Control of hypocotyl gravitropism by photochrome in a dicotyledonous seedling (Sesamum indicum L.)

Abstract The present study was prompted by the question as to whether the strong effect of red and far-red light treatments on blue-light-mediated phototropism in the sesame (Sesamum indicum L.) hypocotyl (Woitzik & Mohr, 1988) should be attributed in part to changes initialed by light in the gravitropic counter-response. Light treatments, operating through phytochrome, do indeed strongly affect the gravitropic response. However, the direction of the light effect is the same in gravitropism, as in phototropism. Thus, the gravitropic counter-response leads to an underestimate, rather than an overestimate, of the importance of phytochrome action on phototropic responsiveness. The effect of red and far-red light, operating via phytochrome, on the gravitropic response of the sesame hypocotyl could be studied in the present paper without any interference due to phototropism or light control of longitudinal growth. It was found that the effects of red and far-red pretreatments (given prior to the onset of the stimulus) as well as the action of simultaneously applied red or far-red light (simultaneous to the phototropic or gravitropic stimulus) are very similar in both phototropism and gravitropism. In particular, the seedling is capable of superimposing information about the actual light conditions during bending on the ‘memory’ it has about the light conditions prior to the onset of phototropism or gravitropic stimulation, This striking similarity between the phototropic and gravitropic responses possibly indicates that phytochrome affects the signal-response-chain at a relatively late stage, after the phototropic and the gravitropic signal-response chains have merged. From a teleonomic point of view the action of red and far-red light on phototropic, as well as gravitropic, responsiveness can be conceived as part of a shade escape strategy.     

Hydrodynamic properties of α-globulin fromSesamum indicum L.

The protein α-globulin fromSesamum indicum L. has been characterised for its size and shape using αarious chemical, physico-chemical and hydrodynamic properties. The protein has an S_20,w ⁰ of 12.8, D_20,w °f 4.9 × 10^-7 cm²/sec and a partial specific αolume of 0.725 ml/g in the natiαe state. The intrinsic αiscosity of the protein was determined to be 3 0 ml/g indicating it to be globular in shape. The molecular weight of the protein as determined by αarious approaches in analytical ultracentrifugation αaries from 2.6–2.74 × 10⁵. The molecular weight from sedimentation equilibrium yields a αalue of 2.74 × 10⁵ in the natiαe state and a αalue of 19000 in the dissociated and denatured state in 6 M guanidine hydrochloride. The eαaluation of frictional ratios using Stokes radius and results from electron microscopy confirms the protein to be globular in shape. The protein consists of at least 12–14 subunits. The eαaluation of hydrophobic parameters and energetics of interaction of subunits indicate that the protein is stabilized predominantly by hydrophobic interactions.     

芝麻灌浆特性与灌浆期籽粒中内源激素含量变化研究

在大田栽培条件下,对芝麻品种‘郑芝98N09’的灌浆特性及灌浆期籽粒中内源激素含量变化进行了研究,为芝麻高产优质高效栽培及品质育种提供理论依据。结果表明:(1)第9～17节位芝麻籽粒干物质率最高;下部(8节以下)蒴果在灌浆24d时的蒴果鲜重达最大值(1.596g/蒴),27d时籽粒鲜重达最大值(0.318g/蒴),灌浆最快的时期为灌浆15～33d,干物质积累量达籽粒干重的61.75%;中部(9～20节)蒴果在灌浆27d时的蒴果鲜重达最大值(1.622g/蒴),籽粒鲜重也同期达最大值(0.379g/蒴),灌浆最快的时期为灌浆21～36d,干物质积累量达籽粒干重的74.21%;上部(20节以上)蒴果籽粒干物质积累最快的时期为灌浆9～12d和24～27d两个阶段。(2)中部蒴果GA3含量大于下部和上部蒴果,而ABA和IAA的含量则小于下部和上部蒴果;除GA3/ZR比值外,中部蒴果的ABA/GA3、ABA/ZR、GA3/IAA和ZR/IAA比值都小于下部和上部蒴果。(3)较高的ZR含量和较低的ABA/ZR、ABA/GA3、IAA/GA3和IAA/ZR比值利于胚乳细胞分裂、蒴果发育、籽粒库容建成及籽粒干物质充实。(4)单一激素含量与不同部位蒴果单蒴粒重均达显著或极显著负相关关系,内源激素相互间的关系对下部蒴果粒重增加影响较小,适当提高IAA/ZR、ABA/GA3、IAA/GA3比值,能显著提高中部和上部蒴果的单蒴籽粒干重。     

