Tolerance of recurrent mechanical wounding and exogenous ethylene is a feature of the rubber tree. Latex harvesting involves tapping of the tree bark and ethephon is applied to increase latex flow. Ethylene is an essential element in controlling latex production. The ethylene signalling pathway leads to the activation of Ethylene Response Factor (ERF) transcription factors. This family has been identified in Hevea brasiliensis. This study set out to understand the regulation of ERF genes during latex harvesting in relation to abiotic stress and hormonal treatments. Analyses of the relative transcript abundance were carried out for 35 HbERF genes in latex, in bark from mature trees and in leaves from juvenile plants under multiple abiotic stresses. Twenty-one HbERF genes were regulated by harvesting stress in laticifers, revealing an overrepresentation of genes in group IX. Transcripts of three HbERF-IX genes from HbERF-IXc4, HbERF-IXc5 and HbERF-IXc6 were dramatically accumulated by combining wounding, methyl jasmonate and ethylene treatments. When an ethylene inhibitor was used, the transcript accumulation for these three genes was halted, showing ethylene-dependent induction. Subcellular localization and transactivation experiments confirmed that several members of HbERF-IX are activator-type transcription factors. This study suggested that latex harvesting induces mechanisms developed for the response to abiotic stress. These mechanisms probably depend on various hormonal signalling pathways. Several members of HbERF-IX could be essential integrators of complex hormonal signalling pathways in Hevea.

Natural rubber is harvested by tapping Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. Harvesting stress can lead to tapping panel dryness (TPD). MicroRNAs (miRNAs) are induced by abiotic stress and regulate gene expression by targeting the cleavage or translational inhibition of target messenger RNAs. This study set out to sequence miRNAs expressed in latex cells and to identify TPD-related putative targets. Deep sequencing of small RNAs was carried out on latex from trees affected by TPD using Solexa technology. The most abundant small RNA class size was 21 nucleotides for TPD trees compared with 24 nucleotides in healthy trees. By combining the LeARN pipeline, data from the Plant MicroRNA database and Hevea EST sequences, we identified 19 additional conserved and four putative species-specific miRNA families not found in previous studies on rubber. The relative transcript abundance of the Hbpre-MIR159b gene increased with TPD. This study revealed a small RNA-specific signature of TPD-affected trees. Both RNA degradation and a shift in miRNA biogenesis are suggested to explain the general decline in small RNAs and, particularly, in miRNAs.

No abstract

Twelve Cry proteins from Bacillus thuringiensis Berliner were tested in bioassays on cacao plantations in Indonesia for activity against the larvae of cocoa pod borer (Conopomorpha cramerella (Snellen)), an insect pest of the cacao tree. Through the damage caused by their feeding, the larvae of cocoa pod borer cause the pods of the cocoa tree to ripen prematurely. They are difficult to control with conventional measures. Preliminary assays identified five toxins that were more active than others. In two subsequent bioassays the activity of selected toxins was determined more accurately. Three Cryl proteins with relatively little homology were all found to be toxic, opening perspectives for controlling cocoa pod borer by expression of Cry proteins in transgenic plants.

Tersedianya peta pautan genetik merupakan salah satu  syarat dalam identifikasi QTL. Konstruksi peta pautan genetik dapat dilakukan pada tanaman turunan pertama dari suatu persilangan untuk tanaman-tanaman yang menyerbuk bebas dengan menggunakan strategi pseudo-testcross. Tujuan penelitian ini adalah untuk memetakan posisi QTL komponen produksi karet (lilit batang, tebal kulit, jumlah pembuluh lateks, partikel karet) yang mempunyai pengaruh langsung paling besar dengan produksi karet menggunakan analisis marka tunggal. Peta pautan genetik RAPD tanaman karet (2n=36) dibuat menggunakan data marka dengan strategi pseudo-testcross. Populasi hasil persilangan antara klon RRIM 600 dan plasma nutfah PN 1546 digunakan sebagai materi genetik untuk penelitian pemetaan QTL komponen produksi karet. Hasil penelitian menunjukkan bahwa, pada tetua betina (RRIM 600) telah diperoleh tiga kelompok pautan yang dikonstruksi pada LOD 3,0 dan lima kelompok pautan yang dikontruksi  pada LOD 2,0.  Sedangkan pada tetua jantan (PN 1546) telah diperoleh dua kelompok pautan yang dikontruksi pada LOD 2,0. Marka OPH19_650 pada kelompok pautan 2 (KP-2) dan OPB20_1650 pada kelompok pautan 3 (KP-3) diduga terkait dengan sifat produksi karet dan lilit batang. Marka OPC13_2000 pada kelompok pautan 2 (KP-2) dan OPB20_1650 pada kelompok pautan 3 (KP-3) diduga terkait dengan sifat produksi karet dan tebal kulit.  Marka OPC13_2000 dan OPH06_850 pada kelompok pautan 2 (KP-2) diduga terkait dengan sifat produksi karet dan jumlah pembuluh lateks.

