Sweet sorghum ideotypes: genetic improvement of the biofuel syndrome

Abstract

Compared to other potential feedstocks such as sugarcane, sugar beet, maize, and watermelon, sweet sorghum possesses higher levels of directly fermentable reducing sugars within the culm and the ability to accumulate high biomass under low-input production systems. In addition, it is tolerant to drought and has more efficient utilization of solar radiation and nitrogen-based fertilizers than maize and sugar cane on marginal lands that are not optimal for food production. These collectively make sweet sorghum to be considered with huge potential as a biofuel crop. Novel phenotypes generated during plant domestication and continued crop improvements via artificial selection constitute the domestication syndrome (Am. J. Bot., 101, 2014, 1711). Here, we draw an analogy and introduce the term the biofuel syndrome to refer to a suite of sweet sorghum traits, such as plant architecture (root, leave, and stem), flowering time and maturity as well as biomass bioconversion efficiency, that are associated with biofuel production and distinguish it from grain and forage sorghum traits. We discuss the biofuel syndrome amenable for targeted genetic modulation and what is currently known about the genetics and genomics of these traits as a potential route to optimize sweet sorghum for biofuel production. Continuous availability of sweet sorghum, transport and storing much mass and minimizing the postharvest loss of fermentable sugars are fundamental to exploiting sweet sorghum as a bioenergy crop. Due to the relatively short history of sweet sorghum breeding, we consider the development of ideotypes adapting to various phenological requirements to maximize the rapid deployment of sweet sorghum for biofuel production.

Transformation of Miscanthus and Sorghum cellulose during methane fermentation

“…It the case of species Sorghum, the plants harvested after the growing season had lower average cellulose percentage, which amounted to 39.8%. The research of cellulose content in the range of energy application of Sorghum was performed by Anami et al (2015). The results they received were significantly lower and amounted to 23%.…”

“…Anami et al (2015) have investigated the content of cellulose in a variety of Sorghum for energy purposes. The authors have shown that percentage of that component is relatively low taking into account plant biomass and is 23%.…”

Sweet Sorghum Originated through Selection of Dry, a Plant-Specific NAC Transcription Factor Gene

“…Similar to common grain sorghum, sweet sorghum is widely found in many geographical regions, with various landraces, and is considered to be an ideal biofuel crop for first-and second-generation bioethanol production. Sorghum can produce high biomass on marginal lands that are not suitable for food or feed production (Anami et al, 2015).…”

Características agronómicas asociadas a la producción de bioetanol en genotipos de sorgo dulce

“…Los sorgos dulces pueden producir entre 58 300 a 80 500 kg/ha de biomasa (Sylvester et al, 2015), en tanto que Pothisoong y Jaisil (2011) reportaron producciones entre 48 300 y 50 800 kg/ha. Potranca x Keller produjo en promedio 52 125 kg/ha de PTP, resultado que se encuentra entre el nivel inferior reportado por los primeros autores y el superior indicado por los segundos.…”

“…En los sorgos dulces las plantas más altas parecen ser la llave para obtener una mayor producción de biomasa y azúcar. Los sorgos dulces S. bicolor, frecuentemente presentan alturas de planta superiores a 3 m (Sylvester et al, 2015) (Cuadro 4). Esto depende de las condiciones de clima, suelo, manejo del cultivo, genotipo, etc.…”