Cytoplasmic male sterility (CMS) is a useful system to produce hybrid seeds in a variety of crop species. In eggplant, CMS systems were developed utilizing the cytoplasms of six wild Solanum species by repeated backcrossings. These CMS systems were classified into two types. The first one is anther indehiscent-type sterility in the CMS systems of eggplant with the cytoplasms of Solanum kurzii Brace & Prain, S. violaceum Ort., and S. virginianum L., in which anther contains normal pollen but does not open to release. The second one is pollen non-formation-type sterility in the CMS systems of eggplant with the cytoplasms of S. aethiopicum Aculeatum Group, S. anguivi Lam., and S. grandifolium C.V. Morton, in which anther of the male-sterile lines is completely devoid of pollen. Both types of sterility system were characterized by investigating pollen and seed fertility. Furthermore, in pollen non-formation CMS systems, two independent dominant fertility restorer (Rf) genes were discovered and a sequenced characterized amplified region (SCAR) marker tightly linked to these genes was developed.
Molecular and genetic analyses of flower development have been conducted primarily in dicot model plants such as Arabidopsis thaliana and Antirrhinum majus. The obtained data are the basis for the ABC model, which was extended to the ABCE model of floral development. This model has been validated in many dicot species using genetic transformation studies and mutant analyses. Many dicot flowers have two distinctive perianth whorls, which include greenish sepals and showy petals. By contrast, the monocot lily flower has two almost identical petaloid whorls, the inner and outer tepals. To explain this type of floral morphology, a modified ABC model, the further extended modified ABCE model, was proposed. According to this model, B-class genes are expressed in whorls 1–3, and whorls 1 and 2 form petaloid structures. This review describes the molecular mechanisms regulating flower development in monocots. Since the showy perianth is one of the most important traits in floricultural crops, we focused on the B- and C-class genes, which are related to the development and modification of the perianth. The review describes the expression patterns of floral organ identity genes, and presents functional studies using double-flowered and viridiflora cultivars in some monocot species. Besides lily-type flowers, there are several types of monocot flower, such as commelina type with two whorls of distinctive perianth, orchid and grass flowers. The review also describes the molecular analyses of these types of monocot flower.
In citrus, fruit bearing affects floral induction and the nutritional condition of the tree. For this reason, bearing too many or too few fruit causes fluctuation in flower number the following spring. This in turn leads to annual alternation between rich and poor crops, known as alternate bearing. To identify the metabolites related to alternate bearing, quantitative metabolomics analysis was conducted with stem tissues of vegetative shoots collected in November. Twelve Satsuma mandarin trees bearing different amounts of fruit were used in this study. Fruit weight per leaf area of these trees was significantly and negatively correlated with the expression of a flowering-related gene, citrus FLOWERING LOCUS T, in the stem in November and the number of flower buds the following spring. In metabolomics analysis, adenosine triphosphate was detected at high concentrations in lightly fruiting trees. Other coenzymes such as uridine triphosphate, nicotinamide adenine dinucleotide phosphate, and ascorbic acid were also more abundant in the off-crop trees. In addition, the off-crop trees accumulated sugar phosphates such as fructose 6-phosphate, glucose 6-phosphate, and ribulose 1,5-diphosphate. Furthermore, heavily fruiting trees accumulated more amino acids. These results indicate that fruit bearing affects the metabolism of coenzymes, sugars, and amino acids in the stem of vegetative shoots.
