The cultivation of sweet sorghum (Sorghum bicolor (L.) Moench) for bioethanol production is receiving global attention due to the plant's sugar‐rich stalk juice, which can be fermented directly to ethanol. One of the important steps toward the development of a superior sweet sorghum cultivar is proper assessment of bioethanol‐related traits in different environments. This study was conducted to characterize global sweet sorghum accessions for bioethanol yield and related traits. To do this and to obtain a final cultivar suitable for efficient bioethanol production, two different environments were chosen to select for the characteristics studied. In total, 53 genotypes, which were selected from 551 accessions and nine cultivars, were evaluated in two contrasting environments and two consecutive years (2014–2015). The results revealed wide variability among the genotypes for the traits investigated. In all the growing years and locations, the highest values for the extractable stalk juice yield, bioethanol yield, and juice Brix content were recorded for BSS55 (22 740 L ha−1), BSS46 (1569.6 L ha−1), and BSS67 (15.63 °Bx), respectively. The genotypes that originated from the USA showed some of the highest values for bioethanol yield and related traits. Positive and very high correlations were observed between the bioethanol yield and extractable stalk juice yield (r = 0.861**) and fructose and glucose concentration (r = 0.856**). The knowledge obtained in this investigation about the variation in the bioethanol yield and related traits led to potential genotypes that can be used in sweet sorghum breeding programs for bioenergy production. © 2020 Society of Industrial Chemistry and John Wiley & Sons Ltd

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Aphids are one of the devastating pests affecting the productivity of sorghum in many countries. The aim of the present investigation was to identify sweet sorghum genotypes resistant to the sugarcane aphid, Melanaphis sacchari (Zehntner). A Sequence Characterized Amplified Region (SCAR) marker linked to an aphid-resistance gene (RMES1) was first used to prescreen for resistant genotypes in 561 sorghum accessions. Molecular assays indicated that 91 sorghum accessions in the collection had the RMES1 resistance marker allele. Of those, 26 agronomically superior sweet sorghum accessions, along with three commercial cultivars and one susceptible check, were further evaluated in two locations (Antalya, a lowland province, and Konya, a highland province) under field conditions. These accessions were scored for resistance to aphid damage under natural aphid infestations. The number of aphids counted on the plant leaves and stalks in the accessions during the growing seasons was used to score resistant genotypes on a scale of 1-5, where 1 was highly resistant (plants having 0-50 aphids/ plant) and 5 was highly sensitive (plants having 1000 + aphids/plant). Fumagine intensity on the leaves was also taken into consideration. Ten accessions from the lowland and one accession from the highland scored "1," indicating a high resistance to aphid infestation. A further 13 accessions scored "1" or "2" in both environments. Only two accessions scored "4," and no accession scored "5," indicating the utility of the RMES1 marker for prescreening purposes. One accession, BSS507, showed outstanding resistance to M. sacchari, with a score of "1" in both environments.

Sorghum (Sorghum bicolor (L.) Moench) is one of the most promising bio-energy crops with the ability to produce high biomass with low input. Plant height that has a significant contribution to gain in bio-ethanol production is among the most important biomass yield components. In the present study, sorghum genotypes were screened with four SSR markers which are associated with plant height QTLs. The molecular assays were confirmed with two different environments in two consecutive years. In the first year of the study, molecular analyses were performed with a sorghum collection consisting of 551 accessions as well as plant height measurements were performed under field condition. In the second year, 53 out of 551 accessions were selected and further tests with nine controls were performed in Antalya (a lowland province) and Konya (a highland province) locations along with molecular marker analyses. The results indicated that four SSR markers efficiency were assessed as 38% at lowland and 39% at highland. Markers 40-9187 and 37-1740 were of more powerful to explain plant height QTLs than the other two markers at two environments. This study reported the successful application of the association between markers and plant height in two environments to identify valuable genetic resources for bio-energy production in sweet sorghum.

Sorghum is an important but arguably undervalued cereal crop, grown in large areas in Asia and Africa due to its natural resilience to drought and heat. There is growing demand for sweet sorghum as a source of bioethanol as well as food and feed. The improvement of bioenergy-related traits directly affects bioethanol production from sweet sorghum; therefore, understanding the genetic basis of these traits would enable new cultivars to be developed for bioenergy production. In order to reveal the genetic architecture behind bioenergy-related traits, we generated an F2 population from a cross between sweet sorghum cv. ‘Erdurmus’ and grain sorghum cv. ‘Ogretmenoglu’. This was used to construct a genetic map from SNPs discovered by double-digest restriction-site associated DNA sequencing (ddRAD-seq). F3 lines derived from each F2 individual were phenotyped for bioenergy-related traits in two different locations and their genotypes were analyzed with the SNPs to identify QTL regions. On chromosomes 1, 7, and 9, three major plant height (PH) QTLs (qPH1.1, qPH7.1, and qPH9.1) were identified, with phenotypic variation explained (PVE) ranging from 10.8 to 34.8%. One major QTL (qPJ6.1) on chromosome 6 was associated with the plant juice trait (PJ) and explained 35.2% of its phenotypic variation. For fresh biomass weight (FBW), four major QTLs (qFBW1.1, qFBW6.1, qFBW7.1, and qFBW9.1) were determined on chromosomes 1, 6, 7, and 9, which explained 12.3, 14.5, 10.6, and 11.9% of the phenotypic variation, respectively. Moreover, two minor QTLs (qBX3.1 and qBX7.1) of Brix (BX) were mapped on chromosomes 3 and 7, explaining 8.6 and 9.7% of the phenotypic variation, respectively. The QTLs in two clusters (qPH7.1/qBX7.1 and qPH7.1/qFBW7.1) overlapped for PH, FBW and BX. The QTL, qFBW6.1, has not been previously reported. In addition, eight SNPs were converted into cleaved amplified polymorphic sequences (CAPS) markers, which can be easily detected by agarose gel electrophoresis. These QTLs and molecular markers can be used for pyramiding and marker-assisted selection studies in sorghum, to develop advanced lines that include desirable bioenergy-related traits.