Gene lineage analysis in populations ofHelianthus niveus andH. petiolaris (Asteraceae)

Helianthus petiolaris andH. niveus are polytypic species which are morphologically distinct at the periphery of their ranges but intergrade in areas of sympatry.Helianthus niveus includes both annual and perennial members, whereasH. petiolaris is strictly annual. Chloroplast DNA and nuclear ribosomal DNA restriction site data were used to reconstruct the evolutionary history of populations of the two species. Cladistic analyses reveal the following: (1) neither species is monophyletic; (2) the annual habit is derived once in this complex; and (3) the region of morphological intergradation appears to be primary in origin. The significance of interbreeding versus common descent in defining species concepts is discussed in relation to the above cladistic analyses.     

中国2种归化植物新记录

报道了发现于辽宁省的2种中国归化植物新记录:白毛马鞭草(Verbena stricta Vent.)和向日葵(Helianthus annuus L.),白毛马鞭草穗状花序粗壮而紧凑,单生枝顶或呈简单的聚伞状或圆锥状排列,且花序轴在果期显著延长,叶卵圆形,无柄,与中国有报道的本属其他物种区别明显。该种原产美国西部至中部地区,近来在辽宁省铁岭市发现有归化。向日葵原产于北美地区,被发现广泛归化于辽宁省大连市,营口市鲅鱼圈也有发现。归化种群形态特征与该地区栽培类型完全不同,其花序极多分枝,头状花序直径较小,瘦果极小,表面纹饰多样性很高。     

Protocols for efficient repetitive and secondary somatic embryogenesis in Helianthus maximiliani (Schrader)

 Indirect somatic embryogenesis was induced on leaf explants of greenhouse-grown Helianthus maximiliani plants. Leaves of the regenerated plants were used as starting explants for the induction of direct somatic embryogenesis. Another cycle of somatic embryogenesis was induced on the leaves of regenerated plants. In both cases, leaf explants were cultured on media containing different auxin/cytokinin ratios. The auxin/cytokinin ratio had an influence on the intensity of embryo formation, germination and the capability to regenerate plants. Somatic embryogenesis was generally more intensive on the medium with lower concentrations of 6-benzylamino-purine. Further, the percentage of regenerated plants was higher when embryos were induced on high-cytokinin, low-auxin medium. Secondary somatic embryogenesis was induced on embryos by culture in liquid hormone-free medium. Similar to direct embryogenesis the efficiency of secondary embryogenesis depended on the medium used for the induction of the primary embryos. In contrast to the mostly low frequencies of conversion of secondary embryos into plants that has been observed in other species, the percentage of regenerated plants from secondary embryos of H. maximiliani was quite high, although slightly lower than that obtained in primary embryos. Received: 28 March 2000 / Revision received: 1 September 2000 / Accepted: 2 October 2000     

菊芋HtCCR1基因的克隆与表达分析

肉桂酰辅酶A还原酶(cinnamoyl-CoA reductase,CCR)是木质素合成代谢的关键酶。该研究以菊芋(Helianthus tuberosus L.)‘廊芋8号’为材料,克隆到1个菊芋的CCR基因,命名为HtCCR1(GenBank登录号为MN205540),其开放阅读框(ORF)长975bp,编码324个氨基酸,其中含有FR_SDR_e保守结构域。系统进化分析表明,HtCCR1与向日葵CCR蛋白(XP_021989763.1)共聚于一支,二者亲缘关系最近。实时定量PCR分析表明,HtCCR1基因在菊芋茎和叶中的表达量显著高于在根和块茎中;盐(150mmol·L-1 NaCl)胁迫处理6、12和24h后,处理组HtCCR1基因的表达量均显著高于对照组;干旱(20%PEG6000)胁迫6和12h后,处理组HtCCR1基因的表达较对照组均显著上调。成功构建pET-28a-HtCCR1原核表达载体,转化大肠杆菌BL21(DE3)并诱导出了符合预期大小的蛋白,表明HtCCR1重组蛋白已成功表达。该研究结果为进一步研究HtCCR1基因的功能及利用基因工程手段调节菊芋中木质素的生物合成奠定了基础。     

Leaf expansion of four sunflower (Helianthus annuus L) cultivars in relation to water deficits. I. Patterns during plant development

Abstract. The influence of a slow stress and recovery cycle on the pattern of leaf expansion in four diverse sunflower cultivars ( Helianthus annuus L. cvs. Hysun 31, Havasupai, Hopi and Seneca) was studied in a glasshouse. Stress had no significant effect on the time of flower bud emergence and anthesis, or on final leaf number, but delayed the appearance of leaves at high insertions in all cultivars except Hysun 31.
Leaf expansion was markedly reduced as the predawn leaf water potential decreased from −0.35 to −0.60 MPa, and the predawn turgor pressure decreased from 0.3 to 0.2 MPa, and expansion ceased at a predawn leaf water potential of about −1.0 MPa, i.e. when the predawn turgor pressure reached zero.
The leaves most reduced in final size when water was withheld were those at the insertions which grew the most rapidly in unstressed plants. The maximum reduction in final leaf size of 25–35% was similar in all cultivars and was due to retardation of the rate of leaf expansion: the duration of leaf expansion was actually increased by stress. However, leaves that were initiated during stress, but emerged after rewatering, had final leaf areas at least equal to those in the unstressed plants: in the cultivar Seneca, the final size of leaves of high insertion was significantly greater in stressed than unstressed plants, whereas in the three other cultivars the final leaf sizes were similar in both treatments. All four cultivars examined adjusted osmotically to the same degree, but leaf water potentials in one, Seneca, increased more rapidly after rewatering than in the other three, and this may have contributed to the greater relative leaf size in the leaves of high insertion in this cultivar.     

