Background: Leaf mold disease caused by Cladosporium fulvum is a serious threat affecting the global production of tomato. Cf genes are associated with leaf mold resistance, including Cf-16, which confers effective resistance to leaf mold in tomato. However, the molecular mechanism of the Cf-16-mediated resistance response is largely unknown. Results: We performed a comparative transcriptome analysis of C. fulvum-resistant (cv. Ontario7816) and C. fulvum-susceptible (cv. Moneymaker) tomato cultivars to identify differentially expressed genes (DEGs) at 4 and 8 days post inoculation (dpi) with C. fulvum. In total, 1588 and 939 more DEGs were found in Cf-16 tomato than in Moneymaker at 4 and 8 dpi, respectively. Additionally, 1350 DEGs were shared between the 4- and 8-dpi Cf-16 groups, suggesting the existence of common core DEGs in response to C. fulvum infection. The up-regulated DEGs in Cf-16 tomato were primarily associated with defense processes and phytohormone signaling, including salicylic acid (SA) and jasmonic acid (JA). Moreover, SA and JA levels were significantly increased in Cf-16 tomato at the early stages of C. fulvum infection. Contrary to the previous study, the number of up-regulated genes in Cf-16 compared to Cf-10 and Cf-12 tomatoes was significantly higher at the early stages of C. fulvum infection. Conclusion: Our results provide new insight into the Cf-mediated mechanism of resistance to C. fulvum, especially the unique characteristics of Cf-16 tomato in response to this fungus.

Background: The Mi-1 gene was the first identified and cloned gene that provides resistance to root-knot nematodes (RKNs) in cultivated tomato. However, owing to its temperature sensitivity, this gene does not meet the need for breeding disease-resistant plants that grow under high temperature. In this study, Mi-3 was isolated from the wild species PI 126443 (LA3858) and was shown to display heat-stable resistance to RKNs. However, the mechanism that regulates this resistance remains unknown. Results: In this study, 4760, 1024 and 137 differentially expressed genes (DEGs) were enriched on the basis of pairwise comparisons (34 °C vs. 25 °C) at 0 (before inoculation), 3 and 6 days post-inoculation (dpi), respectively. A total of 7035 DEGs were identified from line LA3858 in the respective groups under the different soil temperature treatments. At 3 dpi, most DEGs were enriched in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to plant biotic responses, such as “plant-pathogen interaction” and “plant hormone signal transduction”. Significantly enriched DEGs were found to encode key proteins such as R proteins and heat-shock proteins (HSPs). Moreover, other DEGs were found to participate in Ca²⁺ signal transduction; the production of ROS; DEGs encoding transcription factors (TFs) from the bHLH, TGA, ERF, heat-shock transcription factor (HSF) and WRKY families were highly expressed, which contribute to be involved into the formation of phytohormones, such as salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), the expression of most was upregulated at 3 dpi at the 25 °C soil temperature compared with the 34 °C soil temperature. Conclusion: Taken together, the results of our study revealed reliable candidate genes from wild materials LA3858, that are related to Mi-3-mediate resistance to Meloidogyne incognita. A large number of vital pathways and DEGs were expressed specifically in accession LA3858 grown at 34 °C and 25 °C soil temperatures at 3 dpi. Upon infection by RKNs, pattern-recognition receptors (PRRs) specifically recognized conserved pathogen-associated molecular patterns (PAMPs) as a result of pathogen-triggered immunity (PTI), and the downstream defensive signal transduction pathway was likely activated through Ca²⁺ signal channels. The expression of various TFs was induced to synthesize phytohormones and activate R proteins related to resistance, resulting in the development of effector-triggered immunity (ETI). Last, a hypersensitive response in the roots occurred, which was probably induced by the accumulation of ROS.

Root-knot nematode (RKN) infections are among the most serious soil-borne diseases in the world, and tomato is a common host of RKNs. WRKY transcription factors are involved in complex, diverse biological processes in plants. In a previous study, a resistant variety, LA3858 (Mi-3/Mi-3), was treated at different soil temperatures before RNA-seq, and six differentially expressed genes (DEGs) encoding WRKY proteins were screened. In this study, cloning and sequencing were used to identify six target DEGs encoding SlWRKY1, SlWRKY13, SlWRKY30, SlWRKY41, SlWRKY46, and SlWRKY80. Conserved domain identification and phylogenetic tree analysis showed that SlWRKY1, SlWRKY13, and SlWRKY46 have similar functions and are mainly involved in plant growth and development and abiotic stress responses. SlWRKY30 and SlWRKY41 share high homology, while AtWRKY46 and AtWRKY70, which are highly homologous to SlWRKY80, play an important role in the disease resistance of A. thaliana. Considering these findings combined with the high level of SlWRKY80 expression observed in the roots and leaves of the resistant variety Motelle (Mi-1/Mi-1) and the continuous upregulation of SlWRKY80 expression in the roots after inoculation of Motelle with M. incognita, it is speculated that SlWRKY80 plays an important role in the Mi-1-mediated disease resistance pathway. Further study revealed that SlWRKY80 is a typical nuclear-localized protein, and a virus-induced gene silencing (VIGS) assay verified that SlWRKY80 is involved in tomato resistance to RKNs as a positive regulator. SA and JA signals play an important role in Mi-1-mediated resistance to RKNs. SlWRKY80 was able to respond rapidly to treatment with both plant hormones, which indicated that SlWRKY80 might be involved in disease resistance regulation through various immune pathways.

