葡萄胚珠,胚乳及胚的发育

本文研究了“早玫瑰”和“新玫瑰”葡萄胚珠、胚乳和胚的发育。结果表明:花后3天胚珠即开始迅速生长,其生长的最终大小依品种成熟期的不同而各异。胚乳游离核在花后33天成为细胞状态。受精后16—21天,合子才开始第一次分裂。当胚乳充满珠心组织时,胚开始迅速发育并一直持续到果实成熟.胚的发育与果实的发育无明显竞争关系。     

油梨胚和胚乳发育的研究

油梨胚和胚乳发育的研究彭民璋,邓九生,谢荔元（广西农垦职工大学,南宁明阳５３０２２７）油梨（Ｐｅｒｓｅａａｍｅｒｉｃａｎａ）属直生胚珠,细胞型胚乳。花后２天,合子开始分裂,此时胚乳细胞已分裂占居种腔的基部。花后５天,胚发育成具有３－４层细胞的塔形胚,...     

Flame Seedless葡萄胚珠、胚乳及胚发育与败育的研究

对Flame　Seedless葡萄胚珠、胚乳及胚的发育和败育过程进行了系统的细胞学观察,并以有核葡萄品种北醇为对照对Flame　Seedless的胚珠重量及纵横径进行了测定。结果表明：（1）Flame　Seedless内、外珠被及珠孔发育异常,20％～30％的子房未出现受精现象,受精的胚珠重量和纵横径随着胚珠的发育,先呈增加趋势,在某一时期达到最高值,随后下降,最终退化为痕迹。（2）大约有30％的胚乳核能够进行正常分裂,形成胚乳组织,胚乳在花后30d开始退化,其余胚乳核分裂异常。合子在盛花后第19天进行第一次分裂,经过二细胞原胚→多细胞原胚→球形胍,此后胚开始退化;也有的合子始终不发生分裂,最终退化。（3）由于胚乳分裂异常和提早退化,胚缺乏营养致使其发育中止和败育。（4）Flame　Seedless　胚挽救的最佳接种时期在花后第37天。     

普通番茄四倍体与二倍体杂交的杂种不育性研究

以普通番茄的四倍体为母本与二倍体杂交时,花粉萌发、花粉管生长及双受精过程都正常;对受精的胚珠形态结构观察得知:4天前幼胚和胚乳发育正常,授粉后4天胚乳出现异常开始退化,5天时这种异常现象更明显,第7天胚乳已完全解体。幼胚在胚乳完全解体前发育正常,而胚乳解体后,幼胚也开始解体。所以普通番茄二倍体与四倍体杂交的杂种不育的原因,在于胚乳败育以及胚的死亡。     

漆树胚,胚乳发育及花果生长的相关性研究

漆树为倒生胚珠,双珠被,厚珠心,具承珠盘及拟珠孔塞,胚囊发育为蓼型,核型胚乳,胚发育为柳叶菜型,后历经棒状形胚、心形胚、鱼雷形胚和成熟胚各期。花和果实生长与胚及胚乳发育有密切的相关性,胚内具原始的乳汁道系统为重要特征。一些胚珠内无胚或胚乳早期退化引起胚败育是造成种子空籽原因之一。     

中棉×戴维逊氏棉胚胎发育的研究

以棉花栽培种中棉作母本,野生种戴维逊氏棉作父本进行杂交试验,并用中棉自交作对照,比较研究了杂交情况下花粉粒的萌发、花粉管的生长、受精作用及胚和胚乳的发育过程,得到以下结果:(1)中棉×戴维逊氏棉花粉粒的萌发及花粉管在异己花柱中的生长基本正常,有花粉管胚珠的频率约20％,为中棉自交的1/4左右;(2)在杂交情况下,有花粉管进入的胚珠基本上能实现受精;(3)杂种胚乳在授粉后7天发育异常,11天开始解体,16天才有部分胚珠的胚乳开始形成细胞壁;(4)杂种胚不分化或畸形分化,在授粉后11—22天坏死。     

