THE INFLUENCE OF PRESSURE ON THE DIFFERENTIATION OF SECONDARY TISSUES
THE INFLUENCE OF PRESSURE ON THE DIFFERENTIATION OF SECONDARY TISSUES
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DOI：
10.1002/j.1537-2197.1962.tb14997.x
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发表时间：
1962-08
影响因子：
3
通讯作者：
Claud L. Brown;K. Sax
中科院分区：
文献类型：
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作者：
Claud L. Brown;K. Sax
克劳德·l·布朗（美国乔治亚州，雅典），卡尔·萨克斯。压力对次生组织分化的影响。阿米尔。日记账。植物学报，49(7):683-691。说明》1962。在早春时节，将毛杨和油松的纵向树皮条与孔材分离，在湿润的环境中保持，同时附着在母树上，沿着树皮条内表面的形成层区迅速增殖，产生广泛的薄壁愈伤组织。随后，新的木柱和形成层在愈伤组织垫的外周切向延伸，从而形成新的茎状结构。当树皮条被一层聚乙烯塑料薄膜从孔木材中分离出来，并通过外部施加的压力牢牢地固定在树木上时，形成层继续正常运作，而衍生物则分化并成熟为正常的、细长的木质部和韧皮部。相互压力和空间关系在控制次生组织分化模式中的重要性被清楚地证明了。高等植物中与细胞和组织的分化和成熟有关的许多复杂现象构成了一个最令人着迷和丰富的实验研究领域。目前关于形态和组织发生的许多研究都集中在顶端分生组织的一般区域，这并不奇怪，因为最终，在这里，高等植物的整个发育事件序列都是完全控制的。然而，相当奇怪的是，很少有工作者认识到侧向分生组织是研究其他组织发生问题的各种实验方法的最佳材料。也许这是因为许多人认为木本物种的维管形成层只是一个分生组织区，在那里有序的细胞分裂产生了特定物种固有的木质部和韧皮部的或多或少的定型模式。显然，在这个水平上控制细胞分化和成熟的生物学机制并不比在完整植物的其他地方发生的机制少。虽然关于形成层活动本身的生理学有大量的文献，但实际上对控制次生组织组织学发育模式的具体机制知之甚少。在这一领域，一些最相关但又间接的研究是关于伤口周围组织的愈合，更具体地说，是关于植物经过各种手术治疗后，形成层木质部一侧组织的原位再生。其中，Sharples和Gunnery（1933）在几篇关于愈伤组织形成和次生组织再生的文章发表于1961年5月10日。木本物种是特别感兴趣的，Soe（1959）最近的解剖学观察也引起了人们的兴趣，他观察了古代砍伐树木以增加果实或种子产量的做法。本研究描述了树皮节段维管形成层的组织分化模式：(1)从表观压力和正常空间关系中释放出来；或(2)在不同的外部施加压力下保持。材料与方法：北方黑棉杨（Populus trichocarpa Torr.） 45株5年生龄、健壮的幼苗。在马萨诸塞州韦斯顿附近的哈佛大学卡伯特基金会建立的一个实验种植园中，从众多种子来源中选择了这些种子进行处理。另外，选取35株3 ~ 5年龄、生长在相邻地块的白松幼苗进行试验。试验处理在5月初单株形成层极为活跃的梢伸长活跃期开始。使用的手术技术很简单。用锋利的嫁接刀穿过树皮，在胸脯高度的木质部上做两个平行的纵向切口，长约8.0厘米，相距1.5厘米。横切树皮条的基部，小心地从洞中抬起，如图1所示。树皮条被附着在顶端端以提供营养，在与洞分离后，立即被包裹在一个小的，薄的聚乙烯袋中，以防止干燥。因此，这些条被保存在潮湿的环境和允许气体的大气中。《美国植物学杂志》，第49卷，第7期，1962年7月18日出版。
BROWN, CLAUD L. (U. Georgia, Athens), and KARL SAX. The influence of pressure on the differentiation of secondary tissues. Amer. Jour. Bot. 49(7): 683-691. Illus. 1962.-When longitudinal bark strips of Populus trichocarpa and Pinus strobus are separated from the bole wood during early spring and maintained in a humid environment while attached to the parent tree, the cambial zone along the inner surface of the segments rapidly proliferates producing an extensive parenchymatous callus. Subsequently, a new phellogen and cambium differentiate and extend tangentially around the outer periphery of the callus pad, this resulting in the formation of a new stem-like structure. Whenever bark strips are separated from the bole wood by a layer of polyethylene plastic film and held firmly against the tree by externally applied pressure, the cambium continues to function normally, setting aside derivatives which differentiate and mature into normal, elongate xylary and phloic elements. The importance of mutual pressures and spatial relationships in controlling patterns of differentiation in secondary tissues is clearly demonstrated. THE MANY complex phenomena associated with the differentiation and maturation of cells and tissues in higher plants constitute a most fascinating and fertile area of experimental research. It is not surprising that much current research in morphoand histogenesis centers around the general area of apical meristems because, ultimately, it is here that complete control is exercised over the entire sequence of developmental events in the higher plant. It is rather odd, however, that so few workers have recognized lateral meristems as material par excellence for various experimental approaches to other problems of histogenesis. Perhaps this is because many view the vascular cambia of woody species only as a meristematic zone, where orderly cell divisions produce a more or less stereotyped pattern of xylem and phloem inherently peculiar to a given species. Obviously the biological mechanisms controlling cellular differentiation and maturation at this level are no less dynamic than those occurring elsewhere in the intact plant. Although a large body of literature is available on the physiology of cambial activity per se, little is actually known about specific mechanisms controlling the pattern of histological development in secondary tissues. Some of the most pertinent, yet indirect, work in this general area is that concerned with the healing of tissues around wounds and more specifically *to the insitu regeneration of tissues from the xylem side of the cambium on plants subjected to various surgical treatments. Of these, the work of Sharples and Gunnery (1933) on the formation of callus and regeneration of secondary tissues in several I Received for publication May 10, 1961. woody species is of special interest, as are also the more recent anatomical observations of Soe (1959) on the ancient practice of scoring trees to increase fruit or seed production. The present study describes the observed pattern of tissue differentiation in bark segments in which the vascular cambium is: (1) released from apparent pressure and normal spatial relationships; or (2) maintained under different amounts of externally applied pressure. MATERIALS AND METHODS-Forty-five vigorous, 5-year-old seedling trees of northern black cottonwood (Populus trichocarpa Torr. and Gray) were selected for treatment from among numerous seed sources in an experimental plantation established by the Cabot Foundation of Harvard University near Weston, Massachusetts. In addition, 35 white pine (Pinus strobus L.) seedlings ranging from 3 to 5 years of age and growing in adjacent blocks were selected for experimental use. The experimental treatments were initiated in early May during the period of active shoot elongation when the cambium of individual trees was exceedingly active. The surgical techniques used were simple. Two parallel, longitudinal incisions, approximately 8.0 cm in length and 1.5 cm apart, were made with a sharp grafting knife through the bark into the xylem at breast height. The basal portion of the bark strip was severed transversely and carefully lifted outward from the bole as shown in Fig. 1. The bark strips were left attached at the acropetal end to provide nourishment, and, upon separation from the bole, were immediately encased in a small, thin-gauge, polyethylene bag to prevent desiccation. Thus the strips were maintained in a humid environment and in an atmosphere which permitted gas AMERICAN JOURNAL OF BOTANY, Vol. 49, No. 7, 1962 [The Journal for July (49: 547-682) was issued July 18, 1962]