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Nampa, ID, United States

Riday H.,U.S. Department of Agriculture | Reisen P.,Forage Genetics | Raasch J.A.,U.S. Department of Agriculture | Santa-Martinez E.,University of Wisconsin - Madison | Brunet J.,University of Wisconsin - Madison
Crop Science | Year: 2015

Alfalfa (Medicago sativa L.) self-pollination (i.e., selfing) causes inbreeding depression. Determining factors influencing alfalfa seed production selfing rates could inform potential mitigation strategies to reduce selfing. We measured in situ selfing rates from seed sampled from random plants in a commercial alfalfa seed production field pollinated by leafcutter bees (Megachile rotundata F.). Alfalfa selfing rates were estimated by genotyping ~24 progeny from each of 38 maternal plants. Maternal plant distance to pollinator domicile, pod position on racemes, raceme position on stems, and seeds per pod were noted during seed and tissue collection. Selfing rates averaged 11.8% with individual selfing rates ranging from 0% to 52.2%. Seed from pods collected from upper parts of racemes had lower selfing rates (9.1%) compared to pods from lower parts of racemes (15.1%). When “low” self-compatible (<15% selfing rate in 3+ seeded pods) and “high” self-compatible (≥15% selfing rate in 3+ seeded pods) plants were examined separately, however, this pattern remained significant only for low self-compatible plants (upper raceme selfing rates 3.1% vs. lower raceme 8.3%). Low self-compatible plants had higher selfing rates in 1-2 seeded pods (12.9%) compared to 3+ seeded pods (3.8%) while high self-compatible plants showed no differences in selfing rates based on seed number per pod. Genetic differences for self-pollen’s ability to outcompete outcross pollen when growing down the style best explained observed differences between low and high self-compatible plants. Best management practices and selection could help reduce but not eliminate selfing in alfalfa seed production fields. © Crop Science Society of America Source


Jonker A.,University of Saskatchewan | Jonker A.,Agriculture and Agri Food Canada | Gruber M.Y.,Agriculture and Agri Food Canada | McCaslin M.,Forage Genetics | And 5 more authors.
Canadian Journal of Animal Science | Year: 2010

Alfalfa (Medicago sativa L.) is one of the most used forages in the world but suffers the disadvantage of having poor protein utilization by the animal. The poor protein utilization is the result of excessive ruminal protein degradation, which might be reduced by the protein precipitating capacity of anthocyanidin (AC) and condensed tannins (CT). The objective of this study was to determine the effects of the Lc-transgene on survival, anthocyanidin, condensed tannin and chemical profiles in crossed populations of western Canadian-adapted Lc-alfalfa. These were compared with their nontransgenic (NT) parental varieties, Rangelander, Rambler, and Beaver. Lc-alfalfa forage accumulated enhanced amounts of anthocyanidin, with an average concentration of 197.4 μg g-1 DM, while condensed tannins were not detected. Both of these metabolites were absent in the NT parental varieties. Lc-alfalfa had a lower (24.8 vs. 27.3% DM; P<0.02) crude protein (CP) and higher (58.3 vs. 55.5% DM; P<0.01) carbohydrate (CHO) concentration, which resulted in their decreased (P<0.01) N:CHO ratio (68.1 vs. 79.2 g kg-1) compared with NT alfalfa. Slowly degradable N:CHO ratio was decreased by 5.9 g kg-1 (P<0.03) and total rumen-degradable N:CHO ratio was decreased by 12.9 g kg-1 (P<0.03) in Lc-alfalfa compared with NT alfalfa. In conclusion, Lc-gene transformation resulted in the accumulation of anthocyanidin, decreased total protein content, increased total carbohydrate content and improved the balance between nitrogen and carbohydrates in the crossed transgenic populations of western Canadian-adapted alfalfa compared to their NT western Canadian parental alfalfa varieties. Source


Dien B.S.,Bioenergy Research Unit | Miller D.J.,DuPont Pioneer | Hector R.E.,Bioenergy Research Unit | Dixon R.A.,Samuel Roberts Noble Foundation | And 5 more authors.
Bioresource Technology | Year: 2011

Alfalfa (Medicago sativa L.) biomass was evaluated for biochemical conversion into ethanol using dilute-acid and ammonia pretreatments. The two alfalfa lines compared were a reduced S-lignin transgenic cultivar generated through down regulation of the caffeic acid O-methyltransferase gene and a wild-type control. Both were harvested at two maturities. All the samples had similar carbohydrate contents including a mean composition of 316. g glucan and 497. g total neutral carbohydrates per kg dry biomass, which corresponds to a theoretic ethanol yield of 382. l/ton. Ethanol yields for alfalfa stems pretreated with dilute-acid were significantly impacted by harvest maturity and lignin composition, whereas when pretreated with dilute-ammonia, yield was solely affected by lignin composition. Use of a recombinant xylose-fermenting Saccharomyces strain, for converting the ammonia pretreated alfalfa samples, further increased ethanol yields. Ethanol yields for the xylose-fermenting yeast were 232-278. l/ton and were significantly enhanced for the reduced S lignin cultivars. © 2011. Source

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