WRKY transcription factors (TFs) can participate in plant biological stress responses and play important roles. SlWRKY80 was found to be differentially expressed in the Mi-1- and Mi-3-resistant tomato lines by RNA-seq and may serve as a key node for disease resistance regulation. This study used RNAi to determine whether SlWRKY80 silencing could influence the sensitivity of ‘M82’ (mi-1/mi-1)-susceptible lines to M. incognita. Further overexpression of this gene revealed a significant increase in tomato disease resistance, ranging from highly susceptible to susceptible, combined with the identification of growth (plant height, stem diameter, and leaf area) and physiological (soluble sugars and proteins; root activity) indicators, clarifying the role of SlWRKY80 as a positive regulatory factor in tomato defense against M. incognita. Based on this phenomenon, a preliminary exploration of its metabolic signals revealed that SlWRKY80 stimulates different degrees of signaling, such as salicylic acid (SA), jasmonic acid (JA), and ethylene (ETH), and may synergistically regulate reactive oxygen species (ROS) accumulation and scavenging enzyme activity, hindering the formation of feeding sites and ultimately leading to the reduction of root gall growth. To our knowledge, SlWRKY80 has an extremely high utilization value for improving tomato resistance to root-knot nematodes and breeding.

Background Potato, a vegetable crop grown worldwide, has many uses, a short growth period, a large market demand and high economic benefits. The loss of potato seediness due to traditional potato growing methods is becoming increasingly evident, and research on new ways of growing potatoes is particularly important. Bud planting technology has the advantages of more reproduction, faster growth, and simplified maintenance of crop plants under cultivation. Methods In this study, a bud planting method was adopted for the cultivation of potato seedlings. Specifically, we assessed different types of treatments for the production of high-quality buds and seedlings of potato. A total of four disease-free potato varieties (Fujin, Youjin, Zhongshu 4, and Feiwuruita) were selected, potato buds with three different lengths (3 cm, 5 cm, and 7 cm) were considered the T₁, T₂, and T₃ treatments, and terminal buds, middle buds, and tail buds were used as the T₄, T₅, and T₆ treatments. A nutrient pot experiment was performed following a randomized complete block design (RCBD) with three replicates and a natural control (CK) treatment. Cultivation was performed with the common horticultural practices of weeding and hoeing applied as needed. The photosynthetic indices, physiological indices, growth indices and quality of potato seedlings and quality of potato buds were measured at two-week intervals, and yield indices were measured when the final crop was harvested 14 weeks after planting. Results and Conclusions Cultivation of seedlings from potato buds of different lengths increased the reproduction coefficient and reduced the number of seed potatoes needed for cultivation. All morphological, physiological, and yield indices showed positive trends. A potato bud length of 7 cm was optimal for raising seedlings. Moreover, buds located at the terminal of the potato yielded seedlings with the best quality. In conclusion, we recommend that our proven bud planting technique be adopted at the commercial level, which could support good crop production with maximum yield.

Pectin is a structural polysaccharide and a major component of plant cell walls. Pectate lyases are a class of enzymes that degrade demethylated pectin by cleaving the α-1,4-glycosidic bond, and they play an important role in plant growth and development. Currently, little is known about the PL gene family members and their involvement in salt stress in potato. In this study, we utilized bioinformatics to identify members of the potato pectate lyase gene family and analyzed their gene and amino acid sequence characteristics. The results showed that a total of 27 members of the pectate lyase gene family were identified in potato. Phylogenetic tree analysis revealed that these genes were divided into eight groups. Analysis of their promoters indicated that several members’ promoter regions contained a significant number of hormone and stress response elements. Further, we found that several members responded positively to salt treatment under single salt and mixed salt stress. Since StPL18 exhibited a consistent expression pattern under both single and mixed salt stress conditions, its subcellular localization was determined. The results indicated that StPL18 is localized in the endoplasmic reticulum membrane. The results will establish a foundation for analyzing the functions of potato pectate lyase family members and their expression under salt stress.