LIGHT AND HORMONAL CONTROL OF ROOT FORMATION IN ZEA MAYS CALLUS CULTURES

Callus cultures of Zea mays were used to study the interaction of light with exogenous cytokinin/auxin levels in the initiation, growth and development of roots. Three auxins, indoleacetic acid (IAA), naphthaleneacetic acid (NAA) and 2,4 dichlorophenoxyacetic acid (2,4 D) were remarkably different in their effects on callus growth and root initiation. NAA at concentrations of 5 and 25 μM produced the highest combined yields of callus and roots under low light conditions. No significant morphological effects on roots were observed with the three auxins tested nor did low and intermediate light intensities alter root development.
At intermediate light levels the addition of the cytokinin, zeatin, was also able to influence the differentiation of the callus tissue. Increasing the cytokinin/auxin ratio from low to high shifted the development from callus growth to abundant root formation. High light caused the formation of short, thick roots. This effect could be counteracted in part by zeatin which promoted elongation. These observations suggest that both, the cytokinin/auxin ratio and light play an important role in the development of monocotyledonous roots.     

ULTRASTRUCTURAL CYTOLOGY OF CALLUS CULTURES OF STREPTANTHUS TORTUOSUS AS AFFECTED BY TEMPERATURE

Tissue culture cells of Streptanthus tortuosus var. orbiculatus (Cruciferae) which have acquired a spherical viruslike particle located in their nucleoli, designated cell line STV, developed supergranal chloroplasts and lost the ability to differentiate vascular tissues. The effect of temperature on the ultrastructural cytology of one line of the STV tissue, STV-I, was compared with the effect of temperature on the ultrastructural cytology of tissue culture cells lacking the viruslike particles (control cell lines). At 4 C, the cellular and ultrastructural appearance of control tissue culture cells differed from that of tissue grown at 22 C by producing increased amounts of endoplasmic reticulum and dictyosomes and by reduction of chloroplast thylakoids. STV-I cells were generally moribund as a result of 4 C treatment. Chloroplast thylakoids were also reduced in control tissue following growth at 10 C and the apparent quantities of endoplasmic reticulum and dictyosomes were similar to those observed in control cells grown at the control temperature (22 C), but less than those observed in tissue subjected to 4 C. STV-I tissue grown at 10 C demonstrated increased endoplasmic reticulum and dictyosomes and reduction of polysomal configurations. The mitochondrial morphology was variable and the cells contained supergranal chloroplasts and proplastids. At the control temperature (22 C), the fine structural appearance of control tissue culture cells was typical of parenchyma cells, but STV-I cells contained mitochondria of variable morphology and two types of chloroplasts— normal and supergranal. Control tissue grown at 30 C also contained proplastids, but these proplastids contained starch in contrast to the proplastids in control tissue grown at low temperatures. The ultrastructural cytology of STV-I cells grown at elevated temperature (30 C) was characterized by enlarged mitochondria containing massive lipid bodies and the presence of protoplastids with starch and supergranal chloroplasts.     

NUTRITIONAL REQUIREMENTS OF FRAXINUS CALLUS CULTURES

A satisfactory synthetic medium has been developed for continuous growth of Fraxinus pennsylvanica Marsh. callus cultures. The medium contains modified Reinert and White (1956) inorganic nutrient solution with 5 mg/liter Fe as NaFe-EDTA and supplemented with myoinositol 10 mg/liter, pyridoxine HCl 0.1 mg/liter, 2,4-dichlorophenoxyacetic acid 0.04 mg/liter, kinetin 1 mg/liter, sucrose 20 g/liter, and agar 10 g/liter. myo-Inositol, pyridoxine and an auxin are essential. α-Naphthaleneacetic acid is an effective alternate auxin. Kinetin and to some extent gibberellic acid improve the yields. Thiamine has no effect.     

SOMATIC EMBRYOGENESIS AND ORGANOGENESIS FROM CALLUS CULTURES OF SOLANUM CAROLINENSE

Culture of stem segments of Solanum carolinense L. on medium supplemented with 10 mg/1 2,4-dichlorophenoxyacetic acid and 1 mg/1 kinetin, induced callus formation. When subcultured on medium lacking 2,4-D but containing a cytokinin, the callus regenerated. The mode of regeneration depended on the type and concentration of cytokinin employed; high concentrations of benzyladenine and all concentrations of kinetin promoted organogenesis, while low concentrations of benzyladenine induced somatic embryogenesis in addition to organogenesis. With age and continued subculture on 2,4-D containing medium, callus progressively lost its ability to regenerate when the auxin was replaced by cytokinin. In conjunction with previous studies on regeneration from anther cultures of S. carolinense, it appears that in both cases, 2,4-D is required for callus initiation and proliferation but must be exchanged for a cytokinin before differentiation will occur. However, since it was not possible to induce embryogenesis in pollen-derived callus, developmental potential may be influenced by the ploidy level of responding cells in culture.     

