High frequency plant regeneration from immature cotyledons of mungbean

An efficient and simple method for high frequency plant regeneration from immature cotyledons of mungbean is described. Immature cotyledons isolated from embryos, one week prior to harvest were cultured on MS medium with combinations of growth regulators such as benzyladenine (1 or 2 mg l⁻¹), thidiazuron (0.1 or 0.5 mg l⁻¹), gibberellic acid (0.1 mg l⁻¹) and indole-3-acetic acid (0.1 or 0.5 mg l⁻¹). A large number of greenish shoot primordia were initiated from the entire surface of the cotyledons in some of the growth regulators. Medium supplemented with benzyladenine (2 mg l⁻¹) in combination with indole-3-acetic acid (0.5 mg l⁻¹) produced the best response. On subculture to the same medium, well developed shoots were obtained. Addition of 0.5% activated charcoal to the shoot initiation medium completely inhibited initiation of shoot primordia. The shoot buds could be rooted on medium supplemented with 0.1 mg l⁻¹ indole butyric acid and plants transferred to soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

Contest and scramble competitions in two bruchid species,Callosobruchus analis andC. phaseoli (Coleoptera: Bruchidae)

Larval competition between contest and scramble strategists was investigated using the two bruchid species, C. analis (contest species) and C. phaseoli (scramble species) with two different sized mung beans (large and small beans). In both sized beans, the adult emergences of each species dependen on total density of the initial larval densities of the two species and the ratio of the two densities. The emergence of one species was suppressed by the existence of the other species when the initial larval density per bean of the former species was less than that of the latter one. There were many cases in which both C. analis and C. phaseoli emerged from one bean in large beans, but such cases were quite rare in small beans. C. analis performed interference behavior only at late larval stages, whereas C. phaseoli was superior in exploitative competition all through their larval stages. These, combined with the niche segregation inside a bean, are throught to be the major factors of observed density- and frequency-dependent competition results. Based on the above experimental results, long-term competition results between the contest and scramble species were predicted.     

黑果枸杞种子萌发及幼苗生长对盐胁迫的响应

研究不同浓度(0、1、2、3、6、9、14、18g.L-1)的盐溶液(NaCl、MgSO4、盐渍土壤)对河西走廊中部荒漠边缘的黑果枸杞种子吸胀、萌发和幼苗生长的影响,并观察胁迫解除后种子的反应。结果表明:黑果枸杞种子吸胀速率随NaCl、MgSO4和土壤溶液浓度的增大呈先升后降的趋势,吸水速度随胁迫时间的延长而减慢;种子萌发率随3种盐浓度的增大而降低,盐胁迫解除后种子仍具有较高的萌发率;发芽指数、活力指数、根长、下胚轴随3种盐浓度的增大而降低或先升后降,根轴比随盐胁迫的增强先升后降;随3种盐浓度的增大,种苗损害率增大,3种盐的胁迫效应依次NaCl>MgSO4>盐渍土壤溶液。黑果枸杞种子萌发和幼苗生长对NaCl胁迫较为敏感,其耐受的临界阈值是6g.L-1;种子萌发能耐受较高浓度的MgSO4的胁迫,幼苗生长对MgSO4胁迫较敏感,其耐受的临界阈值是9g.L-1;种子萌发和幼苗生长对生境盐渍土壤具有较强的耐受能力和适应性。     

Somatic embryogenesis and plant regeneration from cotyledonary explants of green gram [Vigna radiata (L.) Wilezek.]—A recalcitrant grain legume

Summary This study reports a protocol for plant regeneration from cultured explants of green gram [Vigna radiata (L.) Wilezek] via somatic embryogenesis. Somatic embryos were induced from nature cotyledons of var., TAP-7 and Pusa Baisaki when cultured on Murashige and Skoog (MS) medium fortified with different concentrations of 2,4-dichlorophenoxyacetic acid, α-naphthaleneacetic acid (NAA) and 2,4,5-trichlorophenoxyacetic acid singly or in combination with 2.22–8.88 μM N ⁶-benzylaminopurine (BAP) or 2.32–9.38 μM kinetin. The type and concentration of auxin and plant genotype influenced the frequency of somatic embryogenesis. NAA was the most effective auxin for somatic embryo induction. The well-developed, cotyledonary shaped embryos of var. TAP-7 germinated into plantlets at a frequency of 56.6% on MS medium supplemented with 1.88 μM abscisic acid and 6.66 μM BAP. Regenerated plants were transferred to soil and grown to maturity with 90% survival. The protocol described here offers a good potential for genetic improvement using gene transfer techniques and the production of synthetic seeds of V. radiata.     

