Tetraploids were induced successfully from in vitro plants of diploid Alocasia `Green Velvet' (2n=28) by treating shoot tips with colchicine or oryzalin. Colchicine at a concentration of 0.01, 0.05, 0.1% and oryzalin at 0.005, 0.01, 0.05% (both were dissolved in 1% DMSO, dimethylsulfoxide) were tested for 24, 48 and 72 h. Ploidy levels could be easily determined by flow cytometry. In total, 396 plantlets were investigated. Controls with DMSO maintained the diploid status; 22 tetraploids and 22 chimeras were obtained from treatments with colchicine and oryzalin. The most efficient condition for inducing tetraploids seemed to be treatment with 0.01% oryzalin for 24 h. Variation in the morphological characteristic of leaf shape was found among the multiplied plants under the same growing condition. While the leaves of diploids had elongated-heart shape, the leaves of tetraploids and chimeras tended to be round.

Induction of tetraploids in ornamental Alocasia through colchicine and oryzalin treatments

A B S T R A C T The dimensions of mericlinal sectors in periclinal chimeras resulting from replacement-displacement phenomena have been used to determine the number of shoot apical initial cells and their mitotic activity. Narrow sectors were always short, extending an average of less than three nodes. All long sectors were wide, involving 13 or 12 of the circumference of the stem. These observations define the origin of all primary growth as from 1-3 apical initial cells in each of the apical layers. The sectors reveal a surprising stability of cellular position at the center of growth, with a specific initial cell maintaining its position during formation of over 100 nodes. During vigorous vegetative growth of Ligustrum ovalifolium the initials themselves divide only about once in 12 days during the formation of three nodes. The mitotic index of the initials in privet shoot apices is 1.4, and this rate of division is sufficient for them to be the ultimate source

Determination of number and mitotic activity of shoot apical initial cells by analysis of mericlinal chimeras

The shoot apex in seed plants

Publisher Summary Throughout their life cycle vascular plants carry at the terminal portions of their axes young cells that retain the ability to divide They are the so-called meristematic cells which go to form the primary apical meristems These meristems continually give rise to derivatives, from which new tissues and organs originate; hence they maintain the functions of proliferation and organogenesis that follow segmentation of the zygote They form the essential organs of vascular plants and lay the primary structure of the shoots and roots; for this reason they may be called shoot meristems or root meristems The two types of apices, ie, the shoot and root apices, are very different from each other in their structure, localization, and physiology This chapter focuses on the caulinary meristematic cells, and discusses the histocytological, biochemical, and experimental research that led to clearer conceptions of the origin, structure, function, and development of the apical cells of shoots The root meristem, protected by the root cap, produces an independent axis, the root, which gives rise, at some distance from the meristcm, to lateral roots, organs of internal origin that ensure branching of the root axis The shoot meristem, on the contrary, produces organs of superficial origin on its sides, the leaves, exhibiting bilateral symmetry These leaves, by becoming united at their bases, form the stem, an axis that is therefore entirely dependent on the leaves

Experimental cytology of the shoot apical cells during vegetative growth and flowering.

Colchicine induced tetraploids in yellow-flowered cyclamens and their characteristics

A general cytohistological study of colchicine polyploidy in cranberry

INTRODUCTION.-DERMEN AND Bain (1944) reported that colchicine treatments applied to runner tips or to meristematic lateral buds of the cranberry resulted in the development of polyploid stem sectors much more frequently than in the development of completely polyploid stems. Stem sectors were utilized as sources of completely polyploid material, however, by forcing lateral buds located on the sectors to develop into branches. The presence of sectors was indicated by the simultaneous occurrence of diploid and polyploid types of leaves on the treated branches. The order in which the two types of leaves alternated along the stems was obviously controlled by the interaction between width of the sector and phyllotaxy of the stem. The present paper reports an analysis of the mathematical and anatomical principles underlying the relations between sectors and phyllotaxy. CHARACTERISTICS OF SECTORS.-Sectors as a rule were either totally tetraploid, epidermally tetraploid, or internally tetraploid (Dermen and Bain, 1944), and were usually laid down continuously as long as the stem elongated. Narrow sectors occasionally disappeared completely, particularly after resumption of growth following a period of dormancy. In two instances epidermal and internal sectors occurred on opposite sides of the same runner stem. The most conspicuous feature of sector-bearing stems was the peculiar alternation of diploid and tetraploid leaves along the stems. To understand better the phenomenon of alternation, the stem may be visualized as a long slender cylinder having a br.oad strip, the sector, marked along one side, while the phyllotactic arrangement is thought of as a spiral line winding around the cylinder and bearing nodes at regular angular intervals. Tetraploid leaves would then appear at those node positions which happened to fall within the limits of the marked strip, and diploid leaves at all positions outside of it. But since cranberry runner leaves are spaced relatively far apart on very slender stems, the spiral arrangement of leaves is not readily apparent, the leaves instead appearing to follow one another in simple linear succession. In the linear direction, diploid leaf would succeed diploid leaf until the phyllotactic spiral crossed the tetraploid sector, when there would follow as many successive tetraploid leaves as there were adjacent nodes within its limits; after this, diploid leaves would again appear until the sector is reached once more. Thus as long

Henry F. Bain

Papers

A general cytohistological study of colchicine polyploidy in cranberry

Sectorial polyploidy and phyllotaxy in the cranberry (vaccinium macrocarpon ait.)