Judul: Biochemical and Transcriptomic Analyses in Phalaenopsis Response to Soft-Rot Disease Pathogen (Dickeya dadantii)
Abstrak: Phalaenopsis orchid is one of the orchid genera with high ornamental and economic value. Soft-rot disease (SRD) is a devastating disease in Phalaenopsis orchid caused by the necrotrophic pathogens, Dickeya dadantii. Evaluations of several Phalaenopsis species for their response to D. dadantii infection reveal that P. amboinensis is the most resistant, while P. amabilis is a very susceptible species. Resistant species information related to biochemical and molecular response under pathogen infection is essential in providing resistant parents to conduct conventional and molecular breeding programs of Phalaenopsis. Resistant species can be used as the parent in cross-breeding, while the biochemical and molecular mechanism of plant resistance can be used to develop biochemical and molecular markers for selecting resistant progenies. The main purpose of the research is to identify the intraspecies variation response of P. amboinensis and P. amabilis to SRD pathogens and analyze the possible resistance mechanism through a biochemical and transcriptomic approach. The research is provided on three topics. The first topic aims to evaluate intraspecies resistant variation in the P. amboinensis and P. amabilis wild populations and identify the plants that show resistance or susceptible responses to D. dadantii consistently to be used as breeding materials and resistant mechanism study in further experiments. The second topic was aimed to study the possible role of Phenylalanine ammonia-lyase (PAL), Peroxidase (POD), salicylic acid (SA) and jasmonic acid (JA) in the susceptible or resistance response of P. amboinensis and P. amboinensis to D. dadantii infection and its potential for biochemical markers for resistance to SRD. In the third topic, transcriptomic analyses based on the RNA sequencing approach were performed in P. amboinensis as a prospective resistant parent to predict the molecular plant response to D. dadantii infection and the potential genes and molecular mechanism involved in resistant species. The research results show the intraspecies variation of P. amboinensis and P. amabilis wild populations in their response to D. dadantii infection. The responses of 47 P. amboinensis and 29 P. amabilis individuals were tested against D. dadantii using the detached leaf inoculation method. Soft-rot symptom diameter was measured at 6 to 42 hours post-inoculation (HPI) for disease assessment, including disease symptom diameter, disease severity, and resistance level to D. dadantii. Of 47 plants of P. amboinensis, 2.13% are very susceptible, 2.12% are susceptible, 4.25% are moderate resistant, and 91.49% are resistant, while in P. amabilis, 20.69% are very susceptible, 3.45% are susceptible, 13.78% are moderate susceptible, and 62.08% are resistant. SRD-resistance trait in P. amboinensis is more stable compared to the P. amabilis. The selected resistant plants of P. amboinensis and very susceptible plants of P. amabilis were used for the second and third topics of the dissertation. The second topic of the research was predicting the biochemical defense (defense-related enzymes, PAL and POD, and signal transduction hormones (SA and JA) that may be involved in Phalaenopsis resistance mechanisms to SRD pathogen. The endogenous PAL, POD, SA and JA were measured under mock and D. dadantii inoculation on P. amboinensis and P. amabilis. The results showed that PAL and POD activities were higher in P.
Keyword: orchid, resistance mechanisms, RNA sequencing, species

Judul: Pertumbuhan dan Ketahanan terhadap Penyakit Busuk Lunak pada Anggrek Phalaenopsis dengan Pemupukan dan Asam Salisilat.
Abstrak: Maintaining is one of the important processes in Phalaenopsis plants cultivation to get high quality plants. Practically, it is aimed to promote plant grow quickly, healthy and free of diseases. One of main disease on Phalaenopsis is soft rot which caused by Dickeya dadantii bacteria. The use of resistant varieties, application of NPK fertilizers and salicylic acid for growth and resistance are alternatives that can be used to prevent the disease. The purposes of this study were to analyze the Phalaenopsis orchid resistance to soft rot diseases that caused by D. dadantii, determine the effect of NPK fertilizer and salicylic acid concentration as well as the interaction between them for growth and resistance to soft rot diseases caused by D. dadantii. The experiments were conducted at the Bacterial Plant Laboratory, Department of Plant Protection and Greenhouse Leuwikopo, Bogor Agriculture University and plastic house Alam Sinar Sari Dramaga, Bogor, Indonesia. The treatments used for the first experiment were five Phalaenopsis hybrids, namely Phal. KHM 205, Phal. KHM 1126, Phal. KHM 1318, Phal. AMP 17, and Phal. KHM 2249. Phal. amabilis and Phal. amboinensis used as control. Phalaenopsis hybrids used in the second experiment were Phal. KHM 1318 and Phal. KHM 205. The first factor was NPK concentration (0, 1000 and 2000 ppm) and the second one was the concentration of salicylic acid (0, 5 and 10 ppm). The resistance test on some genotype of Phalaenopsis to D. dadantii showed that all Phalaenopsis hybrid had the symptoms of soft rot disease. Phal. KHM 2249 which had the lowest number of leaves reduction and the highest number of life plants after infection was indicated as resistance genotype relatively compared to others in the experiment. The resistance could be came from highest peroxidase activity, low leaf thickness and water content that were not appropriate for pathogen development. The results in the second experiment showed that NPK fertilizer increased growth of Phal. KHM 1318 and Phal. KHM 205. NPK fertilization 1000 and 2000 ppm showed the same effects on all growth variables. Salicylic acid did not have significant effect in improving plant growth. The increased of NPK concentrations reduced plant resistance to soft rot disease which could be seen from increasing of disease symptoms area and the number of fallen leaves and decreasing of the number of life plants after soft root infection on both genotype. Salicylic acid application on Phal. KHM 1318 could not improve plant resistance to soft root although it increased peroxidase activities. Adversely on Phal. KHM 205, salicylic acid could decreased disease symptom area but did not increased peroxidase activity.
Keyword: D. dadantii, leaf thickness, leaf water content, PAL, peroxydase

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf