Normal Green Plants Research Articles

CO2 Assimilation and Activities of Photosynthetic Enzymes in High Chlorophyll Fluorescence Mutants of Maize Having Low Levels of Ribulose 1,5-Bisphosphate Carboxylase

Photosynthetic properties were examined in several hcf (high chlorophyll fluorescence 11, 21, 42 and 45) nuclear recessive mutants of maize which were previously found to have normal photochemistry and low CO(2) fixation. Mutants usually either died after depletion of seed reserves (about 18 days after planting), or survived with slow growth up to 7 or 8 weeks. Both the activity and quantity of ribulose 1,5-bisphosphate carboxylase (Rubisco) were low in the mutants (5-25% of the normal siblings on a leaf area basis) and the loss of Rubisco tended to parallel the reduction in photosynthetic capacity. The Rubisco content in the mutants was often marginal for photosynthetic carbon gain, with some leaves and positions along a leaf having no net photosynthesis, while other leaves had a low carbon gain. Conversely, the activities of C(4) cycle enzymes, phosphoenolpyruvate carboxylase, pyruvate, Pi dikinase, NADP-malate dehydrogenase, and NADP-malic enzyme, were the same or only slightly reduced compared to the normal siblings. The mutants had about half as much chlorophyll content per leaf area as the normal green plants. However, the Rubisco activity in the mutants was low on both a leaf area and chlorophyll basis. Low Rubisco activity and lower chlorophyll content may both contribute to the low rates of photosynthesis in the mutants on a leaf area basis.

Somatic Embryogenesis and Plant Regeneration in Tissue Culture of Echinochloa glabrescens Munro ex Hook. F.

Summary Embryogenic calli which were compact, globular and white in appearance were initiated from young inflorescences and young leaf segments of Echinochloa glabrescens cultured on MS nutrient medium supplemented with 2,4-D and BAP. The induction frequency of embryogenic calli was more than 91% in young inflorescences and 41% in leaf segments. The embryogenic nature was maintained after more than seven months of subculture. The embryoids gave rise to plants on MS regeneration medium. High frequency of green plant regeneration was obtained from both explant cultures of E. glabrescens . However in leaf cultures, albino plants were also observed. Normal green plants grew to maturity, flowered and set seeds. Scanning electron microscope studies revealed that the white, compact, globular callus contained embryoids in various stages of development. Typical bipolar embryoids with scutella, coleoptiles and coleorhizae were observed.

Plant regeneration and initiation of cell suspensions from root-tip derived callus of Oryza sativa L. (rice)

Root-tip derived suspended callus of Oryza sativa cv. Thaipei showed the capacity for plant regeneration via organogenesis. Cell cultures were induced in liquid Murashige-Skoog medium containing 2 mg/l 2.4-dichlorophenoxyacetic acid. Dicamba or Picloram were effective for induction of organogenesis. Shoots and roots differentiated following subculture on medium lacking auxins but containing kinetin. At 1 and 4 mg/l Dicamba and 1 mg/l Picloram normal green plants were regenerated whereas with 7 mg/l Dicamba in the medium only albino plantlets were obtained. Regenerated plantlets were grown to maturity and set seed. Cell suspension cultures, initiated from the root-tip derived calli, provided suitable material for protoplast isolation.

Plant Regeneration by Somatic Embryogenesis from Callus Initiated from Immature Embryos and Immature Inflorescences of Hordeum vulgare

Callus cultures were obtained from immature embryos and immature inflorescences of Hordeum vulgare. Embryogenic callus was produced from both types of explant tissue and was affected by cultivar, size of explant and media components. The highest number of immature embryos (34.3%) and immature inflorescences (39.1%) formed embryogenic callus in the presence of culture medium containing 10 µM 2,4-dichlorophenoxyacetic acid. The majority of embryoids developed with a leafy structure in place of a scutellum. One to many shoot meristems were arranged along the base of this leafy structure. Morphologically normal green plants with a chromosome number of 2n = 14 were regenerated from both inflorescence and embryo cultures. Regenerated albino plantlets had small undifferentiated plastids containing large plastid DNA nucleoids. Also described is pistil development from embryogenic callus initiated from immature embryos of the cultivar Prior.

The allelic relationship between A IP(internal pigmentation) and A RC (red cabbage) in Brassica oleracea var. capitata L.

