Phenotypic characterization of the dwarf-4 mutant of lettuce

The single recessive mutant dwarf-4 (d-4) of lettuce (Lactuca sativa L.) was selected as a potential genetic source of resistance to premature stem elongation (bolting). This study was undertaken to define the mutant phenotype and to characterize its reaction to applied gibberellin (GA). Scanning electron micrographs of mutant and wild-type achenes revealed surface and subsurface aberrations in d-4, suggesting abnormal development. Observed mutant irregularities included (i) abnormal achene formation causing irregularly shaped seeds, (ii) delayed and irregular germination, (iii) delayed but normal leaf growth and leaf area, (iv) 66% reduction in stem height, (v) 50% reduction in shoot dry weight, (vi) 0.45% viable pollen formation, and (vii) 98.9% self-sterility. Applications of GA3 did not affect the delay in growth, floral sterility, or abnormal achene shape but did increase stem height and shoot dry weight to wild-type levels at maturity. Hand pollinations were able to decrease self-sterility to 93.6%. Component analysis of mutant and wild-type achenes revealed d-4 had 32% lower fatty acid levels. There were no differences in carbohydrates, cell wall constituents, and moisture levels, although higher levels of protein and inorganic compounds were found. The observed d-4 phenotype suggests that its genetic lesion is not directly tied to irregularities of gibberellin biosynthesis but has some other genetic basis. Key words: Lactuca sativa, SEM, germination, stem elongation, sterility.

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Role of Gibberellin A4 and Gibberellin Biosynthesis Inhibitors on Flowering and Stem Elongation in Petunia under Modified Light Environments

HortScience ◽

10.21273/hortsci.40.1.134 ◽

2005 ◽

Vol 40 (1) ◽

pp. 134-137 ◽

Cited By ~ 5

Author(s):

T.A. Cerny-Koenig ◽

J.E. Faust ◽

N.C. Rajapakse

Keyword(s):

Stem Elongation ◽

Dry Weight ◽

Gibberellin Biosynthesis ◽

Shoot Dry Weight ◽

Long Day ◽

Air Temperatures ◽

Biosynthesis Inhibitors ◽

Growing Environment ◽

Ga Biosynthesis

In our previous experiments, greenhouse films that selectively remove far-red (FR) light from the growing environment reduced the stem elongation but delayed anthesis of long day plants. In the present research we investigated if the application of gibberellin A4 and gibberellin (GA) biosynthesis inhibitors could overcome the delay in anthesis of petunia (Petunia ×hybrida Vilm.-Andr.), a quantitative long-day plant, under a FR light deficient environment. The GA biosynthesis inhibitors prohexadione-Ca and exo-C-16,17-dihydro GA5 (GA5) were used because of their ability to prevent catabolism of active GAs. Anthesis and stem elongation were investigated under control, red (R; 600 to 700 nm) and FR (700 to 800 nm) light-absorbing (AR and AFR) films. The R:FR ratios of control, AR, and AFR films were 1.03, 0.71, and 1.51, respectively. Air temperatures among treatment chambers were not different. AR film did not affect anthesis or stem elongation, but AFR film reduced stem elongation and delayed anthesis by 12 days. Exogenous application of GA5 had no effect on stem elongation, shoot dry weight or days to anthesis at any concentration (0 to 100 mg·L-1) tested under control, AR, or AFR films. Anthesis was delayed with increasing concentration (0 to 200 mg·L-1) of prohexadione-Ca under all treatments. Prohexadione-Ca at 200 mg·L-1 delayed anthesis by 11 and 7 days under the control and AFR film, respectively, suggesting an interaction between light quality and prohexadione-Ca treatment. Exogenous GA4 accelerated anthesis under both films but the promotion was greater under the AFR films. However, GA4 treatment increased stem elongation and the increase in stem elongation was greater under the AFR film. Addition of GA5 to GA4 had no added effect on flowering and failed to reduce stem elongation. Therefore, GA or GA inhibitors are not suitable for flower promotion under AFR films.

