(Bodenhausen et al. 2014). In the presence of a 35-member synthetic community‚
Castrillo et al. (2017) found that A. thaliana mutants with an altered Phosphate Stress
Response (PSR) assembled different root microbiota than wild-type plants. The
synthetic community activated PSR and repressed expression of plant immunity
genes under phosphate-limiting conditions by enhancing the activity of the master
transcriptional regulator of the PSR, i.e. PHR1 (Castrillo et al. 2017). Niu et al.
(2017) studied seven-species synthetic community inoculating maize roots and by
eliminating bacterial species one at a time, they concluded that Enterobacter species
is the keystone for community assembly. While in the absence of E. cloacae, the
unlimited abundance of Curtobacterium pusillum increased over other species,
whereas a small synthetic community was superior at resistance against late blight
disease caused by Fusarium verticillioides.
Interestingly, Arkin (2017) conceptualized a single synthetic Pseudomonas by
using two strains of a diverse clade, i.e. P. stutzeri PDA—for perchlorate reduction
and P. stutzeri (strain A1501)—capable of nitrogen fixation. In manned Mars
missions, this synthetic strain will potentiate soil-based agriculture (by plants or
microbes) on Mars. The advantages of this architecture include low initialization
collection of microbial cells, on-demand cell growth with in situ resources, perchlorate wash off to cleanse soil and the exclusion of toxic wastewater.
Another very important sector of agriculture is to develop integrated pest management wherein SynBio-enhanced engineering can be utilized to develop crop
resistance against many evolving pathogens (Pixley et al. 2019). Park et al. (2015)
used SynBio technology to develop abscisic acid (ABA) receptors, engineered to be
turned on by mandipropamid instead of ABA. When sprayed with mandipropamid,
reprogrammed plants successfully survived drought stress by activating the ABA
pathway, which led to the closing up of the stomata to avert water loss. Ostrov et al.
(2016) removed seven codons from the E. coli genome by more than 62,000
mutations to totally recode the E. coli genome for virus resistance. Bennett (2017)
suggested that designing genetically engineered agricultural pests like fruit flies and
bollworm, can substantially drop the application rate of broad-spectrum insecticide.
One of the approaches in the direction can be to insert a self-limiting gene to combat
the pest. Offsprings of pest can inherit the gene in the wild, and die before adulthood
stage, subsequently declining the wild populations. Later, the same self-limiting
gene can be turned off with an antidote to facilitate further construction of the
engineered pests. Since plastid is the target of multiple disease-causing viruses in
plants, a futuristic and transformative approach for broad pest resistance, is the
production and installation of a synthetic chloroplast genome, a synplastome (Piatek
et al. 2018). If replacement of plastome with synplastome becomes successful, it
could facilitate extensive metabolic engineering to recode the genome to endow
broad resistance against all plastid-targeted viruses, for example, against bacteriophage infectivity while utilising bacteria in bioreactors and laboratory cultures.
Recoded genomes make the codons of attacking viruses untranslatable within host,
for example, if a viral stop codon is removed from or recoded to a different stop
codon, the virus cannot transmit a disease to the host (Ma and Isaacs 2016).
450
P. Singla
Castrillo et al. (2017) found that A. thaliana mutants with an altered Phosphate Stress
Response (PSR) assembled different root microbiota than wild-type plants. The
synthetic community activated PSR and repressed expression of plant immunity
genes under phosphate-limiting conditions by enhancing the activity of the master
transcriptional regulator of the PSR, i.e. PHR1 (Castrillo et al. 2017). Niu et al.
(2017) studied seven-species synthetic community inoculating maize roots and by
eliminating bacterial species one at a time, they concluded that Enterobacter species
is the keystone for community assembly. While in the absence of E. cloacae, the
unlimited abundance of Curtobacterium pusillum increased over other species,
whereas a small synthetic community was superior at resistance against late blight
disease caused by Fusarium verticillioides.
Interestingly, Arkin (2017) conceptualized a single synthetic Pseudomonas by
using two strains of a diverse clade, i.e. P. stutzeri PDA—for perchlorate reduction
and P. stutzeri (strain A1501)—capable of nitrogen fixation. In manned Mars
missions, this synthetic strain will potentiate soil-based agriculture (by plants or
microbes) on Mars. The advantages of this architecture include low initialization
collection of microbial cells, on-demand cell growth with in situ resources, perchlorate wash off to cleanse soil and the exclusion of toxic wastewater.
Another very important sector of agriculture is to develop integrated pest management wherein SynBio-enhanced engineering can be utilized to develop crop
resistance against many evolving pathogens (Pixley et al. 2019). Park et al. (2015)
used SynBio technology to develop abscisic acid (ABA) receptors, engineered to be
turned on by mandipropamid instead of ABA. When sprayed with mandipropamid,
reprogrammed plants successfully survived drought stress by activating the ABA
pathway, which led to the closing up of the stomata to avert water loss. Ostrov et al.
(2016) removed seven codons from the E. coli genome by more than 62,000
mutations to totally recode the E. coli genome for virus resistance. Bennett (2017)
suggested that designing genetically engineered agricultural pests like fruit flies and
bollworm, can substantially drop the application rate of broad-spectrum insecticide.
One of the approaches in the direction can be to insert a self-limiting gene to combat
the pest. Offsprings of pest can inherit the gene in the wild, and die before adulthood
stage, subsequently declining the wild populations. Later, the same self-limiting
gene can be turned off with an antidote to facilitate further construction of the
engineered pests. Since plastid is the target of multiple disease-causing viruses in
plants, a futuristic and transformative approach for broad pest resistance, is the
production and installation of a synthetic chloroplast genome, a synplastome (Piatek
et al. 2018). If replacement of plastome with synplastome becomes successful, it
could facilitate extensive metabolic engineering to recode the genome to endow
broad resistance against all plastid-targeted viruses, for example, against bacteriophage infectivity while utilising bacteria in bioreactors and laboratory cultures.
Recoded genomes make the codons of attacking viruses untranslatable within host,
for example, if a viral stop codon is removed from or recoded to a different stop
codon, the virus cannot transmit a disease to the host (Ma and Isaacs 2016).
450
P. Singla