MEKANISME INFEKSI VIRUS KUNING CABAI (PEPPER YELLOW LEAF CURL VIRUS) DAN PENGARUHNYA TERHADAP PROSES FISIOLOGI TANAMAN CABAI

Infeksi virus kuning cabai (Pepper Yellow Leaf Curl Virus) menyebabkan penurunan hasil hingga 75% terutama pada musim kemarau. Penyakit ini hanya dapat ditularkan oleh serangga vektor kutu kebul (Bemisia tabaci L.) dan bukan merupakan seed born diseases. Masa inkubasi virus dalam tanaman hingga memunculkan gejala hanya memakan waktu 15-29 hari. Mekanisme infeksi virus diawali dengan replikasi dan pembentukan protein virus di dalam tubuh tanaman menggunakan ATP dari tanaman inang. Proses ini diikuti dengan perubahan proses fisiologi yang berupa peningkatan aktivitas protein anaplerotik, peningkatan laju fotosintesis dan peningkatan kandungan pati. Setelah proses replikasi selesai maka laju fotosintesis akan turun yang disebabkan oleh induksi dan degradasi dinding sel floem dengan menghidrolisis sukrosa menjadi glukosa dan fruktosa. Gejala yang ditimbulkan akibat infeks i virus ini adalah daun tanaman menjadi menguning dan mengeriting. Hal ini disebabkan oleh menurunnya jumlah membran tilakoid, stroma membesar dan volume fotosintesis mengecil. Hal ini juga menyebabkan menurunnya laju fotosintesis yang dapat menyebabkan penurunan produksi tanaman cabai. Kata Kunci: virus, infeksi, fisiolog

Saponins accumulation and antimicrobial activities on shallot (Allium cepa L.) from marginal land

Saponins are one of the secondary metabolites found in Shallot (Allium cepa L.), particularly in the roots. Microclimate differences in the cultivation area are thought to have a significant impact on the production of secondary metabolites, such as saponins. This research aimed to observe the saponins content in the root of shallot plants cultivated in marginal agricultural land and their antimicrobial activity against bacteria (Ralstonia solanacearum) and fungus (Fusarium oxysporum). This research was observational research with a random sampling method. The samples were collected from the shallot plantation with two different cultivation conditions. Two varieties of ‘Bima' and 'Tiron' cultivated by farmers in sandy coastal land Samas, Bantul were used. The plants were harvested at 1, 1.5, and 2 months after planting, respectively. The crude saponins extract was used to test antimicrobial activity. Shallot plants cultivated in marginal coastal sandy land produced higher saponins accumulated in their roots. The saponins production increased along with the maturity of shallot plants, both cultivated in marginal coastal sandy land and regular paddy field. The saponins extracted from the roots of shallots cultivated in both marginal and regular land showed higher antimicrobial activity than antifungal activity. Saponin merupakan salah satu metabolit sekunder yang terdapat pada bawang merah (Allium cepa L.), terutama pada bagian akar. Perbedaan iklim mikro pada lahan budidaya diduga akan berpengaruh terhadap produksi metabolit sekunder termasuk saponin. Tujuan penelitian ini adalah untuk mengetahui kandungan saponin pada bagian akar tanaman bawang merah yang dibudidayakan di lahan pertanian marginal serta aktivitas antimikrobanya terhadap bakteri (Ralstonia solanacearum) dan jamur (Fusarium oxysporum). Penelitian ini merupakan penelitian observasi dengan metode pengambilan sampel secara acak. Sampel berasal dari perkebunan bawang merah dengan dua lahan budidaya yang berbeda. Digunakan dua varietas yaitu 'Bima' dan 'Tiron' yang dibudidayakan oleh petani di daerah pantai Samas,kabupaten Bantul. Bahan tanaman dipanen pada tiga waktu berbeda, yaitu 1 bulan, 1,5 bulan dan 2 bulan berturut-turut setelah tanam. Ekstrak kasar saponin digunakan untuk menguji aktivitas antimikrobanya. Tanaman bawang merah yang dibudidayakan di lahan marginal pasir pantai menghasilkan saponin yang  lebih tinggi yang terakumulasi pada akarnya. Produksi saponin semakin meningkat seiring dengan umur tanaman bawang merah, baik yang dibudidayakan di lahan marginal pasir pantai maupun di lahan sawah biasa. Saponin yang diekstraksi dari akar bawang merah yang dibudidayakan di lahan marginal dan lahan biasa menunjukkan aktivitas antimikroba yang lebih tinggi daripada aktivitas antijamurnya

