Koichiro Shimomura

Strigolactone signaling regulates rice leaf senescence in response to a phosphate deficiency

Strigolactones (SLs) act as plant hormones that inhibit shoot branching and stimulate secondary growth of the stem, primary root growth, and root hair elongation. In the moss Physcomitrella patens, SLs regulate branching of chloronemata and colony extension. In addition, SL-deficient and SL-insensitive mutants show delayed leaf senescence. To explore the effects of SLs on leaf senescence in rice (Oryza sativa L.), we treated leaf segments of rice dwarf mutants with a synthetic SL analogue, GR24, and evaluated their chlorophyll contents, ion leakage, and expression levels of senescence-associated genes. Exogenously applied GR24 restored normal leaf senescence in SL-deficient mutants, but not in SL-insensitive mutants. Most plants highly produce endogenous SLs in response to phosphate deficiency. Thus, we evaluated effects of GR24 under phosphate deficiency. Chlorophyll levels did not differ of in the wild-type between the sufficient and deficient phosphate conditions, but increased in the SL-deficient mutants under phosphate deficiency, leading in the strong promotion of leaf senescence by GR24 treatment. These results indicate that the mutants exhibited increased responsiveness to GR24 under phosphate deficiency. In addition, GR24 accelerated leaf senescence in the intact SL-deficient mutants under phosphate deficiency as well as dark-induced leaf senescence. The effects of GR24 were stronger in d10 compared to d17. Based on these results, we suggest that SLs regulate leaf senescence in response to phosphate deficiency.

Co-expression of GbMYB1 and GbMYC1 induces anthocyanin accumulation in roots of cultured Gynura bicolor DC. plantlet on methyl jasmonate treatment

Gynura bicolor DC. is a traditional vegetable in Japan. G. bicolor grown in the field has adaxial sides of leaves that are green and abaxial sides that are reddish purple. It has been reported that the responsible reddish purple pigments are anthocyanins, which are acylated and highly stable. We have reported that cultured G. bicolor plantlets treated with methyl jasmonate (MJ) exhibited anthocyanin accumulation in roots, and this was affected by light irradiation. In the present study, to clarify this accumulation induced by MJ treatment, we isolated anthocyanin biosynthesis and regulatory genes from G. bicolor. Expression analysis revealed up-regulated expression of flavonoid biosynthesis genes, GbCHS, GbCHI, GbDFR and GbANS. Furthermore, it was shown that isolated regulatory genes, GbMYB1 and GbMYC1, were also up-regulated by MJ treatment. In addition, it was shown that co-expression of GbMYB1 and GbMYC1 could activate GbDFR and GbANS gene promoters in transient assays with tobacco protoplasts. These results strongly indicate that GbMYB1 and GbMYC1 coordinately regulate flavonoid biosynthetic genes induced by MJ treatment, and thereby cause anthocyanin accumulation in roots.

Methyl jasmonate induces anthocyanin accumulation in Gynura bicolor cultured roots

Gynura bicolor DC., a traditional vegetable in Japan, is cultivated as Kinjisou and Suizenjina in Ishikawa and Kumamoto prefectures, respectively. The adaxial side of the leaves of G. bicolor grown in a field is green, and the abaxial side is reddish purple. It has been reported that these reddish purple pigments are anthocyanins. Although we established a culture system of G. bicolor, the leaves of G. bicolor plants grown under our culture conditions showed green color on both sides of all leaves. We investigated the effects of phytohormones and chemical treatments on anthocyanin accumulation in cultured plants. Although anthocyanin accumulation in the leaves was slightly stimulated, anthocyanins accumulation in the roots of the cultured plant was induced remarkably by 25–50xa0μM methyl jasmonate (MJ) treatment. This induction was affected by light irradiation and sucrose concentration in the culture medium. However, salicylic acid (SA) and 1-aminocyclopropane-1-carboxylic acid did not induce anthocyanin accumulation in roots. And then, combinations of MJ and SA or MJ and AgNO3 did not stimulate the anthocyanin accumulation in the root as found in the case of treatment by MJ solely.

Initial Design of Distributed Identification System for Geographical Origin by Trace Element Analysis

In Japan, districts where agricultural products are cultivated have recently begun to make their locality into a brand. In order to take advantage of this brand creation, some retailer and distributor camouflage agricultural products cultivated in non-branded districts to be sold as the branded districts goods with its attendant higher brand values; thus fraudulently raising their own prices. In order to prevent camouflaging of products from non-branded districts, traceability systems that mark an ID on the packaging have been proposed. However, these traceability systems cannot prevent fraud within the systems themselves, such as the use of illegally acquired IDs. Therefore, we proposed a system that distinguishes the various places of cultivation of green groceries by analyzing trace elements, which means extremely small quantities of elements, in the cultivated products and then storing this information in distributed databases. In this paper, firstly we show that discrimination is possible by correlation analysis on the results of our trace elements analysis, and we describe the outline and design of a system which identifies cultivated places of green groceries

Gibberellic acid improved shoot multiplication in Cephaelis ipecacuanha

The internodes of Cephaelis ipecacuanha elongated when cultured on Gamborg B5 solid medium supplemented with 0.5 or 1xa0mg/L gibberellic acid (GA3). The size of the elongated internode doubled in length compared to the untreated shoots, and the adventitious shoots formed on the elongated internodes. The shoots grew easily into plantlets without the use of auxin for rooting. The ex vitro regenerates cultivated in the greenhouse showed normal characteristics. Emetic alkaloids were detected in the leaves of in vitro shoots and the roots of regenerates cultivated in the greenhouse. This method using GA3 propagated numerous plants at a rate of more than 100 times compared to the method without GA3.