Efficient Production and Purification of Extracellular 1,2-α-L-Fucosidase of Bacillus sp. K40T

When Bacillus sp. K40T was cultured in the presence of L-fucose, 1,2-α-L-fucosidase was found to be produced specifically in the culture fluid. The enzyme was purified to homogeneity from a culture containing only L-fucose by chromatography on hydroxylapatite and chromatofocusing. The molecular weight of the enzyme was estimated to be 200,000 by gel filtration on Sephadex G-200. The enzyme was optimal at pH 5.5–7.0 and was stable at pH 6.0–9.0. The enzyme hydrolyzed the α(1 → 2)-L-fucosidic linkages in various oligosaccharides and glycoproteins such as lacto-N-fucopentaose (LNF)-I 〈O-α-L-fucose-(1 → 2)-O-β-D-galactose-(1 → 3)-N-acetyl-O-β-D-glucosamine-(1 → 3)-O-β-D-galactose-(1 → 4)-D-glucose〉, porcine gastric mucin, and porcine submaxillary mucin. The enzyme also acted on human erythrocytes, which was confirmed by the hemagglutination test using Ulex anti-H lectin. The enzyme did not hydrolyze α(1 → 3)-, α-(1 → 4)- and α-(1 → 6)-L-fucosidic linkages in LNF-III 〈O-β-D-galactose-(1 → 4)[O-α-L-fucose-(1 → 3)-]-N-acetyl-O-β-D-glucosamine-(1 → 3)-O-β-D-galactose-(1 → 4)-D-glucose〉, LNF-II 〈O-β-D-galactose-(1 → 3)[O-α-L-fucose-(1 → 4)-]-N-acetyl-O-β-D-galactose-(1 → 3)-O-β-D-galactose-(1 → 4)-D-glucose〉 or 6-O-α-L-fucopyranosyl-N-acetylglucosamine.     

加快棕种子萌发和幼苗生长的研究

棕种子萌发和幼苗生长十分缓慢 ,为了探索加快种子萌发和幼苗生长的方法 ,对棕种子进行不同处理、不同时间催芽和催芽后不同处理等试验 ,结果表明 :(1)生长调节剂 3号 ABT生根粉、吲哚丁酸和 2 ,4 - D可提高种子萌发率 ,促进幼苗生长。 (2 )播种前催芽可促使种子提前萌发 ,延长幼苗生长期 ,使当年生苗更粗壮 ;贮藏 3个月后催芽可提高 10 %～ 15%的发芽率。 (3)催芽后用 50 mg/ L和 10 0 mg/ L的 3号 ABT生根粉、或者 10 0 mg/ L的萘乙酸浸泡都可以提高幼苗出土率 ,但对幼苗生长没有明显影响。     

Resistance of Hibiscus esculentus L. and Vigna sinensis (L.) Endl. to Pseudocercospora and plant peroxidase activity in relation to infection

Five cultivars of Hibiscus esculentus L. and six cultivars of Vigna sinensis (L.) Endl. were tested for their relative resistance to Pseudocercospora spp. Differences in susceptibility to the leaf spot pathogen were observed in both host and non-host interactions. The H. esculentus cv. South Sea and V. sinensis cv. Purple Mart were most susceptible to Pseudocercospora abelmoschi and P. cruenta, respectively. The H. esculentus cv. Pure Luck was most tolerant to P. abelmoschi while the V. sinensis cv. KY Bush was highly resistant to P. cruenta. A distinct host-specific interaction was observed among the different species of Pseudocercospora. Cultivar specific interactions were most pronounced between V. sinensis and P. cruenta. A direct correlation was observed between the variation in peroxidase activity in the soluble fraction of inoculated leaves and resistance to infection in H. esculentus and V. sinensis cultivars. The soluble fraction of inoculated leaves had higher peroxidase activity than either mitochondrial or chloroplast extracts.     

Effect of brassinosteroids on salinity stress induced inhibition of seed germination and seedling growth of rice (Oryza sativa L.)

