Hiroshi Ehara

Protective effect of silicon on phenolic biosynthesis and ultraviolet spectral stress in rice crop

Abstract A work of ultraviolet microspectrometry and immuno light microscopy of cinnamyl alcohol hydrogenase (CAD) in the cells of leaf blades was carried out on rice plants grown in a paddy field with (+Si) or without (−Si) application of a silicate fertilizer. The pattern of silicon distribution on the longitudinal surface of leaf blades by X-ray microanalyzer, morphological characteristics, and gross composition such as silica, other major mineral elements, cellulose, non-cellulosic polysaccharides, lignin and phenolic acids were also compared between both rice plants. The X-ray microanalysis of silicon indicated the higher deposit on dumbbell bodies and other surface area in the +Si rice plants compared with those of the −Si rice plants. The +Si rice plants also showed the lower immuno-reaction of antiserum of the CAD in the cell walls of sclerenchyma, vascular bundle sheath and metaxylem vessel cells. The +Si rice plants had the lower UV absorbance around 280 and 320 nm in the leaf blades compared with those of the −Si rice plants. Microscopic observations of leaf blades in both sets of rice plants were also consistent with results of phenolic acids examined. This study suggests that silica fertilization and/or silicate accumulation in the leaves can be associated with decreases of the phenolic biosynthesis in rice plants.

Sago palm (Metroxylon sagu, Arecaceae) production in the eastern archipelago of Indonesia: variation in morphological characteristics and pith dry-matter yield.

Eleven local varieties of sago palm (Metroxylon sagu Rottb.) in southeast and north Sulawesi and in northern Maluku were studied: one variety with a weak black band on the back of the petiole: three varieties with a brown band on the back of the petiole: seven bandless varieties comprising two spineless, four short spine and one long spine types. Large variation in morphological characteristics and pith dry-matter yield were estimated at 13 to 34% and 55%, respectively. The difference in pith dry-matter yield is mainly attributed to trunk diameter and dry-matter percentage of pith. Trunk diameter was not affected by the length of growth period, which might reflect the palm’s own characteristics, such as genetic background and growth environment. The dry-matter percentage of pith was not related to any characteristics measured. The pith dry-matter yield was highest in the short spine type, followed by the spineless and the long spine types.RésuméDalam survey tersebut dipelajari sebelas varitas sagu lokal (Metroxylon sagu Rottb.) di Sulawesi Tenggara, Sulawesi Utara, dan Maluku Utara: satu varitas dengan pita sedikit hitam pada bagian belakang dari tulang daun: tiga varitas dengan pita coklat pada bagian belakang belakang dari tulang daun: tujuh varitas tanpa pita terdiri dari dua varitas tanpa duri, empat varitas duri pendek dan satu varitas duri panjang. Terdapat adanya keragaman pada karakteristik morfologi dan hasil bahan kering empulur batang yang diperkirakan beriurut-turut berkisar 13 sampai 34% dan 55%. Perbedaan pada hasil bahan kering empulur batang terutama tergantung pada diameter batang dan proporsi kering empulur batang. Diameter batang tidak dipengaruhi oleh panjangnya periode tumbuh; namun nampaknya lebih terkait dengan gambaran karakteristik khusus, seperti latar belakang genetik dan lingkungan tumbuhnya.Persen bobot kering empulur batang tidak ada hubungannya dengan berbagai karakteristik yang diteliti. Hasil bahan kering empulur batang tertinggi adalah pada tipe duri pendek (511kg/batang), diikuti tipe tanpa duri (417kg/batang) dan tipe duri panjang (329kg/batang).

Brown midrib mutant maize with reduced levels of phenolic acids ether-linked to the cell walls

Abstract Cell wall composition and rumen degradability of leaf blade, leaf sheath and stem of normal and brown midrib mutant 3 (bmr3) maize ( Zea mays L.) phenotypes were determined in this study. Concentrations of ether-linked phenolic acids were determined by acid and alkaline hydrolysis of whole cell wall materials. The bmr3 maize had higher rumen degradability and lower contents of cellulose, lignin, ferulic and p -coumaric acids esterified and/or etherified to the cell walls, and a lower ratio of xylose to arabinose residues as compared with the normal phenotype. Cellulose degradability was inversely correlated with the acetyl bromide lignin, but not with the acid detergent lignin or Klason lignin. The contents of ether-linked ferulic and p -coumaric acids, whether determined by acid or by alkaline hydrolysis, were inversely correlated with degradability. The bmr3 mutation is characterized not only by a lower lignin content, but also by a reduced level of total ether-linked ferulic acid which is thought to play an important role in cross-linking lignin and cell wall polysaccharides.

