The roles of light and pericarp on seed dormancy and germination in feral Raphanus sativus (Brassicaceae)

The timing of seed germination may determine the success of a weed species in an agroecosystem, and its expression is modulated by environmental conditions, but also by seed physiology and anatomy. The aims of this study were to investigate the roles of light, pericarp, dry storage and cold stratification on seed dormancy and germination in feral radish, a troublesome agricultural weed in temperate zones of the Americas that reduces crop yields. To this end, we used isolated intact pods and extracted seeds to test germination over time under contrasting temperature, light and storage conditions. Here, we showed that fresh seeds were non‐dormant, but that light and the presence of the pericarp reduced germination, especially under low temperatures. The pericarp reduced the final water content absorbed by seeds inside pods and decreased absorption/dehydration rates. The pericarp showed several small lignified cell layers in the endocarp, and x‐ray images displayed the lack of space between the partially embedded seed and the endocarp. Dry storage and cold stratification were ineffective in breaking the dormancy imposed by the pericarp. The apparent requirement for darkness and the mechanical restriction of the pericarp may have the potential to induce dormancy, spreading the timing of seed germination over a more extended period and hindering the control of feral radish.     

团头鲂(Megahbrama amblycephala) Caspase 9 基因全长cDNA的克隆及在氨氮胁迫下的表达分析

为了解团头鲂(Megahbrama amblycephala) Caspase 9基因序列特征及其在氨氮胁迫过程中的作用,应用末端快速扩增(Rapid amplification of cDNA ends,RACE)技术克隆得到团头鲂Caspase 9基因全长1613 bp的cDNA序列,包括185 bp的5 '末端非翻译区(Untranslated regions,UTR)、96 bp的3'UTR、1332 bp的开放阅读框(Open Reading Frame,ORF).氨基酸多序列比对显示,平均同源性为77.74％,表明团头鲂Caspase9基因具有较高的保守性;系统进化分析显示,该基因氨基酸序列与其他鱼类Caspase 9聚为一支,并与锦鲤(Cyprinus carpio) Caspase 9亲缘关系较近;荧光定量PCR结果显示,Caspase 9基因在团头鲂各组织中均有表达,在脑中表达量最高,在肌肉中表达量最低,同时,在胁迫和恢复过程中,该基因在肝和脑中的表达规律相似,均在胁迫期间出现表达量上调,整体呈类似波浪形表达谱.研究结果表明,氨氮胁迫下,Caspase 9基因参与团头鲂的免疫防御,并与细胞凋亡分子过程有关.本研究结果可为进一步了解团头鲂应答氨氮胁迫分子机制提供理论依据.     

半滑舌鳎HIRA基因部分cDNA序列克隆及表达分析

为研究HIRA基因在半滑舌鳎胚胎发育中的作用及其组织差异表达,以半滑舌鳎为研究对象,采用同源克隆策略从其精巢中分离了长度为764bp的HIRA部分cDNA序列,该片段编码254个氨基酸,具有5个wD结构域。对氨基酸进行比较发现,半滑舌鳎HIRA与比较物种的氨基酸序列具有很高的同源性,与红鳍东方纯亲缘关系最近。实时定量PCR分析发现,HIRA mRNA在多细胞期到原肠胚期的表达量较高,表明HIRA对胚胎发育起重要作用;HIRA在不同组织中表达差异显著,其中在性腺中表达最高,推测HIRA在维持性腺的功能方面有一定作用。     

锯缘青蟹死亡的组织病理学初步观察

对2008年8月福建省泉州市某海水场养殖锯缘青蟹中发生的死亡现象,开展锯缘青蟹的组织病理学研究。解剖可见肌肉明显坏死、溶解;头胸甲储积大量暗黄色体液,经福尔马林固定成固态物质;光镜下发现病蟹的中肠腺上皮细胞坏死、细胞质中出现大型的包涵体;电镜下发现病蟹的细胞质中有长约为500hm、宽约为200hm杆状结构的疑似杆状病毒存在。     

Sap flow in ‘Hass’ avocado trees on two clonal rootstocks in relation to xylem anatomy

The rates of sap flow and xylem vessel features were studied in two-year-old nongrafted and grafted avocado (Persea americana Mill.) trees. Daily sap flow rates were measured with heat and balance stem gauges in clonal Duke 7 (D7) and Toro Canyon (TC) trees and ‘Hass’ clonal scions grafted onto clonal D7 (H/D7) and TC (H/TC) rootstocks. Vessel features as size, number and total vessel area were determined histologically in the stem of the scion and rootstock and the roots of the grafted trees. Significant differences in the sap flow rate were found among the rootstocks, where D7 had a 29% higher sap flow rate than did TC (grafted and nongrafted trees). There were no differences among xylem vessel features in the stems of any of the varieties. However in the roots, D7 had wider and fewer vessels then TC do. Also, D7 had a 19% higher total vessel area than TC. These results suggest that the differences in water consumption of ‘Hass’ on different rootstocks may be associated with differences in the efficiency of the roots to absorb water across conductive tissue which may be linked to differences in the area of xylem vessels in the root.     

冬枣组织培养的消毒方法

为了优化冬枣组织培养的消毒方法,比较分析了乙醇、升汞、次氯酸钠和吐温等4种消毒剂对冬枣茎尖、叶片、茎段以及叶柄等组织培养的消毒效果.结果表明:70%乙醇30 s,0.1%升汞加3～5滴吐温20消毒6 min既能减少污染,又能提高外植体的成活率,综合效果最佳.     

野菊嫩茎的组织培养

在适宜的培养条件下,利用野菊花的嫩茎作为外植体,用组织培养的方法,在MS培养基上生长良好,获得再生植株.练苗后,成活率达100%,生长势强,茎粗壮叶色浓绿.结果表明:利用组织培养的方式对野菊花进行扩繁,简便易行.     

茄子的组织培养和植株再生体系研究

以2个茄子品种：红茄和紫长茄的子叶和下胚轴为外植体,探讨了不同生长调节物质对外植体分化的影响和不同品种、不同外植体的分化能力差异,并建立了茄子的高频率离体再生体系。结果表明：培养基MS＋2,4-D 1.0 mg/L＋6-BA 0.5 mg/L诱导愈伤组织效果最好;诱导不定芽方面,培养基MS＋4-PU 0.1 mg/L诱导效果最好;1/2MS培养基较MS培养基更适合植株生根。     

色素万寿菊组织培养培养基组成的初步研究

以色素万寿菊腋芽作为外植体材料,筛选各个阶段的培养基配方,研究色素万寿菊的组织培养技术。结果表明：MS＋BA 0.5 mg/L＋NAA 0.1 mg/L对腋芽诱导芽的效果最好;MS＋BA 1 mg/L＋NAA 0.01 mg/L为继代培养基的适宜配方;1/2MS＋IBA 0.1 mg/L生根效果很好。