被子植物多胚苗的研究进展

本文综述了被子植物多胚苗的研究进展。在被子植物中多胚苗材料的种类很多,而只有特定起源的多胚苗材料在作物杂种优势固定中才具有比较大的实用价值。关于被子植物多胚苗的发生机理目前还没形成统一的定论。单倍性、二倍性和多倍性多胚苗在作物育种上具有各自不同的意义。     

多效唑对水稻未成熟胚愈伤组织诱导,分化和壮苗培养的影响

多效唑(Mult-Effect Triazole,MET)是一种良好的植物生长延缓剂,具有多方面的生理效应。已在水稻、小麦、油菜等作物中应用。本文报道了多效唑对水稻未成熟胚愈伤组织诱导、分化以及对壮苗培养的影响,为植物试管苗的正常化生产提供了有效的化学调控措施。1.材料早粳“T53”未成熟胚,愈伤组织,再生绿芽;早籼87-5-0,“湘竹443”再生绿芽。多效唑由本所生理系提供。     

多胚水稻胚位与苗位的观察研究

多胚水稻是进行水稻无融合生殖研究的重要材料,通过对4个多胚水稻品系种子胚位及萌发后的苗位观察发现这些品系中存在着多种胚位及苗位类型,其中以双-13的类型最为丰富。认为不定胚在与合子胚共存的情况下难以萌发表达,而只有当合子胚败育时才有可能得以萌发,并且认为反向单苗,侧向单苗及倒序单苗可能起源于不定胚,因而可能成为进行水稻无融合生殖筛选的重要标志。     

水稻“多胚苗”的形态学观察

“无融合多胚苗”水稻Ｃ１００１Ｂ和它的杂种Ｃ１００１Ｂ×Ｃ１００１Ａ 的未成熟颖果１５００ 粒;田间和人工萌发的单苗、双苗和三苗实生苗共２７０２ 株进行了形态解剖观察,结果如下：１．Ｃ１００１Ｂ和它的杂交颖果中只含一个胚;２． 由单个胚萌发的双苗和三苗幼苗是多苗实生苗。双苗实生苗的侧苗１ 和三苗实生苗的侧苗１ 是由主苗基部胚芽鞘的腋芽所形成,侧苗２由侧苗１ 基生叶的腋部发育而来。因此,多苗实生苗系同一个胚发育的主苗及其腋芽系统所组成;３． 颖果中胚的位置和朝向的变化和侧苗生长的两种类型,导致主苗与侧苗位置上的不同。至于已报道的水稻“多胚苗”形成的无融合生殖类型和推测尚有待提出胚胎学的论据。     

多胚苗水稻APIV不同颖花的多卵和多胚苗频率研究

ＡＰＩＶ的多卵和多胚苗频率与其颖花和种子的发育季节以及颖花的着生部位有一定关系。在夏季条件下抽穗开花,其多卵频率和多胚苗频率均比较低,而在秋季条件下抽穗开花则比较高。在同一稻穗中的多卵和多胚苗频率,强势颖花要明显地高于弱势颖花。在同一季节抽穗开花的主穗和分蘖穗之间,其颖花内的多卵频率不存在明显差异,多胚苗频率的差异也不明显。     

多胚苗水稻APIV不同颖花的多卵和多胚苗频率研究

APIV的多卵和多胚苗频率与其颖花和种子的发育季节以及颖花的着生部位有一定关系。在夏季条件下抽穗开花,其多卵频率和多胚苗频率均比较低,而在秋季条件下抽穗开花则比较高。在同一稻穗中的多卵和多胚苗频率,强势颖花要明显地高于弱势颖花。在同—季节抽穗开花的主穗和分蘖穗之间,其颖花内的多卵频率不存在明显差异,多胚苗频率的差异也不明显。     