Effect of Low pH on the Growth, Physiological Characteristics and Nutrient Absorption of Sago Palm in a Hydroponic System

Abstract The dry matter production, photosynthetic characteristics and nutrient concentrations in the plant tissues of sago palmseedlings cultured for 4.5 months in a hydroponic system at pH 5.7, 4.5, and 3.6 were examined. Plant growth in weekly increment of length, leaf emergence, leaf senescence, and total leaflet area was similar at all pHs. There was no significanteffect of pH on the dry matter weight, although it tended to be lighter at pH 3.6 than at pH 5.7. Similarly, the photosynthetic rate and its related parameter were not significantly affected by the pH. However, the photosynthetic rate at pH 3.6tended to be lower than that at pH 5.7, which was attributed to a decrease in the stomatal conductance. The effect of the low pH on the nutrient concentration in plant tissues was not distinct. We concluded that sago palm seedlings could maintain leaf morphogenesis and nutrient uptake in growth media at a pH ranging from 5.7 to 3.6 for 4.5 months, which led to a high growth rate and maintenance of dry matter production even at pH 3.6.

Morphological and Anatomical Observations of Adventitious and Lateral Roots of Sago Palms

Abstract Sago palm (Metroxylon sagu Rottb.), which produces starch in large quantities in its trunk, could become one of the most important nutritious food resources in the near future. Although its root functions are thought to be very important for the enormous shoot growth, the morphological and anatomical studies are limited. This study investigates external and internal structures of sago roots with reference to their functions to distinguish two types of roots in each plant; i.e., large (about 6-11 mm diameter) and small (about 4-6 mm diameter) roots. Large roots were adventitious roots whose primordia were formed just inside the epidermis in the stem, emerged from the trunk surface and grew downward into the soil. Small roots were lateral roots whose primordia were formed on large roots running horizontally or on other small roots, grew not only downward and obliquely in both deep peat and mineral soils, but also right above in deep peat soils. Anatomical observations revealed that both large and small roots had the same internal structures containing epidermis, exodermis, suberized sclerenchyma cells, cortex and stele, with only differences in their sizes or cell numbers. Both roots had characteristic development of schizogenous or lysigenous aerenchyma, but seem to have different functions. Root primordia were formed successively throughout the trunk. Root primordia in the lower trunk had a large diameter, while density of root primordia per unit trunk surface area was high in the upper trunk.

Salt tolerance in wild relatives of adzuki bean, Vigna angularis (Willd.) Ohwi et Ohashi

Salt stress is becoming a serious problem in food production field. To find sources of salt tolerance, we screened 74 accessions of adzuki bean (Vigna angularis) and 145 accessions of cross-compatible wild relatives (seven species). We performed the primary screening in soil culture and the secondary screening in hydroponic culture, and identified JP205833 of V. riukiuensis (strain ‘Tojinbaka’) and JP107879 of V. nakashimae (strain ‘Ukushima’) as the valuable source of salt tolerance. We found these two strains had different salt tolerance mechanism, where ‘Ukushima’ prevented Na+ accumulation in leaves by filtering Na+ in roots and stems, while ‘Tojinbaka’ accumulated Na+ throughout the whole plant body. We also found ‘Tojinbaka’ and ‘Ukushima’ could retain photosynthesis even under salt stress. In addition, ‘Ukushima’ and especially ‘Tojinbaka’ showed even better growth in a salt-damaged field in Fukushima, Japan where soybean cultivar ‘Tachinagaha’ could not survive. Since both salt tolerant strains are cross-compatible with adzuki bean, our results will facilitate developing salt tolerant cultivar by introducing two different mechanisms of salt tolerance.

Construction of an SSR and RAD-Marker Based Molecular Linkage Map of Vigna vexillata (L.) A. Rich.