Cellulases are the enzymes that hydrolyze cellulosic biomass and are produced by the microorganisms that grow over cellulosic matters. The objective of this research was to isolate and clone cellulase gene from cellulose-degrading bacteria of bovine rumen. Cellulose-degrading bacteria was isolated from rumen fluid using a selective medium. Total RNA was isolated from selected colony having cellulose degrading activity and was used as a template for cDNA construction using reverse transcriptase polymerase chain reaction (RT-PCR) technique. The resulted cDNA was employed as a template for PCR amplification of cellulase gene using specific primers. The cellulase gene candidate obtained was cloned into the pGEM-T-Easy vector followed by determination of its nucleotide sequence. The sequence was then aligned with sequences of cellulase genes from GenBank. Results showed that a number of isolates of rumen bacteria exhibit cellulase activity and the CR-8 isolate was selected for further analysis. The successful isolation of total RNA from CR-8 was indicated by the presence of two intense bands of ribosomal RNA (23S and 16S). The reverse transcription process was successful and the amplification of cellulase gene using the specific primers F1 and R1 resulted in a DNA fragment of 1900 bp as a candidate of cellulase gene. The fragment was successfully cloned into the pGEM-T-Easy vector, and the resulted recombinant plasmid was successfully introduced into the E. coli cells. Nucleotide sequence analysis suggested that the cloned gene is cellulase gene and shares 99% homology with the endo-1,6-beta-glucanase of T. harzianum.

Berdasarkan hasil analisis genetik yang dilakukan terhadap populasi hasil persilangan karet klon RRIM 600 dengan genotipe Plasma Nutfah 1981 menunjukkan bahwa, beberapa karakter yang diamati seperti tinggi tanaman, lilit batang, tebal kulit, jumlah pembuluh lateks, dan produksi karet kering menunjukkan adanya keragaman yang tinggi di antara progeni yang dihasilkan.  Sedangkan untuk karakter jumlah cabang primer, tinggi cabang pertama, diameter pembuluh lateks dan produksi kayu mempunyai keragaman yang rendah di antara progeni yang dihasilkan.  Dari analisis genetik yang dilakukan terlihat adanya nilai heritabilitas (h2) dan nilai kemajuan genetik (KG) yang tinggi masing-masing >0,5% dan  >10% yaitu pada karakter produksi lateks, tinggi tanaman, lilit batang, tebal kulit, dan jumlah pembuluh lateks.  Karakter- karakter tersebut dikendalikan oleh tindak gen aditif dan epistasis, karena itu dapat digunakan sebagai kriteria seleksi pada tanaman karet. Sedangkan karakter tinggi cabang pertama dan produksi kayu dikendalikan oleh tindak gen bukan aditif (overdominan negatif),  demikian halnya dengan karakter diameter pembuluh lateks dikendalikan oleh tindak gen dominan sebagian negatif. Diterima : 21 Januari 2015; Direvisi : 28 Juli 2015; Disetujui : 10 Agustus 2015 How to Cite : Woelan, S., Nissa, C., Chaidamsari, T., & Irwansyah, E. (2015). Analisis genetik populasi hasil persilangan klon RRIM 600 dengan genotipe plasma nutfah 1981. Jurnal Penelitian Karet, 33(2), 101-120. Retrieved from http://ejournal.puslitkaret.co.id/index.php/jpk/article/view/176

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.