The changes in the contents of two functional constituents, γ-aminobutyric acid (GABA) and (1→3)(1→4)-β-D-glucans (β-glucan), during germination were investigated in two malting barley varieties in order to determine the optimal conditions for accumulation and degradation of these constituents in dried barley grains after germination treatment. A time-course analysis during germination treatment revealed that the content of GABA remarkably increased in the 48 hour imbibition process and decreased in the subsequent germination process. On the other hand, β-glucan, which is known to be decomposed during malting, did not undergo substantial degradation after the 48 hour imbibition process. These findings thus indicated that it is possible to produce germinated barley grains containing these functional constituents at high levels by optimal germination treatment. A total of 43 barley varieties were surveyed for the GABA and β-glucan contents in germinated grains. Our results also indicated that there were varietal differences in the content of each ingredient. A waxy starch variety in which the contents of both β-glucan and GABA were higher than those in the other barley varieties tested, could become a promising source of the two functional constituents.
Genetic diversity and geographic distribution of rice landraces in Yunnan, Southwest China were investigated based on 31 morphological traits (including Ding and Cheng’s classification traits) using 6,121 accessions, 41 morphological traits and 12 polymorphic isozyme loci within the primary core collection of 912 accessions, and 20 microsatellite markers within the core collection of 692 accessions. Yunnan is the richest center of genetic diversity of rice (O. sativa L.) germplasm in China, in which indica varieties were derived from 108 counties in 16 prefectures and japonica varieties from 99 counties in 17 prefectures. Geographic distribution and diversity of six ecogroups and classification traits displayed clear differences. The average diversity indices of six ecogroups of rice landraces in Yunnan ranked as follows: javanica (1.2319), aman (1.1738), communis (1.1726), nuda (1.1618), aus (1.1371) and boro (0.9889), and the percentages were 3.6%, 43.9%, 32.1%, 18.1%, 2.1% and 0.2%, respectively. Lincang, Simao, Xishuangbanna and Dehong prefectures form the genetic and gene diversity center of rice landraces in Yunnan, especially Lincang Prefecture is not only the main genetic diversity center of rice landraces in Yunnan but also the diversity center of Ding’s and Cheng’s classification traits. South marginal paddy-upland rice region with Myanmar is the center of the gene diversity of rice landraces in Yunnan. A core collection from Yunnan rice landraces was identified based on morphological, isozyme and DNA variations, which have confirmed that Yunnan is the center of genetic differentiation of indica and japonica subspecies of Asian cultivated rice.
Tomato plants were transformed with a plasmid that included a legdh1 gene for NADH-dependent glutamate dehydrogenase (NADH-GDH) from Lycopersicon esculentum Mill. coupled, in the sense orientation, with the constitutively active 35S promoter from cauliflower mosaic virus. Three independent transformants were obtained. In these transgenic lines, high-level expression of legdh1 mRNA was detected in the leaves, and the NADH-GDH activity in the leaves of the transgenic plants was approximately twice that in the leaves of the non-transgenic plant. In the transgenic tomato fruits examined for six successive weeks after flowering, the levels of total free amino acids were higher (2.1- to 2.3-fold) than those in the controls. In particular, the level of glutamate was about twice that in the control fruits.
Several quantitative trait loci (QTLs) associated with the apparent quality of brown rice were identified. QTL analysis was carried out using F2 and F3 populations derived from a cross between two japonica varieties, Hana-echizen (high quality of brown rice) and Niigatawase (low quality with numerous white-back and basal-white kernels). F2 individuals were grown in paddy fields in 2003, and F3 lines were grown in paddy fields and in a greenhouse to expose them to high temperature stress during the ripening period in 2004. Apparent quality of brown rice was evaluated based on the percentage of white-back and basal-white kernels. Two putative QTLs associated with white-back kernels in the F2 population grown under low temperature conditions in paddy fields in 2003 were identified on chromosomes 3 and 6. The closest SSR markers were RM4512 and RM3034, respectively. One putative QTL associated with basal-white kernels in the F2 population was identified on chromosome 6. The closest marker was RM3034. Two putative QTLs associated with white-back kernels in the F3 population grown under high temperature conditions in paddy fields in 2004 were identified on chromosomes 4 and 6. The closest SSR markers were RM3288 and RM3034, respectively. One putative QTL associated with white-back plus basal-white kernels in the F3 population grown under high temperature stress in the greenhouse was identified on chromosome 6. The closest marker was RM3034. The QTLs identified near RM3034 on the short arm of chromosome 6 contributed most to the apparent quality of brown rice. The QTLs identified near RM4512 and RM3288 which also affected the apparent quality of brown rice, were detected in either the F2 or F3 population. The QTLs identified in the present study should be useful for marker-assisted selection to breed varieties with a high apparent quality of brown rice, especially varieties with tolerance to kernel damage due to high temperature stress during the ripening period.