Target selection by similarity preserve hash in distributed system for geographical origin identification of vegetables

Recently, camouflaging geographical origin of agricultural products is a major problem in Japan. Now we are developing a distributed system which identifies geographical origin of vegetables by analyzing, accumulating and comparing trace element compositions of vegetables. This system stores compositions of trace, or very small quantities of elements into database which located on farming districts, and compares them to trace element compositions of vegetables which gathered from distribution channel such as markets, food factories. Objective of this system is verifying geographical origin information by food traceability system and deter camouflaging geographical origin. However, in this system, all sites in farming districts must be searched to identify geographical origin. In this paper, we describe a method to reduce the number of targets to identify geographical origin using similarity preserve hash (SPH).

Kinetic changes in glucosinolate-derived volatiles by heat-treatment and myrosinase activity in nakajimana (Brassica rapa L. cv. nakajimana).

Nakajimana (Brassica rapa L. cv. nakajimana), of the family Brassicaceae, is a traditional vegetable in Japan. Three isothiocyanates and five cyanides in the leaves of nakajimana were identified by gas chromatography (GC) and GC-mass spectrometry (GC-MS), and their kinetic changes using heat-treatment (temperature and time) were investigated. In addition, myrosinase activity of extracts prepared from fresh nakajimana leaf was determined. In crushed heat-treated leaves of nakajimana (70 °C for 30 s), formation of isothiocyanates and myrosinase activity increased, whereas formation of 1-cyano-3,4-epithiobutane and 1-cyano-4,5-epithiopentane decreased. Heat-treatment can significantly alter the content of potentially beneficial compounds in nakajimana, and ingestion of suitable isothiocyanates for human health may be better facilitated by mild boiling.

Efficient Target Selection in Similarity Preserve Hash for Distributed Geographical Origin Identification System of Vegetables

Recent years, especially in Japan, camouflaging geographical origin of agricultural products is a big problem. Therefore, we introduced a distributed system to identify their geographical origin using their differences of trace elements, or very small quantities of elements. Vegetables grown in farms absorb metals form the soil. Since compositions of trace metal elements differ from geographical places, this can be utilized to identify geographical origin of vegetables. In proposing system, trace element compositions of vegetables are measured when they are shipped from a farm, and the data is stored in databases which are located in farming districts. When a doubtful vegetable is found in food distribution channel, its trace element compositions are measured and compared by calculating correlation coefficients to ones accumulated in databases. This system can be used to verify geographical origin data by food traceability system. Because correlation coefficients are not known when they are once calculated, so correlation coefficients between all accumulated data in databases and doubtful vegetable. This means that proposing system is not scalable when the number of accumulated data is increased. Therefore, we introduced a method to reduce the number of target to calculate correlation coefficients using similarity preserve hash (SPH) which gives similar output for similar input. This could reduce time to calculation itself, however, computation time including picking out target data for calculation of correlation coefficients from database. Therefore, we introduce a method to accelerate picking up data form database by grouping value of SPH

Cryopreservation of Panax (Ginseng)

The genus Panax (family Araliaceae) comprises about half a dozen species. The old Greek term “Panax” implies all healing or a panacea (Kains 1958) and almost all Panax spp. have been used in folk medicine. One of the most famous species, and now uncommon in natural habitats, is P. ginseng C. A. Meyer. Roots from this species have held an honoured place in Chinese medicine for over 4000 years.

Upregulation of DWARF27 is associated with increased strigolactone levels under sulfur deficiency in rice

Abstract Plants produce strigolactones (SLs) in roots in response to nitrogen or phosphate deficiency. To evaluate SL levels under other mineral deficiencies in rice, we cultivated rice seedlings in hydroponic media without nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and iron. Tiller bud outgrowth was stimulated under calcium deficiency because of low SL levels. SL levels increased under sulfur deficiency, in addition to phosphate, and nitrogen deficiencies. To explore which genes are key regulators of SL production under sulfur deficiency, we analyzed the expression of SL‐related genes in sulfur‐sufficient and sulfur‐deficient conditions. An SL biosynthesis gene, DWARF27 (D27), was strongly expressed under sulfur deficiency, and its expression was decreased by sulfur supply. The levels of D10, D17, and OsMAX1 transcripts did not differ between sulfur‐sufficient and sulfur‐deficient conditions. These results suggest that the increased SL levels under sulfur deficiency are due to a high expression of D27. A combination of nitrogen, phosphorus, and sulfur deficiencies had no additive synergistic effect on SL production. Under combined phosphorus and sulfur deficiency, the expression levels of most SL biosynthesis genes were elevated. The number of tiller buds in the d27 mutant was higher than in the wild type, but lower than in other d mutants. Under sulfur deficiency, the chlorophyll content of d27 was lower than those of other d mutants. These results indicate that D27 plays an important role in adaptation to sulfur deficiency in rice.