[Objective] By analyzing the major birch pollen allergen Betv1 gene family in D genomes of cotton and comparing the expression patterns of three diploid D-genome cotton varieties with different Verticillium wilt resistance levels, we aimed to provide a theoretical basis for further studies on the role of Betv1 genes in cotton resistant to Verticillium wilt. [Method] The Betv1 genes were identified, and a bioinformatics analysis of the physicochemical properties of their encoded sequences in Gossypium raimondii (D5) was performed. The transcriptome sequencing and quantitative real time-PCR of G. raimondii (D5), Gossypium trilobum (D8) and Gossypium thurberi (D1) were used to verify the expression patterns of Bet v 1 genes under Verticillium dahlia infection stress. Betv1 genes were silenced by virus-induced gene silencing in G. hirsutum to identify their functions. [Result] The D genome of cotton contains 59 members, 58 of which have introns and are distributed on eight chromosomes, and most encode hydrophilic proteins that localize to the cytoplasm. The expression levels of Betv1 genes in three wild cotton species having D genomes after being inoculated with V. dahliae were consistent with their disease resistance levels. The genes were separated into three groups based on their expression levels. Genes of Group 3 responded to V. dahliae infection and were highly expressed in disease-resistant cotton species G. thurberi. This indicated that Group 3 genes may be involved in the immune response of Verticillium wilt. A gene with a high expression level was screened out of Group 3. A corresponding homologous gene was silenced in G. hirsutum by virus-induced gene silencing, and gene-silenced plants were more susceptible to V. dahliae, indicating that the gene plays a positive regulatory role in the progress of Verticillium wilt resistance in cotton. [Conclusion] The Betv1 genes act in response to V. dahliae infection and are critical in cotton resistance to Verticillium wilt. The information obtained provides a basis for further studies of the cotton Bet v 1 family genes and their functions.
Key words: wild cotton; Verticillium wilt; Betv1 gene; transcriptome; quantitative real time-PCR (qRT-PCR); virus-induced gene silencing (VIGS)
Cotton Science. 2019, 31(5):361-380.