Gossypium hirsutum has proven difficult to sequence owing to its complex allotetraploid (AtDt) genome. Here we produce a draft genome using 181-fold paired-end sequences assisted by fivefold BAC-to-BAC sequences and a high-resolution genetic map. In our assembly 88.5% of the 2,173-Mb scaffolds, which cover 89.6%∼96.7% of the AtDt genome, are anchored and oriented to 26 pseudochromosomes. Comparison of this G. hirsutum AtDt genome with the already sequenced diploid Gossypium arboreum (AA) and Gossypium raimondii (DD) genomes revealed conserved gene order. Repeated sequences account for 67.2% of the AtDt genome, and transposable elements (TEs) originating from Dt seem more active than from At. Reduction in the AtDt genome size occurred after allopolyploidization. The A or At genome may have undergone positive selection for fiber traits. Concerted evolution of different regulatory mechanisms for Cellulose synthase (CesA) and 1-Aminocyclopropane-1-carboxylic acid oxidase1 and 3 (ACO1,3) may be important for enhanced fiber production in G. hirsutum.

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Genome sequence of cultivated Upland cotton ( Gossypium hirsutum TM-1) provides insights into genome evolution

Yu-Xian Zhu, Jun Wang, Shuxun Yu and colleagues report sequencing and assembly of the genome of cultivated cotton, Gossypium arboreum. Comparison with the Gossypium raimondii genome sequence provides insights into genome evolution and speciation, and identifies two shared whole-genome duplication events occurring before the speciation event around 2–13 million years ago.

/pdf/genome-sequence-of-the-cultivated-cotton-gossypium-arboreum-5d7xmfxbyj.pdf

Genome sequence of the cultivated cotton Gossypium arboreum

Cotton fibers are single-celled extensions of the seed epidermis. They can be isolated in pure form as they undergo staged differentiation including primary cell wall synthesis during elongation and nearly pure cellulose synthesis during secondary wall thickening. This combination of features supports clear interpretation of data about cell walls and cellulose synthesis in the context of high throughput modern experimental technologies. Prior contributions of cotton fiber to building fundamental knowledge about cell walls will be summarized and the dynamic changes in cell wall polymers throughout cotton fiber differentiation will be described. Recent successes in using stable cotton transformation to alter cotton fiber cell wall properties as well as cotton fiber quality will be discussed. Future prospects to perform experiments more rapidly through altering cotton fiber wall properties via virus induced gene silencing will be evaluated.

/pdf/cotton-fiber-a-powerful-single-cell-model-for-cell-wall-and-ofgpx9dm21.pdf

Cotton fiber: a powerful single-cell model for cell wall and cellulose research.

Proteomic and virus-induced gene silencing (VIGS) analyses reveal that Gossypol, Brassinosteroids and Jasmonic acid contribute to the resistance of cotton to Verticillium dahliae

How cotton fibers elongate: a tale of linear cell-growth mode.

Comparative Proteomics Indicates That Biosynthesis of Pectic Precursors Is Important for Cotton Fiber and Arabidopsis Root Hair Elongation

The reaction catalyzed by 1-aminocyclopropane-1-carboxylic acid synthase (ACS) is proposed to be the rate-limiting step in ethylene biosynthesis, which has been found as one of the most up-regulated metabolic pathways during cotton fiber development. However, the transcripts of the identified ACS genes did not increase in a similar manner as those of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes, implicating a possible post-transcriptional modification or regulatory mechanism. In this work, cotton ACS2 was shown to interact with Ca 2+ -dependent protein kinase 1 (CPK1). Bacterially expressed and purified recombinant ACS2 was phosphorylated by CPK1 in vitro and site-directed mutagenesis studies suggest that ACS2 S460 is a possible phosphorylation site for CPK1. Phosphorylated ACS2 significantly increased ACS activity, leading to elevated ethylene production. We thus speculated that CPK1 is involved in cotton fiber growth regulation by phosphorylating ACS2, which results in enhanced ethylene production in vitro.

/pdf/1-aminocyclopropane-1-carboxylic-acid-synthase-2-is-4zh0xokh64.pdf

Hui Wang

Papers

Comparative Proteomics Indicates That Biosynthesis of Pectic Precursors Is Important for Cotton Fiber and Arabidopsis Root Hair Elongation

1-Aminocyclopropane-1-carboxylic acid synthase 2 is phosphorylated by calcium-dependent protein kinase 1 during cotton fiber elongation.

Genetic Analysis and Preliminary Mapping of the Photoperiod-Sensitive Male Sterility Gene ys-1 in Upland Cotton