Genetic analysis of seeds for high sugar content suitable for production of bioethanol and high quality silage

甜菊（Sugaryfeterita）是二色高粱（Sorghanbicolor（L.）Moench，它在种子中积累糖分。在这里，我们通过将SugaryFeterita与Nakei MS-3B杂交产生了F2群体，Nakei MS-3B在种子中以低水平积累糖。对F_2群体分离比的分析表明，该性状由一对隐性基因控制。初步定位分析表明，该基因位于第7号染色体上。在候选区域内，定位了编码淀粉生物合成酶SbSU 1的基因。该基因是玉米SU 1的直向同源基因，其突变导致甜玉米种子中的高糖含量。我们对两个亲本系的该基因进行了序列分析，发现了一些SNPs。其中两个导致氨基酸取代。通过比较SbSU 1与其他物种的正向同源基因，我们证实了SugaryFeterita具有一个突变等位基因。SbSU 1成绩单增加对开花时间，在此期间，淀粉被积累在野生型（Feterita）种子。这些结果表明，SbSU 1的突变也可能导致淀粉合成异常，从而导致糖在种子中的积累。

Sugary feterita is a cultivar of Sorghum bicolor (L.) Moench, which accumulates sugar in the seeds. Here, we generated an F2 population by crossing Sugary Feterita with Nakei MS-3B which accumulates sugar in the seeds at low levels. An analysis of the segregation ratio of the F2 population indicated that the phenotype is determined by a recessive gene. A rough mapping analysis indicated that the corresponding gene is located on chromosome 7. Within the candidate region, a gene that encodes a starch biosynthetic enzyme, SbSU1, was located. This gene is an ortholog of maize SU1, the mutation of which is responsible for the high sugar content in the seeds of sweet corn. We carried out sequence analysis of the gene from both parental lines and found someSNPs. Two of them result in amino acid substitutions. After comparing SbSU1 with other orthologous genes from other species, we confirmed that Sugary Feterita possesses a mutant allele. SbSU1 transcripts increased toward flowering time, during which starch is being accumulated in wild-type (Feterita) seeds. These results suggest that the mutation(s) in SbSU1 of Sugary Feterita might also cause abnormal starch synthesis, consequently resulting in the accumulation of sugars in the seeds.