Based on the sequence information of Arabidopsis PIN1, two cDNAs encoding PIN homologues from Brassica juncea, Bjpin2 and Bjpin3, were isolated through cDNA library screening. Bjpin2 and Bjpin3 encoded proteins contai...Based on the sequence information of Arabidopsis PIN1, two cDNAs encoding PIN homologues from Brassica juncea, Bjpin2 and Bjpin3, were isolated through cDNA library screening. Bjpin2 and Bjpin3 encoded proteins containing 640 and 635 amino acid residues, respectively, which shared 97.5% identities with each other and were highly homologous to Arabidopsis PIN1, PIN2 and other putative PIN proteins. BJPIN2 and BjPIN3 had similar structures as AtPIN proteins. Northern blot analysis indicated that Bjpin2 was expressed in stem, leaf and floral tissues, while Bjpin3 was expressed predominantly in stem and hypocotyls. Two promoter fragments of pin genes, Bjpin-X and Bjpin-Z, were isolated by 'genome walking' technique using primers at 5'-end of pin cDNA. Promoter-gus fusion studies revealed the GUS activities driven by Bjpin-X were at internal side of xylem and petal; while those driven by Bjpin-Z were detected at leaf vein, epidermal cell and cortex of stem, vascular tissues and anther. Results of the pin genes with different expression patterns in B. juncea suggested the presence of a gene family.展开更多
Polar auxin transport plays a divergent role in plant growth and developmental processes including root and embryo development, vascular pattern formation and cell elongation. Recently isolated Arabidopsis pin gene fa...Polar auxin transport plays a divergent role in plant growth and developmental processes including root and embryo development, vascular pattern formation and cell elongation. Recently isolated Arabidopsis pin gene family was believed to encode a component of auxin efflux carrier (G(?)lweiler et al, 1998). Based on the Arabidopsis pin1 sequence we have isolated a Brassica juncea cDNA (designated Bjpin1), which encoded a 70-kDa putative auxin efflux carrier. Deduced BjPIN1 shared 65% identities at protein level with AtPINl and was highly homologous to other putative PIN proteins of Arabidopsis (with highest homology to AtPIN3). Hydrophobic analysis showed similar structures between BjPINl and AtPIN proteins. Presence of 6 exons (varying in size between 65 bp and 1229 bp) and 5 introns (sizes between 89 bp and 463 bp) in the genomic fragment was revealed by comparing the genomic and cDNA sequences. Northern blot analysis indicated that Bjpin1 was expressed in most of the tissues tested, with a relatively higher level of transcript in flowers and a lower level in root tissues. Promoter-reporter gene fusion studies further revealed the expression of Bjpin1 in the mature pollen grains, young seeds, root tip, leaf vascular tissue and trace bundle, stem epidermis, cortex and vascular cells. BjPINl was localized on the plasma membrane as demonstrated through fusion expression of green fluorescent protein (GFP). Auxin efflux carrier activity was elevated in transgenic Arabidopsis expressing BjPIN1.展开更多
基金Studies were supported by the National NaturalSciences Foundation of China (No. 30070073, 95-Yu-29-7) and State Key Project of Basic Research (No.G1999011604). We greatly thank Dr. K1aus Palme for providing the Atpinl nucleotide sequences.
文摘Based on the sequence information of Arabidopsis PIN1, two cDNAs encoding PIN homologues from Brassica juncea, Bjpin2 and Bjpin3, were isolated through cDNA library screening. Bjpin2 and Bjpin3 encoded proteins containing 640 and 635 amino acid residues, respectively, which shared 97.5% identities with each other and were highly homologous to Arabidopsis PIN1, PIN2 and other putative PIN proteins. BJPIN2 and BjPIN3 had similar structures as AtPIN proteins. Northern blot analysis indicated that Bjpin2 was expressed in stem, leaf and floral tissues, while Bjpin3 was expressed predominantly in stem and hypocotyls. Two promoter fragments of pin genes, Bjpin-X and Bjpin-Z, were isolated by 'genome walking' technique using primers at 5'-end of pin cDNA. Promoter-gus fusion studies revealed the GUS activities driven by Bjpin-X were at internal side of xylem and petal; while those driven by Bjpin-Z were detected at leaf vein, epidermal cell and cortex of stem, vascular tissues and anther. Results of the pin genes with different expression patterns in B. juncea suggested the presence of a gene family.
基金Studies were supported by 'the National NaturalScience Foundation of China, No. 30070073', StateKey Project of Basic Research, No. G199901l604'and 'National Natural Science Foundation of Pan-Deng'. We thank Dr. Charles Brearley and JianXu for hel
文摘Polar auxin transport plays a divergent role in plant growth and developmental processes including root and embryo development, vascular pattern formation and cell elongation. Recently isolated Arabidopsis pin gene family was believed to encode a component of auxin efflux carrier (G(?)lweiler et al, 1998). Based on the Arabidopsis pin1 sequence we have isolated a Brassica juncea cDNA (designated Bjpin1), which encoded a 70-kDa putative auxin efflux carrier. Deduced BjPIN1 shared 65% identities at protein level with AtPINl and was highly homologous to other putative PIN proteins of Arabidopsis (with highest homology to AtPIN3). Hydrophobic analysis showed similar structures between BjPINl and AtPIN proteins. Presence of 6 exons (varying in size between 65 bp and 1229 bp) and 5 introns (sizes between 89 bp and 463 bp) in the genomic fragment was revealed by comparing the genomic and cDNA sequences. Northern blot analysis indicated that Bjpin1 was expressed in most of the tissues tested, with a relatively higher level of transcript in flowers and a lower level in root tissues. Promoter-reporter gene fusion studies further revealed the expression of Bjpin1 in the mature pollen grains, young seeds, root tip, leaf vascular tissue and trace bundle, stem epidermis, cortex and vascular cells. BjPINl was localized on the plasma membrane as demonstrated through fusion expression of green fluorescent protein (GFP). Auxin efflux carrier activity was elevated in transgenic Arabidopsis expressing BjPIN1.
