Enzymatic browning is a major issue in potato processing, causing a decline in both nutritional value and quality. Although there are numerous studies on the mechanism of enzymatic browning of potato tubers, few relevant reports are available on the changes at the transcriptome level during enzymatic browning as well as on the differences in the browning process of potato tubers with differing degrees of enzymatic browning potential. To gain insights into the molecular mechanism of enzymatic browning after cutting, this study presents the transcriptional characterization of temporal molecular events during enzymatic browning of browning-resistant (BR) and browning-susceptible (BS) potato tubers. RNA-sequencing (RNA-seq) analysis detected 19,377 and 13,741 differentially expressed genes (DEGs) in BR and BS tubers, respectively, with similar function enrichment observed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Up-regulated DEGs were significantly enriched in the pathways related to phenol and lipid biosynthesis, while the down-regulated DEGs were significantly enriched in the pathways related to programmed cell death. Significant redox-related pathways occurred earlier in BS tubers compared to the BR tubers. Further analysis revealed that the BS tubers had a stronger phenolic synthesis ability compared to the BR tubers. However, the BR tubers showed a stronger free radical scavenging ability compared to the BS tubers. The results of our study provide insights into the temporal molecular events that occur during the enzymatic browning of potato tubers after cutting and the potential molecular mechanisms for different degrees of enzymatic browning.

As a non-pathogenic oomycete, Pythium oligandrum possesses unique advantages, particularly in the context of being a biological control agent. With the increasing awareness of consumer consciousness, people are paying more attention to the use of environmentally friendly strategies in plant disease prevention and control. Pythium oligandrum is a type of biocontrol oomycete that can be developed as a biological control agent, and it does not have adverse effects on humans in the prevention and control of plant diseases. Consequently, there is increasing scientific interest in the beneficial plant–microbe interactions mediated by P. oligandrum. Currently, the main points of focus regarding the beneficial role of P. oligandrum in plant interactions are as follows: (i) P. oligandrum can activate plant defense responses and cause plants to produce resistance, thus protecting them from disease attacks; (ii) it is a strong mycoparasite that can coil around various oomycetes and fungi, directly killing pathogenic microorganisms; (iii) in addition, it can also promote plant growth. In this paper, we will discuss the aforementioned three main features in detail.

Potato production is severely threatened by the oomycete Phytophthora infestans, the fungus Alternaria solani, and the bacterium Ralstonia solanacearum; however, strategies capable of simultaneously managing these three pathogen classes remain relatively scarce. In this study, we designed a series of signal peptide (SP)-fused recombinant constructs containing four functional modules with distinct antimicrobial and immune-inducing properties: GAFP1-2×FYVE, an oomycete-inhibiting antimicrobial protein; BbAFP1-ErBD, a fungal-suppressive protein fragment; the pathogen-associated molecular pattern (PAMP) csp22 derived from R. solanacearum, which elicits effective anti-bacterial immunity; and the microbe-associated molecular pattern (MAMP) PpEli2 identified from Pythium periplocum, which triggers broad-spectrum plant defense responses. Through systematic evaluation of six module order rearrangements, we identified SP-cBG as the optimal multi-domain combination. Further optimization via the introduction of a rigid alpha-helical linker (HL4) yielded SP-cBG-HL4, which tended to show superior resistance against all three pathogens, as reflected in smaller lesion diameters and decreased bacterial titers. qRT-PCR analyses revealed that SP-cBG-HL4 significantly upregulated PTI (CYP71D20, PTI5), SA (PR1, PR2), and JA/ET (PR3, PR4) defense marker genes. Collectively, these findings show that modular domain assembly combined with linker-mediated modular combinatorial optimization represents a powerful engineering strategy for achieving broad-spectrum disease resistance, offering a promising approach to simultaneously control oomycete, fungal, and bacterial pathogens of plants.