Study On Feature Of Fiber Development In Gossypium Hirsutum L. LUSO75 And LU7619

Cotton is an important economic crop that is widely grown in the world and the cottonproduct is closely related to people’s lives, especially the cotton fibers. Cotton fibers are seedtrichomes, and they are single cells which as a model for studies of plant cell development. Cellwall is the major composition of fibers, which is effect to the length and strength of fibers. It isreported that programmed cell death (PCD) is participate during the fibers developmentalprocess, but it have not reported that proteasome as the part of PCD process is impact on thedevelopment of fibers. Therefore studies on proteasome in fibers are new ideas to improved thequality of fibers, of course, the studies on feature of fiber development are very significant toimproved cotton varieties.In this study, the developmental stages of cotton fibers of Gossypium hirsutum L. LUS075and LU7619 were observed by light microscope and scanning electronic microscope (SEM),combining with measuring the fiber length. Depend on the Fourier transform infra-red spectrum(FTIR) of fiber cells, immunofluorescence label with four cell wall pectin antibodies (JIM5、JIM7、LM5 and LM6) on ovules. The results showed that different kinds of pectins occurred indifferent periods of fiber development, and the florescent labelling was appeared in differentpositions. Our data suggested that the unesterified pectins may have effects on the fiber cell wallstructure and be involved in the fiber elongation.We cloned the homolog of proteasome subunit PBA1 gene from elongating cotton fiber,GhPBA1. To analysis of full-length cDNAs and DNA of GhPBA1, it contained an open readingframe of 708bp, encoding 235 amino acids with eight functional domains. GhPBA1 mRNAmainly expressed in the fibers of 1DPA, along with the elongation of the fibers from 3DPA to15DPA, its expression was decreased. Detect the proteasome activity for different periods ofovules and fibers, we found that the low proteasome activity in elongate fibers. It was impliedgene GhPBA1 was related to fibers growth. At the same time, the proteasome inhibitor MG132experiments in cotton fiber culture in vitro showed that the inhibition of proteasome activitywould promote the cotton fiber development, in other words, proteasome may inhibit the fiberelongation.