Interpopulation variations in morphochemical characteristics of Stevia rebaudiana Bertoni

Abstract

Introduction Low-calorie sweeteners have gained importance due to an increase in the number of diabetic people in the world. As per a World Health Organization report, the number of diabetic people will be 80 million by 2025. Synthetic lowcalorie sweeteners have been in use for a long time but are associated with some health risks like carcinogenicity, weight gain, headache, and depression (Tandel, 2011). Consequently, people prefer natural sweeteners rather than synthetic ones. Stevia rebaudiana Bertoni is an important natural sweetener-containing perennial plant of the family Asteraceae (Reis et al., 2017). It is a native of Brazil and Paraguay in South America. In these regions, several other Stevia species such as S. salicifolia Cav., S. lucida Lag., S. rhombifolia Kunth, S. eupatoria Spreng., and S. balansae Hieron. are well known for their ethnopharmacological properties. S. salicifolia Cav. and S. lucida Lag. possess antirheumatic, antihelminthic, and antiinflammatory properties while S. rhombifolia, S. eupatoria, and S. balansae have emetic, antidiarrheal, and diuretic properties, respectively (Ferrazzano et al., 2016). Stevioside and rebaudioside-A are two main sweetener compounds present in the leaves of the plant (Ramesh et al., 2006) and are widely used as zero-calorie sweeteners in many food and beverage industries (Midmore and Rank, 2006; Herranz et al., 2010). These are utilized to sweeten various products like tea (Vanek et al., 2001), seafood, candy, and ice cream (Ozdemir et al., 2015). In addition, the leaves have antidiabetic, antiviral, antiobesity, anticancerous, diuretic, and antiinflammatory properties (Yadav et al., 2011). Stevia rebaudiana grows well under semitropical, subhumid climatic conditions with average annual temperature and rainfall of 25 °C and 1375 mm, respectively (Gupta et al., 2013). The species has been introduced as a commercial crop in several countries, such as the United States, Korea, Tanzania, Brazil, and India (Brandle and Rosa, 1992). According to Ramesh et al. (2006), Stevia rebaudiana performs well at a temperature range from 28 to 40 °C under subtropical Indian conditions. Dwivedi (1999) also reported the cultivation of the crop in humid hilly regions of Assam. The crop is found to grow well in regions like Maharashtra, Rajasthan, Kerala, Orissa, and Punjab in India (Singh et al., 2014). Stevia rebaudiana populations grown from seeds show variations in morphology as well as chemical contents (Tamura et al., 1984; Jadeja et al., 2005). Accordingly, morphochemical characterization needs to be applied to natural sweetener plants like S. rebaudiana. Although earlier studies reported the selection of elite genotypes in natural populations and segregant generations of S. rebaudiana (Abdelsalam et al., 2016; Singh et al., 2017), only limited information is available with regard to the identification of superior plant types in segregant populations. Though the segregating individuals are not needed for crop cultivation as associated with

Characterisation of LTR-Retrotransposons of Stevia rebaudiana and Their Use for the Analysis of Genetic Variability

“…Stevia shows wide climatic adaptability, successfully growing in a range of agroecological environments, including semi-humid, subtropical, and temperate zones, which is probably related to a wide genetic variability [ 24 ], reflecting its biochemical variability, i.e., regarding the yield of steviol glycosides in the leaves [ 25 ]. In its native area, stevia is grown as a perennial plant, especially at high altitudes [ 26 ].…”