The accumulation of reactive oxygen species （ROS） is involved in plant cell development. In plant, class III peroxidases are heme-containing enzymes encoded by a large multi-gene family participated in the release or consumption of ROS. The specific function of each member of the family is still elusive. Here, we showed that ROS was significantly generated during cotton fiber initiation and elongation, whereas, application of NADPH oxidase inhibitor diphenyleneiodonium （DPI） and peroxidase inhibitor salicylhydroxamic acid （SHAM） to the wild-type cotton ovule culture significantly suppressed fiber growth, respectively. Their inhibitory effects were caused by the reduction of superoxide radical （O2^-）. Ten GhPOX genes （cDNAs） encoding cotton class III peroxidases were isolated, among them eight GhPOX genes were reported for the first time. Microarray analyses indicated that GhPOX1 was the mostly predominantly expressed in fast-elongating cotton fiber cells. Real-time quantitative PCR analysis revealed the transcript level of GhPOX1 was over 400-fold higher in growing fiber cells than in ovules, flowers, roots, stems and leaves. To reveal the role of GhPOX1 in plant development, its Arabidopsis orthologue atpox13 mutant was demonstrated to be defective in branch root development. Taken together, the data suggest that GhPOX1 plays an important role during fiber cell elongation possibly by mediating production of reactive oxygen species.
Wenqian Mei Yongmei Qin Wenqiang Song Jun Li Yuxian Zhu
Cotton fibers, commonly known as cotton lint, are single-celled trichomes derived from epidermal lay- ers of cotton ovules. Despite of its importance in word trade, the molecular mechanisms of cotton fiber production is still poorly understood. Through transcriptome profiling, functional genomics, pro- teomics, metabolomics approaches as well as marker-assisted molecular breeding, scientists in China have made significant contributions in cotton research. Here, we briefly summarize major progresses made in Chinese laboratories, and discuss future directions and perspectives relative to the develop- ment of this unique crop plant.
Cotton is the world's most important natural textile fi ber, and is practiced on about 2.5% of arable land that supported the life of about 100 million family units. Each cotton fi ber, about 25 000 per seed, is a single, phe-
Cotton fiber strength is mainly determined during the secondary cell wall deposition stage when cel- lulose is synthesized. We obtained cDNA of 20―25 d post anthesis (DPA) fiber from 109 F2 progeny and developed a cotton fiber transcriptome profiling via cDNA-AFLP technology using 37 different primer combinations. The F2 population originated from an interspecific cross between Gossypium hirsutum and Gossypium barbadense. One hundred and thirty-eight absence/presence polymorphic transcript- derived fragments (TDFs), with sizes ranging from 100 bp to 722 bp, were screened. Of these, 75 (53.62%) were polymorphic between the parents of the F2 population. Sequencing the 75 transcripts revealed that 37 of them had been reported to be cotton fiber ESTs. Nine of 75 transcript sequences were homologous to 7 cloned cotton fiber genes, encoding cysteine proteinase, vacuolar H+-pyro- phosphatase, vacuolar H+-ATPase, catalytic subunit, arabinogalactan protein, putative receptor protein kinase PERK1, GIA/RGA-like gibberellin response modulator and cellulose synthase. Some other transcripts may represent new gene fragments in cotton fiber development. Surprisingly, 46 of the 75 transcripts were mapped to a single linkage group. The transcriptome groups and the sequenced TDFs could serve as important resources in the functional genomic research of cotton fiber development.
PAN YuXin MA Jun ZHANG GuiYin HAN GaiYing WANG XingFent MA ZhiYingt
