This study was conducted to evaluate the resistance of Asian pear rootstocks to lime-induced iron chlorosis when grown in calcareous soil. Two experiments were conducted in greenhouse condition, using three pear rootstock species: Pyrus xerophila Yü, P. betulaefolia Bunge, and P. calleryana Decne). Plants were grown over 90 days in pots filled with calcareous soil. Difference in iron chlorosis tolerance was estimated by chlorophyll contents by using chlorophyll meter readings, iron contents in leaves, and growth parameters of plants. Among the three pear rootstocks, P. xerophila showed higher chlorophyll and iron content in fully expanded apical leaves than did P. betulaefolia and P. calleryana in high pH, calcareous soil. It was further confirmed in the grafting experiment with the ‘Housui’ cultivar. These results confirmed that P. xerophila has a higher tolerance to lime-reduced iron chlorosis. However, further plant evaluation under field conditions is needed to verify whether P. xerophila can replace the widely used, P. betulaefolia in the Asian pear producing areas with high pH and calcareous soil, especially in the northwestern region of China.
Self- and cross-incompatibility in European pear (Pyrus communis L.), which is estimated by the fruit set and seed formation, is yet unclear. We carried out self-, cross- and non-pollinations with one flower per cluster on 10 European pear cultivars, and estimated their parthenocarpic potential, and self- and cross-incompatibility. Most cultivars exhibited parthenocarpy, which suggests that the fruit set is not a suitable criterion for distinguishing incompatibility from compatibility. However, clear judgment could be provided by using the self-incompatibility (SI) index, (the number of viable seeds per flower obtained from test pollination / the number of viable seeds per flower resulting from compatible cross-pollination) × 100, as a new criterion. Based on this index, ‘Grand Champion’ has proven to be partially self-compatible, whereas others were classified as self-incompatible. Traits of the seeded fruits, such as weight, size, and soluble solids content, were superior to those of the parthenocarpic fruits. Thus, cross-compatible pollination is necessary for a stable fruit set and production of large, good quality fruits in cultivars with a high parthenocarpic potential. Two cross-incompatible combinations were found between ‘Flemish Beauty’ and ‘Starkrimson’, and ‘Bartlett’ and ‘Seigneur d' Espéren’, respectively.
Significant differences in fructose content were detected among different cultivars of the peach (Prunus persica (L.) Batsch). To investigate the factors that regulate fructose concentrations in peach fruit, we measured the activities of fructose-related enzymes in two eating-quality peaches, ‘Akatsuki’ and ‘Kawanakajima hakuto’, and two native-type peaches, ‘Nagano yaseito Early’ and ‘Noto zairaito No. 2’. Fructose contents in the fruit of the eating-quality peach cultivars, measured from 3 months after flowering to the ripe stage, ranged from 7 to 12 mg · g-1 FW, whereas those of the native-type peach cultivars were less than 1 mg · g-1 FW. There were no clear differences between the two groups with respect to fructokinase, fructose-6-phosphatase, and phosphoglucose isomerase (PGI) enzyme activities although they were low in ‘Noto zairaito No. 2’. In all cultivars, the activity of PGI was much higher than that of the other enzymes. This finding suggests that isomerization by PGI is not the rate-limiting step in the synthesis of fructose. The concentration of fructose-6-phosphate (Fru6P) in the fruit did not differ between the two groups. These results suggest that the differences in fructose content in different peach cultivars are related to different capacities for fructose production rather than to differences in the ability to convert fructose to Fru6P and then to glucose-6-phosphate. NAD-dependent sorbitol dehydrogenase (SDH) activity was found to be higher in the eating-quality peach cultivars than in the native-type peach cultivars during all fruit development stages tested in this study. It is therefore likely that SDH, which contributes to the production of fructose from sorbitol, is responsible for the regulation of fructose concentrations in peach fruit.
