| Study of plant hormone receptor is one of the forward problems in plant physiology. Up to now only auxin-binding protein 1 (ABPl) that largely locating in endoplasmic reticulum was affirmed as the receptor, but this was not argued amply through experiments done by predecessors. Further clarifying the relationship between quantity of ABPl and sensibility of plant to auxin is important in theory and in application of auxin-binding protein 1.Since cultivated widely, cucumber occupies an important place in the vegetable production and national economy. Its varieties being capable of parthenocarpy are not influenced by few entomophilies and low temperature, will produce more and better fruits than those of having poor parthenocarpic ability, therefore they can be grown under glass or in the open where are overcast and rainy. The parthenocarpic capability of cucumber is related to the auxin in ovary, so cucumber fruits were chosen as materials to study auxin-binding protein 1 in this experiment.It's the first time to separate a cucumber auxin-binding protein cDNA fragment, expound its copy number in genome and study its peculiarity in developing phases. This would lay a good foundation for studying ABPl receptor function and other plant hormone receptors.It's the most direct evidence for auxin receptor function that plants could have phenotypes related to auxin when ABPl gene was transformed into them. In this experiment, the transgenic cucumber plants not only gave the direct evidence, but also supplied a new breeding material of strong parthenocarpic ability.1. Cucumber fruit developmentThere were two treatments in experiment, one was pollination done on half past six every morning, and the other was unpollination with corolla of female flower clamped before anthesis.The ovaries in pollination treatment got expanding and elongating, and developed normal fruits with larger cavity and plump seeds, while some of the unpollinated formed parthenocarpic fruits with smaller cavity and seedless, others were wiling. According to statistics, the average parthenocarpic rate of "Jinyansihao" variety was 19.9 per cent. 2. Separation and expression of cucumber auxin-binding protein cDNAReverse transcription and polymerase chain reaction was performed on the primers 5'-GAGATCTGCTCTAGATCGA-3' and 5'-AGGCACTCCTGTGAAGAAGTT-3', after cDNA was synthesized with ovary total RNA and the oligo(dT)-anchor primer 5'-GAGATCTGCTCT AGATCGATi7-3'.The product of RT-PCR was an 800 bp DNA fragment. Its amino acid sequence not only contained the likely ligand-binding site for auxin receptor (RHSCE), potential glycosylation site (NST), possible hydrophobic platform of auxin-binding site (YDDWSVPHTA). signal known to be responsible for the retention of soluble protein to the lumen of the endoplasmic reticulum (KDEL) and two conserving boxes (box A: T PIH R H S C EI/V FI/T/V V L/P/V K G X G T L/V; box B: H E D L Q F/V L D/V I/V IS R P P) which were also found in other plant ABP1, but showed > 70 per cent similarity when aligned with other plant ABP1. The identity to Lycopersicon esculentum (GenBank accession number AJ011943), tyfalus domestica (GenBank accession number U77952), Fragaria ananassa (GenBank accession number X91839), Nicotiana tabacum (GenBank accession number X70902), Capsicum annitum (GenBank accession number Z48451) , Raphanus sativus (GenBank accession number AB000706), Arabidopsis thaliana (GenBank accession number S40550), Avena sativa (GenBank accession number AB000707) and Zea mays (GenBank accession number XI6309) was 76 per cent, 76 per cent. 76 per cent. 75 per cent, 75 per cent, 76 per cent, 75 per cent, 70 per cent and 70 per cent respectively. So the product of RT-PCR was cucumber ABP1 cDNA fragment.The expression level of ABP1 mRNA in ovaries was suggested by quantative RT-PCR using cucumber actin cDNA as internal control. The expression signals were weaker in ovaries of 1 d before anthesis, while got stronger and stronger in 2% 4 and 6 d after pollination. Among the ovaries of 2 d after anthesis...
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