The precise guidance of pollen tubes is important for successful fertilization. Based on abnormalities in interspecific and intergeneric crosses, we investigated pollen tube guidance in Torenia fournieri, which is a model plant for studies on plant fertilization due to its protruding embryo sac. Critical abnormalities of pollen tube growth have never been recorded in interspecific crosses between either T. baillonii or T. concolor, and hybrids could be obtained. In contrast, abnormalities appeared in intergeneric crosses with twelve other species. The abnormalities could be observed for five phases of pollen tube guidance revealed in Arabidopsis mutants as follows: germination of the pollen grains, penetration of pollen tube through stigma cells, growth in the transmitting tract, arrival at the placenta and release of sperm into the micropyle. In the self-pollination of T. fournieri, in vivo, the pollen tubes grew straight from the placenta to the protruding embryo sac, omitting funiculus guidance. In addition, observation of an intergeneric cross between T. fournieri (female) and Mimulus hybridas revealed that 64% of the pollen tubes grew straight to the micropyles of ovules rather than to synergid cells, suggesting that the micropyle in T. fournieri transmits the attraction signal. In addition, the signal attracted pollen tubes of M. hybridas to the micropyle, unlike those of T. fournieri.
Somatic embryos of Glycine max (L.) Merrill cultivar ‘Jack’ were co-transformed with the coat protein (CP) gene of attenuated isolates of Soybean mosaic virus (SMV) and hygromycin phosphotransferase gene by microprojectile bombardment. CP gene was detected in eleven transgenic plants, and three independent lines highly resistant to SMV were obtained in a previous study. One of these lines, line No. 55, which was assumed to have acquired RNA-mediated resistance, was selected for further gene expression analysis of T4 and T5 plants in relation to their viral resistance. The resistant plants contained a lower level of transgene-derived RNA than the susceptible ones. On the other hand, based on RNA analysis after mechanical inoculation, SMV-specific RNAs were detected faintly in the resistant plants, while large amounts of RNAs were found in the susceptible ones. During the development of the resistant lines, SMV CP sequence-specific small interfering RNAs (siRNAs) appeared initially in the leaves of the first leaf stage but not in those of the primary stage, and were detected thereafter in the leaves of later stages constantly. The presence of the siRNAs before SMV inoculation was strongly correlated with the resistant phenotype of the lines tested.
A segregating doubled haploid (DH) population (n = 96) was developed by anther culture of an F1 plant crossed between susceptible (‘Manganji’) and resistant (‘Criollo de Morelos 334’) lines of pepper (Capsicum annuum L.) to conduct a genetic analysis of resistance to Phytophthora rot caused by Phytophthora capsici. In order to perform a quantitative trait locus (QTL) analysis, we constructed a high density simple sequence repeat (SSR)-based map with a total length of 878 cM. Sixteen linkage groups (LGs) and 118 SSR markers were located using the 626 SSR markers that we previously developed. Resistance was evaluated in two root inoculation tests. Interval mapping for the resistance to P. capsici detected a common major QTL in the duplicate tests and a minor QTL specific to the first test. The major QTL was located on LG15 and flanked with an SSR marker, CAMS420. In addition, seven SSR markers were located within 21 cM intervals from the peak of this QTL. In contrast, the QTL on LG3 was detected with small effects in the first test, the nearest marker was a dominant amplified fragment length polymorphism (AFLP) marker, and the QTL was surrounded by eight SSR markers within a distance of 10 cM. Since some of the linkage markers for agriculturally valuable traits cannot detect polymorphism within breeding populations in C. annuum, the present linkage markers may widen the choice in marker-assisted selection in breeding programs for Phytophthora rot resistant pepper cultivars.
In the Republic of Korea (South Korea), many high-yielding rice cultivars, called ‘Tongil-type short-culmed (TG) cultivars’, were developed by indica-japonica hybridizations in the 1970s–1990s. The TG cultivars all show a long basic vegetative growth (BVG) period and low photoperiod sensitivity (PS). Such a combination of BVG period and PS, similar to those of modern indica cultivars for the low latitudes, was absent either among Korean or among Japanese japonica cultivars. Subsequent genetic analysis revealed that the long BVG period of the TG cultivars was due to the allelic constitution between the early heading time gene lh(t) and a non-functional allele at the Se1 locus. The low PS of the TG cultivars was conferred by this allele. Sequence analysis showed that the non-functional allele harbored a 4-bp deletion in exon 2, compared with the functional allele Se1-n of the rice cultivar ‘Nipponbare’, and differed in sequence from the known non-functional allele Se1-e. We designated this novel allele as Se1-k. Also lh(t) was found to be a novel gene located on chromosome 8. We designated this gene as lh4 at the Lh4 locus (Late heading-4). Since both Se1-k and lh4 were not detected in japonica cultivars, it was considered that these two alleles were derived from an indica cultivar(s) used as cross parent(s).