激光对香石竹愈伤组织蛋白质和同工酶谱的影响

用氦氖激光处理香石竹愈伤组织,可使材料中的34kD和28kD蛋白含量高于对照,并产生分子量约为22kD的新的蛋白带。而用氩离子激光处理后,则出现一条分子量约为45kD的新的蛋白带。此外,激光处理亦明显影响愈伤组织的过氧化物酶同工酶谱及其活性,其中氦氖激光处理后产生了Rf为0.17和0.26的新酶带,而用氩离子激光处理则只产生Rf为0.17的新酶带。激光对香石竹愈伤组织的酯酶同工酶无影响。     

PHYSIOLOGICAL AND BIOCHEMICAL CHANGES OF CARROT ROOT CALLUS DURING SUCCESSIVE CULTURES

1. The longer the period of stock culture, the more remarkableis the growth inhibition by 8-azaguanine in callus.
2. Chloramphenicol,5-methyltryptophane and mitomycin C exert greaterinhibitionon growth in CCL than in CCS.
3. Bud formation is inhibited bysome concentrations of chloramphenicolwithout accompanyinginhibition of the growth.
4. Cell size and the contents of RNA,DNA, protein and lipid percell of CCL are greater than thoseof CCS, respectively. Thecontents per cell of RNA and lipidin "mitochondrial fraction"are higher in CCL than in CCS.
5. Incorporationof guanine-8-¹⁴C into RNA of CCS occurs rapidlyin the first12 hr and slows down thereafter, but that in CCL-RNAincreasessteadily for 16 hr. This difference in rate of theincorporationafter 12 hr between CCS and CCL is principallydue to the differencein rate of the incorporation into RNAof nuclear, mitochondrialand soluble fractions.

1. The rate of RNA breakdown in CCL wasnot so great as the rateof synthesis.
2. 8-azaguanine (10^–3and 10^–4M) inhibits incorporationof guanine-8.¹⁴C intoRNA of both CCS and CCL during 14 hr,but thereafter (up to25 hr) it inhibits the incorporation intoCCL-RNA alone leavingthat into CCS-RNA unaffected.

1. In CCL 510^–5M 8.azaguaninedoes not affect total radioactivityincorporated into bulk RNA,but inhibits incorporation intoRNA of "mitochondrial fraction".

(Received December 23, 1964; )     

MORPHOGENESIS OF POLLEN CALLUS CULTURES OF HYOSCYAMUS NIGER

Morphogenesis of calluses of single pollen grain origin shed from anthers of Hyoscyamus niger cultured in a liquid medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) was followed upon their transfer to a solid medium with or without 2,4-D. In a solid medium lacking 2,4-D, small calluses consisting of one to five nodular groups of cells at the time of inoculation differentiated root and shoot systems and formed miniature seedlings. In the same medium large calluses with several nodules initially formed a crop of bipolar somatic embryoids with well-defined root and shoot axes which subsequently differentiated into seedlings. Irrespective of their size at the time of transfer, calluses grown in a solid medium containing 2,4-D continued to proliferate without showing signs of organogenesis or embryogenesis.     

Developmental Physiology of Sugar Beet: I. THE INFLUENCE OF LIGHT AND TEMPERATURE ON GROWTH

Sugar beet plants were grown for 12 weeks from emergence ingrowth rooms at temperatures of 10, 17, 24 and 31 °C and20, 50, 80, and 110 cal visible radiation cm^-2d^-1, and the changeswith time in their dry weight, leaf area, leaf numbers, andstorage root sugar determined. The first stage of growth wasdominated by the development of the shoot, but the storage rootgradually assumed increasing importance and eventually grewat a faster rate and to a greater weight than the shoot. Therelative growth rate and final yield of dry matter of the shootwere greatest at 24 °C and of the root between 17 and 24°C. The relative rate of expansion and the final area ofthe leaf surface were also greatest at 24 °C, whilst therates of production and of unfolding of leaves were greatestat about 17 °C. All these attributes were increased withincreased radiation. Net assimilation rate increased almostproportionately with radiation and was not significantly affectedby temperature.The relationships of total leaf area with plantdry weight, root dry weight with shoot dry weight, and totalleaf number with plant dry weight were scarcely affected bychanges in radiation, but were much influenced by temperature.Plants of the same dry weight generally had bigger roots andsmaller areas of leaf surface as temperatures departed from24 °C and had most leaves at 17 °C. Sugar concentrationsin the storage root were greatest at 17 °C, but the totalamount of sugar was about the same at 17 and 24 °C. Theconcentration of sugar in the storage root depended on rootsize.Thus, temperature affected both the rate and pattern ofdevelopment, and radiation affected the rate but not the patternof development.     