We investigated the effect of soil surface management on radiocesium accumulation in an apple orchard in Fukushima Prefecture over 4 years after Tokyo Electric Power Company’s Fukushima Daiichi nuclear power plant accident in mid-March 2011. Different types of soil surface management such as clean cultivation, intertillage management, intertillage with bark compost application, sod culture, and zeolite application were employed. The radiocesium concentrations in soil were higher in the surface layer (0–5 cm) than in the other layers. The radiocesium concentration in the surface layer soil with sod culture in 2014 increased non-significantly compared with that observed in 2011. The radiocesium concentration in the mid-layer soil (5–15 cm) managed with intertillage was higher than that in soil managed using other types of management. The radiocesium amount in the organic matter on the soil surface was the highest in sod culture, and was significantly lower in the management with intertillage. The radiocesium concentration in fruit decreased exponentially during the 4 years in each types of soil surface management. The decrease in radiocesium concentration showed similar trends with each type of soil surface management, even if the concentration in each soil layer varied according to the management applied. Furthermore, intertillage with bark compost application did not affect the radiocesium concentration in fruit. These results suggest that the soil surface management type that affected the radiocesium distribution in the soil or the compost application with conventional practice did not affect its concentration in fruit of apple trees for at least 4 years since the nuclear power plant accident, at a radiocesium deposition level similar to that recorded in Fukushima City.
Changes in cold hardiness, proline (Pro) content, and related gene expression were confirmed in the shoots of two peach cultivars (Prunus persica ‘Janghowon Hwangdo’ and ‘Odoroki’) during natural cold hardening (CH) and dehardening (DH), and 10 supplemental peach cultivars during experimental DH. Specifically, transcript accumulations of P5CS (Δ1-pyrroline-5-carboxylate synthase) and P5CR (Δ1-pyrroline-5-carboxylate reductase) were examined using quantitative real-time RT-PCR. The cold hardiness of the shoots of the two cultivars differed significantly during the entire experimental period. The cold hardiness of both cultivars increased gradually until December 2012, and then decreased until April 2013, whereas their Pro contents decreased from the beginning of the experiment until February 2013 and then increased in the spring. While the cold hardiness of the 10 peach cultivars decreased, their Pro contents increased during DH. Interestingly, the expression of the P5CS gene encoding an enzyme that catalyzes the conversion from glutamate (Glu) to glutamic-γ-semialdehyde (GSA) in the first step of the Pro pathway showed patterns contrasting with the Pro contents in both experiments. In contrast, the expression of the P5CR gene encoding an enzyme that catalyzes the conversion from Δ1-pyrroline-5-carboxylate (P5C) to Pro in the final step of the Pro pathway showed patterns similar to the Pro contents in both experiments. Our results demonstrate that Pro accumulation responds positively to higher temperatures in the shoots of different peach cultivars, including the 10 supplemental peach cultivars, and the expression of both P5CS and P5CR genes showed contrasting patterns. Our results suggest that identification of the expression of both P5CS and P5CR genes is required for the accurate analysis of Pro biosynthesis because Pro accumulation is more affected by the expression of P5CR genes. Furthermore, notably, during the experimental DH, the expression of OAT (ornithine-δ-aminotransferase) increased. Our results suggest that the ornithine pathway could serve as an alternative pathway in the Pro synthesis process during DH in peach.
This paper reports the level of genetic differentiation between two Japanese and one Chinese species of Eutrema: E. japonicum, “wasabi”; its wild relative in Japan, E. tenue; and their wild relative in China, E. yunnanense. Phylogenetic analyses were based on the DNA sequence of the chloroplast trnK/matK region of 16 Brassicaceae and an outgroup species. Neighbor joining (NJ) and maximum parsimony (MP) trees were constructed, revealing that the three Eutrema species form a single clade clearly separated from other Brassicaceae species. The two Japanese Eutrema species are highly differentiated from Chinese E. yunnanense, and it is estimated that they diverged from E. yunnanense approximately 5 million years ago. An ethnobotanical survey was conducted among ethnic Chinese in Yunnan Province, and the results indicate that E. yunnanense is not perceived as “hot” in taste, while a pungent flavor is associated with wasabi; in addition, no evidence was found for the domestication of E. yunnanense. On the basis of the present molecular phylogenetic study and the ethnobotanical survey, we conclude that wasabi acquired its specific pungent flavor during its long botanical history in Japan, and that its subsequent domestication in Japan was because of this acquired pungent flavor. The culinary habit of using wasabi with raw fish has since become an important feature of Japanese cuisine and culture.