几种具无融合生殖特性的植物多胚和多苗现象的观察

报道6种具无融合生殖特性的植物种子的胚数和萌发实生苗数的观察结果。金桔(Fortunellamargarita (Lour.)Swingle)、蜜桔(Citrus unshiu Marcoritch)和花椒(Zanthoxylum bungeanum Maxim.)具珠心胚,含多胚种子频率分别为97.50％、100％和45.00％;多胚种子的胚数范围分别为2～49,3～54和2～6。草地早熟禾(Poa pratensis L.)、滨草(Elymus rectisetus)和湖北海棠(Malus hupehensis(pampon.)Rehd.)具非减数配子体无融合生殖特性,含多胚种子频率依次为34.25％、8.11％和37.50％;前两种的多胚种子中胚数范围为2～3,后者为2～15。蜜桔、草地早熟禾和湖北海棠种子萌发多苗的频率分别为22.00％、6.14％和2.22％。描述了多胚种子中胚的形态、位置和分布。对6种植物含单胚种子的胚的来源进行了分析。初步结论:1.具无融合生殖现象的植物种子含多胚和萌发多苗的特性可作为寻找具无融合生殖特性的植物的形态学指标;2.对其筛选的材料进行大孢子发生、胚囊形成和早期胚胎发育的研究,以期阐明多胚来源和生殖类型。     

麦类作物多胚的研究 Ⅰ.麦类作物多胚的自然发生

用青海高原自然条件下种植的小麦不同种、杂种、幼胚培养后代,大麦、黑麦和小黑麦的种子作发芽试验,从普通小麦及其杂种、幼胚离体培养后代和大麦中,出现了多胚苗。５９个小麦品种中只有高原６０２及２９０个普通小麦品种间杂种吸８个、１８个幼胚培养后代中有２个出现了双胚苗,出现频率虽低,但能遗传。     

多胚水稻ApⅢ（双13）的胚胎学观察

对多胚水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）ＡｐⅢ的大量成熟颖果、人工萌发的幼苗和开花后３～５ ｄ 的幼嫩颖果进行的整体解剖和显微制片观察表明：ＡｐⅢ的５０００粒成熟颖果中,８９．０％ 含单胚单苗,８．９％ 和１．２％分别含双胚双苗和三胚三苗;７００多粒幼嫩颖果中,９０．０％ ～９５．０％ 含单胚,５．０％ ～７．０％ 含双胚。因制片的数目有限,未见到含三胚的;在含单胚和多胚颖果中,胚均位于同一胚囊的珠孔端,未见到胚囊以外存在不定胚。根据上述结果,似可以认为ＡｐⅢ单粒颖果的双胚和三胚是由同一胚囊内的卵细胞和１或２个助细胞受精或不受精发育而来的     

咖啡多胚现象与多胚苗形态发育的研究

通过目测筛选出咖啡多胚豆(种子),对其进行离体胚培养获得幼小植株,观察分析了多胚及其幼苗的形态发育特征。结果表明,不同倍性咖啡种质均存在多胚现象,不同材料的双胚率不同(变幅在1.06‰ ~ 4.46‰）,其中四倍体材料普遍比二倍体的高。多胚豆中胚的形态和着生位置各异。多胚再生植株生长发育特点各不相同,一般大胚再生植株生长发育正常;小胚植株长势弱,出现畸形植株及生长过程中夭亡等现象。同一咖啡豆中远离正常胚位的额外胚可能是由胚囊外的体细胞发育而形成的不定胚。     

Schmeissneria:An angiosperm from the Early Jurassic

The origin of angiosperms has been a focus of intensive research for a long time.The so-called pre-Cretaceous angiosperms,including Schmeissneria,are usually clouded with doubt.To expel the cloud around the enigmatic Schmeissneria,the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied.These materials include female inflorescences and infructescences.The latter are old materials but were under-studied previously.Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed,and that the ovaries are closed be fore pollination.Thus the plants meet two strict criteria for angiosperms:angiospermy plus angio-ovuly.Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic,more compatible with many molecular dating conclusions on the age of angiosperms,and demanding a reassessment of the current doctrines on the origin of angiosperms.Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question,this study adds to research concerning the origin of angiosperms.     