The effect of 24-epibrassinolide and 28-homobrassinolide on the inhibitionof germination and seedling growth of rice (Oryza sativa) induced bysalinity stress was studied. Brassinosteroids were found to reverse theinhibitory effect on germination and seedling growth. The activation ofseedling growth by brassinosteroids under salinity stress was associatedwith enhanced levels of nucleic acids and soluble proteins.     

GA诱导NaCl胁迫下黄瓜种子萌发和幼苗耐盐性效应

研究外源GA对NaCl胁迫下黄瓜种子萌发和幼苗生长的影响.结果显示:(1)0和75mmol·L-1NaCl处理可促进种子萌发,浓度为100mmol·L-1及以上时,随着浓度的增加,种子萌发受抑程度越严重;(2)150mmol·L-1NaCl胁迫下,添加外源GA可显著提高黄瓜种子发芽率、发芽势、发芽指数、活力指数和a-淀粉酶活性;促进种子萌发,以100和150mg·L-1GA处理效果较好;(3)外源GA显著提高幼苗生物量,提高SOD和POD活性,降低MDA含量,以100mg·L-1GA处理效果较好.研究表明一定范围的外源GA可缓解盐害对黄瓜种子萌发和幼苗生长的抑制作用,诱导其耐盐性的提高.     

臭氧水浸种对黄瓜种子萌发及幼苗生长的影响

臭氧水处理10、30和50 min后的黄瓜种子,种子萌发及幼苗生长均受到促进,种子的发芽率和活力指数、萌发种子的过氧化氢酶(CAT)和淀粉酶的活性以及呼吸速率、幼苗的壮苗指数和根系活力均有提高;处理70和90min的黄瓜种子萌发和生长则受到抑制,种子电解质外渗,过氧化氢酶和淀粉酶活性下降.     

不同基因型紫苏耐盐性比较研究

以不同基因型紫苏为材料,研究150 mmol/L NaCl胁迫对紫苏种子萌发,幼苗生长及其生理指标的影响.结果显示:(1)盐胁迫下,不同基因型紫苏种子发芽率和发芽势均比对照显著降低,种子发芽指数、活力指数等发芽指标下降;不同基因型紫苏幼苗地上部和地下部干重均有不同程度降低,高油1(Y1)、紫野1(Z1)、紫野2(Z2)、紫野3(Z3)和紫野4(Z4)幼苗组织含水量均比对照显著降低,且幼苗存活率低而盐害指数显著高于其他基因型品种.(2)盐胁迫下不同基因型紫苏幼苗根系活力均比对照显著降低,其中Y1降幅最大,紫野6(Z6)和紫野7(Z7)降幅较小,可溶性糖含量均比对照显著提高.基因型Y1、Z1和Z2幼苗中MDA含量显著高于对照,表明其膜脂过氧化程度较高.(3)基因型苏引1(S1)、Z6、Z7、紫野8(Z8)、紫野9旱(ZY9)和紫野10(Z10)幼苗叶片中SOD、CAT和POD活性均显著高于对照,Y1、Z1、Z2、Z3和Z4幼苗中SOD和CAT活性与对照差异不显著,且Y1、Z2和Z4幼苗POD活性较对照显著降低,表明其抗氧化能力较差.研究发现,基因型S1、Z6和Z7在盐胁迫下其种子发芽能力、耐盐能力及幼苗渗透调节能力和活性氧清除能力均较强,表现出较强的耐盐性;基因型Y1、Z1、Z2、Z3和Z4受盐胁迫影响较大,为盐敏感基因型;Z8、Z9、ZY9和Z10为中等耐盐性基因型.     

岩生植物金发草对作物的化感效应

采用生物测定法研究金发草根、茎、叶水浸提液对水稻、小麦、油菜和莴苣等4种受体植物的化感作用。结果表明,金发草根、茎、叶水浸提液对4种受体植物种子萌发和幼苗生长均具化感作用,且随着水浸提液浓度的增高而增强。除水稻外,小麦、油菜、莴苣的发芽速率均受金发草水浸提液的显著抑制,但对最终发芽率影响不显著,说明金发草对植物种子萌发的化感作用主要是延迟种子发芽时间;金发草对作物幼苗生长的化感作用总体上表现为促进地上部分生长而抑制地下部分的生长。受体植物不同发育期对金发草化感作用的敏感程度不同,幼苗期高于萌发期;金发草叶的化感作用最强,其综合效应分别为根与茎的2.14倍和2.56倍。