Calcium, Copper, Magnesium, Manganese, Sodium, and Zinc in Brassica napus,
and increases endogenous Fe levels (Wang et al. 2020).
5.6
Biotechnological Strategies to Ameliorate Stress
and Enhance NUE
Since the beginning of agricultural practices, breeding has been the primary tool for
selection of varieties with improved yield and content quality such as fatty acids,
carbohydrate, and proteins. Towards this goal, optimum supply of mineral nutrients
along with several other promising strategies has been a primary approach to
maintain high output/input ratio and improve NUE. However, it is almost difficult
to make ideal environment for maximum nutrient use and output using traditional
practices. Green revolution was driven by attempting to enhance “output” by
increasing input such as fertilizers and irrigation along with breeding (Borlaug
1972). It is because the primary aim of green revolution was to meet food demand
for the growing population. However soon it was realized that the practice of
applying high level of fertilizers is unsustainable, cannot be practiced for long as
this can harm biodiversity. One of the major factors for this was described as the
concept of diminishing returns, which states that if fertilizers are used at the same
speed, they may not give as much yield as they were giving in the past (Tilman et al.
2002). Also, artificially provided nutrients can cause groundwater and soil pollution/
toxicity which can further lead to eutrophication.
With the advancement in biotechnology, pathways for nutrient uptake and assimilation have been deciphered. This knowledge combined with advancements in
genetic breeding and biotechnological tools has the potential to give more sustainable and long-term method for enhancing NUE which aim to reduce “input”
component of NUE, without compromising “output.”
5.6.1 Genome-Wide Studies
Whole genome sequencing and transcriptome analysis can provide knowledge about
most fundamental regulators that can be exploited for enhancing NUE. Identification
and functional characterization of candidate genes and regulators which have the
ability to increase nutrient uptake and assimilation, or candidates to modify root
architecture for better absorption are the primary targets. Also, such studies can be
useful in identifying QTLs and biomarkers which are helpful in marker assisted
breeding and selection (MAB and MAS). For example, Gua1 has been proposed as a
biomarker for nitrate use efficiency (NitUE) in A. thaliana (Meyer et al. 2019).
Several studies on transcriptome analysis have also been carried out to identify
candidate genes for NitUE (Li et al. 2009, Oono et al. 2013). Recently, Gho et al.
(2018) identified several promoters for improving phosphate use efficiency (PUE) in
rice. Earlier in a separate study, five Pi transporters, two auxin response factors, three
SYG1/Pho81/XPR1 (SPX) domain-containing proteins, two MYB-like transcription
164
E. Bhardwaj et al.
and increases endogenous Fe levels (Wang et al. 2020).
5.6
Biotechnological Strategies to Ameliorate Stress
and Enhance NUE
Since the beginning of agricultural practices, breeding has been the primary tool for
selection of varieties with improved yield and content quality such as fatty acids,
carbohydrate, and proteins. Towards this goal, optimum supply of mineral nutrients
along with several other promising strategies has been a primary approach to
maintain high output/input ratio and improve NUE. However, it is almost difficult
to make ideal environment for maximum nutrient use and output using traditional
practices. Green revolution was driven by attempting to enhance “output” by
increasing input such as fertilizers and irrigation along with breeding (Borlaug
1972). It is because the primary aim of green revolution was to meet food demand
for the growing population. However soon it was realized that the practice of
applying high level of fertilizers is unsustainable, cannot be practiced for long as
this can harm biodiversity. One of the major factors for this was described as the
concept of diminishing returns, which states that if fertilizers are used at the same
speed, they may not give as much yield as they were giving in the past (Tilman et al.
2002). Also, artificially provided nutrients can cause groundwater and soil pollution/
toxicity which can further lead to eutrophication.
With the advancement in biotechnology, pathways for nutrient uptake and assimilation have been deciphered. This knowledge combined with advancements in
genetic breeding and biotechnological tools has the potential to give more sustainable and long-term method for enhancing NUE which aim to reduce “input”
component of NUE, without compromising “output.”
5.6.1 Genome-Wide Studies
Whole genome sequencing and transcriptome analysis can provide knowledge about
most fundamental regulators that can be exploited for enhancing NUE. Identification
and functional characterization of candidate genes and regulators which have the
ability to increase nutrient uptake and assimilation, or candidates to modify root
architecture for better absorption are the primary targets. Also, such studies can be
useful in identifying QTLs and biomarkers which are helpful in marker assisted
breeding and selection (MAB and MAS). For example, Gua1 has been proposed as a
biomarker for nitrate use efficiency (NitUE) in A. thaliana (Meyer et al. 2019).
Several studies on transcriptome analysis have also been carried out to identify
candidate genes for NitUE (Li et al. 2009, Oono et al. 2013). Recently, Gho et al.
(2018) identified several promoters for improving phosphate use efficiency (PUE) in
rice. Earlier in a separate study, five Pi transporters, two auxin response factors, three
SYG1/Pho81/XPR1 (SPX) domain-containing proteins, two MYB-like transcription
164
E. Bhardwaj et al.