over-expression of C-5 sterol desaturase gene from Flammulina velutipes (FvC5SD)
improves drought tolerance in soybean. In this study, FvC5SD gene was introduced
into the soybean variety Shennong9 through the Agrobacterium-mediated transformation in order to enhance drought stress tolerance. Under drought conditions, the
transgenic soybean plants accumulated lower levels of reactive oxygen species and
exhibited higher activities and expression levels of enzymes than wild-type soybean.
The basic leucine zipper (bZIP) family of transcription factors plays an important
role in the growth and developmental process as well as responds to various abiotic
stresses, such as drought. Li et al. (2017b) demonstrated that GmFDL19 also
enhances tolerance to drought and salt stress in soybean at the seedling stage. Wei
et al. (2019) generated transgenic soybean plants and further investigated roles and
biological mechanisms of GmWRKY54 in response to drought stress. Wei
demonstrated that expression of GmWRKY54, driven by either a constitutive promoter (pCm) or a drought-induced promoter (RD29a), confers drought tolerance.
GmWRKY54 is a transcriptional activator and affects a large number of stress-related
genes as revealed by RNA sequencing.
Efforts have been made to study response of soybean plants to drought stress
using advanced genetic engineering and genomic approaches like high-throughput
sequencing technologies, chip-based analysis, RNA seq, etc., which enabled
researchers to utilize enormous nucleotide database to find genes involved in various
metabolic pathways dealing with abiotic stress tolerance. But still, there are many
drought-responsive genes that have been identified but their function is still
unknown. Therefore, genetic engineering through reverse genetics approaches
could be useful for identification and functional elucidation of drought stress tolerance related genes (Azevedo et al. 2011). Identification, a functional characterization
and introgression of stress-related genes through advanced genetic engineering
techniques are important to provide long-term tolerance against drought stress (Jan
et al. 2016, 2017).
The first commercial cultivation of genetically engineered soybean was started in
1996 which has spread in the area of 95.9 million hectares (mHa) till 2018. This area
covers about 78% of the global soybean cultivated area, i.e., 123.5 mHa. The USA is
the world’s top producer of soybean whereas Brazil is the top exporter of soybean in
the world. To bring suitable changes into the molecular structure of soybean,
38 transgenic events were approved in around 31 countries, mostly in the North
and South American continent. These events were attributed to traits like herbicide
resistance, insect resistance, drought tolerance, and pyramiding of two or more gene
traits. All these events account for 50% of the world’s biotech crop area. Among
them, there are two specific transgenic events, commercially available for farmers to
grow drought-tolerant soybeans, namely HB4 (popular as trade name Verdeca HB4
Soybean) and HB4 Â GTS 40-3-2. In these events, gene Hahb, isolated from
Helianthus annuus, has been genetically engineered to produce transcription factor
Hahb-4 which binds to a dehydration transcription regulating region of the plant
responsible for better performance under drought condition. In addtion, new
advances in functional genomics studies in soybean using VIGS, RNAi and genome
108
G. K. Satpute et al.
improves drought tolerance in soybean. In this study, FvC5SD gene was introduced
into the soybean variety Shennong9 through the Agrobacterium-mediated transformation in order to enhance drought stress tolerance. Under drought conditions, the
transgenic soybean plants accumulated lower levels of reactive oxygen species and
exhibited higher activities and expression levels of enzymes than wild-type soybean.
The basic leucine zipper (bZIP) family of transcription factors plays an important
role in the growth and developmental process as well as responds to various abiotic
stresses, such as drought. Li et al. (2017b) demonstrated that GmFDL19 also
enhances tolerance to drought and salt stress in soybean at the seedling stage. Wei
et al. (2019) generated transgenic soybean plants and further investigated roles and
biological mechanisms of GmWRKY54 in response to drought stress. Wei
demonstrated that expression of GmWRKY54, driven by either a constitutive promoter (pCm) or a drought-induced promoter (RD29a), confers drought tolerance.
GmWRKY54 is a transcriptional activator and affects a large number of stress-related
genes as revealed by RNA sequencing.
Efforts have been made to study response of soybean plants to drought stress
using advanced genetic engineering and genomic approaches like high-throughput
sequencing technologies, chip-based analysis, RNA seq, etc., which enabled
researchers to utilize enormous nucleotide database to find genes involved in various
metabolic pathways dealing with abiotic stress tolerance. But still, there are many
drought-responsive genes that have been identified but their function is still
unknown. Therefore, genetic engineering through reverse genetics approaches
could be useful for identification and functional elucidation of drought stress tolerance related genes (Azevedo et al. 2011). Identification, a functional characterization
and introgression of stress-related genes through advanced genetic engineering
techniques are important to provide long-term tolerance against drought stress (Jan
et al. 2016, 2017).
The first commercial cultivation of genetically engineered soybean was started in
1996 which has spread in the area of 95.9 million hectares (mHa) till 2018. This area
covers about 78% of the global soybean cultivated area, i.e., 123.5 mHa. The USA is
the world’s top producer of soybean whereas Brazil is the top exporter of soybean in
the world. To bring suitable changes into the molecular structure of soybean,
38 transgenic events were approved in around 31 countries, mostly in the North
and South American continent. These events were attributed to traits like herbicide
resistance, insect resistance, drought tolerance, and pyramiding of two or more gene
traits. All these events account for 50% of the world’s biotech crop area. Among
them, there are two specific transgenic events, commercially available for farmers to
grow drought-tolerant soybeans, namely HB4 (popular as trade name Verdeca HB4
Soybean) and HB4 Â GTS 40-3-2. In these events, gene Hahb, isolated from
Helianthus annuus, has been genetically engineered to produce transcription factor
Hahb-4 which binds to a dehydration transcription regulating region of the plant
responsible for better performance under drought condition. In addtion, new
advances in functional genomics studies in soybean using VIGS, RNAi and genome
108
G. K. Satpute et al.