Lysin motif (LysM)-containing proteins are important pattern recognition receptors (PRRs) in plants, which function in the perception of microbe-associated molecular patterns (MAMPs) and in the defense against pathogenic attack. To date, the LysM genes have not been systematically analyzed in cotton or effectively utilized for disease resistance. Here, we identified 29, 30, 60, and 56 LysM genes in the four sequenced cotton species, diploid Gossypium raimondii, diploid G. arboreum, tetraploid G. hirsutum acc. TM-1, and G. barbadense acc. 3–79, respectively. These LysM genes were classified into four groups with different structural characteristics and a variety of expression patterns in different organs and tissues when induced by chitin or Verticillium dahliae. We further characterized three genes, Lyp1, Lyk7 and LysMe3, which showed significant increase in expression in response to chitin signals, V. dahliae challenge and several stress-related signaling compounds. Lyp1, Lyk7 and LysMe3 proteins were localized to the plasma membrane, and silencing of their expression in cotton drastically impaired salicylic acid, jasmonic acid, and reactive oxygen species generation, impaired defense gene activation, and compromised resistance to V. dahliae. Our results indicate that Lyp1, Lyk7, and LysMe3 are important PRRs that function in the recognition of chitin signals to activate the downstream defense processes and induce cotton defense mechanisms against V. dahliae.

Aluminum (Al) is the major factor limiting plant growth on acidic soils. Blueberry (Vaccinum spp.) is an acidophilic plant. Highbush blueberry and rabbiteye blueberry are the main commercially cultivated species, while the response of which to Al is still unclear. Therefore, hydroponic experiments were conducted to determine the effect of Al (0 and 100 μmol L−1) on the growth and nutrient uptake of highbush blueberry ‘Brigitta’ and rabbiteye blueberry ‘Brightwell’. The results showed that root biomass, root length per fresh weight, root activity and foliar nitrogen (N) concentration of ‘Brigitta’ were significantly decreased by Al, while root lipid peroxidation was increased by Al. In contrast, the biomass and root activity of ‘Brightwell’ were not affected by Al treatment, root lipid peroxidation was significantly decreased, root length and surface area per fresh weight were increased compared with the control, which was benefic for nutrients absorption. In fact, foliar N concentration of ‘Brightwell’ was increased in Al treatments. However, fewer Al was accumulated in leaves of ‘Brightwell’ compared to ‘Brigitta’. Therefore, it could be concluded that growth and nutrients uptake of ‘Brightwell’ was not negative affected by Al, which meant ‘Brightwell’ was resistant to Al, compared to ‘Brigitta’.

Corolla abscission is an important agronomic trait that affects fruit quality and disease susceptibility in blueberry. However, the underlying molecular mechanisms remain poorly understood. This study aimed to investigate the molecular and physiological factors associated with corolla abscission by comparing two blueberry cultivars with contrasting corolla abscission characteristics: the caducous 'Magica' ('F6') and the persistent 'Eureka-Sunrise' ('L25'). Cytological analysis revealed distinct structural differences in the abscission zone (AZ) between the two cultivars. In 'F6', cell separation occurred after full bloom, whereas AZ cells in 'L25' remained intact and gradually resembled adjacent tissues. To explore the molecular basis of these differences, transcriptome analysis was performed at three developmental stages. Differential expression and enrichment analyses indicated that genes related to plant hormone signaling, cell wall organization, and oxidative stress response were consistently involved. Weighted gene co-expression network analysis further identified modules associated with cultivar-specific traits, with genes related to ethylene and abscisic acid pathways showing higher expression in 'F6', while those associated with auxin metabolism and stress-related processes were more active in 'L25'. To validate these findings, the activities of cell wall-related enzymes were measured. Polygalacturonase activity increased at the stage corresponding to abscission initiation in 'F6', while remaining relatively low in 'L25'. In addition, cellulase activity was consistently higher in 'F6' than in 'L25'. These results indicate that corolla abscission in blueberry is associated with coordinated changes in hormone-related pathways and cell wall modification. Differences in the regulation of these processes between cultivars may contribute to variation in abscission behavior.

This study utilized mature fruits of red-fruited genotype ‘R’ of Rubus hirsutus Thunb and yellow-fruited form Rubus hirsutus Thunb. f. xanthocarpus (Nakai) M.Kim (‘Y’) as materials, employing HPLC, metabolomic, and transcriptomic techniques to describe the differences in amino acid metabolism, metabolite accumulation and gene expression between the mature fruits of the two genotypes of Rubus hirsutus, and analyze the metabolic characteristics between the yellow fruit variant and the wild red fruit. The results showed that the free amino acids of yellow-fruited ‘Y’ (1638.6 μg/g FW) were significantly higher than those of red-fruited ‘R’ (1331.8 μg/g FW), with glutamine showing the most significant difference. Metabolomics identified 232 differential metabolites: red fruits appeared dark red due to enrichment of anthocyanins, while yellow fruits exhibited bright yellow coloration dominated by chalcone glycosides and flavonols. Transcriptomic screening revealed 5052 differentially expressed genes, among which amino acid-related biosynthesis pathways showed the most significant differences. Specifically, genes encoding glutamine synthetase and those involved in branched-chain amino acid metabolism were highly expressed in ‘Y’ fruits, whereas genes associated with cysteine metabolism and aromatic amino acid metabolism were predominantly expressed in ‘R’ fruits. Collectively, these findings characterize the differences in amino acid metabolism, metabolites and transcripts between mature red-fruited and yellow-fruited Rubus hirsutus Thunb., and unravel the potential association between amino acid metabolism and fruit-color variation, providing a theoretical reference for subsequent research on the regulatory mechanisms governing fruit color and quality.