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。     

老芒麦种子人工加速老化条件的筛选比较

以4份不同发芽水平的老芒麦(Elymus sibiricus Linn.)种子作为试验材料,研究比较老化温度(39、41、43℃和45℃)和老化时间(1、2、3、4、5、6、7 d)处理对种子发芽率的影响,筛选确定老芒麦种子进行人工加速老化测定的适宜条件,并建立标准化的测定程序。结果表明:随着老化温度升高,Lot1、Lot2和Lot3样品种子发芽率均下降,且各处理间均差异显著(p<0.05),只有Lot 3在45℃条件下老化后发芽率下降的比例最低;Lot 4样品种子老化后发芽率较低,且45℃处理与其他各处理间均差异显著(p<0.05)。随着老化时间延长,Lot 1和Lot 2老芒麦种子老化发芽率不断降低,老化1、2 d处理与其他各处理发芽率间差异显著(p<0.05);Lot 3和Lot 4老芒麦种子老化至第4天后发芽率出现峰值。老化温度与老化时间互作效应与种子发芽率和休眠程度有关,且对老芒麦种子老化发芽率具有极显著(p<0.01)的影响。老芒麦种子人工加速老化处理的适宜条件为温度45℃老化2 d。     

Effects of variation in seed sources and pre-sowing treatments on seed germination of Tamarindus indica: a multi-purpose tree species in Bangladesh

We investigated the morphology and germination of Tamarindus indica seeds in order to discover the effects of variation in seed sources and pre-sowing treatments on germination. The experiment was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh. Seeds were collected from different but healthy trees from various locations in Bangladesh and subjected to four pre-sowing treatments, i.e., control, immersion in cold water (4°C for 24 h), immersion in hot water (80°C for 10 min) and scarification with sand paper. Seed germination was carried out in poly-bags with a mixture of topsoil and cow dung in the ratio of 3:1. The average length of the fresh seeds was 1.35±0.26 cm, their width 1.07 ±0.20 cm and thickness 0.69±0.11 cm. The results revealed that pre-sowing treatments affected the germination process of seeds, which significantly increased the germination percentage with the cold water (81.67%) and scarification with sand paper (82.33%) treatments, compared with those in the control (58.33%) and hot water treatment (59.00%). In all treatments germination started on average within 5 to 7 days after the start of the treatments and were completed from 13 to 19 days later. The greatest success in germination (82.33%) was found in scarification with sand paper, followed with 81.67% in the cold water treatment. The results of analyses of variance (ANOVA) showed significant differences (p<0.05) in germination closing dates, seed germination periods and germination percentages among the treatments but no significant difference among seed sources. However, the effect of the interaction between seed source variation and pre-treatment differed significantly in seed germination closing dates and germination percentages. We recommend cold water treatment (submersion of seed at a temperature of 4°C for a 24-h period) for seed germination of T. indica in rural Bangladesh.     

Confirmation of Novel Quantitative Trait Loci for Seed Dormancy at Different Ripening Stages in Rice

Seed dormancy contributes resistance to pre-harvest sprouting.Effects on respective quantitative trait loci (QTLs) for dormancy should be assessed by using fresh seeds before germinability altered through storage.We investigated QTLs related to seed dormancy using backcross inbred lines derived from a cross between Nipponbare and Kasalath.Four putative QTLs for seed dormancy were detected immediately after harvest using composite interval mapping.These putative QTLs were mapped near C1488 on chromosome 3 (qSD-3.1),R2171 on chromosome 6 (qSD-6.1),R1245 on chromosome 7 (qSD-7.1) and C488 on chromosome 10 (qSD-10.1).Kasalath alleles promoted dormancy for qSD-3.1,qSD-6.1 and qSD-7.1,and the respective proportions of phenotypic variation explained by each QTL were 12.9%,9.3% and 8.1%.We evaluated the seed dormancy harvested at different ripening stages during seed development using chromosome segment substitution lines (CSSLs) to confirm gene effects.The germination rates of CSSL27 and CSSL28 substituted with the region including qSD-6.1 were significantly lower than those of Nipponbare and other CSSLs at the late ripening stage.Therefore,qSD-6.1 is considered the most effective novel QTL for pre-harvest sprouting resistance among the QTLs detected in this study.