Embryogeny of Carya and Juglans, a Comparative Study
Embryogeny of Carya and Juglans, a Comparative Study
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山核桃与核桃胚胎发生的比较研究
DOI：
10.1086/334448
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发表时间：
1934
影响因子：
--
通讯作者：
L. M. Langdon
中科院分区：
文献类型：
--
作者：
L. M. Langdon
1. 山核桃和核桃的排卵花都由两个心皮组成，由肉质的杯状花托或杯状花托包围。靠近心皮和花托顶端的叶结构被解释为花被。小败育雄蕊偶有发生在水曲柳无心皮花发育的早期阶段。山核桃的排卵花既不发育花被内组，也不发育雄蕊。2. 在核桃科有心皮的花中，一个内部垂直分隔（核桃和山核桃在心皮平面上）支撑着一个大的无梗胚珠。随着核桃果实发育的进行，内果皮组织分化出两个楔形的第二隔，位于中隔的两侧并与中隔成直角。第二隔在水曲柳幼果的发育过程中不出现。3. 大孢子母细胞在幼珠中明显可见，在珠心轴链的深处有一个稍大的细胞，减数分裂期为6 ~ 8天；在曼陀罗，三到四天。两者都形成了一个线性的大孢子四分体，大孢子体从两个内部大孢子中的一个发育而来。4. 大孢子前期到成熟胚囊的时间为15 ~ 16 d；在曼陀罗，5到6天。5. 大角藓和水曲柳的大角藓类在发育上是正常的被子植物类型，在基本特征上是相似的。光草的配子体比水杨花的配子体大，卵器组织更明确。一种，在某些情况下，两种协同剂都被花粉管或囊内的花粉管所破坏；但这两种情况在进入试管之前就明显存在，而且通常在受精后仍然存在。在山核桃中，幸存的助胚可以产生一个小的原胚。6. 赤杨受精卵与合子第一次分裂间隔为17 ~ 18 d；在曼陀罗，六到七天。两者的终核都是立即分裂的，在受精卵分裂之前，胚乳的顶层是增大的胚囊的显著特征之一。7. 不同于双子叶植物原胚的发育过程，山核桃和水杨树幼胚的先端细胞不形成象限，而是被两个斜对的壁分成三个扇形。一个垂直且与前两个分区的平面成直角的分区，形成了一个由六个细胞组成的顶组。在一般情况下，两个子叶的平面和茎尖的长轴的平面与原胚顶端的三个主要部分的位置一致。8. 球形原胚基部的分节是可变的，特别是在核桃；然而，在这部分通常可以看到根轴的首字母，根帽和缩短的多细胞茎柄。9. 在花、胚珠、配子体和胚胎的特征上，核桃可以说比山核桃具有更大的系统发育特征。另一方面，山核桃在前胚胎期和胚胎期的胚胎更大、更明确的特征，使其对组织遗传学研究更有价值。
1. The ovulate flowers both of Carya and Juglans consist of two carpels inclosed by a fleshy, cup-shaped receptacle or cupule. The foliar structures bordering the carpels and borne at the summit of the receptacle are interpreted as a perianth. Small abortive stamens occur occasionally in early stages of development of the carpellate flowers of J. mandshurica. In the ovulate flowers of Carya, neither the inner set of members of the perianth nor the stamens develop. 2. In the carpellate flowers of the Juglandaceae, an internal vertical partition (in Juglans and Carya oriented in the plane of the carpels) supports the single large, sessile ovule. As fruit development progresses in Carya, two wedge-shaped sections of a second septum are differentiated from the tissue of the endocarp, on either side of and at right angles to the middle septum. This second septum does not appear during the development of the young fruit of J. mandshurica. 3. The megasporocyte is distinguishable in the young ovules, both of C. glabra and J. mandshurica, as a slightly enlarged cell lying deep in an axial strand of the nucellus, the phases of meiosis occupying six to eight days in C. glabra; in J. mandshurica, three to four days. A linear tetrad of megaspores is formed in both, the megagametophyte developing from one of the two inner megaspores. 4. In C. glabra, 15-16 days elapsed between the early megaspore stage and the mature embryo sac; in J. mandshurica, five to six days. 5. The megagametophytes of C. glabra and J. mandshurica are normal angiosperm types in their development, and alike in essential features. That of C. glabra is larger than the gametophyte of J. mandshurica and presents a more definitely organized egg apparatus. One, in some cases both, of the synergids are destroyed by the passage of the pollen tube or tubes in the sac; but both are in evidence prior to entrance of the tubes, and frequently one persists after fertilization. In Carya the surviving synergid may produce a small proembryo. 6. There is an interval of 17-18 days between fertilization and the first division of the zygote in C. glabra; in J. mandshurica, six to seven days. In both the definitive nucleus divides immediately, a parietal layer of endosperm being one of the distinctive features of the enlarged embryo sac prior to division of the zygote. 7. Deviating from the procedure generally characterizing the proembryo of dicotyledons, the apex cell of the young proembryo in Carya and J. mandshurica does not form quadrants, but is divided by two obliquely opposed walls into three sectors. A division, vertical and at right angles to the plane of the first two partitions, creates an apical group of six cells. In general the plane of the two cotyledons and that of the long axis of the stem tip coincides with the position of the three primary sectors of the apical section of the proembryo. 8. Segmentation in the basal section of the globular proembryo is variable, especially in Juglans; nevertheless to this section may ordinarily be traced the initials of the root axis, the root cap, and an abbreviated multicellular suspensor. 9. In its flower, ovule, gametophyte, and embryo features, Juglans may be said to present characters of greater phylogenetic interest than does Carya. On the other hand, the larger and more definite character of the embryo of Carya, both in proembryonic and embryonic phases, makes this more valuable for a histogenetic study.