Molecular Plant Breeding 2024, Vol.15, No.2, 63-69 http://genbreedpublisher.com/index.php/mpb 66 will be bound to bring great difficulties to selection in hybrid breeding, and also cause instability of traits of cassava which is engineered but vegetatively propagated. In some cases of improving cassava starch yield and properties by key starch synthesis gene, in addition to expected changes, additional unexpected traits or characteristic changes have also emerged as mentioned above, indicating that precision and targeting are still problematic. Even though engineered cassava that has been obtained, it is unclear whether the traits have genetic stability in propagation and production through stem cutting in the field. Additionally, there seem to be very few cases of cassava germplasm selection/screening with the help of the currently obtained QTLs. The core functional genes in the QTLs have not been identified yet, expression regulation mechanisms of which are still unknown. 7 Opportunities and Future Prospects (1) With regard to cassava materials for engineering cassava and conventional crossing breeding, it is much more important to develop homozygous, heterozygous, and possibly chimeric lines containing a spectrum of different starch contents and properties. In this regard, Bull and his colleagues have done an excellent job through targeted mutagenesis of GBSSor PROTEIN TARGETING TO STARCH1 genes (Bull et al., 2018). (2) As for enzymes, it is very necessary to conduct identifications of isoforms, active enzyme species and their activity profiles with tissues and growth stages due to the lack of holographic information in these aspects. (3) Developing new starch-related QTLs, and integrating QTLs and GWAS data to address expression regulation of the key genes in QTLs and further understand the functional role of both genotype and phenotype-associated variations in cassava. These include splicing QTL which is a genetic variant regulating alternative splicing as one of the major causal mechanisms in GWAS loci (Yamaguchi et al., 2022), and expression quantitative trait loci which are namely the discovery of genetic variants that explain variation in gene expression levels (Nica and Dermitzakis, 2013; Joehanes et al., 2017). (4) Utilizing informative and accurate access maps for engineering cassava. A remarkable research is that the genome-based reconstruction of starch biosynthesis pathway has been established in the form of an informative map with all important information of the pathway to investigate the dynamic regulation of starch biosynthesis in cassava roots, which is available at the Systems Biology and Bioinformatics Research Group’s website (http://sbi.pdti.kmutt.ac.th/?page_id=33) (Saithong et al., 2013). Acknowledgments I would like to express my gratitude to the two anonymous peer reviewers for their comments and suggestions on the manuscript. Conflict of Interest Disclosure The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. References Alves A.A.C., 2002, Cassava botany and physiology, In: Hillocks R.J., Thresh J.M., Bellotti A.C. (eds.), Cassava: biology, production and utilization, CAB Publishing, Wallingford, pp.67-89. https://doi.org/10.1079/9780851995243.0067 Bahaji A., Li J., Sánchez-López Á.M., Baroja-Fernández E., Muñoz F.J., Ovecka M., Almagro G., Montero M., Ezquer I., Etxeberria E., and Pozueta-Romero J., 2014, Starch biosynthesis, its regulation and biotechnological approaches to improve crop yields, Biotechnol Adv., 32(1): 87-106. https://doi.org/10.1016/j.biotechadv.2013.06.006 PMid:23827783 Bull S.E., Seung D., Chanez C., Mehta D., Kuon J.E., Truernit E., Hochmuth A., Zurkirchen I., Zeeman S.C., Gruissem W., and Vanderschuren H., 2018, Accelerated ex situ breeding of GBSS- and PTST1-edited cassava for modified starch, Sci. Adv., 4(9): eaat6086. https://doi.org/10.1126/sciadv.aat6086
RkJQdWJsaXNoZXIy MjQ4ODYzMg==