Effect of H 2O 2 on fiber initiation using fiber retardation initiation mutants in cotton ( Gossypium hirsutum)

Abstract

Single-celled fibers initiate at anthesis from cotton seed epidermal cells of normal developmental cotton cultivars; however, fiber initiation is retarded in some cotton fiber mutants. In this study, the relationship between genes associated with fiber initiation retardation and fiber initiation development was investigated using three cotton fiber developmental mutants: recessive naked seed n2; dominant naked seed N1; and Xinxiangxiaoji Linted-Fuzzless Mutant (XinFLM); with genetic standard line TM-1 (TM-1) as control. Retardation during fiber initiation development was observed in N1 and XinFLM by scanning electron microscope (SEM) analysis. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of genes related to the fiber initiation development showed that the expression of GhEXP1 and GhMYB25 was lower in N1 and XinFLM than in TM-1 and n2, however, the expression of GhTTG1 and GhTTG3 in XinFLM and n2 was higher than in TM-1 and N1. In vivo and in vitro treatments on ovules demonstrated that 30% hydrogen peroxide (H 2O 2) could prevent fiber initiation retardation in XinFLM, but no evident effect on N1. To further confirm the relationship between gene expression and the effects of H 2O 2 in XinFLM, qRT-PCR analysis of four differentially expressed genes was performed using −1 d post-anthesis (DPA) ovules of XinFLM treated for 24 and 48 h with 30% H 2O 2 and H 2O, respectively, with 0 and 1 DPA untreated ovules from XinFLM and TM-1 as control. The results showed that the expression of GhMYB25 and GhEXP1 showed significant difference in XinFLM after −1 DPA ovule treated for 24 h relative to the untreated or H 2O-treated ovules, with the expression of GhMYB25 increased significantly and that of GhEXP1 decreased. This implied that H 2O 2 might be one of the upstream signal molecules affecting the expression of GhMYB25 and GhEXP1 genes. The fiber initiation retardation in XinFLM might be related to the production of reactive oxygen species (ROS).