Send Orders of Reprints at reprints@benthamscience.net Recent Patents on DNA & Gene Sequences, 2013, 7, 13-24 13 Development of Energy Plants and their Potential to Withstand Various Extreme Environments Walid Saibi, Faiçal Brini, Moez Hanin and Khaled Masmoudi * Plant Protection and Improvement Laboratory, Centre of Biotechnology of Sfax [CBS]/University of Sfax, B.P “1177’’ 3018, Sfax -Tunisia Received: November 24, 2011 Revised: February 07, 2012 Accepted: February 07, 2012 Abstract: Biomass utilization is increasingly considered as a practical way for sustainable energy supply and long-term environment care around the world. In concerns with food security, starch or sugar-based bioethanol and edible-oil- derived biodiesel are severely restricted for large scale production. Alternatively, conversion of lignocellulosic residues from food crops could be considered, but due to its recalcitrance, the current biomass process is unacceptably expensive. In this context, genetic breeding of energy crops appears as a promising solution. To fulfil the global world need as both food and biofuel sources, energy crops are expected to be produced with higher yields and especially in marginal lands. This review focus on recent progress and patents dealing with energy plants and the challenges associated with bioenergy development. We also discuss the potential use of molecular approaches including genome sequencing, molecular mark- ers, and genetic transformation for improving specific traits or generating new cultivars of energy plants. Keywords: Abiotic stress, biomass production, biotechnology, bioenergy, cereals, energy plants. 1. INTRODUCTION Rapidly increasing energy demand has become a serious challenge both in developed and developing countries. Ex- ploitation of renewable energy and sustainable energy is one of the effective solutions to this problem. Development of renewable energy can not only contribute to the energy sup- ply, but also to achieve economic and environmental benefits [1]. Biomass energy is the most abundant and versatile type of renewable energy in the world [2]. In recent years, many countries have developed policies and objectives for bio- energy and this includes the production of heat, electricity, and fuel [3, 4]. Since 1975, Brazil has achieved greater en- ergy security based on its focused commitment to developing competitive sugarcane industry and making ethanol a key part of its energy mix [3]. In fact, Brazil has replaced more than half of its gasoline needs with sugarcane ethanol- mak- ing gasoline the alternative fuel. Today, Brazil is the second biggest producer of ethanol in the world (20 billion litres) after the United States (24 billion litres). Close to 80 % of this production is for the domestic market- the fuel used in 45 % of Brazilian vehicles is ethanol. Many observers point to Brazil’s experience as a case study for other nation’s seek- ing to expand use of renewable fuels. The United States has used maize starch for bioethanol at 16.5 million Mg/year [5- 8]. In China, starch bioethanol is mainly produced from the decayed and aged maize, rice and wheat grains at 1.33 mil- lion Mg/year [9]. As a contrast, lignocellulose ethanol pro- duction, because of its recalcitrance, is still under develop- ment [10,11]. In fact, a great effort has been made to in- crease the lignocellulose conversion rate, but the difficulty *Address correspondence to this author at the Plant Protection and Im- provement Laboratory, Centre of Biotechnology of Sfax [CBS], B.P’1177’, 3018 Sfax, Tunisia; Tel/Fax: 216-74 872 091; E-mail: khaled.masmoudi@cbs.rnrt.tn remains with two crucial factors: biomass pretreatment and enzymatic degradation. It is determined by cellulose crystal- linity and lignin linking-styles of the plant cell walls [12,13]. In spite of extreme pretreatment conditions that can be a so- lution, such as strong acid/base, or extreme tempera- ture/pressure, it leads to a negative economic profit of bio- fuel production together with a secondary environmental pollution [14]. Therefore, discovery of energy crops would provide a solution to a bottleneck situation. Without doubt, characterization of germplasm resources should be consid- ered as an essential task to find out valuable genetic materi- als for energy crop breeding and to select high value energy plants. Bioenergy crops can be classified as starch-producing crops, sugar-producing crops, lignocellulosic biomass crops, and oilseed crops for biodiesel production. Starch-producing crops include sweet potato [Ipomoea batatas L.] and cassava [Manihot esculenta Crantz.]; sugar-producing crops include sugarcane [Saccharum officinarum L.] and sweet sorghum [Sorghum bicolor [L.] Moench.]; lignocellulosic biomass crops include switchgrass [Panicum virgatum L.], miscan- thus [e.g. Miscanthus giganteus Greef and Deu.] and poplar [Populus spp.]; and oilseed crops for biodiesel include soy- bean [Glycine max [L.] Merr.] and sunflower [Helianthus annuus L.]. Among the candidate energy crops, switchgrass, miscanthus, poplar, and sugarcane have been studied most extensively worldwide [3,15]. Energy plant resources differ from one geographic region to another according to their production capacity and their resistance to salt, drought, and/or low, high temperature stress. Plant species that have high production and are resistant to abiotic stress can be po- tentially developed as candidate energy plants. In this re- view, we report various strategies used to search alternatives to produce novel energetic forms, based on the valorisation of plant biomass. We reviewed recent progresses and patents 2212-3431/13 $100.00+.00 © 2013 Bentham Science Publishers