The Striking Flower-in-Flower Phenotype of Arabidopsis thaliana Nossen (No-0) is Caused by a Novel LEAFY Allele

The transition to reproduction is a crucial step in the life cycle of any organism. In Arabidopsis thaliana the establishment of reproductive growth can be divided into two phases: Firstly, cauline leaves with axillary meristems are formed and internode elongation begins. Secondly, lateral meristems develop into flowers with defined organs. Floral shoots are usually determinate and suppress the development of lateral shoots. Here, we describe a transposon insertion mutant in the Nossen accession with defects in floral development and growth. Most strikingly is the outgrowth of stems from the axillary bracts of the primary flower carrying secondary flowers. Therefore, we named this mutant flower-in-flower (fif). However, the transposon insertion in the annotated gene is not the cause for the fif phenotype. By means of classical and genome sequencing-based mapping, the mutation responsible for the fif phenotype was found to be in the LEAFY gene. The mutation, a G-to-A exchange in the second exon of LEAFY, creates a novel lfy allele and results in a cysteine-to-tyrosine exchange in the α1-helix of LEAFY’s DNA-binding domain. This exchange abolishes target DNA-binding, whereas subcellular localization and homomerization are not affected. To explain the strong fif phenotype against these molecular findings, several hypotheses are discussed.

The Striking Flower-in-Flower Phenotype of Arabidopsis Thaliana Nossen (No-0) is Caused by a Novel LEAFY Allele

The transition to reproduction is a crucial step in the life cycle of any organism. In Arabidopsis thaliana the establishment of reproductive growth can be divided into two phases: Firstly, cauline leaves with axillary meristems are formed and internode elongation begins. Secondly, lateral meristems develop into flowers with defined organs. Floral shoots are usually determinate and suppress the development of lateral shoots. Here, we describe a transposon insertion mutant in the Nossen accession with defects in floral development and growth. Most strikingly is the outgrowth of stems from the axillary bracts of the primary flower carrying secondary flowers. Therefore, we named this mutant flower-in-flower (fif). However, the transposon insertion in the annotated gene is not the cause for the fif phenotype. By means of classical and genome sequencing-based mapping, the mutation responsible for the fif phenotype was found to be in the LEAFY gene. The mutation, a G-to-A exchange in the second exon of LEAFY, creates a novel lfy allele and results in a cysteine-to-tyrosine exchange in the α1-helix of LEAFY´s DNA-binding domain. This exchange abolishes target DNA-binding, whereas subcellular localization and homomerization are not affected. To explain the strong fif phenotype against this molecular findings, several hypotheses are discussed.

Kloning gen LEAFY kakao dari jaringan bantalan bunga aktif Cloning of cacao LEAFY gene from the active flower cushions

SummaryAttempts to improve productivity of cacaoplantations lead us to study the molecularmechanism of flowering. In the model speciesArabidopsis thaliana as well as some otherspecies, LEAFY is a central regulatory gene forthe transition of shoot apical meristems toflowering meristems. Different from that ofArabidopsis, cacao inflorescence is acauliflorous type, by which flowers can developrepeatedly from the same flower cushion on thetrunk. In this research, a LEAFY homolog wasisolated from active flower cushion with RT-PCRusing a pair of DNA primer specifically designedto isolate its complete cds. Gel electrophoresisexamination indicated the presence of a 1.2 kbamplicon. Purified from the gel, this DNAfragment was cloned into competent cells ofE. coli XL1 Blue using pGEM-T Easy cloningvector at an orientation according to the T7promoter of the plasmid. Sequence analysis usingBLASTX, showed that the amplicon was LEAFY(LFY) homolog. Alignment analysis using ClustalW indicated that the cTcLFY highly homologousto those from other perennial crops such ascitrus, grape, apple and poplar. The highesthomology (conserved region) was found in the Cterminal of the encoded proteins.RingkasanUsaha untuk meningkatkan produktivitasperkebunan kakao telah mendorong penelitianmolekuler tentang mekanisme pembungaankakao. Pada tanaman model Arabidopsis thalianadan lainnya, LEAFY merupakan gen kunci dalamtransisi meristem tunas jadi meristem bunga.Berbeda dengan sistem pada Arabidopsis,pembungaan kakao termasuk tipe cauliflorous,bunga dapat muncul dari bantalan bunga yangsama sepanjang tahun. Dalam penelitian inihomolog LFY diisolasi dari bantalan bunga aktifmenggunakan RT-PCR dengan sepasang primerspesifik yang dirancang berdasarkan sekuenDNA di kedua ujung gen tersebut. Pemeriksaangel elektroforesis menunjukkan adanya amplikontunggal berukuran 1,2 kb. Setelah dimurnikandari gel, amplikon dapat diklon ke dalam selkompeten E. coli galur XL1 Blue menggunakanvektor pGEM-T Easy dengan orientasi yangsesuai dengan promoter T7 dari vektor. AnalisisBLASTX sekuen DNA membuktikan bahwaamplikon tersebut adalah homolog dari genLEAFY. Analisis penjajaran dengan mengguna-kan ClustalW menunjukkan bahwa gen cTcLFYtersebut memiliki homologi yang tinggi dengangen sejenis dari tanaman keras lainnya sepertitanaman jeruk, anggur, apel dan poplar.Homologi tertinggi (daerah terkonservasi)terdapat pada ujung (terminal) C dari proteinyang disandinya.

