8. Future and perspectives
Understanding how plants adapt their root system under changing
environmental conditions to ensure the continued uptake of water and
nutrients is essential for future breeding programs. Due to the
increased occurrence of weather extremes, crops will need to be adapted
more quickly in the future. Previous classical methods, such as
cross-breeding and selection, are not sufficient for this purpose.
CRISPR/Cas technology has proven to be a tool that allows precisely
targeted modification of the target sequence. By refining the methods
(base editing, prime editing) or tissue-specific expression of the
double-strand break-inducing agents, the often pleiotropic effect of
different mutations can be circumvented. The examples shown in the table
can also be applied to other crops. For instance, it would be
interesting to see if the DRO1 gene studied in rice plays a role
in other cereals’ salt and drought stress tolerance. Since knockout of
the CKX genes in barley did not lead to the results obtained in
maize, tissue-specific expression of the molecular scissors could be
used as an alternative to circumvent adverse pleiotropic effects.
Furthermore, Cas fusion proteins show real potential for activating or
repressing the mentioned genes.
Molecular mechanisms of hormonal influence on root growth have relevance
for the plant’s abiotic and biotic interaction. This requires knowledge
of the metabolism and signalling pathways involved. Also, specificity of
molecular regulation exists among cereals, depending on their growth
habitat. Although some futures have been conserved during evolution,
there are variations between the dicot model plants to cereals.
Therefore, interest should also be given to more minor or non-cereal
plants.
Because targeting the hormone metabolism and signalling pathway has very
often adverse pleiotropic effects, one should consider focusing on the
downstream events specific to RSA regulation. For example, targeting the
root angle would have extreme advantages for the plant in periods of
temporary drought. At the same time, mechanical anchoring of the plant
would be improved, which could be advantageous during strong winds or
thunderstorms. It is also interesting to improve the nutrient uptake of
the root by soil microbes. By targeting secreted signals, the microbial
community surrounding the root can be influenced.
In summary, CRISPR/Cas technology with its multiple variants and fusion
possibilities allow for an incredible variety of modifications. In the
future, this will enable a more targeted and rapid transfer of primary
research results into current breeding programs.