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Abstract [Objective] Pepper is the largest vegetable crop planted in China. With the land salinization becoming more and more serious, it is urgent to accelerate the functional study of key genes related to pepper salt tolerance. It is of great significance to strengthen the study of mechanisms underlying salt tolerance in peper to promote sustainable development of the pepper industry. [Methods] In the early stage of research, CaNAC36, a NAC transcription factor family gene related to salt stress response in peppers, was discovered. Based on this, the full-length gDNA and cDNA sequences of CaNAC36 were cloned using salttolerant pepper accession PI201224 and salt-sensitive pepper accession PI438643. The expression of CaNAC36 and its interacting genes in different tissues under salt stress was quantitatively analyzed by fluorescence, and the potential relationship between CaNAC36 and its interacting genes was further explored by bioinformatics analysis. [Results] The gDNA and cDNA sequence homology of CaNAC36 in salt-tolerant and salt-sensitive materials were 99.86% and 100%, respectively. CaNAC36 showed an up-expression in roots and stems in the salt-tolerant pepper, and a down-expression in roots and leaves in the salt-sensitive peper. Throgh analyzing the annotation information of 48 genes that may interact with CaNAC36, it was found that 14 genes were belonging to transmembrane proteins, transporter proteins, water porins, chloride channel proteins, detoxifying proteins, and other genes, which may have functional interaction with CaNAC36. Further analysis revealed that PI201224 and PI438643 exhibited significant differences in the expression of five related genes, inclding Capana08g002748, Capana00g004514, Capana09g000275, Capana07g001450, Capana02g001031, at different time points and tissues under salt stress. Meanwhile, the promoter region of CaNAC36 and five associated genes was found to contain a large number of stressrelated cis-acting elements. [Conclusion] CaNAC36 was an important regulatory gene in pepper in response to salt stress, and might interact with other genes to improve salt tolerance.

The Cucumber mosaic virus (CMV) presents a significant threat to pepper cultivation worldwide, leading to substantial yield losses. We conducted a transcriptional comparative study between CMV-resistant (PBC688) and -susceptible (G29) pepper accessions to understand the mechanisms of CMV resistance. PBC688 effectively suppressed CMV proliferation and spread, while G29 exhibited higher viral accumulation. A transcriptome analysis revealed substantial differences in gene expressions between the two genotypes, particularly in pathways related to plant–pathogen interactions, MAP kinase, ribosomes, and photosynthesis. In G29, the resistance to CMV involved key genes associated with calcium-binding proteins, pathogenesis-related proteins, and disease resistance. However, in PBC688, the crucial genes contributing to CMV resistance were ribosomal and chlorophyll a–b binding proteins. Hormone signal transduction pathways, such as ethylene (ET) and abscisic acid (ABA), displayed distinct expression patterns, suggesting that CMV resistance in peppers is associated with ET and ABA. These findings deepen our understanding of CMV resistance in peppers, facilitating future research and variety improvement. [ABSTRACT FROM AUTHOR]

Seed-consumption watermelon tend to have larger-sized seeds, while flesh-consumed watermelon often require relatively smaller seed. Therefore, the seed size of watermelon has received extensive attention from consumers and breeders. However, the study on the natural variation and genetic mechanism of watermelon seed size is not clear enough. In the present study, 100 seed weight, seed hilum length, seed length, seed width, and seed thickness in 197 watermelon accessions were examined. Furthermore, association analysis was conducted between seed size traits and high-quality SNP data. The results revealed that there was a strong correlation between the five seed traits. And seed enlargement was an important feature during watermelon seed size domestication. Meanwhile, the seed consumption biological species C. mucosospermu and C. lanatus edible seed watermelon had a significantly bigger seed size than other species's. Eleven non-repeating significant SNPs above the threshold line were obtained by GWAS analysis. Four of them on chromosome 5 were considered to be closely associated with seed size traits, i.e. S5: 32250307, S5: 32250454, S5: 32256177, S5: 32260870, which could be used as potential molecular markers for the breeding of watermelon cultivars with target seed size. In addition, combined with gene annotation information and previous reports, five genes near the four significant SNPs may regulate seed size. And qRT-PCR analysis showed that two genes Cla97C05G104360 and Cla97C05G104380, which may be involved in abscisic acid metabolism, may play an important role in regulating the seed size of watermelon. Our findings provide molecular insights into natural variation in watermelon seed size, and gives valuable information of molecular marker-assisted breeding., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved.)