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Effects of an Autoregulatory Senescence-inhibitor Gene Construct on Nicotiana alata Link and Otto.

HortScience ◽

10.21273/hortsci.33.3.519d ◽

1998 ◽

Vol 33 (3) ◽

pp. 519d-519 ◽

Cited By ~ 4

Author(s):

Kenneth R. Schroeder ◽

Dennis P. Stimart

Keyword(s):

Agrobacterium Tumefaciens ◽

Plant Height ◽

Dry Weight ◽

Nicotiana Alata ◽

Wild Type ◽

Gene Encoding ◽

Delayed Senescence ◽

Gene Construct ◽

Shoot Dry Weight ◽

Inhibitor System

Nicotiana alata Link and Otto. was transformed via Agrobacterium tumefaciens encoding a senescence-specific promoter SAG12 cloned from Arabidopsis thaliana fused to a Agrobacterium tumefaciens gene encoding isopentenyl transferase (IPT) that catalyzes cytokinin synthesis. This was considered an autoregulatory senescence-inhibitor system. In 1996, we reported delayed senescence of intact flowers by 2 to 6 d and delayed leaf senescence of transgenic vs. wild-type N. alata. Further evaluations in 1997 revealed several other interesting effects of the SAG12-IPT gene construct. Measurement of chlorophyll content of mature leaves showed higher levels of both chlorophyll a and b in transgenic material under normal fertilization and truncated fertilization regimes. At 4 to 5 months of age transgenic plants expressed differences in plant height, branching, and dry weight. Plant height was reduced by 3 to 13 cm; branch counts increased 2 to 3 fold; and shoot dry weight increased up to 11 g over wild-type N. alata. These observations indicate the system is not tightly autoregulated and may prove useful to the floriculture industry for producing compact and more floriferous plants.

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EFFETS DE LA FERTILISATION AZOTÉE SUR LA CROISSANCE DE TRANSPLANTS DE TOMATE ET DE LAITUE CULTIVÉS EN PLATEAUX MULTICELLULAIRES AVEC OU SANS ÉCLAIRAGE D’APPOINT

Canadian Journal of Plant Science ◽

10.4141/cjps90-148 ◽

1990 ◽

Vol 70 (4) ◽

pp. 1199-1205 ◽

Cited By ~ 4

Author(s):

JEAN MASSON ◽

ANDRÉ GOSSELIN ◽

NICOLAS TREMBLAY

Keyword(s):

Lycopersicon Esculentum ◽

Leaf Area ◽

Lactuca Sativa ◽

Dry Matter ◽

Dry Weight ◽

Root Dry Weight ◽

Shoot Dry Weight ◽

Shoot Ratio ◽

Root To Shoot Ratio ◽

Fertilisation Azotée

Tomato (Lycopersicon esculentum Mill. ’Springset’) and lettuce (Lactuca sativa L. ’Ithaca’) transplants were grown under natural and supplemental light (100 μmol m−2 s−1 PAR) and fertilized with four nitrogen doses (100, 200, 300, and 400 mg L−1 N). Supplemental light increased tomato shoot dry weight, shoot percent dry matter, leaf area, root dry weight, and root-to-shoot ratio. Lettuce transplants showed increased shoot and root dry weight as well as leaf area when supplemental light was present. For both species, nitrogen increased shoot dry weight and leaf area, but decreased shoot percent dry matter and root-to-shoot ratio. High nitrogen doses increased tomato and lettuce shoot dry weight and leaf area chiefly under supplemental light.Key words: Lycopersicon esculentum, Lactuca sativa, pretransplanting nutritional conditioning, seedling

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INFLUENCE OF THE MODE OF SALINIZATION ON REPRODUCTIVE TRAITS OF FIELD-GROWN PROGENY IN SORGHUM BICOLOR

Israel Journal of Plant Sciences ◽

10.1080/07929978.1998.10676702 ◽

1998 ◽

Vol 46 (1) ◽

pp. 9-16 ◽

Cited By ~ 6

Author(s):

G.Nissim Amzallag ◽

Avi Nachmias ◽

Henri Lerner R.

