Disproportionating enzyme (D-enzyme) is a 4-αglucanotransferase (EC 2.4.1.25) that cleaves an α-1,4 glucosidic bond of α-1,4 glucan (donor molecule) and transfers the resulting glucan moiety to a non-reducing end of an acceptor molecule by creating a new α-1,4 glucosidic bond. D-enzymes have been identifi ed in a number of plant species and characterized most extensively in potato 1 7) and Arabidopsis, 8,9) but also studied in pea, 10) wheat, 11) germinating barley seed 12) and sweet potato tubers. 13) These studies showed that plant D-enzymes have common reaction characteristics, where the smallest donor molecule is maltotriose, the smallest acceptor molecule is glucose and the smallest transferred glucan unit is maltose. Similar enzymes are also present in bacteria but bacterial 4-α-glucanotransferases are historically called amylomaltases; the term D-enzyme is only used for plant 4-α-glucanotransferases. Bacterial amylomaltases catalyze similar reactions, but differ slightly in substrate and reaction specifi city. 7) Amylomaltase can use maltose as a donor molecule (although maltose is less effective than larger maltooligosaccharides) and can catalyze glucosyl as well as glucanosyl transfer reactions. 7) It should be noted that reported plant D-enzymes cannot use maltose as a donor and never catalyze glucosyl transfers. The D-enzymes described above are now called DPE1 in order to distinguish them from recently identifi ed isoforms, DPE2, which have been characterized in both Arabidopsis 14 16) and potato. 17) Despite their similarity in primary Abstract: This work aims to characterize disproportionating enzyme (DPE1) and its isoform DPE2 in rice. Rice DPE genes (OsDPE1 and OsDPE2) were cloned and expressed in E. coli. The OsDPE1 and OsDPE2 genes encode proteins of 594 and 946 amino acids with a calculated molecular mass of 67 kDa and 108 kDa, respectively. Purifi ed recombinant OsDPE1 and OsDPE2 showed highest activity at around pH 7.0 and pH 6.0 7.0, respectively. The optimum reaction temperature was 30 C for OsDPE1 and 39 C for OsDPE2. Recombinant OsDPE1 disproportionates maltotriose to produce glucose and maltopentaose, and thus shares the defi ning behavior of D-enzymes. In our experiments, recombinant OsDPE2 catalyzed the glucose transfer reaction from maltose to an acceptor molecule such as glycogen. We also characterized the differences between the diurnal transcription profi les of OsDPE1 and OsDPE2 in rice leaves and seeds, and their temporal expression levels in developing rice seeds.

Subak had been known as superior and sustainable water management system in Bali’s paddy field, and had a long history as an interesting topic for study. Water management in Subak is more or less based on religious practices and the philosophy of the harmony among God, human and nature, that ensures equity and sufficiency of water diversion. Traditionally there is no water regulation in the meaning of gate operation as most Subak has their own water source from definite location, and fixed system was used for water diversion that defined portion of water discharge and not quantity. In this study, field monitoring system had been set up to continuously observe the water balance components such as: rainfall, evapotranspiration, percolation, field water status. With the available data, water balance equation can be used to obtain net inflow, which in this case only minimum, median and maximum for each particular month. These values were used to summarize total annual net inflow to the field, which ranges from 4575 to 7419 mm.  This is accounted as total water use for rice production at the site and generally it can be concluded as the amount of water required to sustain the present paddy field of the Subak.

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