Endogenous cytokinins from developing ‘Shamouti’ orange fruits derived from leafy and leafless inflorescences

Purified extracts of developing fruits of “Shamouti’ orange, derived from leafy and leafless inflorescences, showed two paper chromatographic zones of cytokinin activity by the Amaranthus bioassay. The first zone corresponded to R_f 0.0–0.3 and the second to R_f 0.6–0.9. Sephadex LH-20 fractionation of the cytokinin extracts tentatively showed the occurrence of zeatin and zeatin-riboside. Irrespective of the origin of fruit, highest cytokinin levels were obtained at petal fall (Stage I) and markedly declined thereafter. Levels appeared to be relatively higher in fruit from the leafy than in fruit from the leafless inflorescence type. The involvement of cytokinins in fruit set and growth is discussed.     

An improved micropropagation protocol for the recalcitrant plant Capsicum – a study with ten cultivars of Capsicum spp. (C. annuum,C. chinense,and C. frutescens) collected from diverse geographical regions of India and Mexico

Capsicum spp. is a commercially important crop of the Solanaceae family, well-known for its multipurpose use as a vegetable, spice, medicinal and ornamental plants. The genus Capsicum is a recalcitrant species in terms of in vitro morphogenesis and plant regeneration. An efficient method was developed for multiple shoot regeneration in 10 cultivars of Capsicum collected from diverse geographical regions of India and Mexico. Seeds germinated in vitro on a half-strength Murashige and Skoog (MS) medium supplemented with 3.0 % sucrose. Nodes of the in vitro germinated seedlings were used as explant for micropropagation. The combination of the 6-benzylaminopurine, indole-3-acetic acid, and spermidine was found to be the best for multiple shoot induction. However, the optimum responcse varied accompanied by different cultivers with maximum 8.9 ± 0.52 (Capsi-10) to 15.3 ± 0.69 (Capsi-5) multiple shoot per explant. Depending on the cultivar, multiplied shoots were successfully rooted with maximum 18.4 ± 0.20 (highest for Capsi-9) to 36.8 ± 0.29 (highest for Capsi-5) roots per shoot on half-strength MS medium supplemented with 2.0 mg l^?1 indole-3-butyric acid, 1.0 mg l^?1 α-naphthalene acetic acid, and 1.5 mM spermidine. Finally, the micropropagated plantlets were acclimatized with 40.0–86.7 % survival rate, depending on different cultivars.     

朝鲜白头翁的组织培养与快繁技术

以朝鲜白头翁的叶片、叶柄和花梗为材料,研究了细胞分裂素zeatin、kinetin、6-BA 和生长素IAA 组合对诱导不定芽的影响;以不定芽为材料研究了植物生长调节剂对不定芽的增殖和生根的影响;研究了不同基质配比对组培苗移栽成活的影响。结果表明: 1）叶柄和花梗接种在MS + 0.5 mg · L^-1 zeatin +0.05 mg · L^-1 IAA 培养基培养6 周后不定芽再生率为100%。2）不定芽切成小块或单株带类似愈伤的组织块转到MS + 0.5 mg · L^-1 zeatin + 0.05 mg · L^-1 IAA 或MS + 1.0 mg · L^-1 6-BA + 0.05 mg · L^-1 IAA 的培养基时不定芽的增殖与生长良好。 3）在增殖培养基中长至3 cm 以上的小植株转入到1/2 MS + 1.5 mg · L^-1NAA的生根培养基中培养42 d 后,生根率高达93%,平均根长12.3 cm,每株平均根数11 条,且可缩短生根时间。4）组培苗移栽到东北山土和珍珠岩比例为2︰1 的混合基质时,成活率高达66.7%。     

不同培养基成分对石斛兰继代和生根的影响

对石斛兰(Dendrobium)的继代培养及生根培养进行研究。结果表明:不同的细胞分裂素和生长素比例对石斛兰继代培养的影响不同,石斛兰继代培养最适培养基:MS+6-BA 0.5mg/L+2,4-D 0.5 mg/L+10%椰乳+琼脂8.0 g/L+蔗糖30 g/L;不同的有机添加物组合对石斛兰根的生长也不同,石斛兰壮苗生根最适培养基:1/2 MS+IBA 2.0 mg/L+肌醇2.0 mg/L+水解酪蛋白1.0×103mg/L+香蕉泥1.0×105mg/L+琼脂8.0 g/L+蔗糖30 g/L。     