Kloning gen LEAFY kakao dari jaringan bantalan bunga aktif Cloning of cacao LEAFY gene from the active flower cushions

SummaryAttempts to improve productivity of cacaoplantations lead us to study the molecularmechanism of flowering. In the model speciesArabidopsis thaliana as well as some otherspecies, LEAFY is a central regulatory gene forthe transition of shoot apical meristems toflowering meristems. Different from that ofArabidopsis, cacao inflorescence is acauliflorous type, by which flowers can developrepeatedly from the same flower cushion on thetrunk. In this research, a LEAFY homolog wasisolated from active flower cushion with RT-PCRusing a pair of DNA primer specifically designedto isolate its complete cds. Gel electrophoresisexamination indicated the presence of a 1.2 kbamplicon. Purified from the gel, this DNAfragment was cloned into competent cells ofE. coli XL1 Blue using pGEM-T Easy cloningvector at an orientation according to the T7promoter of the plasmid. Sequence analysis usingBLASTX, showed that the amplicon was LEAFY(LFY) homolog. Alignment analysis using ClustalW indicated that the cTcLFY highly homologousto those from other perennial crops such ascitrus, grape, apple and poplar. The highesthomology (conserved region) was found in the Cterminal of the encoded proteins.RingkasanUsaha untuk meningkatkan produktivitasperkebunan kakao telah mendorong penelitianmolekuler tentang mekanisme pembungaankakao. Pada tanaman model Arabidopsis thalianadan lainnya, LEAFY merupakan gen kunci dalamtransisi meristem tunas jadi meristem bunga.Berbeda dengan sistem pada Arabidopsis,pembungaan kakao termasuk tipe cauliflorous,bunga dapat muncul dari bantalan bunga yangsama sepanjang tahun. Dalam penelitian inihomolog LFY diisolasi dari bantalan bunga aktifmenggunakan RT-PCR dengan sepasang primerspesifik yang dirancang berdasarkan sekuenDNA di kedua ujung gen tersebut. Pemeriksaangel elektroforesis menunjukkan adanya amplikontunggal berukuran 1,2 kb. Setelah dimurnikandari gel, amplikon dapat diklon ke dalam selkompeten E. coli galur XL1 Blue menggunakanvektor pGEM-T Easy dengan orientasi yangsesuai dengan promoter T7 dari vektor. AnalisisBLASTX sekuen DNA membuktikan bahwaamplikon tersebut adalah homolog dari genLEAFY. Analisis penjajaran dengan mengguna-kan ClustalW menunjukkan bahwa gen cTcLFYtersebut memiliki homologi yang tinggi dengangen sejenis dari tanaman keras lainnya sepertitanaman jeruk, anggur, apel dan poplar.Homologi tertinggi (daerah terkonservasi)terdapat pada ujung (terminal) C dari proteinyang disandinya.

Phylogeny of Korean Rubus (Rosaceae) based on the second intron of the LEAFY gene

Yang, J., Yoon, H.-S. and Pak. J.-H. 2012. Phylogeny of Korean Rubus (Rosaceae) based on the second intron of the LEAFY gene. Can. J. Plant Sci. 92: 461–472. The second intron of the LEAFY gene was used for phylogenetic analysis of Rubus (Rosaceae). The LEAFY gene is conserved among a wide variety of plants and is known to be involved in the morphological evolution of plants. Sequence comparison of LEAFY homologues revealed the phylogenetic relationships of previously unresolved taxa, suggesting the usefulness of this marker rather than the ITS region for representing nuclear gene trees. In addition, a combined analysis of the trnL/F intergenic region of chloroplast DNA and the second intron of the LEAFY gene yielded more imformative data. Based on the data, it was inferred that evolution proceeded from herbs to woody plants, compound leaf to simple leaf, and pink petal to white petal within Korean Rubus taxa. Moreover, the LEAFY and trnL/F combined phylogeny had similar topology with the Rubus classification based on morphological characteristics. Therefore, our results indicate that LEAFY and trnL/F were valuable regions for analyzing the phylogenetic relationships among the Rubus taxa in Korea.