Integrative transcriptome, proteome, phosphoproteome and genetic mapping reveals new aspects in a fiberless mutant of cotton.

To investigate the molecular mechanisms of fiber initiation in cotton (Gossypium spp.), an integrated approach combining transcriptome, iTRAQ-based proteome and genetic mapping was taken to compare the ovules of the Xuzhou 142 wild type (WT) with its fuzzless-lintless (fl) mutant at -3 and 0 day post-anthesis. A total of 1,953 mRNAs, 187 proteins, and 131 phosphoproteins were differentially expressed (DE) between WT and fl, and the levels of transcripts and their encoded proteins and phosphoproteins were highly congruent. A functional analysis suggested that the abundance of proteins were mainly involved in amino sugar, nucleotide sugar and fatty acid metabolism, one carbon pool for folate metabolism and flavonoid biosynthesis. qRT-PCR, Western blotting, and enzymatic assays were performed to confirm the regulation of these transcripts and proteins. A molecular mapping located the lintless gene li3 in the fl mutant on chromosome 26 for the first time. A further in-silico physical mapping of DE genes with sequence variations between fl and WT identified one and four candidate genes in the li3 and n2 regions, respectively. Taken together, the transcript abundance, phosphorylation status of proteins at the fiber initiation stage and candidate genes have provided insights into regulatory processes underlying cotton fiber initiation.

[Genome-wide analysis of the LPAAT gene family in Gossypium raimondii and G. arboreum, and expression analysis of its orthologs in G. hirsutum].

Lysophosphatidic acid acyltransferase (LPAAT) which converts lysophosphatidic acid into phosphatidic acid is a key enzyme in biosynthesis pathway of lipid in plants. In this study, we identified 17 members of the LPAAT gene family from genomic data of G. raimondii-D5 and G. arboreum-A2. Analysis of gene structure, chromosome distribution and phylogenetic evolution of LPAAT genes in diploid Gossypium using bioinformatics approaches showed that these genes can be divided into distinct subfamilies based on the distance of their genetic relationship. Moreover, the gene structures were similar within LPAAT subfamily members. The amino acid sequences encoded by LPAAT family genes contained three conserved motifs, including ΦFPEGTR-G binding site and Φ-NHQS- ΦDΦΦ catalytic site. Phylogenetic analysis of LPAAT gene family demonstrated significant differences in evolution of LPAAT in different species. Finally, expression analysis of G. hirsutum ovules in different stages from RNA-seq and qRT-PCR data indicated that LPAAT gene may play a positive role in oil accumulation. Our studies facilitate understanding of the function of LPAAT gene family in Gossypium and selecting better LPAAT genes for further functional validation.