| Cotton (Gossypium spp.) is one of the most important economic crops due to its excellent natural fiber properties. Cotton fiber grows out of a single epidermal cell. Cotton fiber development can be divided into four different development processes, in each process there are many kinds of different genes participating jointly in fiber morphology. So to illustrate cotton fiber development related genes function not only has the production significance, but also can help to elucidate the molecular mechanism of single-celled development. In the experiment, three genes, GhAOC, GhHPSE, and GhGDSL, were selected by comparing the expressional difference of fiber initiation between XinWX and XinFLM using29K cotton genome array. Further, their sequences were cloned from different cotton species respectively. By analyzing the structure of sequences, gene mapping, association analysis, and Q-PCR analysis, these genes function was preliminarily elucidated. Results showed that the three genes were involved in the process of fiber development, which provide genetic resources for deeply studying their molecular mechanisms in fiber development and creating transgenic lines of fiber qualities improved.The open reading frame (ORF) of Gossypium hirsutum Allene Oxide Cyclase (GhAOC) is741bp, encoding246Amino acids. There are two copies in the tetraploid cotton and the D-subgenome of GhAOC is mapped in D8chromosome (Chr.24). GhAOC contains two introns and the second intron length is different between A-genome and D-genome in diploid cotton species, and between A-subgenome and D-subgenome in tetraploid cotton species. Q-PCR results revealed that there was high expression of GhAOC on the8-23DPA, and the expression in TM-1is significantly higher than in H7124during the high transcription period. The results of association analysis with the fiber test data in [(TM-1＝H7124)＝TM-1] BC1S1population and the GhAOC SNP data in D-subgenome, revealed that the GhAOC of D-subgenome is significantly associated with fiber strength (fiber test data from2005) at the0.05level, and the fiber strength average (fiber test data from2005) of homozygous genotype (the same genotype as TM-1) was significantly higher than heterozygous genotype, that is consistent with the Q-PCR results. GhAOC might play a role in the process of the fiber secondary cell wall thickening, and was related to the fiber strength.The ORF of Gossypium hirsutum Heparanase(GhHPSE) is1641bp, encoding546Amino acids, contains8introns. There are two copies in the tetraploid cotton and they are mapping of the chromosomes of A8(Chr.8) and D8(Chr.24) respectively. Q-PCR results reveal that there is high expression of GhHPSE during5-23DPA. The results of association analysis with the fiber test data in [(TM-1×H7124)×TM-1] BC1S1population and the GhHPSE SNP data of A-subgenome and D-subgenome, reveal that the GhHPSE of A-subgenome is significantly associated with seed protein content (seed protein test data from2004) at the0.05level, and the D-subgenome is significantly associated with fiber strength (fiber test data from2006), seed oil content seed protein content (seed protein test data from2003),(seed oil test data from2004) at the0.05level. The results of association analysis from (7235×TM-1) RIL population is that the GhHPSE of D-subgenome is significantly associated with fiber strength, micronaire, maturity index and reflectance at the0.05or0.01level. Taking the association analysis results in the populations, the D-subgenome of GhHPSE plays an important role in fiber quality, especially in the fiber strength.The ORF of Gossypium hirsutum GDSL(GhGDSL) is1062bp, encoding353Amino acids. There are two copies in the tetraploid cotton and they are mapped in the chromosomes of A4(Chr.4) and D4(Chr.22) respectively. It contains4introns, and the second intron length is significantly different between A-genome and D-genome in diploid cotton species, and between A-subgenome and D-subgenome in tetraploid cotton species. Q-PCR results reveal that the expression of GhGDSL in H7124is gradually changed from increase to reduce during3to14DPA, the highest expression level in8DPA. The expression of GhGDSL in TM-1is higher during5to10DPA, reduce significantly after10DPA. The results of association analysis with the fiber test data in [(TM-1×H7124)×TM-1] BC1S1population and the GhGDSL SNP data of A-subgenome and D-subgenome, reveal that the GhGDSL of A-subgenome is significantly associated with seed oil content (seed oil test data from2003) at the0.05level, and the D-subgenome is significantly associated with seed protein content (seed protein test data from2003) at the0.05level. GhGDSL may play a major role in the process of seed lipid and protein metabolism. |
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