The objectives of the present study were to evaluate the tolerance to low temperatures and tuber soft rot in sexual near-pentaploid hybrids between incongruent 2x (1EBN) Solanum commersonii (CMM) and 4x (4EBN) S. tuberosum (TBR). For freezing resistance, killing temperatures both under non-acclimated and under acclimated conditions were determined using the ion leakage procedure. Values for the hybrids were distributed between the wild and cultivated parental values. Some hybrids displayed an acclimation capacity close to 2.5°C, typical of hardy species. Artificial inoculation of tubers with Pectobacterium carotovorum ssp. carotovorum (formerly Erwinia carotovora ssp. carotovora) provided evidence of variability in disease response. Highly resistant hybrids were identified. After conventional phenotypic selection, wild genome content was estimated based on the presence of CMM-specific AFLP fragments. Seven primer combinations were used (Eco-AGG/Mse-CAA; Eco-ACC/Mse-CAT; Eco-ACT/Mse-CAC; Eco-ACT/Mse-CAG; Eco-ACT/Mse-CAA; Eco-ACT/Mse-CAT; Eco-AGG/Mse-CAG). The percentages of CMM-specific AFLPs ranged from 4.3% to 56.7%, with an average value of 28.1%. AFLP analysis was employed for the selection of the hybrids to be used for further breeding objectives.
Sequence rearrangement of rice waxy (wx) mutant N26 induced by thermal neutron irradiation was analyzed by PCR amplification and subsequent DNA sequencing. We found that the genome region of Norin 8, including the Wx locus, had been deleted, corresponding to 39 867 nucleotides for the japonica cultivar Nipponbare. Sequence analysis suggested that a short homologous sequence was used for rejoining without any addition of nucleotides. This is the first mutant in which a complete loss of the Wx locus was induced by thermal neutron irradiation in rice.
Japanese pear exhibits gametophytic self-incompatibility that is controlled by the multiallelic S-locus. The S-locus encodes polymorphic S-RNase for the pistil-part S determinant in Japanese pear. Information about the S-genotypes is important for the selection of pollen donors for fruit production and breeding of Japanese pear cultivars. We determined the S-genotypes of three Japanese pear cultivars, ‘Kinchaku’ (S4Sk), ‘Natsuhikari’ (S3S4) and ‘Wakahikari’ (S3S4), and an F1 hybrid cultivar between a Japanese pear cultivar and a European pear cultivar, ‘Oharabeni’ (S9Se), by PCR-RFLP analysis of S-RNase. A new Sk-RNase allele was identified in ‘Kinchaku’, and full length cDNA encoding Sk-RNase was sequenced. The Sk-RNase was not effectively amplified by the previously published primers. We designed a new PCR primer combination for the amplification of the Sk-RNase allele in addition to the S1- to S9-RNase alleles of Japanese pear, and developed a PCR-RFLP system for identifying the S1- to S9- and Sk-alleles.
Reciprocal crossing was carried out between tetraploid Primula denticulata, section Denticulata and three taxa of P. modesta, diploid P. modesta var. fauriae, diploid P. modesta var. samanimontana and tetraploid P. modesta var. matsumurae, section Aleuritia. Inter-sectional hybrids were successfully obtained in all the reciprocal crosses except when P. modesta var. samanimontana was crossed with the pollen of P. denticulata. The number of hybrids obtained by using P. modesta var. fauriae as maternal parent was extremely low, whereas a large number of hybrids was obtained in the crosses when tetraploid species, P. denticulata and P. modesta var. matsumurae, were used as maternal parent. In all the cross combinations using P. denticulata as maternal parent, both legitimate and illegitimate crosses yielded germinable hybrid seeds. This suggested that in tetraploid P. denticulata heterostylous incompatibility might have decreased or had been lost at least on the female side. In most crosses, the DNA content of the hybrid was intermediate between that of the parents, except for the cross of P. modesta var. fauriae × P. denticulata, where the tetraploid hybrids were mainly produced due to the fertilization of the unreduced female gametes of P. modesta var. fauriae. These results suggest that in most of the zygotes with a lower ratio of female genome than male, development was inhibited in these inter-specific hybridizations.