Vigna vexillata (L.) A. Rich. (tuber cowpea) is an underutilized crop for consuming its tuber and mature seeds. Wild form of V. vexillata is a pan-tropical perennial herbaceous plant which has been used by local people as a food. Wild V. vexillata has also been considered as useful gene(s) source for V. unguiculata (cowpea), since it was reported to have various resistance gene(s) for insects and diseases of cowpea. To exploit the potential of V. vexillata, an SSR-based linkage map of V. vexillata was developed. A total of 874 SSR markers successfully amplified single DNA fragment in V. vexillata among 1,336 SSR markers developed from Vigna angularis (azuki bean), V. unguiculata and Phaseolus vulgaris (common bean). An F2 population of 300 plants derived from a cross between salt resistant (V1) and susceptible (V5) accessions was used for mapping. A genetic linkage map was constructed using 82 polymorphic SSR markers loci, which could be assigned to 11 linkage groups spanning 511.5 cM in length with a mean distance of 7.2 cM between adjacent markers. To develop higher density molecular linkage map and to confirm SSR markers position in a linkage map, RAD markers were developed and a combined SSR and RAD markers linkage map of V. vexillata was constructed. A total of 559 (84 SSR and 475 RAD) markers loci could be assigned to 11 linkage groups spanning 973.9 cM in length with a mean distance of 1.8 cM between adjacent markers. Linkage and genetic position of all SSR markers in an SSR linkage map were confirmed. When an SSR genetic linkage map of V. vexillata was compared with those of V. radiata and V. unguiculata, it was suggested that the structure of V. vexillata chromosome was considerably differentiated. This map is the first SSR and RAD marker-based V. vexillata linkage map which can be used for the mapping of useful traits.

Comparison of Young Seedling Growth and Sodium Distribution among Sorghum Plants under Salt Stress

Abstract Young seedlings of 22 Sorghum cultivars including sorghum, sudangrass and sorghum-sudangrass hybrids, were examined for their growth characteristics and sodium ion accumulation in different plant parts, under salt treatment. The salt treatment was started with 100 mM NaCl and increased to 150 mM during the experiment. The plant dry weight decreased under NaCl treatment in all cultivars, and especially the dry weight of leaf blade decreased markedly. The cultivar difference in the plant dry weight under salt stress was affected by that in relative growth rate which was mainly changed by net assimilation rate (NAR). Cultivars that maintained higher NAR under salt stress had a smaller specific leaf area and higher nitrogen content per unit leaf area. Sorghum plants under salt stress retained Na+ mainly in roots preventing the distribution of excess amount of Na+ to leaves, but the root dry weight was increased by salt stress. It was therefore considered that thicker leaf blades and apparent increases in root dry weight were the main contributors to the maintenance of dry matter yield and enhanced the growth of Sorghum cultivars under NaCl treatment.

Effect of Nitrogen Composition in Culture Solution on the Growth of Rice Seedlings Raised on a Cotton Mat Spread on Hydroponic Apparatus for Vegetables(Agronomy)

Effect of the form and composition of nitrogen in a culture solution on the growth of rice seedlings raised on a cotton mat spread on a hydroponic apparatus for vegetables was investigated. The nitrogen composition, NH4-N:NO3-N, in the Kimura B solution was modified as follows:28%:72% (plot 1), 44%:56% (plot 2), 72%:28% (plot 3), 100%:0% (plot 4). Plant length, root length and root dry weight were greatest in plot 1 followed by plot 2, 3 and 4. In plots 1 and 2, the plant length was same level as that in seedlings raised in a box. However, the seedlings in plots 1 and 2 had longer roots than those raised in a box, and were suspected to be injured by transplanting. Thus, nutrient application was modified to change the plant form as follows:the culture solution was not applied during the first seedling-raising period, NO3-N-rich culture solution (NH4-N:NO3-N=28%:72%) was applied during the second period, and culture solution containing only NH4-N as the nitrogen source was applied during the last period. The seedlings raised by this method had nearly the same plant length and root length as those raised in boxes. Moreover, there was no distinctive difference in growth characteristics after transplanting between the seedlings raised by this method including different nitrogen compositions and raised in box.