Phylogenetic Analysis of the Membrane Attack Complex/Perforin Domain-Containing Proteins in Gossypium and the Role of GhMACPF26 in Cotton Under Cold Stress

Functional divergence of CAD-like family genes in Saccharum complex under biotic and abiotic stress

KEY MESSAGE

A total of 54 genes of membrane attack complex/perforin (MACPF) superfamily were identified in Saccharum complex and function divergence among SsaCAD-like genes were present in plant against stressors. The membrane attack complex/perforin (MACPF) superfamily belongs to pore-forming proteins involving in innate and adaptive immunity in eukaryotes. The constitutively activated cell death (CAD) proteins contained the MACPF domain participate in plant defense responses under adverse conditions. However, the characteristics and functions of CAD-like genes in sugarcane are still poorly understood. In this study, 54 CAD-like genes were identified in three genomes from Saccharum complex including two clones (Np-X and AP85-441) of Saccharum spontaneum and a clone (Yunnan2009-3) of Erianthus rufipilus. All CAD-like genes were categorized into five phylogenetic groups (I-V). Various cis-acting elements related to stress responses, such as phytohormone response elements, were found in promoter regions. Transcriptome and RT-qPCR analysis demonstrated these genes possessing diverse expression profiles. The SsaCAD1-like1 gene was upregulated in sugarcane cultivars after cold treatment and infection by Xanthomonas albilineans (Xa) causing leaf scald. Meanwhile, this gene was downregulated under drought and ABA treatments but was upregulated and then downregulated across time-points of SA treatment. The SsaCAD4-like1 gene was downregulated under five abiotic stressors. Expression levels of two alleles (SsaCAD2-like1/2) were significantly decreased under all abiotic stressors except for salinity treatment. Similar expression patterns of three alleles (SsaCAD3-like1/2/4) were found under abiotic stress. The SsaCAD1-like1 exhibited a negative role but SsaCAD3-like2/4 acted as positive roles in transgenic Arabidopsis lines against bacterial pathogen infection. Our results provide novel gene resources for developing disease-resistant cultivars in sugarcane.

A cysteine-rich transmembrane module peptide GhCYSTM9 is involved in cold stress response

BACKGROUND

Cysteine-rich transmembrane module (CYSTM) peptides, which are widely distributed and highly conserved in eukaryotes, are largely involved in stress response and defence. However, the role of cotton CYSTM genes in the stress response has not been functionally characterized.

RESULTS

In this study, we identified GhCYSTM9 as a cold stress-responsive CYSTM member from upland cotton. Compared with that in control cotton plants, GhCYSTM9 silencing in cotton resulted in reduced tolerance under cold stress, accompanied by higher MDA contents and lower proline contents and SOD activities in leaves. Overexpressing GhCYTMS9 in Arabidopsis significantly increased the seed germination rates and root elongation at the germination stage. Compared with wild-type seedlings, GhCYSTM9-overexpressing seedlings presented lower MDA contents and greater proline contents in leaves under cold stress. Transcriptome analysis of transgenic Arabidopsis revealed that GhCYSTM9 may contribute to the cold response by regulating oxidative stress-related genes to mediate ROS levels. Yeast two-hybrid and bimolecular fluorescence complementation assays confirmed that GhCYSTM9 interacted with the light-harvesting chlorophyll a/b-binding protein GhLHBC2A1.

CONCLUSIONS

Overall, our results revealed a positive role of GhCYSTM9 in cold stress defence and suggested candidate genes for the genetic breeding of cold defence.

Genome-Wide Analysis of the Membrane Attack Complex and Perforin Genes and Their Expression Pattern under Stress in the Solanaceae

The Membrane Attack Complex and Perforin (MACPF) proteins play a crucial role in plant development and adaptation to environmental stresses. Heretofore, few MACPF genes have been functionally identified, leaving gaps in our understanding of MACPF genes in other plants, particularly in the Solanaceae family, which includes economically and culturally significant species, such as tomato, potato, and pepper. In this study, we have identified 26 MACPF genes in three Solanaceae species and in the water lily, which serves as the base group for angiosperms. Phylogenetic analysis indicates that angiosperm MACPF genes could be categorized into three distinct groups, with another moss and spikemoss lineage-specific group, which is further supported by the examination of gene structures and domain or motif organizations. Through inter-genome collinearity analysis, it is determined that there are 12 orthologous SolMACPF gene pairs. The expansion of SolMACPF genes is primarily attributed to dispersed duplications, with purifying selection identified as the principal driving force in their evolutionary process, as indicated by the ω values. Furthermore, the analysis of expression patterns revealed that Solanaceae genes are preferentially expressed in reproductive tissues and regulated by various environmental stimuli, particularly induced by submergence. Taken together, these findings offer valuable insights into and a fresh perspective on the evolution and function of SolMACPF genes, thereby establishing a foundation for further investigations into their phenotypic and functional characteristics.

Overexpression of the Arabidopsis MACPF Protein AtMACP2 Promotes Pathogen Resistance by Activating SA Signaling

Immune response in plants is tightly regulated by the coordination of the cell surface and intracellular receptors. In animals, the membrane attack complex/perforin-like (MACPF) protein superfamily creates oligomeric pore structures on the cell surface during pathogen infection. However, the function and molecular mechanism of MACPF proteins in plant pathogen responses remain largely unclear. In this study, we identified an Arabidopsis MACP2 and investigated the responsiveness of this protein during both bacterial and fungal pathogens. We suggest that MACP2 induces programmed cell death, bacterial pathogen resistance, and necrotrophic fungal pathogen sensitivity by activating the biosynthesis of tryptophan-derived indole glucosinolates and the salicylic acid signaling pathway dependent on the activity of enhanced disease susceptibility 1 (EDS1). Moreover, the response of MACP2 mRNA isoforms upon pathogen attack is differentially regulated by a posttranscriptional mechanism: alternative splicing. In comparison to previously reported MACPFs in Arabidopsis, MACP2 shares a redundant but nonoverlapping role in plant immunity. Thus, our findings provide novel insights and genetic tools for the MACPF family in maintaining SA accumulation in response to pathogens in Arabidopsis.