Judul: Peranan strain pineapple mealybug wilt associated virusdan kutu putih dalam menginduksi gejala layu pada tanaman nanas
Abstrak: ARTA JUNITA HUTAHAYAN. The Role of Pineapple Mealybug Wiltassociated Virus Strain and Mealybug (Dysmicoccus spp.) in Inducing Wilt Symptom on Pineapple Plants. Dibimbing oleh GEDE SUASTIKA dan SOBIR Indonesia is a tropic country which have potential to produce exotic fruits like pineapple. Pineapple is very important fruit for world trade. Indonesia is the third largest pineapple tin exporter after Philippine and Thailand. The main problem in pineapple cultivation is wilt disease. Mealybug wilt of pineapple (MWP) is currently present in pineapple-growing areas of West Java, Indonesia. MWP is characterized by severe tip dieback, downward curling, reddening, and wilting of the leaves which can lead to total collapse of the plant. Mealybug feeding on the pineapple plant has been associated with MWP symptom. Furthermore, flexuous rod-shaped virus particles, designated Pineapple mealybug wilt-associated virus (PMWaV) have been isolated from both symptomatic and asymptomatic pineapple plants. PMWaV is actually a complex of at least two different viruses, PMWaV-1 and PMWaV-2 that are transmitted by mealybug. The objectives of this research are to study the role of PMWaV isolates infection and mealybug feeding in inducing wilt symptom on pineapple plants, and to study the incidence of MWP in pineapple-growing areas of Indonesia. Survey for MWP were conducted in pineapple production areas of East Java (Blitar), West Java (Subang and Bogor), and North Sumatera (Simalungun). The incidence of the disease in all of the areas surveyed were found to be ranging from 50% to 90%. These results indicated that MWP has already spread widely in pineapple-growing areas of Indonesia. Transmission of PMWaV from infected pineapple plant to the pineapple test plants using mealybugs Dysmicoccus spp. under greenhouse condition were successfully conducted. The symptoms on the test plants were the same as that on naturally infected plants. The plants inoculated with virus and colonized by mealybug produce more severe symptoms than the plants inoculated with virus only. This indicated that PMWaV infection and mealybug feeding play important role in inducing wilt symptom. But, some pineapple plants surveyed on the field showing MWP symptoms without colonized by mealybug. This finding suggested that PMWaV likely to be the most important causal agent of the MWP, and mealybug feeding making the symptom more severe.
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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: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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