Farmers' production constraints, preferred varietal traits and perceptions on sorghum grain mold in Senegal.

Improving sorghum adoption rates by developing adapted varieties that meet end-user preferences is a major challenge in West Africa. In this study, a participatory rural appraisal was undertaken to identify the main sorghum production constraints, farmers' preferred variety traits and their perceptions on sorghum grain mold. The study was conducted in four representative rural communities located in the main sorghum producing area of Senegal. A total of 260 farmers were interviewed and data were collected through focus group discussions and individual questionnaires. Our results indicated that Striga, insects, poor soil fertility and drought are the major sorghum producing constraints in Senegal. Grain mold was identified as the second most important sorghum disease after the damping-off. Discoloration on grain surface was the most important criteria farmers used to recognize the disease. The most important sorghum traits farmers desired in improved varieties are medium to short plant maturity cycle, medium plant height, large open or semi-compact panicle, big and white grain, and adaptation to local growing conditions. The results showed that the sorghum cropping system is dominated by male farmers who mainly grow local landraces. These results will provide updated recommendations for the breeding products profile to meet end-user preferences in Senegal.

Mutations in the dwarf3 gene confer height stability in sorghum.

Dwarfism is a useful trait in many crop plants because it contributes to improved lodging resistance and harvest index. The mutant allele dw3-ref (dwarf3-reference) of sorghum [Sorghum bicolor (L.) Moench] is characterized by an 882 bp tandem duplication in the fifth exon of the gene that is unstable and reverts to wild-type at a frequency greater than 0.001 in many genetic backgrounds. The goal of this research was to identify stable alleles of dw3 (dwarf3) that could be backcrossed into elite parent lines to improve height stability of the crop. To discover new alleles of dw3, a panel consisting mostly of sorghum conversion lines (SC-lines) was screened by polymerase chain reaction for the 882 bp tandem duplication in the fifth exon of dw3-ref. Sanger sequencing was used to characterize the DNA sequence of this fragment in genotypes that did not contain the 882 bp tandem duplication. Sequence analysis identified three indel mutations, including an 82 bp deletion, a 6 bp duplication, and a 15 bp deletion in this region of the gene. Field trials of the donor genotypes with these new alleles indicated no wild-type revertants of dw3-sd3 (dwarf3-stable dwarf), dw3-sd4, and dw3-sd5. These alleles were backcrossed into Tx430. Field trials of backcross progeny (BC2F4) with the dw3-sd3, dw3-sd4, and dw3-sd5 alleles indicated no revertants. The plant height and flowering time characteristics of the backcross progeny were similar or slightly shorter and earlier than the recurrent parent. These findings demonstrate that dw3-sd3, dw3-sd4, and dw3-sd5 alleles will be useful in breeding for the stable dwarf trait.

Rapid determination of protein digestibility in sorghum before and after cooking.

Quantifying the digestibility of proteins in cereal grain is important for assessing and improving the nutritional quality of the grain after ingestion. This trait is particularly important for sorghum since the grain protein is known to be less digestible after wet cooking compared to other cereals. The reduced digestibility contributes to malnutrition in regions where sorghum is consumed as a staple food. We describe here a modified, high-throughput protocol to quantify pepsin-digestible proteins in sorghum grain before and after cooking. The protocol includes three basic steps: •grinding and cooking the sorghum into a small porridge for 20 min,•digesting the porridge with pepsin for at least 2 h,•extracting and assaying the protein extract. This method closely resembles the reality of sorghum usage as food and feed, can be scaled to process large numbers of samples and can be adapted for use with other cereal crops. This protocol requires only basic lab equipment and expertise, and one person can easily process 280 samples (140 accessions) in 7-8 h.