Internal anthocyanin pigmentation (IP), previously reported to be controlled by a single gene dominant to aa of normal green cabbage, was studied further to determine its relationship to A RC A RC of red cabbage. When IP line R52 was crossed with an early red cabbage line. F1 heads were pigmented throughout, but pigment intensity was intermediate. Subjective classification of F2 plants by pigmentation intensity and distribution scores gave a ratio of 1 intense red throughout (red cabbage):2 medium red throughout:1 medium to light red, restricted to the central portion of the head (IP). The genotypes A RC A RC: A RC A IP: A IP A IP. respectively, are proposed to explain these 3 phenotypic classes. F2 progenies contained no normal green plants, supporting the conclusion that A IP and A RC are alleles.

Improved efficiency of somatic embryogenesis and plant regeneration in tissue cultures of maize (Zea mays L.)

Immature embryos of eleven cultivars of hybrid maize (Zea mays L.), cultured on 2,4-D-containing nutrient media, showed rapid proliferation of the scutellum and improved efficiency in the formation of embryogenic callus and somatic embryos. High concentrations of sucrose were found to be most favorable for the formation of the embryogenic callus. Embryoids obtained in cultures of all eleven cultivars germinated in vitro and produced normal green plants which were grown to maturity in soil. The effect of genotype and other factors on somatic embryogenesis in maize are discussed.

CHARACTERIZATION OF AN EMBRYOGENIC CELL SUSPENSION CULTURE DERIVED FROM CULTURED INFLORESCENCES OF PENNISETUM AMERICANUM (PEARL MILLET, GRAMINEAE)

An embryogenic suspension culture was established from cultured inflorescence segments of Pennisetum americanum in Murashige and Skoog's medium supplemented with 2.5 mg/1 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 5% coconut milk. The suspension was composed of two major cell types: 1) small, richly cytoplasmic and starch‐containing cells, generally found in small, compact clumps, here termed embryogenic cells; and 2) elongated, thick‐walled cells with large vacuoles. By manipulating the duration of culture and dilution ratios (cell suspension: fresh medium) at the time of subculture, suspensions consisting predominantly of embryogenic cells were obtained. Suspensions grown for 2‐3 wks were transferred to agar media with reduced amounts of 2,4‐D. This resulted in the production of hundreds of globular and early cotyledonary embryoids. Further development of the embryoids was promoted by their transfer to a medium containing abscisic acid. Many of the embryoids germinated and produced normal green plants. Atypical embryoids, some containing many shoot meristems and a leafy scutellum, were also observed. The relevance of such atypical embryoids in the interpretation of organogenesis and embryogenesis reported in tissue cultures of cereal species is discussed. It is also suggested that somatic embryogenesis occurs in tissue cultures of most, if not all, species of cereals and grasses.

Somatic embryogenesis in Zea mays L.

Immature embryos of 12 genotypes of Zea mays L. were cultured on agar nutrient media containing various concentrations of 2,4-dichlorophenoxyacetic acid and sucrose. An opaque, white, compact and organized callus tissue was formed by the proliferation of the scutellar cells present in the vicinity of the scutellar node near the coleorhiza. Well-organized somatic embryos were formed on the surface of the proliferating scutellar callus within about three weeks. The embryos showed the typical organization of grass embryos with a scutellum, coleoptile and coleorhiza, and germinated to form normal green plants which were grown to maturity. An embryogenic cell suspension culture obtained from the scutellar callus is now being used for the isolation and culture of protoplasts.

GENETICS AND ULTRASTRUCTURE OF A CYTOPLASMICALLY INHERITED YELLOW MUTANT IN SOYBEANS

A chimeric plant was observed in the F(2) generation of a cross between a male-sterile line and a plant introduction homozygous for a chromosome interchange in soybeans [Glycine max (L.) Merr.]. F(3) progeny of this plant included one chimera, 36 yellow plants and 16 green plants. The yellow plants, which progressively turn green, were viable and fertile in field, greenhouse and growth-chamber environments. Reciprocal cross-pollinations were made between these yellow plants and four known nuclear yellow mutant plants, between these yellow plants and sibling green plants and between these yellow plants and unrelated green plants. Segregation data from F(1) and F(2) generations indicated cytoplasmic inheritance of the newly discovered yellow phenotype. Pollinations in which reciprocal F(1) hybrid plants were used as male or female parents were made with unrelated green plants. Observations in F(1) and F(2) generations substantiated the hypothesis of cytoplasmic inheritance. No interactions have been observed between this mutant and the various nuclear backgrounds. This is the first report of a cytoplasmically inherited mutant affecting plant color in soybeans. Exchange grafts were made between cytoplasmic yellow plants and sibling green plants and between cytoplasmic yellow plants and unrelated green plants. The phenotype was controlled by the scion, indicating that graft-transmissible agents were not involved. When grown in darkness, cytoplasmic yellow plants and normal green plants accumulated the same amount of protochlorophyllide. Cytoplasmic yellow plants grown in dim light accumulated slightly less chlorophyll than did their green siblings. Electron photomicrographs showed that the prolamellar body (a structure associated with synthesis of protochlorophyllide) and chloroplast ultrastructure were normal in the cytoplasmic yellow mutant. These observations led to the hypothesis that the synchrony involved in deposition of nuclear and cytoplasmic gene products during organelle development is impaired in this cytoplasmic mutant.

