Characterization of ScORK28, a transmembrane functional protein receptor kinase predominantly expressed in ovaries from the wild potato species Solanum chacoense

Solanum chacoense ovule receptor kinase 28 (ScORK28) was found among 30 receptor kinases from an ovule cDNA library enriched for weakly expressed mRNAs. This LRR-RLK displayed high level of tissue specificity at the RNA and protein levels and was predominantly expressed in female reproductive tissues. Protein expression analyses in planta revealed that ScORK28 was N-glycosylated and ScORK28::GFP fusion analyses showed that it was localized at the plasma membrane. Bacterial expression of ScORK28 catalytic domain followed by kinase activity assays revealed that ScORK28 is an active Mg2+-dependent protein kinase and that the juxtamembrane domain is necessary for kinase activity.     

大叶杨配囊及胚珠的形成和发育

本文应用细胞化学方法研究了大叶杨胚珠、胚囊的形成和发育过程中核酸、蛋白质及不溶性多糖的分布和消长。大孢子母细胞、大孢子四分体及功能大孢子中含较少不溶性多糖,但却含丰富的RNA和蛋白质。功能大孢子经分裂发育成八核的蓼型胚囊。四核胚囊开始积累细胞质多糖,成熟胚囊中除反足细胞外充满淀粉粒。反足细胞形成后不久即退化。助细胞具多糖性质的丝状器,受精前两个助细胞退化。卵细胞核对Feulgen反应呈负反应。二极核受精前由胚囊中部移向卵器,与卵器接触后融合形成次生核。发育早期的胚珠为厚珠心,双珠被。晚期,内珠被退化,故成熟胚珠为单珠被。四核胚囊时期,珠孔端珠心组织退化,胚囊伸向珠孔形成胚囊喙。合点端珠心组织含丰富的蛋白质和核酸,这一性质与绒毡层性质相似,可能涉及胚囊的营养运输。胚囊的营养来源于子房和胎座细胞内贮存的淀粉粒。     

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。     

Effect of parthenocarpy on ovule development in cucumber (Cucumis sativus L.) after pollination with normal and irradiated pollen

In nonparthenocarpic cucumber, analysis of the interaction between season and female receptivity demonstrated two different modes of fruit development and seed set. Spring climatic conditions induced significantly longer ovaries at anthesis with an autonomous fruit set as in natural parthenocarpy. Autumn climatic conditions induced smaller ovaries with fruit set influenced by the pollination stage of the female flower. These differences involve, during fruit development, a regulation of the empty seed number especially at both ends of female receptivity period. Indeed, seasons have no effect on ovule receptivity and fertility measured by full seed number. It is supposed that priority is given to seeds with an embryo in the competition for limited maternal resources in spring as well as in autumn. In spring, the use of irradiated pollen during the whole female receptivity period did not modify the seed set profile. Moreover, a cytological study of 6-day-old ovules pollinated by irradiated pollen has revealed a similar precocious embryogenesis compared to the control. In cucumber, pollination with irradiated pollen involves stenospermocarpy rather than induced parthenocarpy. However, we have not been able to determine whether the early abortive embryogenesis induced by irradiated pollen is gynogenetic or abnormal zygotic.     

Interspecific hybridization between Nicotiana repanda Willd. and N. tabacum L. through the pollen irradiation technique and the egg cell irradiation technique

Summary Two techniques were useful in overcoming hybrid inviability between N. repanda and N. tabacum. These techniques combine gamma-ray irradiation to pollen or to egg cells (in ovules) with in vitro culture of fertilized ovules. When in vitro culture of fertilized ovules from in situ hybridization of N. repanda x N. tabacum was combined without gamma-ray irradiation to pollen or to egg cells (in ovules), all of the resulting seedlings developed chlorosis and died. Furthermore, in the case of in situ hybridization of N. repanda x N. tabacum with gamma-ray irradiated N. tabacum pollen, no viable seeds were obtained. By using both techniques, combining gamma-ray irradiation to N. tabacum pollen or to egg cells in (N. repanda ovules) with in vitro culture of fertilized ovules, we were successful in obtaining flowering hybrid plants. Thus, it appears that it may be possible to overcome hybrid inviability to a certain extent using both the pollen irradiation technique and the egg cell irradiation technique, i.e., gamma-ray irradiation to pollen or to egg cells (in ovules) before pollination and in vitro culture of fertilized ovules.The research reported in this paper is in partial fulfillment of PhD requirements for the senior author     

向日葵离体孤雌生殖的超微结构研究

本文是研究未受精胚珠培养诱导的孤雌生殖过程超微结构变化的首次报道。向日葵(Heliaanthus annuus L.)的卵细胞在离体条件下被激活,发生细胞核移位、极性丧失、细胞器增多并转变成活动状态、液泡化程度增大、合点端形成细胞壁等一系列变化,预示即将启动孤雌生殖。孤雌生殖的原胚具有若干显著特征,如极性颠倒、有自体吞噬活动、壁的自由生长、游离核分裂等。对这些现象作了初步的讨论。     

向日葵未受精胚珠培养时胚状体发生的显微观察

由开花前1—4天的向日葵子房中取出胚珠,在液体培养基上进行漂浮培养,诱导了未受精的卵细胞发育为单倍体的胚状体.亦诱导了珠被绒毡层产生胚状体。对两种胚状体的发生和发育过程及其形态发生特点作了显微观察与描述。     

Ovules and seeds ofDirachma socotrana (Dirachmaceae)

Dirachma has a bitegmic, crassinucellate and anatropous ovule with a single median provascular tegumentary bundle. The seed coat is characterized by an exotesta and an endotegmic pigment layer. Although the fruit ofDirachma superficially resembles that of theGeraniaceae s. str., the characters of ovule and seed do not support a relationship with that family. Also a relationship withBarbeyaceae, as suggested by recentrbcL studies, is not supported by seed anatomical characters. The true relationships ofDirachma are difficult to assess on the basis of ovule and seed characters alone. TheRhamnaceae may be a closer relative.     

Interspecific crosses in the genus Tulipa L.: identification of pre-fertilization barriers

 Pollen tube growth in the pistil and pollen tube penetration of ovules have both been studied in crosses between cultivars from Tulipa gesneriana L. and 12 tulip species from all eight sections of the genus Tulipa to identify pre-fertilization barriers. Depending on the cross, pollen tubes grew as far as the stigma or the style or continued growing down into the ovary. Pollen tubes penetrated none or only a few percent of the ovules of some crosses, despite the presence of many pollen tubes in the ovary. In other crosses, from which no or only a few hybrids have been obtained after seed maturation on the plant, pollen tube penetration was found in up to 79% of the ovules. Apparently, various kinds of barriers preventing fertilization or normal embryogenesis occur in interspecific tulip crosses. Received: 26 July 1996 / Revision accepted: 31 January 1997