Genetic Engineering of Crop Plants for Salinity and Drought Stress Tolerance: Being Closer to the Field
Pravin V. Jadhav1, Prashant B. Kale1, Mangesh P. Moharil1, Deepti C. Gawai1, Mahendra S. Dudhare1, Shyam S. Munje1, Ravindra S. Nandanwar1, Shyamsundar S. Mane1, Philips Varghese2,
Joy G. Manjaya3 and Raviprakash G. Dani1
1 Biotechnology Centre, Department of Agricultural Botany, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola-444 104, Maharashtra state, India 2Agharkar Research Institute, Pune-411004, Maharashtra, India 3NucIear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre (BARC),
Trombay, Mumbai-400085, Maharashtra, India E-mail: jpraveen26@yahoo. со. in
Abiotic stresses such as drought, salinity, heat and cold, are greatly affecting the plant growth and agricultural productivity and causes more than 50% of worldwide yield loss of major crops every year. Many efforts have been made by researchers to mitigate these stresses and to increase crop productivity under unfavourable environments. Traditional measures are niche-specific and exhibit tremendous vulnerability to the climactic conditions due to varied intensity of edaphic factors. Genetic engineering is one of the tools being used to develop crop plants which are tolerant to these stresses. It is imperative to understand the adaptive mechanism of plants to drought especially the type and expression levels of drought responsive genes. Several genes upregulated during abiotic stress have been exploited to develop drought tolerant plants. Genetic engineering of crop plants with stress responsive genes has been an effective method of generating drought tolerant plants. Keeping this in purview, the present chapter makes a serious attempt to accumulate the available information and finally come out with a sound strategy by deploying cutting edge science and modem biotechnological approaches paying special attention towards development of large scale cultivation of transgenic crops, which is deemed to be conclusive by halting menaces caused by biotic and abiotic stresses to enhance productivity especially at the interface of global climatic changes, which are amplifying alarmingly, which would lead to acute food and nutritional insecurity which would fail to sustain an livelihood.
Keywords: Abiotic stress, Genetic engineering, Nutritional insecurity.
Abiotic stresses are serious threats to agriculture and the environment which have been exacerbated in the current century by global warming and industrialization. Worldwide approximately 70% of yield reduction is the direct result of abiotic stresses (Acquaah, 2007). According to FAO, globaly more than 800 million hectares of land are currently salt-affected, including both saline and sodic soils equating to more than 6% of the world’s total cultivated area. Continuing salinization of arable land is expected to have overwhelming global impact, resulting in a 30% loss of cultivated land over the next 25 years it will be double by 2050. Currently, the world is losing three hector of arable land every minute due to soil salinity. Some of the most serious effects of abiotic stresses occur in the arid and semiarid regions where rainfall, high evaporation, low native rocks, saline irrigation water and poor water management etc., contribute in agricultural areas. The increasing pressure put on agricultural land by burgeoning human populations has resulted in land degradation, a cultivation shift to more marginal areas and soil types and heavier requirements for agricultural productivity per unit area. Additionally, climate change has worsen the frequency and severity of various abiotic stresses, particularly drought, salinity and high temperatures with significant yield reductions reported in major cereal species (Lobell and Field, 2007). Diseases, pests and weed competition losses account for 4.1% and 2.6% yield reductions, respectively, with the remainder of the yield reduction of 69.1% due to unfavorable abiotic stresses induced by problematic soils and erratic climate patterns. Certainly, some of these losses are caused by inherently unfavorable environments as well as by suboptimal management practices by fanners, often due to economic constraints or lack of training (Godfray et al, 2010; Peleg et al, 2011). Agricultural practices for improving crop productivity per unit area have, in many cases, accelerated the rate of land degr adation, with particularly marked effects in inigated areas. Irrigation has led to salinity across large tracts of agricultural land, with cases, such as in India, where it has reportedly led to the loss of seven million hectares from cultivation (Martinez-Beltran and Manzur, 2005). Higher yields are also only sustainable with higher nutrient use, and the heavy demand for fertilizers has caused rising cultivation costs for fanners worldwide. The environmental and economic consequences of increased nutrient use have been widely reported. For sustainability of crop production, there is a need to reduce the environmental footprint of food and fiber production, and nutrient use efficient crops are highly sought after.