植物叶片衰老的特性、基因表达及调控

综述了植物叶片衰老的特性、机理及分子调控方面的研究进展，介绍了异戊烯基转移酶基因（ipt)作为外源基因转入各种农作物在很大程度上延缓了衰老进程，并展望了目前植物衰老研究的热点及方向。     

土壤改良对越橘根域细胞分裂素含量及年变化规律的影响

【目的】研究不同土壤改良物质对越橘Vaccinium vitis-idaea根际土和非根际土中细胞分裂素[玉米素(Z)、玉米素核苷(ZR)和异戊烯基腺苷(iPA)]含量及年变化规律的影响.【方法】以2年生盆栽越橘为试材,应用"根际微区土壤剥落分离法"收集与根系黏着程度不同的非根际土和根际土样品,用高效液相色谱法测定土壤样品细胞分裂素含量.【结果和结论】不同根域处理的根系分泌物中,玉米秸秆配施氮肥处理(k4)的细胞分裂素含量最高,其他依次为添加玉米秸秆处理(k3)、添加草炭处理(k2)、无添加(k1,对照);不同时期越橘根际土和非根际土中细胞分裂素含量总趋势为ZZRiPA,如k4处理的Z、ZR和iPA平均质量比分别为9.89、9.76和3.57 ng/g,分别比k1(对照)高出67.9%、84.2%和105.6%.越橘根系细胞分裂素含量年变化规律表现为早春时期呈上升趋势,秋末季节含量呈下降趋势,而在早春至秋末之间,根系分泌物含量较高.     

断根与打顶对番茄嫁接愈合的抑制作用

[目的]断根嫁接苗和打顶双干或多干嫁接苗日益广泛用于番茄栽培,丰产作用显著.了解断根与打顶对番茄嫁接愈合的作用机制,可为番茄嫁接生产提供理论依据.[方法]以'硬粉8号'为接穗品种,'砧爱1号'为砧木品种,观测断根和打顶后番茄嫁接愈合进程、成活率和木质部连通性等,同时测定嫁接接合部生长素和细胞分裂素的含量及愈合相关基因的...     

细胞分裂素调控的不同茬高黑麦草再生机制

通过检测植物生长激素研究不同茬高多花黑麦草(Lolium multiflorum)叶再生的机制。试验结果表明,遮光条件下,高茬和高茬断根的再生叶片生物量均显著高于低茬的再生叶片生物量(P＜0.05)。光照试验结果表明,低茬在单次去叶时、高茬在多次去叶时均易提高总生物量系数(总生物量系数表示单位茬质量所支撑的再生过程中总有机物质量的变化,是用来评价非贮存有机物质参与叶片的再生能力,是不同茬高黑麦草再生能力强弱的指标)。通过检测光照条件下的叶片和伤流液中玉米素+玉米素核苷(Z+ZR)及脱落酸(ABA)含量,发现叶Z+ZR含量与总生物量系数相关密切,且叶Z+ZR含量受根系的直接调控。基于根系对叶片的影响,根系诱导的叶片细胞分裂素是影响不同茬高黑麦草再生的关键因素。     

Chemical Defoliation of Machine-Harvested Cotton was Accompanied by Intense Ethylene and Cytokinin Signal Responses

[Objective] Chemical defoliation is a necessary technical measure for machine-harvested cotton, and the effect of chemical defoliation directly affects the efficiency of mechanical-picking and fiber quality. Study on the molecular mechanism of defoliant in regulating defoliation could effectively guide the screening and improvement of defoliant-sensitive cotton germplasms. [Method] In this study, 200 cotton accessions were collected and planted in greenhouse, and treated with defoliant at the early flowering stage. Different varieties with high or low sensitivity to defoliant were selected according to the defoliation rate on the 4th day after treatment. The selected cotton varieties were also treated with defoliant at the boll opening stage in the field, and the defoliation rate on the 7th day after treatment was calculated. Meanwhile, samples from the abscission zone of the selected varieties were collected on the first and third day after treatment. And the expression of ethylene-, cytokinin- and hydrolase- related genes were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). [Result] Six defoliant sensitive and 6 insensitive varieties were selected from greenhouse and field tests. According to the qRT-PCR results, cytokinin-related genes, ethylene-related genes and hydrolase-related genes showed different expression patterns following defoliant treatment in different varieties, and most of these genes showed significant different expression in the defoliant sensitive and insensitive varieties. [Conclusion] This study indicates that different cotton germplasms respond to differently to defoliant, which might be the result of differential expression of cytokinin- and ethylene-related genes.