Summary: CRISPR/Cas systems provide bacteria and archaea with molecular immunity against invading phages and foreign plasmids. The class 2 type VI CRISPR/Cas effector Cas13a is an RNA‐targeting CRISPR effector that provides protection against RNA phages. Here we report the repurposing of CRISPR/Cas13a to protect potato plants from a eukaryotic virus, Potato virus Y (PVY). Transgenic potato lines expressing Cas13a/sgRNA (small guide RNA) constructs showed suppressed PVY accumulation and disease symptoms. The levels of viral resistance correlated with the expression levels of the Cas13a/sgRNA construct in the plants. Our data further demonstrate that appropriately designed sgRNAs can specifically interfere with multiple PVY strains, while having no effect on unrelated viruses such as PVA or Potato virus S. Our findings provide a novel and highly efficient strategy for engineering crops with resistances to viral diseases.

Cold-induced sweetening (CIS), the undesirable sugar accumulation in cold-stored potato (Solanum tuberosum L.) tubers, is a severe postharvest issue in the potato processing industry. Although the process of sucrose hydrolysis by vacuolar invertase during potato CIS is well understood, there is limited knowledge about the transportation of sucrose from the cytosol to the vacuole during postharvest cold storage. Here, we report that among the three potato tonoplast sugar transporters (TSTs), StTST1 exhibits the highest expression in tubers during postharvest cold storage. Subcellular localization analysis demonstrates that StTST1 is a tonoplast-localized protein. StTST1 knockdown decreases reducing sugar accumulation in tubers during low-temperature storage. Compared to wild-type, potato chips produced from StTST1-silenced tubers displayed significantly lower acrylamide levels and lighter color after cold storage. Transcriptome analysis manifests that suppression of StTST1 promotes starch synthesis and inhibits starch degradation in cold-stored tubers. We further establish that the increased sucrose content in the StTST1-silenced tubers might cause a decrease in the ABA content, thereby inhibiting the ABA-signaling pathway. We demonstrate that the down-regulation of β-amylase StBAM1 in StTST1-silenced tubers might be directly controlled by ABA-responsive element-binding proteins (AREBs). Altogether, we have shown that StTST1 plays a critical role in sugar accumulation and starch metabolism regulation during postharvest cold storage. Thus, our findings provide a new strategy to improve the frying quality of cold-stored tubers and reduce the acrylamide content in potato chips.

Abscisic acid (ABA) is critical in drought tolerance and plant growth. Group A protein type 2C phosphatases (PP2Cs) are negative regulators of ABA signaling and plant adaptation to stress. However, our knowledge about the functions of potato group A PP2Cs is limited. Here, we report that potato group A PP2C StHAB1 is broadly expressed in potato plants and strongly induced by ABA and drought. Suppression of StHAB1 enhanced potato ABA sensitivity and drought tolerance, whereas overexpression of the dominant mutant StHAB1^G276D compromised ABA sensitivity and drought tolerance. StHAB1 interacts with almost all ABA receptors and the Snf1-Related Kinase OST1. Suppressing StHAB1 and overexpressing StHAB1^G276D alter potato growth morphology; notably, overexpression of StHAB1^G276D causes excessive shoot branching in potato. RNA-seq analyses identified that auxin efflux carrier genes, StPIN3, StPIN5, and StPIN8, were upregulated in StHAB1^G276D-overexpressed axillary buds. Correspondingly, auxin concentration was reduced in StHAB1^G276D-overexpressed axillary buds, consistent with the repressing role of auxin in lateral branch outgrowth. The expression of BRANCHED1s (StBRC1a and StBRC1b) does not change in StHAB1^G276D-overexpressed axillary buds, suggesting that overexpression of StHAB1^G276D caused axillary bud outgrowth is not due to regulating BRC1 expression. Our findings demonstrate that StHAB1 is vital in potato drought tolerance and shoot branching.

The integration of molecular markers in the realm of potato genetics has opened new avenues for accelerating genotype analysis and developing improved varieties. Many markers linked to important features have been discovered so far and are consistently distributed across 12 chromosomes (× = 12) of potato. Notably, the genes allied to disease resistance stand out as significant and prevalent. Molecular markers associated with these genes have revolutionized selection processes, making them faster and more effective. Besides, advanced technologies such as kompetitive allele-specific PCR, high-resolution melting assay, SNP-array, genotyping by sequencing, and genome-wide association study, are emphasizing the use of those molecular markers with greater accuracy to detect R genes aligning with the phenotypes. This review discusses advances in potato breeding for resistance against common stresses, focusing on progress made through molecular marker-assisted selection.