Confirming a major QTL and finding additional loci responsible for field resistance to brown spot (Bipolaris oryzae) in rice

Brown spot is a devastating rice disease. Quantitative resistance has been observed in local varieties (e.g., ‘Tadukan’), but no economically useful resistant variety has been bred. Using quantitative trait locus (QTL) analysis of recombinant inbred lines (RILs) from ‘Tadukan’ (resistant) × ‘Hinohikari’ (susceptible), we previously found three QTLs (qBS2, qBS9, and qBS11) that conferred resistance in seedlings in a greenhouse. To confirm their effect, the parents and later generations of RILs were transplanted into paddy fields where brown spot severely occurred. Three new resistance QTLs (qBSfR1, qBSfR4, and qBSfR11) were detected on chromosomes 1, 4, and 11, respectively. The ‘Tadukan’ alleles at qBSfR1 and qBSfR11 and the ‘Hinohikari’ allele at qBSfR4 increased resistance. The major QTL qBSfR11 coincided with qBS11 from the previous study, whereas qBSfR1 and qBSfR4 were new but neither qBS2 nor qBS9 were detected. To verify the qBSfR1 and qBSfR11 ‘Tadukan’ resistance alleles, near-isogenic lines (NILs) with one or both QTLs in a susceptible background (‘Koshihikari’) were evaluated under field conditions. NILs with qBSfR11 acquired significant field resistance; those with qBSfR1 did not. This confirms the effectiveness of qBSfR11. Genetic markers flanking qBSfR11 will be powerful tools for marker-assisted selection to improve brown spot resistance.     

DNA-RAPDs detect genetic variation and paternity in Malus

Summary DNA amplification fingerprinting using arbitrary primer(s) was applied to the identification of Malus species. Highly variable DNA fragment patterns were clearly detected by polyacrylamide gel electrophoresis of the amplified extension products, although three sports of Delicious exhibited the same fingerprint as the original cultivar. The fingerprinting of two triploid apple cultivars suggested that the parent contributing the 2n gamete was the female. We applied this fingerprinting to paternity analysis of an apple cultivar of which the pollen parent was unknown. By using 5 arbitrary primers and RFLP analysis of the amplified products, one cultivar was singled out for paternity among six putative candidates.     

The indica-japonica classification of Asian rice ecotypes and Japanese lowland and upland rice (Oryza sativa L.)

Summary Rice cultivars (Oryza sativa L.) belonging to five ecotypes (aus, aman, boro, bulu and tjereh) and to two groups of Japanese rice (lowland and upland) are examined with respect to KClO₃ resistance, phenol reaction and apiculus hair length. These characters have been used as available criteria to classify rice into two types indica and japonica, for the last thirty years.The findings of this study are that the aman, boro and tjereh ecotypes should be classified as typical indica; and that the Japanese lowland rice cultivars are mainly typical japonica. Some of the aus, bulu and Japanese upland rice cultivars differ from typical indica and typical japonica, so the respective terms aus type, bulu type and J.u.r. type, are proposed. Aman, boro tjereh and Japanese lowland rice are cultivated in lowland. Some of the aus, bulu and Japanese upland rice cultivars have the characteristics of upland rice. In general, lowland rice cultivars can be clearly classified into indica or japonica, while upland cultivars cannot.Abbreviations Aph dominant gene for apiculus hair length > 0.7 mm - aph recessive gene for apiculus hair length < 0.7 mm - J.u.r. type Japanese upland rice type     

Studies on the distribution of complementary genes causing F1 weakness in common rice and its wild relatives. 2. Distribution of two complementary genes,Hwc-1 and Hwc-2 gene in native cultivars and its wild relatives of tropical Asia

Summary Distribution of two complementary genes Hwc-1 and Hwc-2 causing F₁ weakness was examined using 159 native rice cultivars and 30 strains of wild relatives collected from various sites of tropical Asia including the Himalayan foothills. Hwc-1 is carried by a Peruvian cultivar, Jamaica, a tester cultivar of this experiment. It was not found in the tested cultivars and strains. Hwc-2 was widely distributed in the Japonica types tested. No wild strains had either Hwc-1 or Hwc-2. Hwc-2 was infrequent in the Japonica types collected from Southern Asian countries. Hwc-2 was estimated to be indigenous to the Japonica types, may be linked with certain gene(s) related to adaptation.     

Methods for evaluation of soybean chilling tolerance at the reproductive stage under artificial climatic conditions

Several evaluation methods for soybean chilling tolerance at the reproductive stage were examined under artificial climatic conditions. Comparisons were made on plants in control and treated plots using three cultivars differing in the level of chilling tolerance. In all methods, plants were grown at 22/17°C (day/night) until first flowering, and then transferred to growth chambers at 24/17°C for control and 15/15°C for chilling treatment, respectively. A method, in which plants were grown at 20/16°C after 4 weeks of the different temperature treatments, proved comparable to the conventional one, in which chilling tolerance at the flowering stage is evaluated using natural and artificial conditions. Another method, in which the plants in chilling treatment plots were grown at 15°C until maturity, also proved usable to evaluate genotypic differences in chilling tolerance independently of maturity time.     

