Genome-Wide Identification of LOX Gene Family and Its Expression Analysis under Abiotic Stress in Potato (Solanum tuberosum L.).

The lipoxygenases (LOXs) are non-heme iron-containing dioxygenases that play an important role in plant growth and defense responses. There is scarce knowledge regarding the LOX gene family members and their involvement in biotic and abiotic stresses in potato. In this study, a total of 17 gene family members (StLOXs) in potato were identified and clustered into three subfamilies: 9-LOX type I, 13-LOX type I, and 13-LOX type II, with eleven, one, and five members in each subfamily based on phylogenetic analysis. By exploiting the RNA-seq data in the Potato Genome Sequencing Consortium (PGSC) database, the tissue-specific expressed and stress-responsive StLOX genes in double-monoploid (DM) potato were obtained. Furthermore, six candidate StLOX genes that might participate in drought and salt response were determined via qPCR analysis in tetraploid potato cultivars under NaCl and PEG treatment. Finally, the involvement in salt stress response of two StLOX genes, which were significantly up-regulated in both DM and tetraploid potato under NaCl and PEG treatment, was confirmed via heterologous expression in yeast under salt treatment. Our comprehensive analysis of the StLOX family provides a theoretical basis for the potential biological functions of StLOXs in the adaptation mechanisms of potato to stress conditions.

Comprehensive Characterization of the C3HC4 RING Finger Gene Family in Potato (Solanum tuberosum L.): Insights into Their Involvement in Anthocyanin Biosynthesis.

The C3HC4 RING finger gene (RING-HC) family is a zinc finger protein crucial to plant growth. However, there have been no studies on the RING-HC gene family in potato. In this study, 77 putative StRING-HCs were identified in the potato genome and grouped into three clusters based on phylogenetic relationships, the chromosome distribution, gene structure, conserved motif, gene duplication events, and synteny relationships, and cis-acting elements were systematically analyzed. By analyzing RNA-seq data of potato cultivars, the candidate StRING-HC genes that might participate in tissue development, abiotic stress, especially drought stress, and anthocyanin biosynthesis were further determined. Finally, a StRING-HC gene (Soltu.DM.09G017280 annotated as StRNF4-like), which was highly expressed in pigmented potato tubers was focused on. StRNF4-like localized in the nucleus, and Y2H assays showed that it could interact with the anthocyanin-regulating transcription factors (TFs) StbHLH1 of potato tubers, which is localized in the nucleus and membrane. Transient assays showed that StRNF4-like repressed anthocyanin accumulation in the leaves of Nicotiana tabacum and Nicotiana benthamiana by directly suppressing the activity of the dihydroflavonol reductase (DFR) promoter activated by StAN1 and StbHLH1. The results suggest that StRNF4-like might repress anthocyanin accumulation in potato tubers by interacting with StbHLH1. Our comprehensive analysis of the potato StRING-HCs family contributes valuable knowledge to the understanding of their functions in potato development, abiotic stress, hormone signaling, and anthocyanin biosynthesis.

Anthocyanin Profiles in Colored Potato Tubers at Different Altitudes by HPLC-MS Analysis with Optimized Ultrasound-Assisted Extraction.

The elevated anthocyanin content of colored potatoes produces numerous health benefits in humans. However, there is a paucity of studies exploring the influence of environmental factors on anthocyanin components in colored potatoes. In our work, the Box-Behnken design was adopted to optimize anthocyanin extraction from colored potato tubers with ultrasound assistance. The response surface model was stable and reliable (R2 = 0.9775), and under optimal extraction conditions, namely an ultrasonic power of 299 W, an extraction time of 10 min, and a solid-liquid ratio of 1:30 (g/mL), the yield reached 4.33 mg/g. Furthermore, the anthocyanins of colored potato tubers grown at different altitudes were determined by high-performance liquid chromatography-mass spectrometry with optimized ultrasound-assisted extraction, the results showed that anthocyanin levels were the highest at high altitudes, whereas anthocyanins were almost undetectable at mid-altitude. Moreover, the types of anthocyanin compounds present in colored potatoes varied at different altitudes. The red clones exhibited substantial accumulation of pelargonidin across all three altitudes. In contrast, the main anthocyanins found in purple clones were malvidin, petunidin, and cyanidin. We identified the anthocyanin components with a strong correlation to the environment, thereby establishing a fundamental basis for the breeding of potato clones with high anthocyanin content.