The size distribution patterns of tannin molecules in the fruits of ‘Luo Tian Tian Shi’ (a Chinese PCNA) and several Japanese PCNA and non-PCNA (PVNA, PVA, PCA) cultivars were examined by size-exclusion chromatography by using a TSK gel Toyopearl HW-55F column with a mobile phase of acetone-8 M urea (6:4; adjusted to pH 2.0). The progeny from the cross between ‘Luo Tian Tian Shi’ and ‘Taishu’ (a Japanese PCNA), or between ‘Fuyu’ (a Japanese PCNA) and 275-13 (a selection from the cross between ‘Aizumishirazu’ (a Japanese non-PCNA) and ‘Taishu’), were also examined for the size distribution pattern of tannin molecules. The tannin molecules of the fruits from Japanese PCNA cultivars were relatively small, whereas those from Japanese non-PCNA cultivars were large. Moreover, all PCNA individuals segregated from the cross between ‘Fuyu’ and 275-13, had small tannin molecules in the fruits, and all non-PCNA-type individuals segregated from the same cross had large tannin molecules. However, the size distribution in the fruits of ‘Luo Tian Tian Shi’, a Chinese PCNA cultivar, was the same as that in non-PCNA cultivars that have large tannin molecules. Although both PCNA-type and non-PCNA-type were segregated in the F1 progeny from the cross between ‘Luo Tian Tian Shi’ and ‘Taishu’, the fruits of all offspring in this progeny had large tannin molecules irrespective of whatever it was PCNA or non-PCNA. These results clearly indicate that the Chinese PCNA, ‘Luo Tian Tian Shi’, is distinguishable among PCNA cultivars of Japanese origin and supported the previous hypothesis that the origin of PCNA-type in China differs from that in Japan.
To improve rust resistance of bunching onion (Allium fistulosum L.), we applied a recurrent selection program by using six cultivars (C0): ‘Seito Ippon’, ‘Iwai 2’, ‘Choju’, ‘Senami’, ‘Fuyuogi Ippon’ and ‘Toyokawa Futo’. Each cycle of recurrent selection consisted of two steps: selfing and selection among selfed progenies in the first year, and intercrossing and maternal-line selection in the second year. A second-cycle improved population (C2), consisting of 10 maternal lines, was obtained by two cycles of recurrent selection. Furthermore, we conducted two generations of selfing and progeny selection, and obtained 13 C2S2 lines. To evaluate the effectiveness of this recurrent selection, we conducted two rounds of simultaneous inoculation tests and compared the rust resistance of all generations obtained in the selection program. Under inoculation tests in the spring and autumn, the value of the area under the disease progress curve (AUDPC), an index of disease intensity, definitely decreased with the progress of recurrent selection. Although the resistance gain from C1 to C2 was small, much progress was made in the C2S2 generation; the AUDPC in C2S2 lines was approximately 38% of that in the initial parental cultivars. Our results demonstrate that recurrent selection is effective in improving the rust resistance of bunching onion.
Sex, as a factor affecting recombination during meiosis, was investigated in Cucumis melo L. A pair of backcrosses, using an F1 male parent (BCM) and an F1 female parent (BCF) was generated. The two populations were mapped at 34 loci. Total map lengths in the respective populations were nearly indistinguishable, whereas 4 marker intervals, parts of the linkage groups in the map, were significantly different between BCM and BCF.
Sudden wilting of grafted plants after a long-term normal growing is a characteristic of a typical delayed graft-incompatibility. Although hydraulic conductance is low at the root of plants grafted onto dwarfing rootstocks, it is unclear whether hydraulic conductance is low at the graft union in delayed graft-incompatible combinations of scions and rootstocks. Hence, growth, stem thickening, water potential, hydraulic resistance and xylem morphology at the graft union of tomato plants grafted onto tomato, eggplant, and torvum (Solanum torvum) rootstocks were compared. Indices of stem thickening, absolute value of water potential and curving of xylem vessels immediately above graft interface were the greatest in torvum rootstock, less in eggplant rootstock and the least in tomato rootstock. The index of hydraulic resistance was larger in Solanum rootstocks than in tomato rootstock. It is concluded that increased hydraulic resistance at the graft union is a cause of delayed graft-incompatibility.
It was determined from the morphology, chromosome and isozyme analyses that Camellia × vernalis (Makino) T. Tanaka et al. resulted from hybridization between C. sasanqua and C. japonica. Since the chloroplast in Camellia is entirely maternally inherited, the presence of C. sasanqua chloroplasts in C. × vernalis would indicate the species is the seed parent of these hybrids. PCR products of the atpI-atpH gene region from all accessions of C. sasanqua and C. × vernalis showed a single band at ca. 800 bp, while those of C. japonica showed one at ca. 1200 bp, suggesting that 1) the seed parent of the putative primary (F1) hybrid, ‘Gaisen’ is C. sasanqua, 2) the seed parents of the first backcross generation to C. japonica, triploid cultivars of C. × vernalis, are considered to be ‘Gaisen’, and 3) the seed parents of the second backcross generation, the ‘Egao’ type tetraploid cultivars, are derived from triploid C. × vernalis cultivars. That C. × vernalis originated about four hundred years ago as determined from the age of the oldest tree on Hirado Island and from the records in the Japanese books published in 1630 was confirmed by our data. Furthermore, we conclude from our evidence that the seed parent of C. × vernalis is C. sasanqua.