Schmeissneria: An angiosperm from the Early Jurassic

The origin of angiosperms has been a focus of intensive research for a long time. The so-called preCretaceous angiosperms, including Schmeissneria, are usually clouded with doubt. To expel the cloud around the enigmatic Schmeissneria, the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied. These materials include female inflorescences and infructescences. The latter are old materials but were under-studied previously. Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed, and that the ovaries are closed before pollination. Thus the plants meet two strict criteria for angiosperms: angiospermy plus angio-ovuly. Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic, more compatible with many molecular dating conclusions on the age of angiosperms, and demanding a reassessment of the current doctrines on the origin of angiosperms. Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question, this study adds to research concerning the origin of angiosperms.     

3D Participatory Sensing with Low-Cost Mobile Devices for Crop Height Assessment – A Comparison with Terrestrial Laser Scanning Data

The integration of local agricultural knowledge deepens the understanding of complex phenomena such as the association between climate variability, crop yields and undernutrition. Participatory Sensing (PS) is a concept which enables laymen to easily gather geodata with standard low-cost mobile devices, offering new and efficient opportunities for agricultural monitoring. This study presents a methodological approach for crop height assessment based on PS. In-field crop height variations of a maize field in Heidelberg, Germany, are gathered with smartphones and handheld GPS devices by 19 participants. The comparison of crop height values measured by the participants to reference data based on terrestrial laser scanning (TLS) results in R² = 0.63 for the handheld GPS devices and R² = 0.24 for the smartphone-based approach. RMSE for the comparison between crop height models (CHM) derived from PS and TLS data is 10.45 cm (GPS devices) and 14.69 cm (smartphones). Furthermore, the results indicate that incorporating participants’ cognitive abilities in the data collection process potentially improves the quality data captured with the PS approach. The proposed PS methods serve as a fundament to collect agricultural parameters on field-level by incorporating local people. Combined with other methods such as remote sensing, PS opens new perspectives to support agricultural development.     

灌溉对土壤盐分的影响及微咸水利用的模拟研究

在土地利用分析模型PS123的基础上,以土壤盐分主要影响作物水分吸收为突破口,将盐分对作物生长的影响结合到模型中,以使模型更加适合于盐渍化土地和微咸水灌溉的使用。并运用田间试验对模型进行了验证,模拟结果较好。利用模型对微咸水不同的灌溉方案对土壤盐分的影响进行分析,提出了合理的灌溉方案。盐渍化地区地下水位埋深应控制在2．0～2．5m以下,微咸水灌溉宜采用少次多量的措施进行较大定额灌溉,且不能连续灌溉。     

APERTURE EVOLUTION IN THE POLLEN OF PRIMITIVE ANGIOSPERMS

Diversity of pollen apertures in 35 families of the ranalean complex is compared through a series of representative scanning electronmicrographs, and the evolution of pollen aperture types in primitive angiosperms is outlined. A classification of pollen apertures found in the ranalean complex is presented, and ten basic aperture types are recognized: anasulcate, anatrichotomosulcate, zonasulculate, anaulcerate, catasulcate-cataulcerate, inaperturate, disulculate-diulculate, forate, colpate, and porate. Evidence is adduced for the primitive (ancestral) status of anasulcate pollen, and transitional stages in the evolution of other pollen aperture types in the ranalean complex are examined. From an early stock of ranalean angiosperms with anasulcate pollen, there appears to have been development of a number of interesting but evolutionally dead-end lines, represented among others by zonasulculate, anaulcerate, and catasulcate-cataulcerate pollen types. The most important evolutionary trend in early angiosperm pollen seems to have been the development of inaperturate pollen grains in many families of primitive angiosperms, from which there was a second major radiation of aperture types, including evolution of disulculate and forate pollen. Comparative study of pollen apertures observed in living primitive angiosperms suggests a de novo origin of the uniquely angiospermous (dicotyledonous) colpate pollen type from such inaperturate pollen.     

