cyanobacterial Form-1A RuBisCO large and small subunit genes, along with genes
for two key α-carboxysome structural proteins. This minimal gene set organizes
carboxysomes, which encapsulate the introduced RuBisCO and allow autotrophic
growth at elevated CO 2 .
Another CCM, i.e. C4 photosynthesis, in some photosynthetic algae, bacteria and
plants have evolved mechanisms to decrease the oxygenation reaction by RuBisCO,
thus signifying its incorporation into C3 crop plants (Price et al. 2013; Long et al.
2016; Schuler et al. 2016). A lot of research has been done to express the genes of the
C4 pathway in rice; however, it requires many changes in both anatomy and
expression of CBBC enzymes, i.e. characterisation of C4-plants into CCM-free
crops (von Caemmerer et al. 2012). Wang et al. (2017) transferred the ectopic
expression of Golden-like (GLK) transcription factor genes from Zea mays for
establishing C4 photosynthesis in rice. In these rice plants, enlarged organelle
volume of cells neighbouring the vasculature (attribute of proto-Kranz anatomy) is
considered an imperative groundwork and anatomical enabler for further engineering of rice plants with C4 photosynthetic mechanism (Roell and Zurbriggen 2020).
Stomatal kinetics is another factor serving a dual role in promoting photosynthetic
carbon assimilation (facilitating carbon dioxide influx) and Water Use Efficiency
(WUE—restricting water efflux via transpiration). Papanatsiou et al. (2019)
expressed the synthetic, blue light-gated K
+ channel (BLINK1) in guard cells
surrounding stomatal pores in Arabidopsis to modulate guard cell K
+ conductance.
Introduction of BLINK1 accelerated both stomatal opening under light exposure and
closing after irradiation and drove enhancement in stomatal kinetics to recover WUE
leading to a twofold raise in biomass. Lastly, reducing redundant respiratory activity
leading to unnecessary CO 2 release is the long-established scheme utilised in the
engineering revolution to raise crop yield. Respiratory enzyme and transporter genes
that can be engineered to (1) suppress redundant protein turnover, (2) reform
respiratory metabolic activities, (3) cut futile cycles, and (4) make ion transport
more efficient, can reduce respiratory costs are extensively reviewed by Amthor
et al. (2019).
15.3 Ecologically Sustainable Fertilization
For sustainable food production and to prevent soil nutrient depletion, soil needs to
be constantly replenished with essential nutrients like nitrogen (N), phosphorus
(P) and potassium (K) [Goulding et al. 2008]. The growing demand of food
production was partly dealt by the Green Revolution of the 1960s when crop yields
were significantly improved through the massive implementation of chemical
fertilizers, high-yielding varieties and breeding strategies to exploit plant lightharvesting capacity. However, this fails to keep pace with the increasing food
demands of the growing world population, which calls for a minimum of 2.4%
increase in annual yield (Ray et al. 2013). Moreover, there are many masked hazards
related to chemical fertilization, for example, their toxic bioaccumulation, the release
of toxic by-products causing air pollution, water eutrophication and degradation of
444
P. Singla
for two key α-carboxysome structural proteins. This minimal gene set organizes
carboxysomes, which encapsulate the introduced RuBisCO and allow autotrophic
growth at elevated CO 2 .
Another CCM, i.e. C4 photosynthesis, in some photosynthetic algae, bacteria and
plants have evolved mechanisms to decrease the oxygenation reaction by RuBisCO,
thus signifying its incorporation into C3 crop plants (Price et al. 2013; Long et al.
2016; Schuler et al. 2016). A lot of research has been done to express the genes of the
C4 pathway in rice; however, it requires many changes in both anatomy and
expression of CBBC enzymes, i.e. characterisation of C4-plants into CCM-free
crops (von Caemmerer et al. 2012). Wang et al. (2017) transferred the ectopic
expression of Golden-like (GLK) transcription factor genes from Zea mays for
establishing C4 photosynthesis in rice. In these rice plants, enlarged organelle
volume of cells neighbouring the vasculature (attribute of proto-Kranz anatomy) is
considered an imperative groundwork and anatomical enabler for further engineering of rice plants with C4 photosynthetic mechanism (Roell and Zurbriggen 2020).
Stomatal kinetics is another factor serving a dual role in promoting photosynthetic
carbon assimilation (facilitating carbon dioxide influx) and Water Use Efficiency
(WUE—restricting water efflux via transpiration). Papanatsiou et al. (2019)
expressed the synthetic, blue light-gated K
+ channel (BLINK1) in guard cells
surrounding stomatal pores in Arabidopsis to modulate guard cell K
+ conductance.
Introduction of BLINK1 accelerated both stomatal opening under light exposure and
closing after irradiation and drove enhancement in stomatal kinetics to recover WUE
leading to a twofold raise in biomass. Lastly, reducing redundant respiratory activity
leading to unnecessary CO 2 release is the long-established scheme utilised in the
engineering revolution to raise crop yield. Respiratory enzyme and transporter genes
that can be engineered to (1) suppress redundant protein turnover, (2) reform
respiratory metabolic activities, (3) cut futile cycles, and (4) make ion transport
more efficient, can reduce respiratory costs are extensively reviewed by Amthor
et al. (2019).
15.3 Ecologically Sustainable Fertilization
For sustainable food production and to prevent soil nutrient depletion, soil needs to
be constantly replenished with essential nutrients like nitrogen (N), phosphorus
(P) and potassium (K) [Goulding et al. 2008]. The growing demand of food
production was partly dealt by the Green Revolution of the 1960s when crop yields
were significantly improved through the massive implementation of chemical
fertilizers, high-yielding varieties and breeding strategies to exploit plant lightharvesting capacity. However, this fails to keep pace with the increasing food
demands of the growing world population, which calls for a minimum of 2.4%
increase in annual yield (Ray et al. 2013). Moreover, there are many masked hazards
related to chemical fertilization, for example, their toxic bioaccumulation, the release
of toxic by-products causing air pollution, water eutrophication and degradation of
444
P. Singla