Judul: Identification of Viruses Cause Pineapple Mealybug Wilt Disease on Pineapple Clone 7350 and Clone MD2 in Blitar Regency, East Java
Abstrak: Nanas (Ananas comosus L. Merr) merupakan salah satu komoditas ekspor penting di Indonesia. Namun, produksinya terkendala oleh infeksi patogen, termasuk virus. Baru-baru ini, survei lapangan di area produksi nanas di Kabupaten Blitar menemukan gejala mirip infeksi virus seperti daun kemerahan bercampur dengan klorosis dan ujung daun nekrotik dengan kejadian hingga 50% pada klon 7350. Penyakit ini telah diketahui menginfeksi nanas. Namun sampai saat ini identitas genetik virus penyebab penyakit layu mealybug di Indonesia masih terbatas. Penelitian bertujuan untuk mendeteksi dan mengidentifikasi spesies virus yang berasosiasi dengan penyakit layu nanas di Kabupaten Blitar. Total RNA diekstraksi dan dideteksi dengan One-Step RT-PCR menggunakan primer universal Ampelovirus, primer spesifik dari pineapple mealybug wilt-associated virus (PMWaV) 1 dan 2. Sampel positif kemudian dikonfirmasi dengan analisis runutan nukleotida. PMWaV-1 dan -2 berhasil diamplifikasimenggunakan primer spesifik pada klon 7350 dan tidak ada sampel yang terdeteksi menggunakan primer universal Ampelovirus. Di sisi lain, semua pasang primer tidak mendeteksi virus target pada klon MD2, menunjukkan gejala klorosis mungkin disebabkan oleh patogen lain. Urutan parsial gen HSP70 mengkonfirmasi keberadaan kedua spesies virus. Isolat PMWaV-1 Blitar memiliki kesamaan tertinggi (100%) nukleotida dan asam amino dengan isolat dari Taiwan dan Meksiko. Selain itu, isolat PMWaV-2 Blitar menunjukkan homologi masing-masing 99% dan 100% untuk kesamaan nukleotida dan asam amino, dengan isolat dari Taiwan, Mauritius, Kuba, dan Ghana. Hasil dari penelitian ini memastikan adanya dua spesies virus (PMWaV-1 dan -2) yang menyebabkan penyakit layu mealybug., Pineapple (Ananas comosus L. Merr) is one of the essential export commodities in Indonesia. However, virus infection causes significant yield loss. Current field survey at a pineapple production area in Blitar Regency found virus-like infection symptoms such as leaf reddish intermingle with chlorosis and necrotic leaf tips on clone 7350 and MD2 with incidence 50% and 3%, respectively. To date, there was still few information of viruses infecting pineapple in Indonesia. The aim of this study is to identify the virus species associated with mealybug wilt pineapple disease in Blitar Regency. Total RNA was extracted then detected through one-step RT-PCR method using three primer sets, including a universal primer of Ampelovirus and two specific primer pairs (PMWaV-1 and -2). Positive samples then were confirmed by nucleotide sequencing. The PMWaV-1 and PMWaV-2 were successfully amplified using specific primers on clone 7350 and there were no samples detected using Ampelovirus universal primers. In the other hand, all the primer sets did not detect any virus target on clone MD2, indicating chlorosis symptom might be caused by other pathogens. Partial sequences of the HSP70 gene confirmed the existence of both virus species. The PMWaV-1 Blitar isolates shared the highest similarities (100%) of nucleotide and amino acid with isolates from Taiwan and Mexico, respectively. Moreover, the PMWaV-2 Blitar isolates shared 99% and 100% similarities of nucleotide and amino acid, respectively with isolates form Taiwan, Mauritius, Cuba, and Ghana. The finding of this study confirmed the existence of two viruses (PMWaV-1 and -2) causing pineapple mealybug wilt disease.
