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OsABCG15 encodes a membrane protein that plays an important role in anther cuticle and pollen exine formation in rice.

Wu L, Guan Y, Wu Z, Yang K, Lv J, Converse R, Huang Y, Mao J, Zhao Y, Wang Z, Min H, Kan D, Zhang Y - Plant Cell Rep. (2014)

Bottom Line: Using map-based cloning, we found a spontaneous A-to-C transition in the fourth exon of OsABCG15 that caused an amino acid substitution of Thr-to-Pro in the predicted ATP-binding domain of the protein sequence.Our results suggested that OsABCG15 played an essential role in the formation of the rice anther cuticle and pollen exine.This role may include the secretion of the lipid precursors from the tapetum to facilitate the transfer of precursors to the surface of the anther epidermis as well as to microspores.

View Article: PubMed Central - PubMed

Affiliation: College of Agronomy and Biotechnology, Southwest University, Chongqing, 400715, China.

ABSTRACT

Key message: An ABC transporter gene ( OsABCG15 ) was proven to be involved in pollen development in rice. The corresponding protein was localized on the plasma membrane using subcellular localization. Wax, cutin, and sporopollenin are important for normal development of the anther cuticle and pollen exine, respectively. Their lipid soluble precursors, which are produced in the tapetum, are then secreted and transferred to the anther and microspore surface for polymerization. However, little is known about the mechanisms underlying the transport of these precursors. Here, we identified and characterized a member of the G subfamily of ATP-binding cassette (ABC) transporters, OsABCG15, which is required for the secretion of these lipid-soluble precursors in rice. Using map-based cloning, we found a spontaneous A-to-C transition in the fourth exon of OsABCG15 that caused an amino acid substitution of Thr-to-Pro in the predicted ATP-binding domain of the protein sequence. This osabcg15 mutant failed to produce any viable pollen and was completely male sterile. Histological analysis indicated that osabcg15 exhibited an undeveloped anther cuticle, enlarged middle layer, abnormal Ubisch body development, tapetum degeneration with a falling apart style, and collapsed pollen grains without detectable exine. OsABCG15 was expressed preferentially in the tapetum, and the fused GFP-OsABCG15 protein was localized to the plasma membrane. Our results suggested that OsABCG15 played an essential role in the formation of the rice anther cuticle and pollen exine. This role may include the secretion of the lipid precursors from the tapetum to facilitate the transfer of precursors to the surface of the anther epidermis as well as to microspores.

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Phylogenetic analysis of OsABCG15 and related proteins. A bootstrap neighbor-joining phylogenetic tree was constructed using MEGA 5.0 and 1,000 replicates. The number on each interior branch is the bootstrap percentage. The scale bar indicates the estimated number of amino acid substitutions per site (for alignment, see Supplementary Fig. 4 online) and the proteins are named by their NCBI accession numbers. Black dots and squares indicate OsABCG15 and AtABCG26/WBC27, respectively. At Arabidopsisthaliana; Al Arabidopsis lyrata; Bd Brachypodium distachyon; Gm Glycine max; Mt Medicago truncatula; Os rice; Pp Physcomitrella patens; Pt Populus trichocarpa; Rc Ricinus communis; Sb Sorghum bicolor; Vv Vitis vinifera; Zm Zea mays
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Fig6: Phylogenetic analysis of OsABCG15 and related proteins. A bootstrap neighbor-joining phylogenetic tree was constructed using MEGA 5.0 and 1,000 replicates. The number on each interior branch is the bootstrap percentage. The scale bar indicates the estimated number of amino acid substitutions per site (for alignment, see Supplementary Fig. 4 online) and the proteins are named by their NCBI accession numbers. Black dots and squares indicate OsABCG15 and AtABCG26/WBC27, respectively. At Arabidopsisthaliana; Al Arabidopsis lyrata; Bd Brachypodium distachyon; Gm Glycine max; Mt Medicago truncatula; Os rice; Pp Physcomitrella patens; Pt Populus trichocarpa; Rc Ricinus communis; Sb Sorghum bicolor; Vv Vitis vinifera; Zm Zea mays

Mentions: Subsequently, a neighbor-joining phylogenetic tree of the 26 genes was constructed (Fig. 6). It showed that OsABCG15 was clustered in a Poaceae sub-clade (boxed in Fig. 6) together with four other proteins from Brachypodium distachyon, Sorghum bicolor and Zea mays. In this sub-clade, OsABCG15 homologs were encoded by a single subfamily member in rice, Brachypodium distachyon, and Zea mays, but not Sorghum bicolor. Among the species sampled, only Medicago truncatula, Brachypodium distachyon and Physcomitrella patens contained a single copy of the gene, while two or more orthologs existed in other species. For example, there were six different loci encoding this protein in Glycine max. Remarkably, clade 1 and clade 4 diverged quite early, although both comprised similar homologues from angiosperms. After searching the eFP (electronic fluorescent pictograph) browser in the Bio-Array Resource (BAR, http://bar.utoronto.ca/welcome.htm), we found that most of the homologs in clade 1 were expressed mainly in flowers, and most in clade 4 were predominantly expressed in leaves. Thus, these ABC transporter members have evolved different biological functions, although all have conserved functional NBD and TMD domains.Fig. 6


OsABCG15 encodes a membrane protein that plays an important role in anther cuticle and pollen exine formation in rice.

