In order to prevent patented new cultivars from unauthorized cultivation, a DNA analysis technique aimed at identifying sweetpotato cultivars used for making Hoshi-imo, steamed and dried sweetpotato slices, was developed based on retrotransposon insertion polymorphisms. Insertion sites of the Rtsp-1, an LTR (Long Terminal Repeat) retrotransposon identified in sweetpotato genome, were displayed by the S-SAP (sequence-specific amplification polymorphism) technique for 12 cultivars, which included traditional cultivars and advanced breeding lines for Hoshi-imo production. The S-SAP products, which were present for at least one cultivar but were absent for the others, were cloned and sequenced. PCR primers were designed on the host sequences adjacent to Rtsp-1 insertion. Absence or presence of PCR products of nine cloned Rtsp-1 insertion sites could successfully differentiate the 12 cultivars. An anion-exchange column was able to isolate DNA from Hoshi-imo, although the steaming process had led to the formation of DNA fragments with small sizes. The PCR for Rtsp-1 insertion sites, nevertheless, amplified the expected products from Hoshi-imo DNA and correctly identified the cultivar used for Hoshi-imo production.

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In recent years, sugar beet has been grown by the transplanting method in 95% of the sugar beet fields. However, this method is labor- and cost-intensive. Consequently, a drilled crop that could lead to cost-saving cultivation is now being targeted. To improve the adaptability of the drilling method, it is important to select heavier true seeds correlated with early growth. However, since the investigation depends on manual procedures, the processing of all the materials was associated with much labor and time. Therefore, a new method for estimating the true seed weight simply and efficiently using the spectra of the pulverized sugar beet fruits by Near-Infrared Diffuse Reflectance spectroscopic (NIR) analysis was developed. This method, enabled the estimation of the ratio of true seed in fruits by a quantitative analysis focusing on the spectrum of fat, namely 2310 nm–2346 nm. As a result of Partial Least Squares (PLS) regression analysis, it was considered that the calibration curve included five factors. Therefore, Standard Error for Calibration (SEC) and Standard Error for Prediction (SEP) were the same at 2%. Thus, the correlation coefficient between an actual measurement and an estimated measurement by the NIR method was 0.81. Furthermore, it became possible to compute the true seed weight from the product of this ratio and fruit weight. The actual measurement and the NIR measurement of the true seed weight was closely correlated (correlation coefficient of 0.91). Based on there data, it was shown that the true seed weight of sugar beet could be efficiently estimated by the NIR method. Since the true seed weight could be estimated accurately enough for practical use, this method was found to be useful for selecting lines with a high adaptability to drilled cultivation.

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Three polymorphic loci selected from 5 microsatellite loci isolated from E. colona and 10 microsatellite loci isolated from the chloroplast and nuclear genome of rice were studied by analyzing 170 samples of Japanese Echinochloa spp. Three microsatellite loci revealed a total number of 16 alleles and the DNA sequence of each allele was determined. One hundred and sixty-nine samples of Japanese Echinochloa spp. were classified into 14 types by the combination of these alleles. The samples of the cultivated species E. esculenta were classified into only 2 types among 11 types of the ancestral species E. crus-galli. A tetraploid species E. oryzicola was distinguished from hexaploid species. Moreover, the polymorphisms of ISSR classified 143 Japanese Echinochloa spp. samples into 14 types. E. esculenta showed only one type among 9 types of E. crus-galli. These results suggest that E. esculenta was domesticated from a limited part of the E. crus-galli population.

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