Effect of Frankia inoculation on the growth of Alnus sieboldiana on unsterilized soil

The effect of inoculation with Frankia, a N-fixing actinomycete, on the growth of Alnus sieboldiana seedlings was studied on unsterilized soil from a nursery and an alder stand (forest of Alnus firma). The seedlings of A. sieboldiana were inoculated with Frankia before or after a 2-month culture on sterilized vermiculite, during which they nodulated, and transplanted to unsterilized soil from the nursery and the alder stand. The control seedlings were also cultured on sterilized vermiculite for about 2 months and transplanted to unsterilized soil without Frankia inoculation. The seedling growth, nodulation and N-fixing activity were measured 3, 10 and 16 weeks after the transplantation. Growth and nodule biomass of the seedlings inoculated with Frankia and those grown on the alder soil were better than those without inoculation with Frankia and grown on the nursery soil, respectively. The seedlings inoculated before spontaneous nodulation grew better than those inoculated at the transplantation. Nitrogen-fixing activity measured by acetylene reduction assay at 16 weeks after the transplantation was higher in the seedlings grown on the soil from the nursery than on the soil from the alder stand.     

Butt rot ofChamaecyparis obtusa (Sieb. et Zucc.) Endlicher trees caused byPerenniporia subacida in Shikoku district, Japan: Pathogen, distribution of damaged trees in the stand, and soil investigation

The rot ofChamaecyparis obtusa (hinoki) trees was studied in the northern part of Kagawa Prefecture, Japan. Among 158 hinoki examined, butt rot was found in 28.6, 58.3, and 100% of trees in the 29, 30, and 34-year-old stands, respectively. All trees with butt rot, and 11 trees without it had rotted roots. Thirteen hinoki were peeled byCervus nippon (sika deer) and all of them were infected with butt rot. The maximum height of rot in deer-damaged trees was 2.6 m from the ground level, but was 1.9 m in undamaged trees. About eighty-two percent of rotted trees showed rotted areas of less than 40 cm² on the cross section of stems at the ground level. White mycelia and black flecks sometimes appeared in the rotted wood. Basidiocarps of polyporaceous fungus were often found on felled logs and rotted stumps of hinoki and identified asPerenniporia subacida. Basidiomycetous fungus was isolated frequently from rotted wood of roots and stems, and determined to beP. subacida by comparative study on cultural characteristics. An inoculation experiment and wood-decay test proved that the fungus was the cause of the rot of hinoki. Few absorbing roots of living trees were found in the clayey subsurface soil of the high dry bulk density and the less soil aeration. Some absorbing roots had root rot and the rot spread from the base of the absorbing root to the central part of the woody root. This is the first report on the rot of hinoki caused byP. subacida in Japan.     

QTL pyramiding for improving of cold tolerance at fertilization stage in rice

Vigorous cold tolerance at the fertilization stage (CTF) is a very important characteristic for stable rice production in cold temperature conditions. Because CTF is a quantitatively inherited trait, pyramiding quantitative trait loci (QTLs) using marker-assisted selection (MAS) is effective for improving CTF levels in rice breeding programs. We previously identified three QTLs controlling CTF, qCTF7, qCTF8 and qCTF12, using backcrossed inbred lines derived from a cross between rice cultivar Eikei88223 (vigorous CTF) and Suisei (very weak CTF). However, pyramiding of these QTLs for the application of MAS in practical rice breeding programs have not yet been elucidated. In this study, we examined the effect of pyramiding QTLs for improvement of CTF level using eight possible genotype classes from the 152 F₃ population derived from a cross between Eikei88223 and Suisei. Increasing of CTF levels in combinations between qCTF7 and qCTF12 and between qCTF8 and qCTF12 were detected. Furthermore, we compared the haplotype pattern around the QTLs for CTF among the rice cultivars from Hokkaido. These results are useful for improvement of new cultivars with high CTF levels using MAS and identification of genetic resources with the novel QTL(s) for CTF.     

Major QTLs associated with green stem disorder insensitivity of soybean (Glycine max (L.) Merr.)

Green stem disorder (GSD) is one of the most serious syndromes affecting soybean (Glycine max) cultivation in Japan. In GSD, stems remain green even when pods mature. When soybean plants develop GSD, seed surfaces are soiled by tissue fluid and seed quality is deteriorated during machine harvesting. We performed quantitative trait locus (QTL) analyses for GSD insensitivity using recombinant inbred lines (RILs; n = 154) derived from a cross between an insensitive line (‘Touhoku 129’) and a sensitive leading cultivar (‘Tachinagaha’) during a 6-year evaluation. Three effective QTLs were detected. The influences of these QTLs were in the following order: qGSD1 (LG_H) > qGSD2 (LG_F) > qGSD3 (LG_L). At these three QTLs, ‘Touhoku 129’ genotypes exhibited more GSD insensitivity than ‘Tachinagaha’ genotypes. The lower incidence of GSD for ‘Touhoku129’ was attributable primarily to these three QTLs because RILs harboring a ‘Touhoku 129’ genotype at the three QTLs exhibited a GSD incidence similar to that of ‘Touhoku 129.’ Although a limitation of this study is that only one mapping population was evaluated, this QTL information and the flanking markers of these QTLs would be effective tools for resolving GSD in soybean breeding programs.     