Wu L, Guan Y, Wu Z, Yang K, Lv J, Converse R, Huang Y, Mao J, Zhao Y, Wang Z, Min H, Kan D, Zhang Y - Plant Cell Rep. (2014)

Phylogenetic analysis of OsABCG15 and related proteins. A bootstrap neighbor-joining phylogenetic tree was constructed using MEGA 5.0 and 1,000 replicates. The number on each interior branch is the bootstrap percentage. The scale bar indicates the estimated number of amino acid substitutions per site (for alignment, see Supplementary Fig. 4 online) and the proteins are named by their NCBI accession numbers. Black dots and squares indicate OsABCG15 and AtABCG26/WBC27, respectively. At Arabidopsisthaliana; Al Arabidopsis lyrata; Bd Brachypodium distachyon; Gm Glycine max; Mt Medicago truncatula; Os rice; Pp Physcomitrella patens; Pt Populus trichocarpa; Rc Ricinus communis; Sb Sorghum bicolor; Vv Vitis vinifera; Zm Zea mays
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4197380&req=5

Fig6: Phylogenetic analysis of OsABCG15 and related proteins. A bootstrap neighbor-joining phylogenetic tree was constructed using MEGA 5.0 and 1,000 replicates. The number on each interior branch is the bootstrap percentage. The scale bar indicates the estimated number of amino acid substitutions per site (for alignment, see Supplementary Fig. 4 online) and the proteins are named by their NCBI accession numbers. Black dots and squares indicate OsABCG15 and AtABCG26/WBC27, respectively. At Arabidopsisthaliana; Al Arabidopsis lyrata; Bd Brachypodium distachyon; Gm Glycine max; Mt Medicago truncatula; Os rice; Pp Physcomitrella patens; Pt Populus trichocarpa; Rc Ricinus communis; Sb Sorghum bicolor; Vv Vitis vinifera; Zm Zea mays
Mentions: Subsequently, a neighbor-joining phylogenetic tree of the 26 genes was constructed (Fig. 6). It showed that OsABCG15 was clustered in a Poaceae sub-clade (boxed in Fig. 6) together with four other proteins from Brachypodium distachyon, Sorghum bicolor and Zea mays. In this sub-clade, OsABCG15 homologs were encoded by a single subfamily member in rice, Brachypodium distachyon, and Zea mays, but not Sorghum bicolor. Among the species sampled, only Medicago truncatula, Brachypodium distachyon and Physcomitrella patens contained a single copy of the gene, while two or more orthologs existed in other species. For example, there were six different loci encoding this protein in Glycine max. Remarkably, clade 1 and clade 4 diverged quite early, although both comprised similar homologues from angiosperms. After searching the eFP (electronic fluorescent pictograph) browser in the Bio-Array Resource (BAR, http://bar.utoronto.ca/welcome.htm), we found that most of the homologs in clade 1 were expressed mainly in flowers, and most in clade 4 were predominantly expressed in leaves. Thus, these ABC transporter members have evolved different biological functions, although all have conserved functional NBD and TMD domains.Fig. 6

Bottom Line: Using map-based cloning, we found a spontaneous A-to-C transition in the fourth exon of OsABCG15 that caused an amino acid substitution of Thr-to-Pro in the predicted ATP-binding domain of the protein sequence.Our results suggested that OsABCG15 played an essential role in the formation of the rice anther cuticle and pollen exine.This role may include the secretion of the lipid precursors from the tapetum to facilitate the transfer of precursors to the surface of the anther epidermis as well as to microspores.

View Article: PubMed Central - PubMed

Affiliation: College of Agronomy and Biotechnology, Southwest University, Chongqing, 400715, China.

ABSTRACT

Key message: An ABC transporter gene ( OsABCG15 ) was proven to be involved in pollen development in rice. The corresponding protein was localized on the plasma membrane using subcellular localization. Wax, cutin, and sporopollenin are important for normal development of the anther cuticle and pollen exine, respectively. Their lipid soluble precursors, which are produced in the tapetum, are then secreted and transferred to the anther and microspore surface for polymerization. However, little is known about the mechanisms underlying the transport of these precursors. Here, we identified and characterized a member of the G subfamily of ATP-binding cassette (ABC) transporters, OsABCG15, which is required for the secretion of these lipid-soluble precursors in rice. Using map-based cloning, we found a spontaneous A-to-C transition in the fourth exon of OsABCG15 that caused an amino acid substitution of Thr-to-Pro in the predicted ATP-binding domain of the protein sequence. This osabcg15 mutant failed to produce any viable pollen and was completely male sterile. Histological analysis indicated that osabcg15 exhibited an undeveloped anther cuticle, enlarged middle layer, abnormal Ubisch body development, tapetum degeneration with a falling apart style, and collapsed pollen grains without detectable exine. OsABCG15 was expressed preferentially in the tapetum, and the fused GFP-OsABCG15 protein was localized to the plasma membrane. Our results suggested that OsABCG15 played an essential role in the formation of the rice anther cuticle and pollen exine. This role may include the secretion of the lipid precursors from the tapetum to facilitate the transfer of precursors to the surface of the anther epidermis as well as to microspores.

Show MeSH
Related in: MedlinePlus