Einfluß eines variierten N-Angebots auf α-Amylase-Aktivität, primäre Dormanz und Auswuchsresistenz von Weichweizen (Triticum aestivum L.), Roggen (Secale cereale L.) und Triticale (X Triticosecale Wittmack)

Influence of Varying N-Fertilization Rates on α-Amylase Activity, Primary Dormancy and Resistance to Pre-Harvest Sprouting in Wheat ( Triticum aestivum L.), Rye ( Secale cereale L.) and Triticale (X Triticosecale Wittmack)
Pre-harvest sprouting, induced by unfavourable ecological conditions, can affect the grain growers success considerably. Positive correlations are reported between resistance to pre-harvest sprouting and primary dormancy. Genotypes with a short dormancy period have a high pre-harvest sprouting risk. In the case of a premature germination of caryopses in the head of grain a hydrolysis of intact starch granules caused by the endoenzyme α-amylase takes place in the endosperm.
Negative correlations between falling number and protein content are reported, however, it is unknown, if a varying N-application influences pre-harvest sprouting rates, dormancy periods and amylase activity. For this reason, both greenhouse and field trials were conducted with different N-fertilization rates and (additional in the greenhouse) a rain simulation treatment.
High amounts of α-amylase a few days post anthesis are opposed to small enzyme activities in mature kernels. Stratificating temperatures and germination inducing precipitations at the same time are inducing pre-harvest sprouting and a high α-amylase activity especially in rye and triticale. It seems as if N-deficiency reduces the possibility of pre-harvest sprouting, on the other hand high N-rates increase the enzymes' activity and promote germination processes in the kernel. Effects of N-fertilization on dormancy are not known.
In the discussion of reasons for an increase of α-amylase activity in sprouted grain caryopses, changes in the relation of the phytohormones gibberellic acid (promoter of enzyme activities) and abscisine acid are mainly presumed.     

Effects of bud scales and gibberellins on dormancy of in vitro cultured Japanese pear leaf buds

Leaf buds of Japanese pear were collected in early June and early November and regarded as summer and winter dormant buds, respectively. Bud explants with and without scales were prepared from each of them, and cultured in vitro for 75 days at 25°C with 14 h photoperiod, on a medium either without growth regulators, or supplied with BA and GAs (GA₃ and GA₄₊₇), singly or in combination.When either BA or GA₄₊₇ was contained in the medium, bud expansion occurred. Thereafter, summer dormant buds grew into shoots in the presence of BA, while winter dormant buds, although they swelled profusely, remained in a rosette. In the presence of BA, GA₄₊₇ markedly stimulated shoot elongation of summer dormant buds, but GA₃ did not. In winter dormant buds, GA₄₊₇ not only failed to stimulate shoot elongation, but also interfered with the BA-induced swelling described above.The presence of bud scales delayed expansion of summer dormant buds, while it had little effect on winter dormant buds. The delaying effect of scales on expansion of summer buds was effectively removed by application of GA₄₊₇ to the medium.     

辽东半岛不同生境天然结缕草种群冬眠构件的结构

按生物的构件理论,将冬眠苗和冬眠芽视为结缕草种群的冬眠构件,并将全体冬眠苗和冬眠芽看作潜在种群,将全体分蘖株看作现实种群,分析了4个不同生境中冬眠苗和冬眠芽的结构以及潜在种群与现实种群的数量特征。结果表明,同一生境中结缕草种群的冬眠苗和冬眠芽具有相似的结构;不同生境中,结缕草种群的冬眠构件数量、分蘖株数量差异极显著,但根状茎冬眠构件占分蘖株数量的比率没有显著差异,从而揭示了不同生境结缕草种群保持大小相对稳定及其与生境长期适应的种群动态。     