湖北双蝴蝶的胚胎发生湖北双蝴蝶的胚胎发生

对湖北双蝴蝶大孢子发生、雌配子体形成、受精、胚及胚乳发育过程进行了解剖学观察研究。结果显示：（1）子房2心皮,1室,侧膜胎座,薄珠心,单珠被,倒生胚珠,胚珠列数为4列 大孢子母细胞减数分裂形成的4个大孢子多呈直线形排列,少数为“T”形四分体,合点端的大孢子具功能 胚囊发育为蓼型 3个反足细胞宿存至8-细胞原胚。（2）珠孔受精 胚乳发育为核型 胚发育为茄型。（3）果实成熟时,种子发育至球形胚阶段。     

宁夏枸杞果实与种子形态发育初探

研究了宁夏枸杞不同发育时期果实和种子形态的变化特征及种子内胚的变化.结果表明:宁夏枸杞果实的生长发育曲线为花后8d以前为其第一次快速生长期,花后8～24 d为缓慢生长期,花后24～34 d是第二次快速生长期,属于典型的双“S”型.宁夏枸杞种子的生长曲线既不属于单“S”型,也不属于双“S”型,表现为果实的第一次快速生长期同样也是种子的快速生长期,但种子完成的生长比例快于果实完成的生长比例,此期种子内的胚乳生长快;当果实进入缓慢生长期,种子也表现出缓慢生长的特性,且种子长度和宽度的增加速率均显著低于果实第一次快速生长期种子的生长速率,此期种子主要进行胚的分化;在果实的第二次快速生长期,果实体积和重量迅速增加,而种子的长度和宽度增加很少,此期种子内仅胚进一步增大,从而反映出宁夏枸杞果实的发育与种子发育有一定的相关性.     

白桦雌花发育、大孢子发生及胚胎发育的解剖学观察

白桦雌花从开花到雌性器官的成熟需经历1个月左右的时间,解剖学观察表明：四月下旬越冬的雌蕊原基开始了活跃的分裂和分化。子房和柱头开始生长。四月末开花,五月初授粉。此后胚珠开始长大。五月中旬即分化形成珠被,珠心,珠被为单层珠被,胚珠为厚珠心胚珠,胚珠倒生,五月中下旬,珠心内产生大孢子母细胞,一周左右发育为成熟胚囊-七细胞八核胚囊,五月末完成双受精,白桦胚胎发育经过合子,原胚,球形胚,心形胚和鱼雷形胚等时期最后发育成熟,胚乳发育与胚胎同步,即受精的极核进行几次分裂后形成核型胚乳,胚乳核不断增多,在形成心形胚后胚乳细胞形成细胞壁。     

獐牙菜的胚胎发生

对獐牙菜大孢子发生、雌配子体形成、受精、胚及胚乳发育过程进行了研究。主要结果如下：子房2心皮,1室,4列胚珠,侧膜胎座;薄珠心,单珠被,倒弯生胚珠。大孢子母细胞减数分裂形成4个大孢子直线形排列,合点端的大孢子具功能,胚囊发育为蓼型。3个反足细胞宿存,每个细胞均多核和异常膨大,反足吸器明显,并在胚乳之外形成染色较深的类似“外胚乳”的结构。珠孔受精,受精作用属于有丝分裂前类型。胚乳发育为核型;胚胎发育为茄型。果实成熟时,种子发育至球形胚阶段。反足细胞在龙胆科一些短命植物中的宿存与分裂具有重要的生殖适应与进化意义。     

Evidence of Dichogamy in Santalum album L.

Flowering, fruit set, embryological development, and pollination trials were Investigated In Santslum album L. Each ovary may have three to four ovules. Mlcrosporogenesls and megasporogenesls In the same flower were synchronized at the earlier stages of flower development. However, at anthesls, when pollen was mature, the magaspore had developed only to the stage of a one- to two-nucleus embryo sac. As the eight-nucleus embryo sac developed, some mamelon cells began to undergo programmed cell death, forming holes Into which the eight-nucleus embryo sacs extended, becoming ＂N＂ or ＂S＂ shaped. The development from a two-nucleus embryo sac to a matured eight-nucleus embryo sac lasted up to 10 d. Fruit-set from open pollination was less than 2%. The endosperm develops prior to division of the zygotic embryo and one to three embryos and endosperms were formed In the same fruit. A mature seed usually germinates to produce one seedling; however, two and three seedlings from one seed were also observed, albeit at a low frequency. Pollination trials showed that no seed sets when Inflorescences were covered with s bag; however, artificial pollination could Improve fruit set. Our pollinaUon trials and embryological studies proved that the flower of S. album Is dlchogamous and fruit set has high heterozygosity.     