Ferrous and ferric iron ratio in normal and chlorotic bean plants (Vicia faba L.)

AbstractThe objective of this study was to determine the ratio and amount of Fe II and Fe III iron in different parts of 20 and 40 day old bean plants grown in pots under normal and HCO‐treatment. The Fe II and Fe III iron determination was carried out by a modification of a method described by Vogel (1969).The Fe II and Fe III concentrations in the plant varied according to its age, the plant part, the order of leaves and HCO‐treatment. At the second sampling date, the lower total iron content in the lower leaf particularly under the HCO‐treatment suggests that the supply of iron from the roots was restricted. The iron content of the different leaves was almost evenly divided into Fe II and Fe III at the first date. At the second date, most of the iron in the bud leaf was present as Fe II. Under HCO‐treatment the Fe II content of the bud leaf and the flower was similar as in the corresponding parts of the normal green plants whereas the Fe III content was considerably lowered in these plant parts as result of the HCO‐treatment.The results indicate a substantial retranslocation of iron from older to younger leaves and a higher Fe II/Fe III ratio in flowers and bud leaves particularly under HCO‐induced chlorosis.

Unequal formation of prenyl-lipids in a plant tissue culture and in leaves of Nicotiana tabacum L.

The synthesis of prenyl-lipids (chlorophylls, carotenoids and lipoquinones) in a yellow-green tobacco tissue culture is compared with that of leaves from an aurea mutant (Su/su) and from a normal green plant of Nicotiana tabacum L. The tissue culture contained all of the thylakoid prenyl-lipids; however, much less on a dry weight basis and also of a different concentration to green leaf tissue. With respect to chlorophyll the tissue culture contained very high concentrations of the electron carriers plastoquinone-9 and vitamin K 1 and was similar to the leaves from the aurea mutant with respect to prenyl-lipid synthesis. The tobacco tissue culture seemed to be photosynthetically active and exhibited variable fluorescence, which can be inhibited by 3-(3′ 4′-dichlorophenyl)-1,1-dimethylurea (DCMU).

INHERITANCE OF A YELLOW FOLIAGE CHARACTER IN RUSSIAN WILD RYEGRASS

Segregation in populations derived by crossing Sc. 260180, a yellow foliaged plant of Russian wild ryegrass (Elymus junceus Fisch.) and Sc. 25311, a normal green plant, showed the yellow foliage character carried by this population to be monogenic and recessive. The gene symbol y1 has been proposed for this character.

Der einfluß von stickstoffmangel auf die lipochinon- und isoprenoid-synthese der chloroplasten von Hordeum vulgare L.

