Recent advances and challenges in potato improvement using CRISPR/Cas genome editing

New Frontiers in Potato Breeding: Tinkering with Reproductive Genes and Apomixis

Potato is the most important non-cereal crop worldwide, and, yet, genetic gains in potato have been traditionally delayed by the crop's biology, mostly the genetic heterozygosity of autotetraploid cultivars and the intricacies of the reproductive system. Novel site-directed genetic modification techniques provide opportunities for designing climate-smart cultivars, but they also pose new possibilities (and challenges) for breeding potato. As potato species show a remarkable reproductive diversity, and their ovules have a propensity to develop apomixis-like phenotypes, tinkering with reproductive genes in potato is opening new frontiers in potato breeding. Developing diploid varieties instead of tetraploid ones has been proposed as an alternative way to fill the gap in genetic gain, that is being achieved by using gene-edited self-compatible genotypes and inbred lines to exploit hybrid seed technology. In a similar way, modulating the formation of unreduced gametes and synthesizing apomixis in diploid or tetraploid potatoes may help to reinforce the transition to a diploid hybrid crop or enhance introgression schemes and fix highly heterozygous genotypes in tetraploid varieties. In any case, the induction of apomixis-like phenotypes will shorten the time and costs of developing new varieties by allowing the multi-generational propagation through true seeds. In this review, we summarize the current knowledge on potato reproductive phenotypes and underlying genes, discuss the advantages and disadvantages of using potato's natural variability to modulate reproductive steps during seed formation, and consider strategies to synthesize apomixis. However, before we can fully modulate the reproductive phenotypes, we need to understand the genetic basis of such diversity. Finally, we visualize an active, central role for genebanks in this endeavor by phenotyping properly genotyped genebank accessions and new introductions to provide scientists and breeders with reliable data and resources for developing innovations to exploit market opportunities.

Role of microRNAs and their putative mechanism in regulating potato (Solanum tuberosum L.) life cycle and response to various environmental stresses

The exponentially increasing population and the demand for food is inextricably linked. This has shifted global attention to improving crop plant traits to meet global food demands. Potato (Solanum tuberosum L.) is a major non-grain food crop that is grown all over the world. Currently, some of the major global potato research work focuses on the significance of microRNAs (miRNAs) in potato. miRNAs are a type of non-coding RNAs that regulate the gene expression of their target mRNA genes by cleavage and/or their translational inhibition. This suggests an essential role of miRNAs in a multitude of plant biological processes, including maintenance of genome integrity, plant growth, development and maturation, and initiation of responses to various stress conditions. Therefore, engineering miRNAs to generate stress-resistant varieties of potato may result in high yield and improved nutritional qualities. In this review, we discuss the potato miRNAs specifically known to play an essential role in the various stages of the potato life cycle, conferring stress-resistant characteristics, and modifying gene expression. This review highlights the significance of the miRNA machinery in plants, especially potato, encouraging further research into engineering miRNAs to boost crop yields and tolerance towards stress.

The applications of CRISPR/Cas-mediated microRNA and lncRNA editing in plant biology: shaping the future of plant non-coding RNA research

MAIN CONCLUSION

CRISPR/Cas technology has greatly facilitated plant non-coding RNA (ncRNA) biology research, establishing itself as a promising tool for ncRNA functional characterization and ncRNA-mediated plant improvement. Throughout the last decade, the promising genome editing tool clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated proteins (Cas; CRISPR/Cas) has allowed unprecedented advances in the field of plant functional genomics and crop improvement. Even though CRISPR/Cas-mediated genome editing system has been widely used to elucidate the biological significance of a number of plant protein-coding genes, this technology has been barely applied in the functional analysis of those non-coding RNAs (ncRNAs) that modulate gene expression, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Nevertheless, compelling findings indicate that CRISPR/Cas-based ncRNA editing has remarkable potential for deciphering the biological roles of ncRNAs in plants, as well as for plant breeding. For instance, it has been demonstrated that CRISPR/Cas tool could overcome the challenges associated with other approaches employed in functional genomic studies (e.g., incomplete knockdown and off-target activity). Thus, in this review article, we discuss the current status and progress of CRISPR/Cas-mediated ncRNA editing in plant science in order to provide novel prospects for further assessment and validation of the biological activities of plant ncRNAs and to enhance the development of ncRNA-centered protocols for crop improvement.

Challenges for crop improvement

The genetic improvement of crops faces the significant challenge of feeding an ever-increasing population amidst a changing climate, and when governments are adopting a 'more with less' approach to reduce input use. Plant breeding has the potential to contribute to the United Nations Agenda 2030 by addressing various sustainable development goals (SDGs), with its most profound impact expected on SDG2 Zero Hunger. To expedite the time-consuming crossbreeding process, a genomic-led approach for predicting breeding values, targeted mutagenesis through gene editing, high-throughput phenomics for trait evaluation, enviromics for including characterization of the testing environments, machine learning for effective management of large datasets, and speed breeding techniques promoting early flowering and seed production are being incorporated into the plant breeding toolbox. These advancements are poised to enhance genetic gains through selection in the cultigen pools of various crops. Consequently, these knowledge-based breeding methods are pursued for trait introgression, population improvement, and cultivar development. This article uses the potato crop as an example to showcase the progress being made in both genomic-led approaches and gene editing for accelerating the delivery of genetic gains through the utilization of genetically enhanced elite germplasm. It also further underscores that access to technological advances in plant breeding may be influenced by regulations and intellectual property rights.

3Bs of CRISPR-Cas mediated genome editing in plants: exploring the basics, bioinformatics and biosafety landscape

The recent thrust in research has projected the type II clustered regularly interspaced short palindromic repeats and associated protein 9 (CRISPR-Cas9) system as an avant-garde plant genome editing tool. It facilitates the induction of site-specific double-stranded DNA cleavage by the RNA-guided DNA endonuclease (RGEN), Cas9. Elimination, addition, or alteration of sections in DNA sequence besides the creation of a knockout genotype (CRISPRko) is aided by the CRISPR-Cas9 system in its wild form (wtCas9). The inactivation of the nuclease domain generates a dead Cas9 (dCas9), which is capable of targeting genomic DNA without scissoring it. The dCas9 system can be engineered by fusing it with different effectors to facilitate transcriptional activation (CRISPRa) and transcriptional interference (CRISPRi). CRISPR-Cas thus holds tremendous prospects as a genome-manipulating stratagem for a wide gamut of crops. In this article, we present a brief on the fundamentals and the general workflow of the CRISPR-Cas system followed by an overview of the prospects of bioinformatics in propelling CRISPR-Cas research with a special thrust on the available databases and algorithms/web-accessible applications that have aided in increasing the usage and efficiency of editing. The article also provides an update on the current regulatory landscape in different countries on the CRISPR-Cas edited plants to emphasize the far-reaching impact of the genomic editing technology.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01397-3.