植物离体培养产生草珊瑚有效成分

报道了以草珊瑚外植体诱导愈伤组织的适宜培养基和各种植物激素在诱导及其生长培养中的调节作用。应用薄层层析（ＴＬＣ）和紫外光鉴定，证明所获得的愈伤组织具有合成与原植物材料相同的黄酮类、异嗪上以啶类、延胡索酸等有机酸的能力。亦通过愈伤组织无性系筛选过程，得到一个增长率和代谢物产量比愈伤组织母系高４倍左右的优良愈伤组织系。     

培养条件对齿瓣延胡索愈伤组织生长及延胡索乙素含量的影响

研究了不同培养条件对齿瓣延胡索(Corydalis remota)愈伤组织生长及延胡索乙素(THP)含量的影响。结果表明, 2, 4-D较NAA更有利于提高培养物鲜重,加速细胞增殖。培养基添加2.0 mg/L 2, 4-D和1.0 mg/L BA不仅有利于干物质积累,而且显著提高THP水平。蔗糖不仅可提高培养物鲜重,而且与半乳糖组合可显著促进干物质积累和THP水平的提高。水解酪蛋白和水解乳蛋白均有利于愈伤组织生长和THP含量的提高, 450mg/L的水解乳蛋白处理组THP含量最高。光照可提高培养物鲜重和THP含量。     

ULTRASTRUCTURAL ASPECTS OF SHOOT INITIATION IN TOBACCO CALLUS CULTURES

An ultrastructural investigation of shoot initiation in tobacco (Nicotiana tabacum L. var. W. 38) callus cultures was made. Zones of preferential division were observed in the basal portion of the tissue by eight days in culture and these led, sequentially, to meristemoids, primordia, and shoots. During the initial stages of meristemoid formation, protein inclusions and large accumulations of plastid starch were present in the cells, while vacuoles were filled with membranous and cytoplasmic protrusions. At later stages of meristemoid development, these features were not observed in the cells, which were also smaller in size and possessed numerous small, peripheral vacuoles. It appears that the membranous and cytoplasmic protrusions are involved in vacuolar reduction during meristemoid formation. It would also appear that the storage materials supply the energy and other reserves needed for the organogenetic process. By contrast, tissue cultured under nonshoot-forming conditions and nonmeristemoid regions of shoot-forming tissue remained parenchymatous over the same time period.     

NUTRITIONAL AND MORPHOGENETIC INVESTIGATIONS ON CALLUS CULTURES OF NEOMAMMILLARIA PROFILERA MILLER (CACTACEAE)

Neomammillaria prolifera (Cactaceae), when grown on Murashige and Skoog's medium supplemented with fresh coconut milk, showed very little growth. Various concentrations and combinations of growth regulators which did not cause callusing had no apparent effect on the normal growth rates of intact plants. Healthy green calli obtained on a 2,4-D and kinetin-containing medium exhibited extremely fast growth and very specific growth requirements. Relatively high amounts of 2,4-D (10–20 mg/liter), kinetin (1–2 mg/liter), and coconut milk (20–60%) were required at all times for continued proliferation of callus on subculturing. Moreover, the callus was very tolerant to extremely high concentrations of other growth regulators (IAA, NAA, IBA, and GA up to 100 mg/liter) in the presence of 2,4-D and coconut milk. These substances could not replace 2,4-D for callusing or continued growth of callus. It was not possible to establish root cultures or to induce callusing of roots. Attempts to induce differentiation in callus were unsuccessful, except for sporadic root initiation in some cultures. A comparison of these results with similar studies on other succulents demonstrates some basic physiological similarities among this group of plants.     

光与激素对于杜鹃花种子发芽的作用

本文报道24种杜鹃花种子的光照发芽试验,结果表明杜鹃花种子是需光性种子。所有种子的发芽都必须有光照,假如在黑暗条件下进行发芽试验,种子的发芽率几乎等于零。杜鹃花种子的发芽受光敏素的控制,红光促进种子发芽,远红光可以逆转这种促进作用,种子发芽与否取决于最后一次照射的光质。 不同种的杜鹃花种子对光的敏感性存在差异。敏感的种子可以在蓝光,短光照时间下正常发芽,并且它们的需光要求可以被1000 ppm赤霉素所代替。迟钝的种子发芽则要求红光和长光照时间,1000 ppm赤霉素不能代替光,光和赤霉素并用具有增效作用。