栽培番茄×秘鲁番茄杂交后的胚胎发育

“北京早红”番茄(Lycopersicon esculentum)×秘鲁番茄(L.peruvianum)PI,128657中的8号株系杂交后杂种种子不能正常发育的原因观察。结果表明,杂种胚和胚乳发育缓慢。授粉后16天胚乳开始退化。杂种胚的分裂是随机的,没有经历正常的发育阶段。授粉后30天杂种胚开始退化,35天完全解体。授粉后4天有些珠被绒毡层出现增生。     

栽培番茄X秘鲁番茄杂交后的胚胎发育

"北京早红"番茄(Lycopersicon esculentum)X秘鲁番茄(L. peruvianum )PI,128657中的8号株系杂交后杂种种子不能正常发育的原因观察。结果表明,杂种胚和胚乳发育缓 慢。授粉后16天胚乳开始退化。杂种胚的分裂是随机的,没有经历正常的发育阶段。.授粉后30天杂种胚开始退化,35天完全解体。投粉后4天有些珠被绒毡层出现增生。     

Fertilization and Embryo Development in Wheat x Maize Crosses

The fertilization and embryo development in crosses of hexaploid wheat “Kangxuan 9” X maize “SS 7700” were studied. Of 180 florets fi,ced after pollination 34(18.9%) had embryo and endosperm, 46(25.6%) had only embryo and 12(6.7%) had only endosperm. Percentages of single or double fertilization were higher than that in control (“Chinese Spring” X maize). The hybrid embryos and endosperms obtained were karyotypically unstable and characterized by rapid elimination of the maize chromosomes to produce haploid wheat embryos. The potentials for wheat haploid production and transfer of DNA segments, including transposable elements, from maize to wheat is discussed.     

Measurement of Indole-3-Acetic Acid in Peach Fruits (Prunus persica L. Batsch cv Redhaven) during Development

The amount of indole-3-acetic acid (IAA) was measured in peach fruits by gas chromatography-mass spectrometry-selective ion monitoring using an isotope dilution assay with [¹³C₆]IAA as an internal standard throughout the growing season. Ethylene evolution of the fruit was also measured. IAA levels were 25 nanograms per gram fresh weight, 18 days after anthesis. Both IAA levels and rates of ethylene evolution declined to their lowest levels (7 nanograms IAA per gram fresh weight and 0.01 nanoliter ethylene per gram per hour) in the second stage of fruit growth. Endogenous levels of free-IAA and ethylene evolution increased in the last stage of peach fruit development to 32 nanograms per gram fresh weight and 0.27 nanoliter per gram per hour, respectively. IAA amounts peaked in the ovules 67 days after anthesis.     

On the Embryonic Development and Ovule Culture of Interspecific Hybrids Between Populus simonii Carr and P.pyramidalis Borkh

The embryonic development following P. simonii Cart. × P. pyramidalis Borkh. is described in the present paper. The majority of pollen grains of P. pyramidalis Borkh. may germinate on the stigma of P. simonii Cam and the pollen tubes grow normally through the style and enter the embryo sac from the micropyle. Fertilization occurs as usual 4–7 days after pollination. A lot of proembryos and heart-shaped embryos are abortive; however, the others may develop normally and grow into mature embryos. Some of the endosperms appear normal and others may degenerate at free nuclear stage or cease to develop further at cellular stage. The ovules containg immature hybrid embryos of 19 days, 22 days, 26 days and 29 days after pollination at various developmental stages (heart-shaped stage, torpedo-stage and cotyledonary elongation stage) are excised and inoculated on nutrient agar for culture. The results show that: ( 1 ) Mll0 medium ( 1/2 MS+IAA 0.01 mg/L+BA 0.1 mg/L+sucrose 2% ) is the best of all the media used; (2) immature hybrid embryos of various developmental stages contained in ovules cultured in vitro may grow into normal plantlets.     