The Brassica genus comprises various important species, of which three diploid species, B. rapa (A genome), B. nigra (B), and B. oleracea (C), yielded three different pair-wise amphidiploids: B. juncea (AB), B. napus (AC), and B. carinata (BC), showing the “triangle of U”. Although DNA sequences of many genes have been analyzed to reveal the relationships between A, B, and C genomes, the phylogeny of any single-copy nuclear gene has not supported the entire relationships of U’s triangle. Most nuclear genomic sequences of plants have genetically recombined between alleles in inter-specific hybrids, while we recently found that intron 19 and nucleotide tag (Ntag) sequences of the single-copy nuclear PolA1 gene, encoding RNA polymerase I’s largest subunit, had rarely recombined during the introgressive hybridizations in Aegilops speltoides. Because phylogenetic analysis including recombined sequences cannot reveal the phylogeny before the recombination occurred, only analysis of non-recombinational DNA sequences can resolve the true evolutionary route. In this study, the phylogenetic relationships of the PolA1 gene in the six Brassica species were clearly consistent with U’s triangle. In addition, two groups of B. napus were shown divergently to have originated from the amphidiploidization between B. oleracea and two progenitors of B. rapa.
The flower colors and anthocyanin constitution of sixteen cultivars of Saintpaulia were surveyed to determine the relationship between their flower colors and anthocyanin components. Six anthocyanins were isolated from the flowers of these cultivars as major anthocyanins along with three minor ones, and their structures were identified by co-HPLC or chemical and spectroscopic techniques. Among them, a novel anthocyanin, pelargonidin 3-O-[6-O-(4-O-(acetyl)-α-rhamnopyranosyl)-β-glucopyranoside] (pelargonidin 3-acetyl-rutinoside; 8) was found in cultivars of ‘Georgia’ and ‘Jessica’ as a major anthocyanin. Regarding the flower color variation in these cultivars, the hue values (b*/a*) of these flower colors were responsible for the glycosidic positions in the anthocyanidin molecule and also the combination of anthocyanins. These flower colors were classified into six groups, A–F, based on the flower colors and anthocyanin components were arranged as follows. In violet-blue flowers of group A (hue values b*/a* = −2.61–−1.72, VB N89B–VB 94B) and purple-violet flowers of group B (−1.06 and −0.81, PV N82A and PV N80B), malvidin 3-acetyl-rutinoside-5-glucoside was the most effective major anthocyanin for flower colors. In purple-violet flowers (−0.69 and −0.53, PV N80B and PV N81A) of group C, peonidin 3-acetyl-rutinoside-5-glucoside was the most effective major anthocyanin for flower colors. In red-purple flowers (−0.44–−0.27, RP 73A–RP N74B) of groups D, pelargonidin 3-acetyl-rutinoside-5-glucoside, in red-purple flowers (−0.03 and −0.02, RP 60D and RP 71D) of group E, pelargonidin 3-acetyl-rutinoside, and in red-purple flowers (0.04 and 0.13, RP 61A and RP 71A) of group F, peonidin 3-acetyl-rutinoside were the most effective major anthocyanins for flower colors. From these results, the glucosylation of 5-OH in anthocyanidin 3-acetyl-rutinoside and an increase in the methylation of the B-ring in anthocyanidin were considered to have the most important effects on flower color variations in these Saintpaulia cultivars.