Attitudes of small-scale forest owners to their properties in an ageing society: Findings of survey in Yamaguchi prefecture, Japan

Populations of most developed countries have been ageing, and the populations of Japanese mountain villages are estimated to have reached into a super-ageing society. In particular, because forestry is unprofitable and due to the economic recession in Japan, many small-scale forest owners face the problems of ageing. For policy-makers, it is important to assess the socioeconomic impacts of forest owners’ ageing in order to ensure the sustainable management of forests. A survey was conducted of forest owners in Yamaguchi Prefecture, which is famous for overall depopulation and ageing of the rural population. It was found that 83% of 687 plantation forest owners who responded in the survey were 60 years or older and 76% did not have forestry income over the past three years, but 81% had kept up ownership of their forest as the traditional family property. In terms of forest management intentions, the respondents were found to consist of four types, namely ‘family management’, ‘commissioned management’, ‘de-accession’ and ‘possession without proper management’. Differences in evaluations of hypothetical policies were found among the four types.     

A soil seed bank in a mature conifer plantation and establishment of seedlings after clear-cutting in southwest Japan

Compositions and spatial distribution patterns of buried viable seeds, and demographic transition from buried viable seeds to seedlings after clear-cutting were examined in a 75-year-old conifer plantation in southwest Japan. A part of the plantation was cleared in December 1997 and study plots were set up on a cleared site and a preserved site. Soil samples (a total of 105 l for the preserved plot and 90 l for the cleared plot) were collected from surface soils in spring 1998 and were incubated in a greenhouse for 120 days. There were an estimated 1064 buried viable seeds per square meter from 67 species in the preserved plot and 1754 seeds/m² from 53 species in the cleared plot. The soil seed bank was from mostly low density species with some high density species, and contained many pioneer species that were absent in the floor vegetation. Buried viable seeds were clumped together, especially in gravity-dispersal species. Although plenty of buried viable seeds were pooled in the soil, few seedlings emerged on the forest floor. In contrast, a number of seedlings, including many pioneer species, emerged in the cleared plots, showing a positive correlation between seed weight and germination rate. It is assumed that dominance of the seedlings established after clear-cutting depends on germination rates and/or growth rates of the seedlings rather than the initial density of buried viable seeds. These results suggest strong contribution of the soil seed bank to the establishment of the secondary vegetation after disturbance in a mature conifer plantation.     

An application of the alkaline extraction – glucoamylase hydrolysis method to analyze starch and sugar contents of bamboo

The alkaline extraction – glucoamylase hydrolysis (AG) method, which extracts sugars and starch by using sodium hydroxide and hydrolyzes starch by using glucoamylase and α-amylase, was compared with the established ethanol extraction – perchloric acid hydrolysis (EPA) method to analyze the sugar and starch contents of moso bamboo (Phyllostachys pubescens Mazel). The results suggested that the two methods had comparable abilities to extract free sugars from moso bamboo. However, the AG method analyzed starch in moso bamboo more accurately than the EPA method under the proper conditions. When we take into account the better time performance of the AG method versus the EPA method, we can conclude that the AG method is superior to EPA for analyzing the sugar and starch contents of moso bamboo.     

Yield and Nutrient Content of Chestnut (<Emphasis Type="Italic">Castanopsis piriformis</Emphasis>) in Natural Central Highlands Forests,Vietnam

Chestnuts have historical importance as a food source worldwide. Planting of chestnuts has focused on a few species, including Castanea dentata, Castanea sativa, Castanea mollissima, and Castanea crenata, although others species are also edible. Castanea species are members of the beech family (Fagaceae) and are native to tropical and temperate areas. In this study, the yield and nut quality of Castanopsis piriformis in natural forests of the Central Highlands of Vietnam were investigated to provide evidence that C. piriformis is worth growing as a food species. Data were collected from 12 plots of 50 m × 50 m size located in four altitude zones. Nuts were collected from three to five chestnut trees in each plot judged to be of typical sized based on diameter at breast height and crown diameter. Average dry yield of nuts was found to be elevation-dependent, being highest at 500–1000 m (1152 kg/ha/year), decreasing to 815 kg/ha/year below 500 m, and to 770 kg/ha/year at 1000–1500 m. The lowest yield was observed at above 1500 m (252 kg/ha/year). Protein and lipid contents in the kernels of C. piriformis chestnut were 4.4 and 0.1 %, respectively. Glucose accounted for 73.1 % and was significantly higher than that of commercially grown Castanopsis boisii chestnuts in Northern Vietnam. With the current price of 0.6 US$/kg nuts, collecting nuts growing in natural forest can bring at least 480 US$/ha/year to local people. These results indicate the possibility of growing and consuming C. piriformis chestnut as a crop to decrease poverty. However, governmental support is required for the sustainable development of C. piriformis.     

Role of metal proteinases in the fruit-body formation ofHypsizygus marmoreus

We investigated the possible role of metal proteinase on the fruit-body formation ofHypsizygus marmoreus. The addition of a specific metal proteinase inhibitor, phosphoramidon, to the culture medium (10g/ml) completely inhibited fruit-body formation. Metal proteinase activity in both the medium and the mycelia of this fungus increased markedly during vegetative mycelial growth, and activity was maximal 25 days after inoculation. When phosphoramidon was added to the culture medium during vegetative mycelial growth, the metal proteinase activity in the mycelium decreased to 56% of the control (without inhibitor) level. Isoelectric focusing analysis showed that two kinds of metal proteinases with a pl of 7.7 and 8.4, respectively, were obtained from 29-day-old mycelia. Uptake of phosphoramidon into the mycelia was confirmed as the result of inhibition of thermolysin activity by the mycelial extracts. The degree of inhibitor uptake into mycelia was about 2.0% and was independent of the initial concentration of the inhibitor administered. The addition of peptone and amino acids to medium treated with phosphoramidon resulted in fruit-body dry weight yields that were about 50% that of the control.