Removal of Heavy Metals from Soil Polluted with Effluents from a Paint Industry Using Helianthus annuus L. and Tithonia diversifolia (Hemsl.) as Influenced by Fertilizer Applications

Contamination of soils by effluents from industries is on the increase. There is the possibility of remediating these contaminated soils through the use of certain plants. This work investigated the remediating ability of Helianthus annuus and Tithonia diversifolia on the soil polluted with effluents from a paint industry in Ibadan, Nigeria. The experiment consisted of three treatments (H. annuus, T. diversifolia, and control) each replicated three times in a factorial combination of four different fertility managements, viz mineral fertilizer (MF); Grade A organomineral fertilizer (OMF); control₁, plants without fertilizer application; and control₂, where no fertilizer and no crop was planted using randomized complete block design. A total of 12 plots of 2 × 4 m² each per phytoplant were obtained. Each plot was planted with the viable seeds of the phytoplant at a spacing of 60 × 30 cm² and at the seed rate of four seeds per hole. The seedlings were thinned to two stands per hole 2 weeks after planting (WAP) and also weeded two times (2 and 5 WAP). After in situ second successive cultivation, percentage removal of heavy metals by Helianthus annuus with MF and OMF, respectively, were Cu 32.5 and 41.6; Pb 30.3 and 42.8; and Cd 44.5 and 56.7. Tithonia diversifolia, similarly, removed, respectively, Cu 16.9 and 23.4; Pb 36.9 and 43.7; and Cd 20.1 and 35.1. Lower percentages were removed in the controls where no fertilizer was applied. In the shoot of H. annuus with OMF, significantly (p< .05) higher values of 0.27, 1.72, and 0.11 mg kg^?1 of Cu, Pb, and Cd, respectively, were removed and stored at second cultivation as against 0.21, 3.39 and 0.08 mg kg^?1 in the shoot of T diversifolia. Lower values of Cu, Pb, and Cd were removed with MF, and also at first cultivation with OMF and MF. This study therefore recommends the use of sunflower plants, whether hybrids or wild-types along with the application of OMF for the effective remediation of soils contaminated with heavy metals, particularly in tropical climate.     

Ultrastructure of the micropyle and its relationship to pollen tube growth and synergid degeneration in sunflower

Summary Ultrastructural studies made on the micropyle of sunflower before and after pollination resulted in the following observations. (1) The micropyle is closed instead of a hole or canal. The inner epidermis of the integument on both sides of the micropyle is in close contact at the apex of the ovule. The boundary between the two sides consists of two layers of epidermal cuticle. (2) The micropyle contains a transmitting tissue. The micropyle is composed of an intercellular matrix produced by the epidermal cells of the integument. (3) The micropyle is asymmetrical, and is much wider on the side proximal to the funicle. On the funicle side the cells adjacent to the micropyle are similar to those of the transmitting tissue: they have large amounts of intercellular matrix and contain abundant dictyosomes, rough ER, and starch grains, and provide an appropriate environment for growth of the pollen tubes. The cells distal to the funicle are rich in rough ER and lipid bodies; they lack large intercellular spaces. (4) The micropyle is variable in the axial direction, i.e., it is much larger and more asymmetric at the level distal to the embryo sac than at a level close to the embryo sac. After pollination, one to four pollen tubes are seen in a micropyle. During their passage through the micropyle, most pollen tubes are restricted to the side proximal to the funicle. There is a greater tendency (81%) for the degenerate synergid to be located toward the funicle, i.e., at the same side as the pollen tube pathway. The data indicate a close relationship between micropyle organization, orientation of pollen tube growth, and synergid degeneration.     

Homology among RAPD fragments in interspecific comparisons

The use of RAPDs for comparative purposes relies on the assumption that similarity of fragment size is a dependable indicator of homology. To test the validity of this assumption, homology among 220 pairs of comigrating fragments from three wild sunflower species was determined. Ninety-one per cent cross-hybridized and/or displayed congruent restriction fragment profiles suggestive of homology. However, comparative linkage mapping data indicated that 13% of the homologous loci mapped to genomic locations that were incongruent with the majority of loci, suggestive of paralogous rather than orthologous relationships. Thus, of the 220 pairwise comparisons, only 174 (79.1%) identified loci that are useful for comparative genetic studies. These problems, as well as several other factors discussed in the text, will introduce noise into RAPD data sets and thereby reduce the probability of generating accurate estimates of genetic relationships. Recommended methods for reducing noise in RAPD data sets include increasing gel resolution and/or testing fragment homology. However, implementation of these approaches will not eliminate all uncertainties, and it is also recommended that RAPD data sets be tested for structure and reliability.     

向日葵茎芯多糖的提取工艺优化及其体外抗肿瘤活性研究

研究了向日葵茎芯中主要活性物质多糖的提取工艺,并对此工艺进行了优化,选取的提取方法为水提醇沉法,以多糖含量作为指标,采用单因素试验研究了提取次数、原料颗粒的大小（目数）、料液比、提取时间、提取温度对向日葵茎芯多糖含量的影响。用苯酚-硫酸法测定提取液中多糖的含量,得出向日葵茎芯中多糖的最佳提取工艺条件为：提取次数2次,原料颗粒的大小（目数）60~80目,料液比（g·mL^-1）1：50,提取时间3.0 h,提取温度90℃,在最优提取条件下,多糖的提取得率为6.56%,多糖的含量为266.03 mg·g^-1。本文也对多糖的体外抗肿瘤活性进行了研究,结果表明向日葵茎芯多糖的体外抗肿瘤活性较弱。这些条件的确定为向日葵茎芯的深入研究奠定了基础。