The synthesis of all thylakoid prenyl-lipids is lower during nitrogen deficiency than in normal green cultures. The inhibition observed is of different degree for the individual lipid classes: carotenoids, chlorophylls, prenyl chains, and the isoprenoid lipoquinones. 1. Carotenoid synthesis in nitrogen deficient (−N) and in normal green plants (+N) is strongly correlated with chlorophyll synthesis. The synthesis of both lipid classes is regulated with the formation of thylakoids. A specific change of chloroplast metabolism during nitrogen deficiency towards a promotion of the synthesis of the nitrogen-free carotenoids has not been observed. 2. The formation of the isoprenoid plastid-quinones during nitrogen deficiency is much less inhibited than that of carotenoids and chlorophylls. This is equally due for the naphthoquinone K 1 and the benzoquinone derivates. 3. On a chlorophyll basis the synthesis of vitamin K 1 and of the benzoquinones, plasto-quinone-9 (+ hydroquinone) and α-tocopherol (+ α-tocoquinone), is enhanced during nitrogen deficiency. It is assumed that a higher level of endogenous aromatic precursors, as caused by the inhibition of protein synthesis, is responsible for this promotion. 4. During nitrogen deficiency the reduced benzoquinone forms α-tocopherol and plasto-hydroquinone-9 are synthesized to a higher degree than in the controls. This is an indication for their deposition in the osmiophilic plastoglobuli. 5. On a chlorophyll a basis during nitrogen deficiency there are formed a relative higher portion of chlorophyll b, a lower portion of β-carotene, but more xanthophylls, and in the group of lipoquinones somewhat less plastoquinone-9 (+ hydroquinone) and more α-tocopherol (+ α-tocoquinone) than in the controls. It is postulated that a lower concentration of IAA (reduced synthesis of IAA during nitrogen deficiency) is responsible for these synthesis shifts within the lipid classes. 6. Inhibition and promotion of the synthesis of the different prenyl lipids is discussed in connection with their biosynthesis. Literatur

Inheritance of an Albino Seedling Character in Arachis hypogaea L.1

SummaryTwenty F2 progenies of reciprocal crosses between Arachis hypogaea L. cultivars ‘Argentine’ and ‘Early Runner’ were grown in greenhouse or field plantings. At 2 to 4 weeks of age 11,973 seedlings were classified for albino vs. normal green plant color. All chlorophyll‐deficient lethal seedlings were scored as albino. The results indicate that the two cultivars differ at three loci conditioning albinism. No differences occurred for the reciprocal cross. Results indicate that chlorophyll production is controlled by duplicate loci interacting in an epistatic manner with another locus. Gene symbols C1 and C2 are proposed for the duplicate alleles; L designates the third locus. Chi‐squares give good fits to a phenotypic ratio of 60 green:3 albino:1 zygotic lethal. A reexamination of results from earlier studies shows that those data are not incompatible with this new genetic model.

MONOSOMIC ANALYSIS OF THE CORRODED CHARACTERISTIC IN WHEAT

A corroded leaf mutation which was first reported by Sears (1954) was found in the variety Kurrachee. The present investigation includes a more detailed phenotypic description of this mutant. The expressivity of this mutation was more pronounced under greenhouse conditions than in the field. A monosomic analysis was carried out in which the Koga monosomics were crossed with the variety Kurrachee. The mutation behaved as a deletion and was located on chromosome 6D. To obtain normal green plants, more than four of the six homoeologous alleles on the chromosomes of group 6 had to be present. With only four or less wild-type alleles the mutant characteristic was always evident, no matter on which of the homoeologous chromosomes the particular alleles were present.

Reproduction of sugar beet mosaic and tobacco mosaic viruses in anthocyanized beet plants

During our studies on the interaction of anthocyanins and plant virus diseases, reproduction of sugar beet mosaic (SBMV) and tobacco mosaic viruses (TMV) was investigated. Experiments were carried out in leaves of sugar beet,Beta vulgaris cv. Dobrovicka N and its spontaneous anthocyanized mutant. SBMV induces a systemic infection while TMV is responsible for primary local symptoms in sugar beet leaves only. Our quantitative analyses onAmaranthus caudatus L. andChenopodium quinoaWilid. showed a significant decrease in concentration of SBMV in juice extracted from anthocyanized beet plants as compared with extracts from normal green infected plants. Significant differences were also obtained when SBMV — containing juice was tested in mixtures with healthy extracts from anthocyanized and normal green plants. Also the intensity of TMV symptoms in beet leaves was considerably decreased in leaves of antho-eyanized plants.

Photosynthetic apparatus in Selaginella. I. Morphology and photosynthesis under different light and temperature regimes

Several hydrophytic and umbrophilic species of Selaginella were grown in sterile culture and scrutinized for morphological and photosynthetic variability under light intensities between 0 and 500 ft-c and temperatures of 9° and 22 °C. Bleaching was induced by raising light intensity; and for a particular light intensity was enhanced by lowering temperature. Regreening could be achieved by reversing conditions. Branching patterns, leaf symmetry, and orientation of leaves to axis were also light dependent. Light levels which produced normal green plants for S. uncinata initiated only half-saturation photosynthetic rates. Photosaturating light intensities, if applied for several weeks, induced bleaching. Based on fresh or dry weight bleaching plants had lower photosynthetic rates than green plant's; but based on chlorophyll content the photosynthetic rates of green and bleaching plants were the same.