Portulaca umbraticola Kunth, with ephemeral flowers, has become an important summer bedding plant in Japan. A lot of new cultivars have recently been bred with different flowering characteristics, but there is little information about P. umbraticola cultivars. In this study, we investigated the differences in flower longevity, endogenous ethylene production and ethylene sensitivity between a conventional cultivar, ‘Single Red’ (SR), and a newly released cultivar, ‘Sanchuraka Cherry Red’ (SCR). The flowers of SR opened and closed earlier than those of SCR and the flower longevity of SCR was significantly longer than that of SR. The effects of pollination, filament wounding and pistil removal on flower longevity were also investigated in both cultivars. Pollination, filament wounding and pistil removal significantly accelerated senescence in both cultivars, but filament wounding was much more significant in accelerating senescence. Endogenous ethylene production from flower opening to closure was significantly higher in SR than in SCR. The peak ethylene production in SR occurred 2 h earlier than that in SCR. Exogenous ethylene treatments of 0.5, 1, and 2 μL·L−1 significantly accelerated the rate of senescence in both SR and SCR. The use of ethylene action inhibitor 1-methylcyclopropene (1-MCP) and ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) significantly improved flower longevity in both cultivars, with the latter being much more effective. The better flower longevity of SCR seems to be related to lower endogenous ethylene production. The senescence of P. umbraticola cultivars seems to be ethylene-dependent.
In order to extend the “eating window”, the optimum ripening phase suitable for eating, the combination of treatment with propylene (an ethylene analog) and 1-methylcyclopropene (1-MCP; an ethylene inhibitor) was assessed in three kiwifruit cultivars: ‘Rainbow Red’ Actinidia chinensis, ‘Sanuki Gold’ A. chinensis, and ‘Hayward’ A. deliciosa. Propylene treatment initiated the ripening process by inducing fruit softening, increasing soluble solid content (SSC), and decreasing titratable acids (TA), with or without endogenous ethylene production, depending on the duration of exposure. Once endogenous ethylene was induced, it accelerated fruit ripening, resulting in an over-ripening phase and shortening of the “eating window”. ‘Rainbow Red’ and ‘Sanuki Gold’ fruit treated with propylene continuously or for 48 h initiated endogenous ethylene production that led to an “eating window” lasting only 2 days (range of 3–5 days after the start of treatment), whereas it lasted for 7 days (range 3–10 days) in ‘Hayward’ fruit. Limited propylene treatment of the three cultivars for 24 h induced ripening without the detection of ethylene production, suggesting that the optimum ripening phase suitable for eating can be attained without endogenous ethylene production, resulting in a longer “eating window”. ‘Rainbow Red’ and ‘Sanuki Gold’ fruit treated with propylene for 48 h followed by 1-MCP treatment had extended “eating window” and shelf-life, with the suppression of endogenous ethylene. These results illustrate the practicability of different durations of propylene treatment in facilitating kiwifruit ripening and the additional benefit of 1-MCP treatment to the extend shelf-life of new high-quality kiwifruit cultivars, ‘Rainbow Red’ and ‘Sanuki Gold’.
Blue mold (Penicillium italicum) is the primary postharvest pathogen affecting citrus fruit. In the present study, we investigated the effect of ultraviolet (UV-B) irradiation on blue mold, and the influence of UV-B on the internal fruit quality and peel color of satsuma mandarin. All UV-B doses examined (15, 30, 60, and 120 kJ·m−2) had inhibitory effects on P. italicum growth in vitro (reduction of spore germination > 99%). Additionally, we examined the disease incidence, the soft rot (water soaked) area diameter, and the mycelium (mycelial growth inside soft rot area) area diameter of Citrus unshiu Marc. ‘Aoshima unshu’, which was treated by UV-B irradiation 24 h before or after inoculation at two different harvest periods．The diameter and incidence of soft rot areas were not significantly reduced by UV-B irradiation at 5 days after inoculation. However, a UV-B dose of 60 kJ·m−2 reduced the diameter of mycelial growth on fruit for 5 days after inoculation, at both early and commercial harvests. At early harvest, UV-B irradiation at doses of 30 kJ·m−2 and 60 kJ·m−2 was effective at reducing the incidence of mycelial growths, regardless of whether irradiation occurred 24 h before inoculation or whether inoculation occurred immediately prior to UV-B irradiation. UV-B irradiation did not affect fruit quality with respect to soluble solid concentration, titratable acidity, or peel color. Although UV-B irradiation did not significantly control disease development in inoculated fruit, our results indicate that it might be effective by directly inactivating fungi and inducing an antifungal response in satsuma mandarin fruit.