| Cotton fiber is regarded as an important raw material for textile industry. Improvement of cotton fiber quality has been a research hotspot for decades. Cloning and genetic analysis of more genes associated with the fiber trait will not only facilitate the illumination of fiber developmental mechanism but also lay the foundation for genetic improvement of fiber quality. In this study, we conducted a genetic analysis and premary mapping of the fuzzless gene by using fuzzless mutant DPL972 and WT DPL971(G. arobreum). Transcriptome of ovules at the stage of fuzz inatiation were also analyzed. The main results were as follows:The cotton line DPL971 and a fuzzless mutant DPL972 were employed to construct F2 segregating population for preliminary mapping. According to the investigation, the fiber trait of individuals in this F2 population can be divided into two groups: fuzzy and fuzzless. The segregation of 3004 fuzzless individuals and 1006 fuzzy individuals, tested by a Chi-Square(χ2) Test,was consistent with an expected ratio of 3:1, confirming a conclusion that the fuzzless gene( we named it GaFzl) controlling the fuzzless trait was a single, complete dominant gene.Total 1567 SSR primer pairs distributed over all 13 chromosomes on A genome were screened between two mapping parents. Subsequently, markers showing polymorphisms were analyzed in the segregating population and linkage map was constructed by using Join Map4.0. Fifteen SSR markers on chromosome A08 were identified to be linked to the gene Ga Fzl. Thus, the GaFzl was mapped to chromosome A08 and the closest marker was SSR82 with a genetic distance of 6.6 cM.In addition, ovules on +1、+3 and +5 DPA of DPL971 and DPL972 were respectively collected for transcriptome sequencing. A total of 90.28 G clean data and 300,927,495 clean reads were obtained from the transcriptome libraries. The CycleQ20, known as an assessment of sequencing quality, equaled to 100% and the Q30 exceeded 90%. Besides, more than 87% of the clean reads of each sample can be aligned to the genome sequence, revealing a high quality of the transcriptome sequencing and assembly.Based on a criterion of |log2(ratio)| ≥ 1 and FDR < 0.01, a total of 405 genes were differentially expressed between DPL972 and WT. The number of differentially expressed genes on +1 DPA was 370,of which 266 were up-regulated, and 104 were down-regulated. While there were only 13 and 22 differentially expressed genes on +3 DPA and +5 DPA, respectively. The results above indicate that genes differentially expressed on +1DPA may have determined the inatiation and differentition of fuzz,despite the fuzz inatiation occurs on +5DPA.Gene Ontology enrichment analysis showed that Binding and Catalytic Activity had a higher enrichment percentage in Biological Process. And according to the functional annotation, plenty of differentially expressed genes were identified to encode transcription factors and enzmyed, indicating that multiple transcription factors and enzymes may play important roles in the process of fiber initiation and fuzz formation. In addition, we conducted a STRING protein interaction network analysis using the encoded protein of DEGs, and the results showed that DNA replication and cell cycle control、response to plant hormones may exert an important influence on regulating the fiber initiation and fuzz formation. |
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