**1. Introduction**

Climate change alters environmental conditions and therefore has direct and biophysical effects on agricultural production. The biophysical and direct effects of climate change induce alterations on the prices and production of agriculture. Such changes are reflected on the economic system as farmers and other market participants make adjustments autonomously. They are both compelled to modify their crop combinations, use of supplies, level of production, and food demand, consumption and trade. Climate change causes a changes in rainfall regimes which have direct effects on crop yields as well as indirect effects through changes in the availability of water irrigation [1].

and intensity (severe or mild) of stress and also the type of affected tissue [18–21]. Water stress also affects both cane and sugar yield substantially. The most common water stress responses in sugarcane are leaf rolling, stomatal closure, inhibition of stalk and leaf growth, leaf senescence and reduced leaf area [12, 22]. Moreover, under water stress, both cell division and cell elongation are interrupted [23] and stem and leaf elongation are the most severely affected growth processes [24, 25]. Root development is also influenced by water deficit [19, 26] but its overall biomass is relatively less than the above-ground biomass. Sugarcane is a tropical crop with C4 photosynthetic metabolism. A moderate water stress causes a stomatal limitation, which triggers a decrease in stomatal conductance (gs), transpiration rate (E),

in photosynthetic rate is mainly caused by a decrease in phosphoenolpyruvate carboxylase (PEPcase) and ribulose-1,5-biphosphate carboxylase (Rubisco) activity [26, 27, 31]. It is worth to note that photosynthesis rate is also impacted by sugar accumulation in leaves [32]. Under non-stressed condition low leaf sugar content is conducive to photosynthesis, while high sugar content moderates carbon fixation [33]. Interestingly, increased levels of some sugars, such as trehalose, can help plants to cope with water deficit, reducing the damage on cell membrane [34]. The capacity to accumulate trehalose was demonstrated in sugarcane roots under drought conditions. Sales et al. [35] reported an increase in starch hydrolysis, leading to higher levels of soluble sugars that helped sustain carbon supply even in a reduced CO2

Sugarcane crop productivity has progressively increased to remarkable levels worldwide in the last century [36]. This increase in productivity has been ascribed to the development and widespread use of improved cultivars with increased resistance to diseases and pests, better management of water, nutrients and other resources, and the availability of relatively cheap chemical fertilizers and pesticides. Sustaining this pace of improvement in crop productivity by innovative and intensive agriculture, whilst ensuring minimal environmental impact, will

Biotechnology offers excellent opportunities for sugarcane crop improvement. Commercial sugarcane, mainly the interspecific hybrids of *S. officinarum* and *S. spontaneum* [37], would greatly benefit from biotechnological improvements due to its complex polyploid-aneuploid genome, narrow genetic base, poor fertility, susceptibility to various diseases and pests, and the long duration (12–15 years) required to breed elite cultivars. More importantly, there is an ongoing need to provide durable disease and pest resistance commercial clones in combination with superior agronomic performance. This led to considerable research in different areas of biotechnology pertinent to sugarcane breeding and disease control. Despite the availability of molecular tools and strategies and advancements in our understanding of stress responses, engineering crops for drought tolerance remains a major challenge. This is not only due to the complexity of the plant responses to water deficit but also due to the difficulty of identifying and exploiting of large effect genes and alleles and the associated selection traits for developing drought tolerant varieties suitable for commercial crop production

be one of the major challenges to maintain a profitable sugar industry in the future.

fixation condition, facilitating growth recovery after stress.

**3. Sugarcane and biotechnology**

concentration (Ci), and photosynthetic rate [26–30]. Under water stress, a decline

Transcriptome, Genetic Transformation and Micropropagation: Some Biotechnology…

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internal CO2

conditions [38].

Sugarcane (*Saccharum officinarum* L.) is a monocotyledonous perennial plant belonging to the gramineous family *Saccharum officinarum* L. [2]. Sugarcane is a commercial crop in tropical and subtropical regions. According to FAOSTAT [3], sugarcane is cultivated in 26.1 million hectares producing 1.83 trillion canes. Sugarcane is a multi-purpose industrial cash crop and the main source of raw material for sugar production. It is responsible for almost 70% of world-produced centrifugal sugar [4]. Some mitigation and adaptation strategies for climate change in sugarcane production are the use of biotechnological techniques such as transcriptome, genetic transformation and *in vitro* micropropagation. In this chapter, we will talk about water stress in sugarcane caused by the climatic change and the biotechnological alternatives such as transcriptome, genetic transformation and micropropagation which are currently being carried out in our laboratory to counteract this problem.

### **2. Climate change, water stress and its effect in sugarcane**

A large scale of plant production grown under different agricultural production systems is lost under the effects of abiotic stresses, which may result in a 70% reduction of the potential yields of crop plants [5]. During growth and developmental periods, crops suffer seasonal floods and droughts, extreme temperatures or salinity all year round. Globally, about 22% of global agricultural land is saline, and the increased damage caused by drought has been reported to limit plant growth and development followed by a loss of productivity, especially in crop species [6, 7]. Thus, drought stresses are one of the most serious kind of abiotic stresses that implies a threat on crop productivity worldwide.

Sugarcane, an important source of sugar and ethanol, is a relatively high water-demanding crop and its growth is highly sensitive to water deficit [8]. It is estimated that sugarcane produces 8–12 ton cane per ML of water irrigation [9], and water deficit can lead to productivity losses of up to 60% [10–13]. For this reason, production areas are concentrated in regions with favorable rain regime to sugarcane growth and development [14], while in other areas crop production requires supplemental or full irrigation [15].

According to various studies, water stress triggers many physiological, biochemical, and molecular responses that influence various cellular processes in plants and this impacts on its productivity [16, 17].

Severe water stress such as drought affects the entire plant. Morphological and physiological responses in sugarcane plants vary according to its genotype, duration (rapid or gradual) and intensity (severe or mild) of stress and also the type of affected tissue [18–21]. Water stress also affects both cane and sugar yield substantially. The most common water stress responses in sugarcane are leaf rolling, stomatal closure, inhibition of stalk and leaf growth, leaf senescence and reduced leaf area [12, 22]. Moreover, under water stress, both cell division and cell elongation are interrupted [23] and stem and leaf elongation are the most severely affected growth processes [24, 25]. Root development is also influenced by water deficit [19, 26] but its overall biomass is relatively less than the above-ground biomass. Sugarcane is a tropical crop with C4 photosynthetic metabolism. A moderate water stress causes a stomatal limitation, which triggers a decrease in stomatal conductance (gs), transpiration rate (E), internal CO2 concentration (Ci), and photosynthetic rate [26–30]. Under water stress, a decline in photosynthetic rate is mainly caused by a decrease in phosphoenolpyruvate carboxylase (PEPcase) and ribulose-1,5-biphosphate carboxylase (Rubisco) activity [26, 27, 31]. It is worth to note that photosynthesis rate is also impacted by sugar accumulation in leaves [32]. Under non-stressed condition low leaf sugar content is conducive to photosynthesis, while high sugar content moderates carbon fixation [33]. Interestingly, increased levels of some sugars, such as trehalose, can help plants to cope with water deficit, reducing the damage on cell membrane [34]. The capacity to accumulate trehalose was demonstrated in sugarcane roots under drought conditions. Sales et al. [35] reported an increase in starch hydrolysis, leading to higher levels of soluble sugars that helped sustain carbon supply even in a reduced CO2 fixation condition, facilitating growth recovery after stress.