Keyword: Ampelovirus, Ananas comosus, HSP70, PMWaV, RT-PCR

Judul: Deteksi dan identifikasi pineapple mealybug wiltassociated virus penyebab penyakit layu pada tanaman nanas di Indonesia
Abstrak: Field surveys on pineapple wilt disease were conducted on pineapple production areas in Subang, West Java, Indonesia. The disease was characterized by severe tip dieback, downward curling, reddening, and wilting of the leaves which can lead to total collapse of the plant. The objective of the research is to identify the viruses causing wilt disease on pineapple in Indonesia. Tissue blot immunoassays (TBIAs) using two different antibodies specific to either Pineapple mealybug wilt-associated virus-1 (PMWaV-1) or PMWaV-2 (Agdia Inc., USA) successfully detected the viruses in leaf tissues from both symptomatic and asymptomatic pineapple plants. A reverse transcription-polymerase chain reaction (RT-PCR) assays using oligonucleotide primers specific to HSP 70 gene of PMWaV-1 and PMWaV-2 were also successfully amplified the regions succesfully. These finding indicated that both closteroviruses were associated with wilt disease on pineapple plants in Indonesia. Protein analysis by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the viruses have a major structural protein with molecular mass of approximately kDa. Flexuous filamentous particles were also observed in electron microscopy preparations from infected plants. These results were in agreement with characteritics of the closteroviruses. Aligments of partial nucleotide sequences of the viral genomes exhibited 96 to 98% homology with that of PMWaV-1 and PMWaV-2 Hawaiian isolates as previously reported by Sether et al. (2001), respectively. Phylogenetic analysis revealed that Indonesian and Hawaiian virus isolates were belong to mealybugtransmitted closterovirus and closely related to Grapevine leafroll-associated virus-3 (GLRaV-3)., Penelitian ini bertujuan untuk mendeteksi dan mengidentifikasi PMWaV yang berasosiasi dengan penyakit layu pada tanaman nanas di Indonesia. Diharapkan penelitian ini dapat memberikan informasi dan laporan pertama mengenai keberadaan PMWaV yang berasosiasi dengan penyakit layu nanas di Indonesia. Hasil deteksi secara serologi dengan metode Tissue blot immunoassays (TBIA) menggunakan dua antibodi monoklonal spesifik terhadap PMWaV-1 maupun PMWaV-2 (Agdia Inc., USA) berhasil mendeteksi keberadaan PMWaV- 1 dan PMWaV-2 pada jaringan daun tanaman nanas yang menunjukkan maupun dari yang tidak menunjukkan gejala layu. Pendeteksian secara molekuler dengan metode reverse transcription-polymerase chain reaction (RT-PCR) menggunakan dua primer yang spesifik terhadap PMWaV-1 dan PMWaV-2 berhasil mengamplifikasi gen Heat Shock Protein 70 (HSP 70) pada kedua virus. Penemuan ini mengindikasikan bahwa PMWaV-1 dan PMWaV-2 berasosiasi dengan penyakit layu nanas yang terjadi di Indonesia. Analisis protein menggunakan sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDSPAGE) menunjukkan adanya sebuah struktural protein besar dengan perkiraan ukuran sebesar 23 kDa. Keberadaan partikel virus berbentuk batang lentur juga teramati pada preparasi mikroskop elektron yang berasal dari tanaman nanas yang terinfeksi virus. Hasil pengamatan menggunakan mikroskop elektron ini sesuai dengan ciri-ciri virus dari anggota Closterovirus. Analisis parsial genom HSP 70 virus layu nanas isolat Indonesia menunjukkan kisaran homologi sebesar 96 hingga 98% dengan PMWaV-1 dan PMWaV-2. Selain itu, analisis filogenetik menunjukkan bahwa isolat PMWaV Indonesia dan Hawaii merupakan anggota Closterovirus yang ditularkan oleh kutu putih, dan memiliki hubungan kekerabatan yang dekat dengan Grapevine leafroll-associated virus-3 (GLRaV-3).
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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