Abstract: Heat-shock proteins (HSPs), known as stress proteins, are created when cells are exposed to elevated temperatures, or to other kinds of environmental stress. Although HSPs were first characterized because their expression increased in response to elevated temperature, some of them are found in normal, nonstressed cells. HSPs have many biochemical functions in cell metabolism during plant developmental process. The objective of the study was to isolate low-molecular-weight HSP genes, further put a foundation to illustrate them function in cotton fiber developmental stages. Six low-molecular-weight HSP genes were isolated from cotton fiber cDNA library. Sequence analysis showed that they belong to three different types of low-molecular-weight HSP. RT-PCR analysis revealed that they exhibit different transcripional profile in cotton. The mitochondrial and cytoplasmic I HSP genes were regulateded by the fiber initiation; however, cytoplasmic II HSP genes were more closely correlated with the growth and development of cotton leaf. Using genetic map of the tetraploid cotton constructed by our laboratory, three of these genes, LMWHSP1, LMWHSP2, and LMWHSP3, were mapped on the cotton chromosomes A4, D8, and A6, respectively.

Key words: Cotton, Low-molecular-weight heat-shock protein, Expression, Gene mapping