| RFC (replication faction C) which was originally purified from extraction of Hela cells of human cervical cancer and found to be required for the synthesis of DNA replication in vitro is a necessary factor existed in many eukaryotes. Nowadays, the importance of RFC as a whole in DNA replication, DNA damage repair, cell division and resistance to stress has been gradually uncovered in the efforts of understanding the biologic function of RFC. The biological function of plant RFC, especially each subunit of RFC and its regulation of plant growth and development, however, is still one of the questions needed to be answered urgently in plant system. In this study, RNAi interference experiments were conducted on the small subunit of AtRFC5to get the rfc5mutant homozygote. Then, WT, rfc5, rfc3-1, rfc5rfc3and rfc3-1/RFC3plants were used as materials to study the effects of mutation of AtRFC5as well as AtRFC3on the resistance to stress and DNA replication toxicant of MMS and cisplatin of different concentrations. The regulatory roles of RFC5on growth and development were also analyzed in Arabidopsis thaliana.The main results are as the follows:1. rfc5mutant with stable phenotype was identified via genetic screening. Comparing with wild type plant, rfc5mutant homozygote has dwarf stature phenotype with small leaves, early flowering, not serrate leaf margins, few branchs, shorter main root and less lateral roots. It is suggested that plant growth and development is significantly affected by AtRFC5mutant.2. Double mutants were obtained by cross rfc5mutant homozygote with other growth and development related mutants like rfc3, rfc1and pcna2. The progenies of rfc5rfc3double mutant homozygote has been identified and confirmed by specific primer PCR. Nevertheless, the progenies of double mutant homozygote of rfc5rfcl and rfc5pcna2are still remained to be determined in the near future.3. The suppressive effects on plant growth of rfc3-1, wild type and rfc3-1/RFC3plants increase with the concentration of MMS and cisplatin. However, the length of the main root and the number of true leaves of rfc3-1plant is significantly smaller than that of wild type and rfc3-1/RFC3plants, and the complementary plant rfc3-1/RFC3rescues the mutated phenotype of rfc3-1. Real time PCR analyses show that mutation of AtRFC3compromises the resistance to the toxicant of DNA replication of MMS and cisplatin, and AtRFC3plays an important regulatory role in replication damage repair in Arabidopsis thaliana.4. The resistance of rfc5to toxicant of DNA replication of MMS and cisplatin is compromised by AtRFC5mutation. The results of real time PCR and conductivity of detached leaves from wild type, rfc3-1, rfc5and rfc5rfc3further suggest that mutant of RFC5compromises the resistance to stress and AtRFC5plays an important regulatory role in replication damage repair and resistance to stress in Arabidopsis thaliana. |
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