The megafossil record of early angiosperms in China since 1930s

The study history of early angiosperms in China can be dated back to 1930s, and there have been numerous papers published. Most of the publications are about leaves of angiosperms, especially in the early days. More attention is attracted to Chinese fossil materials when increasing fertile parts of early angiosperms come into light since the late 1990s. In this review, I will summarise the related studies. By referring to the previous literature, I play a role introducing to readers the references that usually are eclipsed by the shining glamour of recent discoveries. Readers interested in any specific taxon should refer to the original and related publications for detailed information.     

Multiple cryptic species with divergent substrate affinities in the Serpula himantioides species complex

Serpula himantioides is a widespread saprotrophic morphospecies mainly colonising coniferous wood in nature, but it appears frequently in buildings as well. From an earlier study, it is known that at least three divergent lineages occur within the S. himantioides species complex. In this study, a broader sample of S. himantioides isolates has been analysed by multi-locus sequencing, including new isolates from Asia, North and South America. Altogether five phylogenetical species (PS1-5) were detected, all recognised across independent gene phylogenies. A new southern South American phylogenetic species (PS1) was found, representing an early diverging lineage within the S. himantioides species complex. The two closely related PS2 and PS3 lineages included isolates from North America only, and PS4 was also dominated by North American isolates. Most of the investigated isolates (76%) clustered into PS5, a lineage that has been found on most continents, including North America. Overall, little phylogeographical structure was found in PS5, indicating frequent and recent long-distance dispersal events within this widespread lineage. Our analyses indicate that South and North America are the centres of divergence for the S.?himantioides species complex. Some of the lineages seem adapted to various substrates, but PS5 is able to decay a wide array of angiosperms and gymnosperms, which may have facilitated the spread of this lineage throughout the world.     

ABSOLUTE DIVERSIFICATION RATES IN ANGIOSPERM CLADES

Abstract The extraordinary contemporary species richness and ecological predominance of flowering plants (angiosperms) are even more remarkable when considering the relatively recent onset of their evolutionary diversification. We examine the evolutionary diversification of angiosperms and the observed differential distribution of species in angiosperm clades by estimating the rate of diversification for angiosperms as a whole and for a large set of angiosperm clades. We also identify angiosperm clades with a standing diversity that is either much higher or lower than expected, given the estimated background diversification rate. Recognition of angiosperm clades, the phylogenetic relationships among them, and their taxonomic composition are based on an empirical compilation of primary phylogenetic studies. By making an integrative and critical use of the paleobotanical record, we obtain reasonably secure approximations for the age of a large set of angiosperm clades. Diversification was modeled as a stochastic, time‐homogeneous birth‐and‐death process that depends on the diversification rate (r) and the relative extinction rate (∈). A statistical analysis of the birth and death process was then used to obtain 95% confidence intervals for the expected number of species through time in a clade that diversifies at a rate equal to that of angiosperms as a whole. Confidence intervals were obtained for stem group and for crown group ages in the absence of extinction (∈= 0.0) and under a high relative extinction rate (∈= 0.9). The standing diversity of angiosperm clades was then compared to expected species diversity according to the background rate of diversification, and, depending on their placement with respect to the calculated confidence intervals, exceedingly species‐rich or exceedingly species‐poor clades were identified. The rate of diversification for angiosperms as a whole ranges from 0.077 (∈= 0.9) to 0.089 (∈= 0.0) net speciation events per million years. Ten clades fall above the confidence intervals of expected species diversity, and 13 clades were found to be unexpectedly species poor. The phylogenetic distribution of clades with an exceedingly high number of species suggests that traits that confer high rates of diversification evolved independently in different instances and do not characterize the angiosperms as a whole.