不同光周期条件下PhyB和ABA对不同苜蓿品种的秋眠性调控

短日照和低温是导致苜蓿秋眠的主要环境因子。本研究检测了3个不同秋眠型苜蓿在8,12和16 h光照光周期条件下叶片和顶芽中PhyB和ABA的含量,并探讨其对秋眠的影响机制。结果表明,1)和非秋眠苜蓿相比,秋眠苜蓿叶片中PhyB含量高,PhyB作为绿色植物主要光受体可能通过光周期调控或参与了苜蓿的秋眠;并且3个品种均是在8 h光照下PhyB合成量高,暗示长暗期利于其合成。2)和12,16 h光照相比,8 h处理顶芽和第一展开叶中ABA含量最高,显然短日照利于ABA的合成;8 h光照处理时,秋眠型苜蓿品种Vernal ABA含量分别比半秋眠型CW5 0 2和非秋眠型CUF1 0 1高2.1 2和2.0 3倍,1 2 h光照处理ABA含量Vernal比CW5 0 2和CUF1 0 1分别高3 6.2 4%和46.46%,但16 h光照处理ABA含量并不表现上述规律,说明8和12 h光照程度不同地为苜蓿创造了逆境效应,ABA可能是调控或诱导秋眠的激素。3)8 h光照下苜蓿秋眠特征明显,生长严重受抑,不开花;12 h光照下苜蓿秋眠特征比8 h光照处理轻,生长受抑但抑制程度低于8 h光照处理,不开花;16 h光照下3个品种生长、开花正常。可能是PhyB含量多寡程度不同地调控了光周期反应,进而影响了ABA合成,而ABA在不同光周期诱导下通过合成量不同调控了不同秋眠基因表达,诱发了秋眠。     

Inheritance mode of seed dormancy in the hybrid progeny of sesame,Sesamum indicum,and its wild relative,Sesamum mulayanum Nair

Sesamum mulayanum is a wild relative of cultivated sesame, Sesamum indicum, and sometimes grows in sesame crop fields as an associated weed. This species shows deep seed dormancy and is characterized by conspicuous purple pigmentation on the lower lip of the corolla. The present study examined the inheritance mode of seed dormancy by using reciprocal progeny from crosses between the two species. The seeds of S. indicum and F₁ (S. indicum×S. mulayanum) showed good germination, but those of S. mulayanum and F₁ (S. mulayanum×S. indicum) showed deep dormancy. The F₂ seeds from both reciprocal crosses showed deep dormancy. These results, combined with the maternal inheritance of seed‐coat characteristics, indicated that the seed dormancy of S. mulayanum can be attributed to its seed‐coat structure (coat‐enhanced dormancy). The F₃ (S. indicum×S. mulayanum) seeds varied in their depth of seed dormancy and those seeds with deep dormancy (<50% germination) and those with no or shallow dormancy (≥50% germination) occurred in the expected ratio of 3:1, indicating that this trait is polygenic but is controlled by a single dominant major gene. The purple pigmentation of the corolla was expressed in both reciprocal F₁ plants and the presence and absence of pigmentation was segregated among the F₂ plants at the expected ratio of 3:1, indicating that this trait is also controlled by a single dominant gene. The segregation of the major gene controlling seed dormancy and that controlling purple pigmentation was not independent (9:3:3:1), indicating that these genes are linked, providing insights on sesame domestication.     

东北刺人参研究现状与展望

综述了目前东北刺人参的研究进展,包括种子休眠和萌发、分子生物学、栽培、生长环境、化学成分、药理作用等方面的研究,并对东北刺人参的进一步研究进行了展望。     

濒危植物永瓣藤种子休眠与解除

永瓣藤(Monimopetalum chinense Rehd)为我国特有的单种属植物,国家二级稀有濒危保护树种,其种子具休眠特性。测定了永瓣藤种子千粒质量、含水量、吸水率和种子生活力等指标,分别采用层积、酸蚀和GA3处理种子,分析不同处理对种子萌发的影响。结果表明:永瓣藤种子千粒重为(4.504 8±0.055 8)g,含水率为13.18%±1.84%,吸水率为29.95%±1.58%,种子生活力为94.25%±0.017 1%,种子萌发实验的发芽率为0;层积时间对种子萌发影响不显著,最高仅为2.67%±1.53%,种子经50%H2SO4处理20 min的发芽率为18.00%±3.46%,种子经250 mg/L GA3处理24 h然后再经室内层积75 d,发芽率达到72.67%±7.02%,对照仅为1.67%±1.15%,永瓣藤种子休眠首次有效破除。永瓣藤种子休眠可能与种皮障碍有关,种子内可能存在活性较强的内源抑制物质是引起种子休眠的重要原因,GA3处理能有效解除其种子休眠。     

‘短柄樱桃’花芽休眠解除过程中差异表达基因的研究

 以中国樱桃的优良品种‘短柄樱桃’（Prunus pseudocerasus Lindl.‘Duanbing’）的花芽为材料,采用mRNA 差异显示技术,分析休眠解除的过程中相关差异表达基因。共克隆获得79 个差异cDNA片段;通过半定量RT-PCR 验证,确定18 个阳性差异cDNA 片段为休眠解除相关候选基因;休眠解除过程中上调的基因片段11 个,下调的7 个。测序及同源性比对结果显示：差异表达基因主要参与糖代谢、信号转导、跨膜转运及氧化还原等反应过程。这些基因在‘短柄樱桃’休眠解除阶段可能起到直接或间接的作用。