Judul: Over-expression of OsDREB1A gene for improvement of drought tolerance on rice.
Abstrak: Drought is a major factor that influence the growth and productivity of rice. Drought tolerant rice varieties are needed to increase rice production. Development of improved rice varieties can be done through classical breeding and genetic transformation. The research objective was to obtain rice plants containing the construct 35S::OsDREB1A. Agrobacterium tumefaciens mediated transformation of rice cv. Nipponbare using OsDREB1A gene under the control of CAMV 35 promoter produced 81 putative transgenic rice plants (T0) positively containing the transgene based on PCR analysis. The plant height, panicle number, panicle length, and the grain number of transgenic plants were in general lower than the Nipponbare wild type. T1 seeds from selected genotypes were screened for hygromycine resistence, and rice seedlings were evaluated for tolerance to drought stress in the glasshouse, based on the standard evaluation system for rice (IRRI 1996). Five independent transgenic rice plants were identified to be tolerant to drought stress. Molecular characterization using Southern hybridization showed that these plants had 2- 4 copies of transgene. Physiological analysis showed that the drought avoidance is the possible mechanism of adaptation to drought of the transgenic plants. The drought tolerant transgenic plants were crossed to Indonesian elite rice cultivars (Ciherang, Batutegi, Code, and Konawe). Glasshouse evaluation showed that F1 transgenic plants derived from cultivars Batutegi, Code, and Konawe were more tolerant to drought than their wild-type counterparts. F1 transgenic plants were backcrossed into corresponding elit rice cultivars, and PCR analysis showed that those plants contained the transgene. These results showed that 35S::OsDREB1A could be transferred and inherited to elite rice genotipes through crossing. The new drought tolerant germplasms generated in this research can be useful materials for breeding program for improvement of drought tolerance on rice in Indonesia.
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Judul: Morphological and physiological study for drought tolerance in rice (Oryza sativa L.) line
Abstrak: Rice (Oryza sativa L.) is one important source of food, since rice is the staple food of the majority of the people in Indonesia. Increased demand for rice due to the rapid population growth was not met by the slower increase of rice production in Indonesia. Increasing rice production every years, can not compensate for the basic needs population in Indonesia. In addition, an increase in atmospheric temperature is expected to greatly affect of climate global world. Such as the possibility of increasing the frequency and level of drought, this situation can affects the growth and decline in rice production. Drought is a major constrain to increase rice production and it is more prominent with the atmospheric temperature and climate change. Selection for drought tolerant lines and understanding the tolerance mechanism were needed to develop drought tolerant rice variety. A research was conducted in the green house of Cikabayan, University Farm, IPB, during May to September 2010, aimed to study the morphological and physiological aspects related to drought tolerance in rice and to identify drought tolerant lines. A split-Plot Design in a randomized complete block design was applied to a pot experiment with two factor treatments of drought stresses as the main plots and rice lines as the suplots. The drought stress treatment were no drought P1 where the standing water was maintained at 2.5 cm depth and with drought stress P2 where irrigation to 2.5 cm water depth was applied when the soil water potential reaching ≤ - 32 kPa. The line treatments including 100 rice lines obtained from the Indonesian Center for Rice Research (ICRR). Ten rice seeds were sowed on the pots filled with soil media up to 4 cm below the top pot surface. Three healthy and uniform seedlings were maintained in each pots by discarding the others at 3 weeks after sowing. Fertilizers; Urea, TSP, and KCL, were applied rating (2.5 g/pot, respectively). Analysis for prolin and relative water content (RWC) in leaf were done in Molecular marker and Spectrophotometry UV-VIS laboratory, IPB. Analysis chlorophyll content and stomatal density in Micro technique laboratory, IPB. The results of this study indicated that in drought stress treatment, drought tolerant lines exhibit morphological characteristics of broader leaves, more tillers, shorter canopies, and heavier dry canopy weights; and physiological characteristics of higher relative water content (RWC) of leaves as well as higher content of prolin and chlorophyll b. Eighteen drought tolerant lines were identified based on less dry weight reduction by the drought treatment among which B11599D-TB-2-24, B11629C-MR-1-2-1, B11598C-TB-4-1-1 were the most tolerant.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular