Multiple shoot regeneration of kenaf (Hibiscus cannabinus L.) from a shoot apex culture system

 In this research, a medium was developed that would stimulate multiple shoot initiation from shoot apex explants of Hibiscus cannabinus L. (kenaf). Adventitious shoot formation on a shoot induction media supplemented with combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) (0, 0.5, 2.3 μmol·l^–1) and thidiazuron (N-phenyl-N′-1,2,3-thiadiazol-5-ylurea; TDZ) (0, 1, 5, 20 μmol·l^–1) was evaluated. Multiple shoot induction medium with 1 μmol·TDZ l^–1 resulted in the highest number of regenerated shoots per explant for all three kenaf cultivars tested (Tainung 1, Tainung 2, and Everglades 71). The 2,4-D did not enhance multiple shoot formation. Additionally, kenaf cultivars 7N and SF459 also produced multiple shoots on the induction medium with 1 μmol·TDZ l^–1. Multiple shoot clumps formed after 2 weeks in culture without callus formation. Shoots elongated and rooted within 2 weeks after subculture on a plant growth regulator-free medium. A histological study demonstrated the de novo regeneration of shoots from the shoot apex. Received: 2 February 2000 / Revision received: 30 March 2000 / Accepted: 22 June 2000     

The role of AUX1 gene and auxin content to the branching phenotype of Kenaf (Hibiscus cannabinus L.)

The objectives of this research were to identify auxin gene, AUX1, and to determine the plant auxin content and their role in conferring branching on Kenaf. PCR analysis using AUX1 primer capable to amplify the DNA of non branching (KR11) and branching kenaf mutant, resulting in 800 bp PCR product. The sequence of the PCR product showed high degree of homology with the sequence of AUX1 gene of other plants in the NCBI GenBank database, confirming kenaf possession of the gene AUX1. However, some variation on the DNA sequence was found between branching and non branching phenotype indicated allele differences of the same gene which were responsible for the variation in the type of branching. Identification of auxin content in the roots, apical shoot, and axillary branches using spectrophotometry method showed that the branching plant has higher auxin content in the apical shoot compared to the content in the branches. This indicate that AUX1 controls the formation of branches by controlling either the content of auxin in the apical shoot and branches, or the ratio of auxin content in the shoot and branches.     

Genetic diversity and phylogenetic relationship of kenaf (Hibiscus cannabinus L.) accessions evaluated by SRAP and ISSR

Understanding genetic diversity and phylogenetic relationships is useful for plant breeding. In this study, we assessed the genetic diversity in a panel of 84 accessions of kenaf from 26 countries using SRAP and ISSR markers. The kenaf accessions could be divided into L1 (60 cultivated varieties) and L2 (24 wild accessions) at the level of 0.145 genetic dissimilarity coefficient by UPGMA. The L₂ group was further divided into two subgroups (16 relative-wide and 9 origin wide accessions) at the level of 0.207 genetic dissimilarity. Out of the 9 wild accessions in the L₂ group, 6 were from Tanzania and the remaining 3 lines were from Kenya. These results suggest that the center of origin for kenaf might be Tanzania and Kenya.     

盐胁迫对红麻幼苗生长及抗氧化酶活性的影响

为研究不同盐胁迫时间和不同盐浓度胁迫对红麻（Hibiscus cannabinusL.）幼苗的生长及抗氧化酶活性的影响,探寻红麻耐盐的生理机制,为盐碱地种植红麻提供科学依据,本研究对红麻幼苗进行了两种不同条件的盐胁迫处理。一种将红麻幼苗在0（对照组）、140 mmol/L NaCl的半强度Hoagland营养液下分别处理3、6、9 d,另一种是在0（对照组）、70、140、200 mmol/L NaCl的1/2 Hoagland营养液下处理6 d,分别测定两种盐胁迫条件下植株的鲜重、根长、茎长、叶片H2O2、丙二醛（MDA）含量、超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）活性。结果显示：（1）在第一种处理条件下,随着盐胁迫时间的延长,处理组红麻幼苗的鲜重相对于对照分别减轻了19.63%、19.35%和39.03%,株高则分别降低了25.59%、19.17%和18.48%,处理组的SOD活性先增后减,POD活性先减后增,MDA和H2O2的含量、CAT和GR活性基本随胁迫时间的增长而增高。（2）在第二种处理条件下,随着胁迫盐浓度的增加,处理组鲜重相对于对照分别减轻了16.79%、19.35%和44.73%,株高则分别降低了11.21%、19.17%和23.62%,处理组SOD活性都稍高于对照,但三者无显著差异,POD活性先减后增,MDA和H2O2的含量、CAT和GR活性基本上随着盐浓度增加而增加。实验表明,在两种不同条件的盐胁迫下,红麻幼苗受盐害的程度基本上随胁迫时间和盐浓度的增加而加重。处理组植株的SOD和POD活性较对照组增加不明显,甚至有所降低,而CAT和GR活性则相对较高,CAT和GR可能在红麻幼苗抵御盐害时起较重要作用。     

高产花色苷玫瑰茄细胞系的筛选

花色苷在植物中呈现粉红、红、紫红、紫等颜色,可以用作食品、药品及化妆品的着色剂,亦有药用价值。作为食品添加剂,颜色较合成色素自然,且安全无毒性。早在１９８７年,Ｍｉｚukami^[1]就建议用植物细胞培养物生产花色苷类代替合成色素。所有的植物培养细胞都是异源性的。各细胞之间产花色苷的能力相差很大^[2].因为产花色苷的细胞系带有颜色标记,所以容易识别并通过肉眼选择即可获得高产花色苷的细胞系。筛选的方法很多,如平板饲喂法^[3]、小细胞团法^[4]、细胞块法^[5]、肉眼观察直接挑选法及细胞分栋器法^[6]等。高产系花色苷的含量可增加几倍到几十倍,而且产量稳定。本文采用平板法及小细胞团法筛选高产花色苷的玫瑰茄(Hibiscus sabdariffa L.)细胞系。     

玫瑰茄培养细胞中花色苷积累的代谢调节

调整培养基组成是提高玫瑰茄（ＨｉｂｉｓｃｕｓｓａｂｄａｒｉｆｆａＬ．）培养细胞花色苷产量的有效途径之一。改变Ｂ５培养其中钙、锰、铜等离子的浓度,增加了培养细胞花色苷的积累量,其中又以锰离子最为有效。其浓度为６＊１０＾４ｍｏｌ／Ｌ时,花色苷磁量达０．３４１ｇ／Ｌ,是对照的２．８２倍。     

The effect of temperature on leaf appearance and canopy establishment in fibre hemp (Cannabis sativa L.)

The effects of temperature on the development and growth of hemp (Cannabis sativa L.) have never been quantified. Therefore, to establish the effect of temperature on leaf appearance and canopy establishment of fibre hemp under controlled and field conditions, plants were grown in growth chambers at 11 regimes with average temperatures between 10°C and 28°C, and three cultivars were sown in the field in March, April and May in 1990, 1991 and 1992. In the field, thermal time (base 0°C) between sowing and emergence ranged from 68°Cd to 109.5°Cd (average 88.3°Cd). Rates of leaf appearance and stem elongation increased linearly with temperature between 10°C and 28°C. The base temperature for leaf appearance was 5.7°C from the growth chamber experiments and 1°C from the field experiments. In the field, the base temperature for the relationship between light interception by the canopy and thermal time was 2.5°C, and thermal time, calculated at the appropriate base temperature, accounted for about 98% of the variance in the number of leaves and for 98.6% of the variance in the proportion of light intercepted by the canopy. Days from emergence accounted for less of the variance in both parameters than thermal time. Interception of 90% of light was attained on average at 465°Cd (base 0°C) after emergence. It is concluded that thermal time is a simple and accurate tool to describe leaf appearance and light interception in fibre hemp.     

The potential of hemp (Cannabis sativa L.) for sustainable fibre production: a crop physiological appraisal

Hemp (Cannabis sativa L.) fibre can be used as a raw material for paper and textile production. A comprehensive research programme in the Netherlands has concluded that fibre hemp is a potentially profitable crop, having the right profile to fit into sustainable farming systems. This paper presents an appraisal of the crop physiological characteristics and the agronomic potential of hemp. Parameter values of basic crop physiological characteristics such as light interception potential, radiation use efficiency and dry matter partitioning coefficients are given. The effect of crop management decisions such as cultivar choice, sowing date, plant density, and harvest date on the value of these parameters is discussed. A simple crop growth model was used to assess the yield potential of hemp for the climate of the Netherlands. Calculations made for a non-stressed late-flowering hemp crop sown on 15 April and harvested on 15 September give a stem dry matter yield of 17.1 t ha^-1. The effects of advancing or delaying sowing or harvest date on stem yield were calculated. Crop physiological characteristics of hemp are compared to those of kenaf (Hibiscus cannabinus L.). Radiation use efficiency and dry matter partitioning coefficients of the two crops are similar. Base temperatures for development and growth are lower in hemp than in kenaf. In a temperate climate with cool springs, canopy establishment will be more rapid in hemp than in kenaf. Hemp seems an excellent candidate to fill the niche for an annual fibre crop in a temperate climate.     

扫帚菜、蕨菜营养成分分析

对扫帚菜、蕨菜两种山野菜的粗蛋白、粗脂肪、膳食纤维、胡萝卜素、氨基酸、维生素及微量元素等营养成分进行了分析.结果表明,两种山野菜营养丰富,各种营养成分较为齐全,为开发食用山野菜等绿色食品提供科学依据和参考.     

SEMI-ROLLED LEAF 10 stabilizes catalase isozyme B to regulate leaf morphology and thermotolerance in rice (Oryza sativa L.)

Plant architecture and stress tolerance play important roles in rice breeding. Specific leaf morphologies and ideal plant architecture can effectively improve both abiotic stress resistance and rice grain yield. However, the mechanism by which plants simultaneously regulate leaf morphogenesis and stress resistance remains elusive. Here, we report that SRL10, which encodes a double-stranded RNA-binding protein, regulates leaf morphology and thermotolerance in rice through alteration of microRNA biogenesis. The srl10 mutant had a semi-rolled leaf phenotype and elevated sensitivity to high temperature. SRL10 directly interacted with catalase isozyme B (CATB), and the two proteins mutually increased one other's stability to enhance hydrogen peroxide (H₂O₂) scavenging, thereby contributing to thermotolerance. The natural Hap3 (AGC) type of SRL10 allele was found to be present in the majority of aus rice accessions, and was identified as a thermotolerant allele under high temperature stress in both the field and the growth chamber. Moreover, the seed-setting rate was 3.19 times higher and grain yield per plant was 1.68 times higher in near-isogenic line (NIL) carrying Hap3 allele compared to plants carrying Hap1 allele under heat stress. Collectively, these results reveal a new locus of interest and define a novel SRL10–CATB based regulatory mechanism for developing cultivars with high temperature tolerance and stable yield. Furthermore, our findings provide a theoretical basis for simultaneous breeding for plant architecture and stress resistance.     

Transgene integration and organization in Cotton (Gossypium hirsutum L.) genome

While genetically modified upland cotton (Gossypium hirsutum L.) varieties are ranked among the most successful genetically modified organisms (GMO), there is little knowledge on transgene integration in the cotton genome, partly because of the difficulty in obtaining large numbers of transgenic plants. In this study, we analyzed 139 independently derived T0 transgenic cotton plants transformed by Agrobacterium tumefaciens strain AGL1 carrying a binary plasmid pPZP-GFP. It was found by PCR that as many as 31% of the plants had integration of vector backbone sequences. Of the 110 plants with good genomic Southern blot results, 37% had integration of a single T-DNA, 24% had two T-DNA copies and 39% had three or more copies. Multiple copies of the T-DNA existed either as repeats in complex loci or unlinked loci. Our further analysis of two T1 populations showed that segregants with a single T-DNA and no vector sequence could be obtained from T0 plants having multiple T-DNA copies and vector sequence. Out of the 57 T-DNA/T-DNA junctions cloned from complex loci, 27 had canonical T-DNA tandem repeats, the rest (30) had deletions to T-DNAs or had inclusion of vector sequences. Overlapping micro-homology was present for most of the T-DNA/T-DNA junctions (38/57). Right border (RB) ends of the T-DNA were precise while most left border (LB) ends (64%) had truncations to internal border sequences. Sequencing of collinear vector integration outside LB in 33 plants gave evidence that collinear vector sequence was determined in agrobacterium culture. Among the 130 plants with characterized flanking sequences, 12% had the transgene integrated into coding sequences, 12% into repetitive sequences, 7% into rDNAs. Interestingly, 7% had the transgene integrated into chloroplast derived sequences. Nucleotide sequence comparison of target sites in cotton genome before and after T-DNA integration revealed overlapping microhomology between target sites and the T-DNA (8/8), deletions to cotton genome in most cases studied (7/8) and some also had filler sequences (3/8). This information on T-DNA integration in cotton will facilitate functional genomic studies and further crop improvement.     

Corn (Zea mays L.) growth, leaf pigment concentration, photosynthesis and leaf hyperspectral reflectance properties as affected by nitrogen supply

Plant nitrogen (N)deficiency often limits crop productivity. Early detection of plant N deficiency is important for improving fertilizer N-use efficiency and crop yield. An experiment was conducted in sunlit, controlled environment chambers in the 2001 growing season to determine responses of corn (Zea mays L. cv. 33A14) growth and leaf hyperspectral reflectance properties to varying N supply. Four N treatments were: (1) half-strength Hoagland's nutrient solution applied throughout the experiment (control); (2) 20% of control N starting 15 days after emergence (DAE); (3) 0% N starting 15 DAE; and (4) 0% N starting 23 DAE (0% NL). Plant height, the number of leaves, and leaf lengths were examined for nine plants per treatment every 3–4 days. Leaf hyperspectral reflectance, concentrations of chlorophyll a, chlorophyll b,and carotenoids, leaf and canopy photosynthesis, leaf area, and leaf N concentration were also determined during the experiment. The various N treatments led to a wide range of N concentrations (11 – 48 g kg^–1 DW) in uppermost fully expanded leaves. Nitrogen deficiency suppressed plant growth rate and leaf photosynthesis. At final harvest (42 DAE), plant height, leaf area and shoot biomass were 64–66% of control values for the 20% N treatment, and 46-56% of control values for the 0% N treatment. Nitrogen deficit treatments of 20% N and 0% N (Treatment 3) could be distinguished by changes in leaf spectral reflectance in wavelengths of 552 and 710 nm 7 days after treatment. Leaf reflectance at these two wavebands was negatively correlated with either leaf N (r = –0.72 and –0.75^**) or chlorophyll (r = –0.60 and –0.72^**) concentrations. In addition, higher correlations were found between leaf N concentration and reflectance ratios. The identified N-specific spectral algorithms may be used for image interpretation and diagnosis of corn N status for site-specific N management.     

The genome of cowpea (Vigna unguiculata [L.] Walp.)

Cowpea (Vigna unguiculata [L.] Walp.) is a major crop for worldwide food and nutritional security, especially in sub‐Saharan Africa, that is resilient to hot and drought‐prone environments. An assembly of the single‐haplotype inbred genome of cowpea IT97K‐499‐35 was developed by exploiting the synergies between single‐molecule real‐time sequencing, optical and genetic mapping, and an assembly reconciliation algorithm. A total of 519 Mb is included in the assembled sequences. Nearly half of the assembled sequence is composed of repetitive elements, which are enriched within recombination‐poor pericentromeric regions. A comparative analysis of these elements suggests that genome size differences between Vigna species are mainly attributable to changes in the amount of Gypsy retrotransposons. Conversely, genes are more abundant in more distal, high‐recombination regions of the chromosomes; there appears to be more duplication of genes within the NBS‐LRR and the SAUR‐like auxin superfamilies compared with other warm‐season legumes that have been sequenced. A surprising outcome is the identification of an inversion of 4.2 Mb among landraces and cultivars, which includes a gene that has been associated in other plants with interactions with the parasitic weed Striga gesnerioides. The genome sequence facilitated the identification of a putative syntelog for multiple organ gigantism in legumes. A revised numbering system has been adopted for cowpea chromosomes based on synteny with common bean (Phaseolus vulgaris). An estimate of nuclear genome size of 640.6 Mbp based on cytometry is presented.     

烤烟冠层光谱参数与叶片叶绿素含量的相关分析

为了明确烤烟冠层光谱参数与叶片叶绿素含量的相关性,测定了不同氮肥施用量条件下烤烟冠层光谱特征和烤烟鲜烟叶片叶绿素a(Chl-a)、叶绿素b(Chl-b)、类胡萝卜素(Cars)含量,并对光谱参数与叶绿素含量进行了相关分析和回归分析。结果表明:随着氮肥施用量增加,团棵期和旺长期鲜烟叶片的Chl-a、Chl-b和Cars含量均增加,可见光波段反射率降低、近红外波段反射率增加;而打顶期叶片的3种色素含量和光谱特征的变化规律不明显。可见光460～670nm范围内,460nm反射率与叶片叶绿素含量呈显著正相关,其他波段反射率与叶片叶绿素的含量呈显著负相关;近红外780～1260nm范围内,所有波段与叶片叶绿素含量的都呈显著正相关,1480nm反射率与叶片叶绿素含量呈显著负相关。反映Chl-a、Chl-b、Cars含量与光谱参数——比值植被指数(ratio vegetation index,RVI)定量关系的最佳回归方程分别为幂函数、幂函数和指数函数:Chl-a=0.250RVI(730,550)1.511,Chl-b=0.049RVI(730,550)1.841,Cars=0.0998e0.379RVI(730,550)。     

糜子根系与旗叶协同衰老的生理生化机理研究

以榆糜3号糜子为试验材料,测定了拔节至成熟期糜子根系与旗叶生长指标、保护酶活性、可溶性蛋白含量等变化,初步分析了其根系与旗叶协同衰老的生理生化机制.结果表明:从拔节期到成熟期,糜子根系活性、表面积和干物质重,旗叶绿叶面积和干物质重,以及根系与旗叶的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性均呈先升高后降低的趋势,并均在拔节后34~41 d(籽粒灌浆前期~中期)达到最大值;根系与旗叶的可溶性蛋白质含量逐渐降低,而丙二醛(MDA)含量却持续大幅度上升;糜子旗叶的保护酶(SOD、CAT、POD)活性、可溶性蛋白含量始终极显著高于同期根系,而其MDA含量却始终极显著低于同期根系.研究发现,在糜子生育后期,其光合产物分配中心转移,造成根系和旗叶中光合产物亏缺;同时其旗叶和根系中保护酶活性逐渐降低,清除活性氧的能力减弱,引起细胞内活性氧积累和膜氧化伤害逐渐加重,最终导致植株逐渐衰老;在植株衰老过程中,根系与叶片衰老密切相关,并且根系抗氧化酶的活性相对较弱.     

Genome-wide Investigation of Intron Length Polymorphisms and Their Potential as Molecular Markers in Rice (Oryza sativa L.)

Intron length polymorphisms (ILPs) have been used as geneticmarkers in some studies. However, a systematic investigationand large-scale exploitation of ILP markers has not been reported.In this study, we performed a genome-wide search of ILPs betweentwo subspecies (indica and japonica) in rice using the draftgenomic sequences of cultivars 93-11 (indica) and Nipponbare(japonica) and 32 127 full-length cDNA sequences of Nipponbareobtained from public databases. We identified 13 308 putativeILPs. Based on these putative ILPs, we developed 5811 candidateILP markers via electronic-PCR with primers designed in flankingexons. We further conducted experiment to verify the candidateILP markers. Out of 215 candidate ILP markers tested on 93-11,Nipponbare and their hybrid, we successfully exploited 173 codominantILP markers. Further analyses on 10 rice accessions showed thatthese ILP markers were widely applicable and most (71.1%) exhibitedsubspecies specificity. This feature suggests that ILPs wouldbe useful for the studies of genome evolution and inter-subspeciesheterosis and for cross-subspecies marker-assisted selectionin rice. In addition, by testing 51 pairs of the ILP primerson five Gramineae plants and three dicot plants, we found anotherdesirable characteristic of rice ILP markers that they havehigh transferability to other plants.