ISOLASI DAN KARAKTERISASI BAKTERI PROTEOLITIK DARI LIMBAH CAIR INDUSTRI TAHU

Abstrak Penelitian ini bertujuan untuk mengisolasi bakteri proteolitik dari limbah cair industri tahu, mengetahui karakter dan indeks protease bakteri proteolitik terpilih dari limbah cair industri tahu. Produksi enzim protease oleh bakteri proteolitik diketahui dengan adanya zona bening di sekitar koloni bakteri pada media Skim Milk Agar (SMA). Perhitungan indeks proteolitik dilakukan pada bakteri yang memiliki aktivitas protease. Hasil penelitian menunjukkan terdapat 13 isolat yang memiliki aktivitas protease. Satu isolat (LTN 19) dengan indeks protease tertinggi sebesar 3,15 dipilih untuk dikarakterisasi morfologi, mikroskopik, dan biokimia. Berdasarkan karakterisasi yang telah dilakukan, isolat LTN 19 memiliki kemiripan dengan genus Staphylococcus dengan persentase kemiripan sebesar 85,7%. Kata kunci: bakteri proteolitik, enzim protease, limbah cair industri tahu Abstract The aims of this study were to do proteolytic bacteria isolation, to determine the character and protease index of selected proteolytic bacteria from tofu industry liquid waste. The production of protease enzyme by proteolytic bacteria is known by the presence of clear zone around bacterial colonies on Skim Milk Agar (SMA) media. Proteolytic index calculations are performed on bacteria that have protease activity. The results showed that there were 13 isolates that had protease activity. One isolate (LTN 19) with the highest protease index of 3.15 was selected for morphological, microscopic, and biochemical characterization. Based on the characterization that has been done, isolate LTN 19 has similarities with the genus Staphylococcus with a similarity percentage of 85.7%. Keywords: proteolytic bacteria, protease enzyme, tofu industry liquid wast

LESSON STUDY DALAM PERKULIAHAN BIOLOGI UMUM DENGAN SOCIOSCIENTIFIC ISSUES-BASED INSTRUCTION UNTUK CHARACTER BUILDING

ABSTRAK   Telah dilakukan kegiatan Lesson Study (LS) dalam rangka pengembangan kompetensi pendidik bidang biologi di perguruan tinggi untuk agar mengembangkan dan mengimplementasikan pembelajaran biologi yang berorientasi pada character building sekaligus meningkatkan kualitas pembelajaran. Secara spesifik, fokus pencapaian kegiatan LS ini adalah: 1) pengembangan kemampuan dosen biologi dalam mengembangan dan mengimplementasikan pembelajaran biologi umum dengan socioscientific issues-based instruction secara kolegial dalam tim LS, dan 2) menumbuhkembangkan karakter peduli dan reflective judgement mahasiswa pendidikan kimia dalam konteks ilmu biologi umum. Prosedur pelaksanaan LS ini mengikuti tahap-tahap plan-do-see, yang dilaksanakan sebanyak tiga putaran. Instrumen yang digunakan meliputi: 1) perangkat pembelajaran biologi umum berbasis socioscientific issues, 2) lembar pengamatan aktivitas dosen, 3) lembar pengamatan aktivitas belajar mahasiswa, dan 4) lembar penilaian reflective judgment. Data yang diperoleh dianalisis secara deskriptif. Hasil kegiatan LS menunjukkan adanya dinamika, tantangan dan hambatan yang dialami baik oleh dosen model maupun subjek mahasiswa.   Kata kunci: lesson study, biologi umum, socioscientific issues, character buildin

Anatomical, morphological and physiological leaf characters of black betel (Piper betle L. var. nigra) in varying natural and man-made habitats