Strong antimicrobial activity was observed in water extracts of tulip anthers. Purification by column chromatography and structural analysis by various methods, such as liquid chromatography-mass spectrometry (LC-MS), 1H-, and 13C-nuclear magnetic resonance (NMR) revealed that the active compound was 6-tuliposide B (6-O((S)-4', 5'-dihydroxy-2'-methylenebutyryl)-D-glucopyranose). The antimicrobial susceptibility test revealed that it showed a strong growth inhibition against Gram-positive, Gram-negative bacteria and certain fungicide tolerant strains except for a yeast. Among the 22 cultivars (Tulipa gesneriana L.) and 15 Tulipa species, antimicrobial activities of the anthers from cultivars were stronger than those of the wild species. These production abilities of 6-tuliposide B in anthers were not related to pollen fertility. During anther development, the production of 6-tuliposide B was confined for a short period of approximately 7 to 12 days before flowering. Hence, it appeared that the 6-tuliposide B in anthers was produced in a tissue- and stage-specific manner with higher 6-tuliposide B accumulation than that observed in other tissues that produce both 6-tuliposides A and B. These results suggest that a novel defense strategy evolved in tulips to protect pollens from bacterial pollution in the reproductive process by producing an anther-specific 6-tuliposide B.
Fluorochrome staining with chromomycin A3 (CMA) was used to characterize and compare the CMA banding patterns of chromosomes in eight species of citrus that are cultivated in Japan. Chromosomes were classified into five types based on the number and position of CMA positive bands; A: two terminal and one proximal band, B: one terminal and one proximal band, C: two terminal bands, D: one terminal band, E: no band. The CMA banding patterns were 1A+1C+8D+8E in Hassaku, 2A+2C+5D+9E in Hyuganatsu, 1A+2C+7D+8E in Natsudaidai ‘Kawano natsudaidai’, 1A+1B+1C+8D+7E in Iyo ‘Miyauchi iyokan’, 1A+1B+1C+8D+7E in Tankan ‘Tarumizu 1 gou’, 3B+2C+5D+8E in Kabosu, 1B+2C+9D+6E in Sudachi and 2B+1C+11D+4E in Yuzu ‘Yamane’. A similar CMA banding pattern was observed in related species examined in this study.
Multiple tomato shoots were regenerated from calli formed on pruning wounds of young stock plants. Plants that unfolded their 10th true leaf were decapitated between the 7th and the 8th true leaves to force numerous lateral shoots. When these shoots were cut just beneath their first leaf, numerous adventitious buds differentiated from calli that developed into shoots. During 36 days after heading back lateral shoots, 79 shoots were regenerated from the stock plant. More than 62.5% of the lateral shoots developed calli from which additional shoots differentiated. The average number of shoots regenerated from each lateral stem increased with higher leaf positions. Thus, a reliable method is offered to regenerate multiple shoots from young stock plants.
Minor floral anthocyanins of a red-flowered petunia were isolated and determined by chromatographic and spectroscopic methods. Petunidin 3-glucoside (1.7%) and malvidin 3-glucoside (1.3%) were determined for the first time in the genus Petunia. Incomplete substrate specificity of anthocyanin 3'- and 3', 5'-methyltransferase is considered to be a cause for accumulating a small amount of 3-glucosides of petunidin and malvidin in the flowers.
A new cropping system for the warm temperature zone in Japan was developed on the basis of the flowering response in the non-pinching cultivation in snapdragons (Antirrhinum majus L.). First, the duration between the time the seeds were sown (every month) and the time to flowering were determined. The number of days from sowing to flowering was longest when seeds were sown in October; it was shortest when sown in June. The plant height was shortest when seeds were sown in June whereas it was tallest when sown in September. The cultivars bred in Japan seemed to belong to Group I or Group II. For harvest of cut flowers from summer to autumn, seeds of Group III cultivars that were sown in the mid-June to the end of July or those of Group IV sown between mid-June to mid-July yielded the best results. For optimum harvest from autumn to winter, seeds of Group I or II cultivars should be planted from mid-August to mid-October. To harvest flowers from spring to summer, we planted seeds of Group I and II cultivars in February or those of Group III and IV from the end of February to March. This cropping system makes cut snapdragon flowers available throughout the year.