Genes expression analyses of sea-island cotton (Gossypium barbadense L.) during fiber development

A thaumatin-like protein gene involved in cotton fiber secondary cell wall development enhances resistance against Verticillium dahliae and other stresses in transgenic tobacco

For the first time, a sea-island cotton (Gossypium barbadense L.) thaumatin-like protein gene (GbTLP1) with a potential role in secondary cell wall development has been overexpressed in tobacco to elucidate its function. The presence of the transgene was verified by Southern blotting and higher expression levels of GbTLP1 in transgenic tobacco plants were revealed by reverse-transcription and quantitative real-time polymerase chain reaction analyses. Transgenic plants with constitutively higher expression of the GbTLP1 showed enhanced resistance against different stress agents, particularly, its performance against Verticillium dahliae was exceptional. Transgenic tobacco plants also exhibited considerable resistance against Fusarium oxysporum and some abiotic stresses including salinity and drought. In this experiment, transgenic plants without GbTLP1 expression were also used as controls, which behaved similar to non-transgenic control plants. Overexpression of GbTLP1 had no significant deleterious effect on plant growth except that flowering was delayed for 3-5 weeks. The apparent pleiotropic effect of this novel gene has given us insight to the plant defense mechanism.

Transcript profiling during fiber development identifies pathways in secondary metabolism and cell wall structure that may contribute to cotton fiber quality

A global gene expression profiling study at different stages of fiber development was undertaken on two cotton species cultivated for fiber, Gossypium hirsutum (L.) and G. barbadense (L.). A large proportion of the genome was expressed during both fiber elongation and subsequent secondary cell wall thickening. There was a major shift in abundance of transcripts for gene regulation, cell organization and metabolism between fiber elongation and fiber thickening that was fundamentally similar in both species. Each stage had its own distinctive features represented by specific metabolic and regulatory genes, a number of which have been noted previously. Many of the genes expressed in the fibers were of a similar type and developmental expression to those seen in other fiber-producing plants, indicating a conservation of mechanisms of cell elongation and wall thickening across diverse plant genera. Secondary metabolism and pectin synthesis and modification genes were amongst the most statistically significant differentially expressed categories between the two species during fiber elongation. The gene profiles of the fiber thickening stage, however, were almost identical between the two species, suggesting that their different final fiber quality properties may be established at earlier stages of fiber development. Expression levels of representative phenylpropanoid and pectin modification genes showed high correlations with specific fiber properties in an inter-specific cotton recombinant inbred line (RIL) population, supporting a role in determining fiber quality.