Content and De Novo Synthesis of Cocaine in Embryos and Endosperms from Fruit of Erythroxylum coca Lam

There is controversy as to whether the mature fruit of Erythroxylumcoca var. coca Lam. contains the cocaine alkaloid (benzoylmethylecgonine).In the present study, cocaine was monitored to determine ifit was present in embryos and endosperms of mature fruit ofE. coca var. coca Lam., and if present, the time required forde novo synthesis in imbibing seed. Seeds from mature fruitof E. coca were dissected to separate the embryos from the endosperms.The separated embryos and endosperms were analysed for cocaine.Subsequently, endosperms and embryos from seed imbibed. undera light and dark treatment were separated on days 3, 6, 9, 12and 15 and analysed for cocaine. Cocaine was present in embryos(0.005% of d. wt) and endosperms (0–001% of d. wt) ofmature fruit of E. coca. De novo synthesis of cocaine occurredonly in embryos of seed imbibed under light after day 9 of imbibition. Erythroxylum coca, alkaloid, benzoylmethylecgonine, cocaine, embryo, endosperm, seed imbibition     

Variability in the developmental stage of apricot ovules at anthesis and its relationship with fruit set

The stage of ovule development at anthesis and its relationship with fruit set was studied in several apricot cultivars growing in Mediterranean climatic conditions. Although generally the ovule was immature at anthesis, a great variability was found in the stage of development of the ovules from different cultivars. Considering functional ovules to be those with an embryo sac with at least four nuclei at anthesis, the earliest flowering varieties frequently showed more than 50% of functional ovules. Though these results could suggest that there is an influence of the chilling requirement on the percentage of functional ovules at anthesis, data recorded from two cultivars, ‘Goldrich’ and ‘Colorao’, with high chilling requirements, contrast with this suggestion. These results indicate that in apricot flowers the development of the embryo sac at anthesis is genotype dependent. The fact that a high frequency of functional ovules at anthesis was found, in cultivars with more than 50% of fruit set, suggests that, to be fertilised, a certain level of development of the apricot ovules at this time is necessary.     

Autonomous endosperm induction by in vitro culture of unfertilized ovules of Viola odorata L.

Autonomous endosperm was found in unfertilized ovules of V. odorata L. cultured on MS medium supplemented with 2,4-D as a sole growth regulator or on media with 2,4-D and BAP or kinetin. Frequency of endosperm induction was approximately 9% in ovules analyzed. The induction rate depended mainly on genotype of the donor plant, and to lesser degrees, on floral stage, flower series and medium type. Multinuclear endosperms consisting of 10–37 nuclei were found in ovules after as few as 4 days of culture. In some ovules at this stage, the egg cell and two polar nuclei were present. The process of endosperm degeneration began after 3 weeks of culture. In some ovules, degenerating autonomous endosperm was observed up to the 7th week. Parthenogenetic development of egg cells or apogamy did not accompany autonomous endosperm, supporting the hypothesis of independent pathways for embryo and endosperm development. Received: 1 December 1998 / Revision accepted: 6 April 1999     

焦核与大核龙眼雌配子体发育、授粉受精及早期胚胎发育的比较研究

利用人工授粉,采用压片法对大核龙眼‘九月乌’和焦核龙眼‘闽焦64-1’、‘闽焦64-2’、‘白核’等的自交与杂交后花粉管的生长特性进行研究,同时应用常规石蜡切片技术对大核与焦核龙眼的雌配子体以及合子胚早期发育进行观察。结果表明,龙眼胚珠在单核胚囊形成前就开始败育,且焦核品种(系)的败育率显著高于大核品种。不同亲本组合的授粉率存在差异,所有授粉组合在授粉36～48 h后均能观察到1个花粉管生长并进入胚囊受精。焦核品种(系)的胚胎在谢花后10 d开始败育,且败育率明显高于大核品种。受精是龙眼子房发育的首要条件,胚珠败育的雌蕊在谢花后10 d不膨大,不能发育形成焦核果实。谢花后10～30 d的早期胚胎败育是形成焦核龙眼的主要原因。焦核品种‘白核’胚乳具有成胚能力。约有24%的‘闽焦64-1’胚珠在胚胎发育过程中,其助细胞、合点端细胞及胚乳发生异常,这可能与早期胚胎败育有关。