Fluorescence properties of chloroplasts from manganese deficient and mutant tobacco

1. The kinetics of the fluorescence induction are described for chloroplasts from normal green tobacco, from the aurea tobacco mutant Su/su, from the photosynthetically inactive yellow patches of a variegated tobacco, and from tobacco plants grown in absence of manganese. The first two types display the well-known biphasic induction, but the Su/su chloroplasts have a distinctly slower rise time. Manganese deficient chloroplasts show a significantly higher fluorescence yield than any other type of chloroplasts studied. The kinetics of their fluorescence, on the other hand, are similar to those observed with the inactive chloroplasts from the variegated tobacco: the fluorescence rise is small, and the fluorescence yield is not changed very much by the addition of a reducing agent like hydrosulfite, or by addition of an oxidant like ferricyanide, or by an inhibition of the electron flow in Photosystem II with 3(3,4-dichlorophenyl)-1,1-dimethylurea. 2. Determinations of the amount of the primary electron acceptors associated with Photosystem II point to a 2- to 3-fold larger electron acceptor pool in chloroplasts of young Su/su plants than in chloroplasts of old Su/su plants and of various green leaves, including those from green tobacco. This finding agrees with recently published data on the size of the photosynthetic unit in tobacco mutants and normal green plants. 3. The different fluorescence characteristics of all four types of chloroplasts under study are discussed on the basis of their structure and their activity in photosynthetic O 2 evolution.

Genetic studies on the leaf variegation of Allium cepa L.

Only one plant of onion having yellow-green stripes on leaves was found under field conditions in 1960. Because of male sterility, it was propagated vegetatively to maintain the clonal line. Fortunately, male-fertile variegated plants were found out of those male-sterile clones in 1965. The variegated leaves were striped alternately with green and yellow bands. The width of the stripes varied considerably as shown in Fig. 1. These male-fertile variegated plants were used as materials in the present experiments to clear up the genetic behavior.The results of self-pollination in the variegated plants are shown in Table 1. When self-pollinated the variegated plant produced green and yellowish white seedlings. The yellowish white seedlings perished immediately after germination. The variegated plants were distinguished from the green plants during the late stage of growth. The green plants obtained from the original variegated plants by vegetative propagation bred true for green in the first generation of selfing (Table 1).The results of the reciprocal crosses between variegated and normal green plants are shown in Table 2. The F1 generation from the cross variegated plant _??_×normal green plant _??_ segregated green and yellowish white in seedling stage, and green and variegated in adult stage.The self-pollinated green F1 plants bred true for green in F2. The variegated F1 plants produced green, yellowish white, and variegated plants in the F2 and F3 generations.The F1 plants of the cross normal green plants _??_×variegated plant _??_ were green, which produced only green plants with the exception of a single variegated plant in the F2 generation.From these results the leaf variegation of onion seems to be maternally inherited, and controlled by plastogenes.A genetical mechanism is not known by which the male-fertile variegated plants were induced from the male-sterile ones. It would be due to somatic segregation during vegetative propagation (Smsms→SMsms, cf. JONES and CLARKE, 1943).The genetic interrelation between male sterility and variegation requires further study.

A Laboratory Study of Feeding Habits of Melanoplus differentialis in Maryland (Orthoptera: Acrididae)

Among the food plants offered to the differential grasshopper, Melanoplus differentialis (Thomas), Taraxacum officinale proved to be preferred. However, unlike many other forbivorous acridids, this grasshopper can also develop and reproduce by feeding on Gramineae only, although individuals reared exclusively on this diet were small. In addition to their normal green plant food, M. differentialis also feeds on entirely dried-up plants, even in the presence of fresh plants—an adaptation for survival during the hot, dry part of the year. The feeding habits of this grasshopper were greatly influenced, among other ecological factors, by its own behavior toward light and temperature, in addition to the physical features and orientation of the food plants themselves. Consequently, the plants actually used as food in nature may be very different from those the insect prefers. The mandibles of this species are typically of the forbivorous type, while the maxillae resemble those of Tetrix, the moss feeders. The ventral digestive caeca are always longer than the dorsal, and the proportions of anterior and posterior lobes of the caeca vary in different age groups. Other morphological variations in this organ also were noted. The mid-gut of adult M. differentialis was heavily infested by gregarines, which were seen in various stages of development in the alimentary canal. No detectable influence on the host was noticed; the host-parasite relationship is obscure.