Anthrasesamones D and E from Sesamum indicum Roots

Two anthraquinone derivatives, named anthrasesamones D and E, were isolated from the roots of Sesamum indicum. Their respective structures were determined to be 1,2,4-trihydroxy-3-(4-methylpent-3-enyl)anthraquinone and 1,2-dihydroxy-3-(4-methylpent-3-enyl)anthraquinone on the basis of spectroscopic evidence.     

Biosynthesis of anthraquinone derivatives in a Sesamum indicum hairy root culture

In order to investigate the intermediacy of 2-(4-methylpent-3-en-1-yl)anthraquinone (MPAQ), a possible intermediate for the biosynthesis of anthraquinone derivatives in sesame (Sesamum indicum), ²H-labeled MPAQ was administered to a hairy root culture of S. indicum. Efficient conversion of fed MPAQ to 2-[(Z)-4-methylpenta-1,3-dien-1-yl]anthraquinone ((Z)-MPDEAQ) was observed. Furthermore, administration experiment with ²H-labeled 2-geranyl-1,4-naphthohydroquinone, another possible intermediate, showed that it was converted to MPAQ and (Z)-MPDEAQ. The results clearly demonstrated that these substrates are the actual precursors for the production of (Z)-MPDEAQ. In contrast, neither MPAQ nor 2-geranyl-1,4-naphthohydroquinone was converted to anthrasesamone B and 2,3-epoxyanthrasesamone B, other anthraquinone derivatives in the hairy roots, suggesting that these substrates may not be the common precursors in the biosynthesis of anthraquinone derivatives.     

芝麻染色体核型及似近系数分析

芝麻（Sesamum indicum L.）是世界上最古老的油料作物之一,在植物进化中具有重要地位。以8个二倍体栽培种、4个四倍体栽培种以及2个野生种S.radiatum Schum ＆ Thonn和S.schinzianum Asch.为材料,比较分析了芝麻不同种的核型特征。结果表明：栽培种与野生种的核型及结构具有明显的差异,栽培种的着丝点类型有m、sm和st,臂比均值（AAR）为2.11–2.25,核型不对称系数（AKC）为66.05%–66.99%,核型分2B、3A和3B三类;野生种S.radiatum和S.schinzianum仅有M和m两种着丝点类型,AAR值分别为1.09和1.08,AKC为52.12%和51.68%,核型分1B和1A两类。核型聚类结果表明,野生种与栽培种的似近系数范围介于0.027–0.107之间,亲缘关系较远;与地理来源相比,种皮颜色能够显示不同种间的进化地位,推测芝麻进化方向为野生种→栽培种黑芝麻→栽培种白芝麻。     

Characterization of plant growth-promoting traits of Penicillium species against the effects of high soil salinity and root disease