Piper betle L. var. nigra or black betel (known as Sirih hitam in Indonesia) contains valuable secondary metabolites, such as alkaloids, flavonoids, saponins, tannins, phenols, carotenoids, steroids and terpenoids. Black betel leaf extract has been shown to have antimicrobial activity thus there is a prospect to be developed as a promising herbal plant. Nevertheless, little information is available about its development as a medicinal plant. This research studies the influence of different habitats on several characters of black betel leaves with the aim to understand the suitable environmental conditions for the optimum growth of black betel plants. We used a survey method and random sampling of black betel leaves in four locations in Java Island, Indonesia, namely Banyuwangi which represents natural habitat, and Karanganyar, Ngaglik and Pakem which represent man-made habitats. Measurements of temperature, humidity, soil moisture and light intensity were carried out at each location. Analyses of leaf area, leaf water content, total leaf chlorophyll content and flavonoid content were undertaken and statistically analyzed using SPSS software. Leaf transverse sections were also observed. The results showed that the environmental parameters differed in the four locations. Leaves samples from the natural habitat in Banyuwangi were significantly different (P<0.05) from the three man-made habitats for chlorophyll and flavonoid content. For water content, significant difference was only for Banyuwangi samples with those from Karanganyar and Pakem. For leaf area, significant difference was only found between the Banyuwangi samples and Karanganyar. Observations on the transverse cross section of midrib of black betel leaves from the four locations showed structures that are generally found in Piper betle species, namely the presence of an epidermal layer, trichomes in the abaxial part of the leaf, several layers of the hypodermis, visible vascular tissue and the presence of secretion cells. There were several differences in the leaf anatomy such as greater number of trichomes on the leaves from Karanganyar, the secretory cells that were more visible in the leaves from Ngaglik and Banyuwangi and the sclerenchymal tissue that was more visible in the leaves from Banyuwangi. Such differences are likely influenced by variations in environmental parameters thus showing that the man-made habitat in the Karanganyar location can affect leaves characters similar to black betel plant grown in its natural habitat in Banyuwangi

Classification of chili plant origin by using multilayer perceptron neural network

The geographical origin of the plants can affect the growth and hence the quality of the plants. In this research, the origin of the chili plants has been investigated by using Fourier transform infrared (FTIR) spectroscopy. The spectroscopy generated 3734 data with a wavenumber range from 4000–400 cm −1 . The pre-processing of the spectra was done by using baseline correction and vector normalization. The analysis was then taken in the biofingerprint area of 1800–900 cm −1 range which has 934 data points. Feature extraction for dimension reduction was achieved using principal component analysis (PCA). The PC scores from PCA were then fed into a k-means and a multilayer perceptron neural network (MLPNN). The k-means clustering shows that the samples can be distinguished into three different groups. Meanwhile, for the MLPNN, the number of the hidden layer's neurons and the learning rate of the system were optimized to get the best classification result. A hidden layer with twenty neurons had the highest accuracy, while a learning rate of 0.001 had the highest value of 100%

Gas chromatography-mass spectrometry analysis of compounds emitted by pepper yellow leaf curl virus-infected chili plants : a preliminary study

Pepper yellow leaf curl virus (PYLCV) is a threat to chili plants and can significantly reduce yields. This study aimed as a pilot project to detect PYLCV by analyzing compounds emitted by chili plants using gas chromatography-mass spectrometry (GC-MS). The samples investigated in this research were PYLCV-infected and PYLCV-undetected chili plants taken from commercial chili fields. The infection status was validated by using a polymerase chain reaction (PCR) test. A headspace technique was used to extract the volatile organic compounds emitted by plants. The analysis of GC-MS results began with pre-processing, analyzing sample compound variability with a boxplot analysis, and sample classification by using a multivariate technique. Unsupervised multivariate technique principal component analysis (PCA) was performed to discover whether GC-MS could identify PYLCV-infected or not. The results showed that PYLCV-infected and PYLCV-undetected chili plants could be differentiated, with a total percent variance of the first three principal components reaching 91.32%, and successfully discriminated between PYLCV-infected and PYLCV-undetected chili plants. However, more comprehensive studies are needed to find the potential biomarkers of the infected plants