ (PI 632433)/OK05312. Seedlings of both parents and the RIL population were infested by A. tosichella Biotype 1 in greenhouse experiments. One major quantitative trait locus was identified on the short arm of chromosome 6D, which corresponds to the previously reported gene Cmc4 for A. tosichella resistance. This gene explained up to 71% of the phenotypic variation and was delimited in a 1.7-Mb (?3.3-cM) region by SNPs 370SNP7523 and 370SNP1639. We successfully converted 12 GBS-SNPs into Kompetitive allele specific polymerase chain reaction (KASP) markers. Two of them tightly linked to Cmc4 were validated to be highly diagnostic in a US winter wheat population and can be used for marker-assisted breeding for incorporation of Cmc4 into new wheat cultivars

Reducing dispersal limitation via seed addition increases species richness but not above‐ground biomass

Seed dispersal limitation, which can be exacerbated by a number of anthropogenic causes, can result in local communities having fewer species than they might potentially support, representing a potential diversity deficit. The link between processes that shape natural variation in diversity, such as dispersal limitation, and the consequent effects on productivity is less well known. Here, we synthesised data from 12 seed addition experiments in grassland communities to examine the influence of reducing seed dispersal limitation (from 1 to 60 species added across experiments) on species richness and productivity. For every 10 species of seed added, we found that species richness increased by about two species. However, the increase in species richness by overcoming seed limitation did not lead to a concomitant increase in above-ground biomass production. This highlights the need to consider the relationship between biodiversity and ecosystem functioning in a pluralistic way that considers both the processes that shape diversity and productivity simultaneously in naturally assembled communities.Publikationsfonds ML

Estimativa de energia metabolizável de rações com polpa cítrica em substituição ao milho para tourinhos em terminação Estimation of metabolizable energy in diets with varying ratios of dried citrus pulp plus corn fed to finishing Canchim bulls

Avaliou-se a substituição do milho moído fino (MM) por polpa cítrica (PC) em rações para bovinos machos não-castrados terminados em confinamento. As rações continham 70% de concentrado e 30% de silagem de cana-de-açúcar e foram formuladas com 0, 50, 75 e 100% de PC em substituição ao milho. Além dos suplementos energéticos estudados, as rações continham grãos de soja quebrados, uréia, mistura mineral e vitamínica e monensina sódica. Foram utilizados 72 machos Canchim não-castrados, com 318 kg de PV inicial e 18 meses de idade. O delineamento utilizado foi o de blocos casualizados e a duração do período experimental foi de 130 dias - 14 para adaptação e 116 para a coleta de dados (divididos em quatro subperíodos). A eficiência alimentar e a energia líquida de mantença e de ganho foram maiores nos animais alimentados com a dieta formulada com 50% de PC em comparação àquela isenta de polpa. O ganho de peso diário e o consumo de MS (IMS) obtidos com as dietas com 75 e 100% de PC foram inferiores aos encontrados com 50% de substituição. A espessura de gordura e o rendimento de carcaça não foram influenciados pelos níveis de substituição do milho por polpa cítrica. Considerando os dados obtidos, os dois modelos, NRC (2001) e NRC (1996), subestimam o valor energético da PC em comparação ao MM.<br>Seventy-two finishing Canchim bulls averaging 318 kg of initial body weight and 18 months of age were assigned to a completely randomized block design to evaluate the effects of replacing ground corn (GC) with dried citrus pulp (CP) on average daily weight gain, dry matter intake, feed efficiency, carcass yield, and Longissimus dorsi fat thickness. Diets contained forage (sugarcane silage) to concentrate ratio of 30:70 and the following levels of CP and GC: 100% GC (CP0), 50% GC + 50% CP (CP50), 25% GC + 75% CP (CP75), or 100% CP (CP100). The experiment lasted 130 days with 14 days for diet adaptation and 116 days for data and sample collection. Feed efficiency and net energy for maintenance and gain were all greatest on CP50 than on CP0 diet. Daily weight gain and DM intake were lower on CP100 and CP75 compared to CP50. No significant differences were observed for fat thickness and carcass yield across treatments. Based on the actual data, both the NRC (1996) and NRC (2001) models underestimated the energy value of CP compared to GC