Efficient haploid and doubled haploid production from unfertilized ovule culture of gentians (Gentiana spp.)

Factors affecting reliable plant regeneration from unfertilized ovule culture of gentians (Gentiana spp.) were examined. Cold pretreatment (4°C) of flower buds enhanced or maintained production of embryo-like structure (ELS). When 43 genotypes were surveyed in two different labs, 40 of them produced ELSs ranging from 0.01 to 26.5 ELSs per flower bud. No ELSs could be obtained in three genotypes. A significant correlation (r = 0.64) was observed between the number of ELS per flower and the frequency of responding flower buds. Eight genotypes of G. triflora, which were used as common materials in two different labs, produced ELSs in both labs. The ploidy levels of a total of 1,515 regenerated plantlets were determined, revealing that the majority of these plants consisted of haploids (57.9%) and diploids (34.3%). However, the frequency of haploids and diploids was different between G. triflora and G. scabra, and G. triflora showed higher frequencies of haploids than G. scabra. When haploids were treated with oryzalin for chromosome doubling, diploids and tetraploids were obtained. These results demonstrate that the unfertilized ovule culture technique of gentians is a powerful tool for obtaining haploids and DHs because of its reproducible and reliable nature and application to a wide range of genotypes.     

Identification of QTL controlling post-flowering period in soybean

The length of the reproductive period affects the grain yield of soybean (Glycine max [L.] Merr), and genetic control of the period might contribute to yield improvement. To detect genetic factor(s) controlling the reproductive period, a population of recombinant inbred lines (RILs) was developed from a cross between Japanese landrace ‘Ippon-Sangoh’ and, Japanese cultivar ‘Fukuyutaka’ which differ in their duration from flowering to maturation (DFM) relative to the difference in the duration from sowing to flowering (DSF). In the RIL population, the DFM correlated poorly (r = −0.16 to 0.34) with the DSF in all field trials over 3 years. Two stable QTLs for the DFM on chromosomes (Chr-) 10 and 11 as well as two stable QTLs for the DSF on Chr-10 and -16 were identified. The QTL on Chr-11 for the reproductive period (designated as qDfm1; quantitative trait locus for duration from flowering to maturation 1) affected all three trials, and the difference in the DFM between the Fukuyutaka and Ippon-Sangoh was mainly accounted for qDfm1, in which the Fukuyutaka allele promoted a longer period. qDfm1 affected predominantly the reproductive period, and thus it might be possible to alter the period with little influence on the vegetative period.     

Erratum to: Biomass and nutrient accumulation by cover crops and upland rice grown in succession under no-tillage system as affected by nitrogen fertilizer rate

Journal of Crop Science and Biotechnology - Due to an unfortunate oversight the author’s name and affiliation have been given erroneously. It should be read:     

Determination of leghemoglobin components and xylem sap composition by capillary electrophoresis in hypernodulation soybean mutants cultivated in the field

The hypernodulation soybean mutant lines (NOD1-3, NOD2-4, NOD3-7) and their parent Williams, and the mutant En6500 and its parent Enrei were cultivated in a sandy dune field in Niigata, and the nodules and root bleeding xylem sap were sampled at 50, 70, 90, and 120 d after planting (DAP). The nodule size distribution patterns and concentration of leghemoglobin components were determined. The number of nodules of the hypernodulation mutant lines was about two to three times higher than that of the parent lines irrespective of the sampling date. At 50 DAP the nodule size was relatively smaller in the hypernodulation mutant lines, and the total dry weight of the nodules was almost the same in the mutant lines and their parents. At 70 DAP and 90 DAP, the size distribution of the hypernodulation mutant nodules became .almost the same as that of the parent lines, and both the number and total dry weight of the nodules were higher than those of the parent lines. The concentration of four Lb components was separately measured by capillary electrophoresis. The concentration of the Lb components in the hypernodulation mutant lines tended to be lower than in the parents, but the component ratios were not different between the hypernodulation mutants and their parents. Under field conditions, plant growth and nodulation characteristics were more similar between mutants and parents than in the hydroponic culture reported previously, although the mutants did exhibit hypernodulation traits. These findings suggest that the decrease in the Lb concentration and the different Lb components ratios in the mutants may be caused by secondary effects of excess nodulation, such as photosynthate deficiency, rather than by a genetic defect in mutation. The concentration of major nitrogenous compounds (allantoic acid, allantoin, asparagine, aspartic acid, and nitrate) in the xylem sap was also measured by capillary electrophoresis. The concentration of ureides and nitrate in xylem sap decreased with the plant age, but the asparagine concentration increased during the same period. The concentrations of ureides and asparagine were higher, and the nitrate concentration was lower in the mutant lines than in their parents, possibly due to the higher dependence on N₂ fixation than N0₃ ^- utilization. In the xylem sap, nitrate was the major inorganic anion followed by phosphate, sulfate, and chloride, and potassium was the major cation followed by calcium or magnesium and sodium.