This study investigated the plant growth promotion and stress mitigation effects of Penicillium species RDA01, NICS01, and DFC01 on sesame (Sesamum indicum L.) plants. The fungal isolates NICS01 and DFC01 significantly enhanced shoot length, root length, and fresh and dry seedling weight, due to the secretion of various concentrations of amino acids (Asp, Thr, Ser, Asn, Glu, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe, Lys, His, Try, and Arg). Penicillium sp. NICS01 increased the amount of chlorophylls, proteins, amino acids, and lignans in the sesame plants more so than in controls. Sesame plant growth was stunted by high soil salinity, and application of the three fungal isolates increased plant survival. The RDA01 and NICS01 strains significantly increased shoot length and fresh and dry seedling weights under salt stress conditions. In addition, an in vitro study of the Penicillium spp. revealed their antagonistic activity toward the pathogenic fungi Fusarium spp. Fusarium spp. reduce shoot length; co-inoculation with the NICS01 or DFC01 isolates significantly increased shoot length in infected plants. Our results suggest that exogenous application of the Penicillium sp. NICS01 can act as a biofertilizer and a biocontrol agent to improve plant growth and enhance plant survival against salt stress and Fusarium infection.     

Tropical Rotation Crops Influence Nematode Densities and Vegetable Yields

The effects of eight summer rotation crops on nematode densities and yields of subsequent spring vegetable crops were determined in field studies conducted in north Florida from 1991 to 1993. The crop sequence was as follows: (i) rotation crops during summer 1991; (ii) cover crop of rye (Secale cereale) during winter 1991-92; (iii) ''Lemondrop L'' squash (Cucurbita pepo) during spring 1992; (iv) rotation crops during summer 1992; (v) rye during winter 1992-93; (vi) ''Classic'' eggplant (Solanum melongena) during spring 1993. The eight summer crop rotation treatments were as follows: ''Hale'' castor (Ricinus communis), velvetbean (Mucuna deeringiana), sesame (Sesamum indicum), American jointvetch (Aeschynomene americana), weed fallow, ''SX- 17'' sorghum-sudangrass (Sorghum bicolor x S. sudanense), ''Kirby'' soybean (Glycine max), and ''Clemson Spineless'' okra (Hibiscus esculentus) as a control. Rotations with castor, velvetbean, American jointvetch, and sorghum-sudangrass were most effective in maintaining the lowest population densities of Meloidogyne spp. (a mixture of M. incognita race 1 and M. arenaria race 1), but Paratrichodorus minor built up in the sorghum-sudangrass rotation. Yield of squash was lower (P ≤ 0.05) following sorghum-sudangrass than after any of the other treatments except fallow. Yield of eggplant was greater (P ≤ 0.05) following castor, sesame, or American jointvetch than following okra or fallow. Several of the rotation crops evaluated here may be useful for managing nematodes in the field and for improving yields of subsequent vegetable crops.     

Chloroplast DNA Variation in the genusSesamum

It is widely approved that comparing restriction profiles and maps of chloroplast DMA provides valuable information concerning inter-and/or intra-specific relationships among plant species. Such chloroplast DNA analysis was applied to species and strains inSesamum which is a genus of approximately 38 species and contains a large number of strains of the cultivated sesame,S. Indlcum. Our chloroplast DNA investigations of 22 species and strains showed that; (i) among four species (S. capense, S. radiatum, S. schinzianum andS. indicum), the chloroplast genome ofS. capense was most distantly related to that of the cultivated species,S. indicum, (ii) chloroplast DNA polymorphism was also recognized among eight cultivated stralns collected from various regions in the tropical zone, but not among eight different varieties grown in the temperate zone, and (iii) the chloroplast DNA alterations observed could be attributed to the site gains or losses with the exception of the alterartion detected within the inverted repeat sequences inS. capense chloroplast DNA. These results demonstrate the presence of chloroplast genome diversity amongSesamum species and strains, suggesting the usefulness of chloroplast DNA analysis for elucidating the species relationships in the genusSesamum and the origin and evolutionary process of the cultivated sesame species. The present paper is based on the contribution which was read in a symposium entitled “Organellar DNA Variations in Higher Plants and Their Taxonomic Significance”, at the 50th Annual Meeting of the Botanical Society of Japan in Shizuoka on October 2, 1990, under the auspices of the Japan Society of Plant Taxonomists.