Molecular Cloning and Sequence Analysis of an Aquaporin Gene Related to Tapping Panel Dryness in Rubber Tree( Hevea brasiliensis Muell. Arg. )

As a syndrome with tapping incision blocked partly or entirely during latex exploiting in rubber tree （Hevea brasiliensis ）, ＂Tapping panel dryness （TPD）＂ causes great yield losses, thereby becoming the most important factor limiting rubber production. On the basis of an EST down-regulated in TPD-affected rubber trees, a 903 bp cDNA denoted HbPIP2;2 was isolated from the bark tissue with a combination of in silico cloning and RT-PCR. The cDNA contains an 867 hp ORF, 13 bp 5＇UTR and 23 bp 3＇ UTR. Sequence analysis indicated that HbPIP2;2 encodes 288 amino acids with a theoretical molecular weight （Mw） of 30. 71 kDa and isolectric point （Pi） of 8.20. Bioinformatics analysis suggested that the deduced protein is predicted to have six transmembrane helices located to the plasma membrane and harbor one conserved MIP domain that can be grouped into plasma membrane intrinsic proteins （PIPs） of aquaporin （AQP） family. Homolo- gy search revealed that the protein shares a similarity of more than 90% with the homologues in Ricinus communis, Popttlus trichocarpa, Juglans regia and Theobro- ma cacao, suooorting a hie.hly conserved evolution. This study provided basis for further uncovering the regulatory role of AOPs in TPD occurrence.

Molecular Cloning and Sequence Analysis of a Tonoplast Aquaporin Gene TIP1 Associated with Tapping Panel Dryness in Hevea brasiliensis

[Objective]To address the role of aquaporins（AQPs）in the occurrence of Tapping Panel Dryness（TPD）,a phenomenon with tapping incision blocked partly or entirely during latex exploiting in the rubber tree（Hevea brasiliensis）that causes great losses on rubber production,a tonoplast aquaporin gene associated with TPD occurence was cloned and analyzed.[Method]Based on an EST down-regulated in TPD-affected rubber trees,a 774 bp cDNA designated HbTIP1 was isolated from the bark tissue of Hevea brasiliensis with a combination of in silico cloning and RT-PCR.And the gene structure and sequence characteristics were analyzed using bioinformatics tools.[Result]The cDNA includes a 759 bp ORF,8 bp 5’UTR and 7 bp 3’UTR.Sequence analysis indicated that HbTIP1putatively encodes 252 amino acids with a theoretical molecular weight（Mw）of 25.88 kDa and isolectric point（pI）of 4.96.Bioinformatics analysis suggested that the deduced protein is predicted to have six transmembrane helices located to the vacuolar membrane and to harbor one conserved MIP domain that can be grouped into the tonoplast intrinsic proteins（TIPs）of aquaporin family.Homology search revealed that the protein shares a similarity of more than 90%with the homologues in Theobroma cacao,Prunus persica,Citrus sinensis and Ricinus communis,supporting a highly conserved evolution.[Conclusion]This study provided basis for further revealing the regulatory role of AQPs in the TPD occurrence.

Molecular Cloning and Bioinformatical Analysis of a cDNA Encoding Mitochondrial 50S Ribosomal Protein L21 from Hevea brasiliensis Muell. Arg.

[Objective] ＂Tapping panel dryness （TPD）＂, a syndrome known as tapping incision blocked partly or entirely during latex exploiting, has become the most important factor causing great losses for rubber production. Aiming to elucidate the molecular mechanism of tapping panel dryness occurrence, this study carried out molecular cloning and bioinformatical analysis of a mRPL21 cDNA sequence, a gene associated with TPD. [Method] In a preliminary study, an expressed sequence tag （EST） encoding a deduced protein homologous to mitochondrial 50S ribosomal protein L21 （mRPL21）, which showed to be down-regulated in the latex of TPD-affected rubber trees, was isolated by suppression subtractive hybridization （SSH）. After ESTs assembling and RT-PCR validation, an 853 bp cDNA sequence with an open reading frame （ORF） was cloned, which was named as HbmRPL21 under GenBank accession number of HM230670. [Result] Bioinformatical analysis suggests that HbmRPL21 encodes a deduced polypeptide of 271 amino acids with a theoretical molecular weight （Mw） of 30.52 kDa and isolectric point （pI） of 8.40, and HbmRPL21 is a mitochondrion-targeted protein with a conserved domain of Ribosomal_L21p involving translation. Homology analysis reveals high amino acid sequence identity of mRPL21 from plants, while diversity of that between plant and animal kingdom. [Conclusion] This study laid the basis for further revealing the biological functions of mRPL21 in TPD-affected rubber trees.