Keyword(s):

Sorghum Bicolor ◽

Saline Water ◽

Phenotypic Variability ◽

Reproductive Traits ◽

Dry Weight ◽

Similar Increase ◽

Stem Height ◽

Shoot Dry Weight ◽

Late Exposure ◽

Parent Generation

The offspring of Sorghum bicolor (L.) Moench plants exposed to 150 mM NaCl eight or twenty-one days following germination were grown in field conditions, and were irrigated with non-saline water. As compared to the offspring of non-treated plants, the progeny of plants early-exposed to NaCl displayed an increase in shoot dry weight and stem height, but some of them showed a significant decrease in fertility. Similar changes were observed, but to a lesser extent, in the offspring of plants late-exposed to salinity. A similar increase in phenotypic variability was observed in populations of progeny from early-and late-treated plants. After verifying that the changes observed did not result from an artifactual selection, it was concluded that the NaCl treatment is able to influence characters expressed during the late development of the plant progeny. The nature of the induced change is discussed in relation to the plant response, adaptation or resistance, induced by the early or late exposure to salinity in the parent generation.

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INDUCED MODIFICATIONS IN REPRODUCTIVE TRAITS OF SALT-TREATED PLANTS OF SORGHUM BICOLOR

Israel Journal of Plant Sciences ◽

10.1080/07929978.1998.10676701 ◽

1998 ◽

Vol 46 (1) ◽

pp. 1-8 ◽

Cited By ~ 10

Author(s):

G.Nissim Amzallag

Keyword(s):

Sorghum Bicolor ◽

Phenotypic Variability ◽

Reproductive Traits ◽

Dry Weight ◽

Salt Adaptation ◽

Early Exposure ◽

Stem Height ◽

Shoot Dry Weight ◽

Adaptation Response ◽

Reproductive Characters

Plants of Sorghum bicolor were grown hydroponically in a solution containing 150 mM NaCl, and the reproductive characters were analyzed at the end of the life cycle. A subpopulation was exposed to salinity on day 8 following germination (early-exposed plants), and another subpopulation was first exposed to salinity on day 21 following germination (late-exposed plants). Fertility and stem height, as determined per g shoot dry weight (DW), were similar for control and late-exposed plants. However, these parameters were largely modified in early-exposed plants. The population of late-exposed plants displayed an increase in phenotypic variability. However, the monomodal structure of the population remained similar to that of the population of control plants. In contrast, a large increase in diversity was observed in the population of early-exposed plants, and the frequency distribution of the reproductive characters appeared as plurimodal for this population. Early exposure to NaCl has been previously shown to induce an increase in salinity tolerance of the plant (termed salt adaptation). This effect was not observed for late-exposed plants. The significance of the induced modifications in reproductive characters is discussed in the light of the salt adaptation response in Sorghum.

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Use of Cold Water for Irrigation Reduces Stem Elongation of Plug-grown Tomato and Cabbage Seedlings

HortScience ◽

10.21273/hortsci.34.5.852 ◽

1999 ◽

Vol 34 (5) ◽

pp. 852-854 ◽

Cited By ~ 2

Author(s):

Junne-Jih Chen ◽

Yung-Wei Sun ◽

Tzay-Fa Sheen

Keyword(s):

Lycopersicon Esculentum ◽

Brassica Oleracea ◽

Room Temperature ◽

Cold Water ◽

Stem Elongation ◽

Dry Weight ◽

Stem Length ◽

Shoot Dry Weight ◽

Different Temperatures

Seedlings of tomato (Lycopersicon esculentum Mill.) and cabbage (Brassica oleracea L. var. Capitata) were planted in 240-cell plug trays in the greenhouse and subjected to irrigation with water at different temperatures once a day. Irrigation with cold (5 to 15 °C) water reduced stem length of tomato by 28% to 32% in comparison with irrigation with water at room temperature (27.5 to 30.5 °C). Use of water at 10 °C did not affect total shoot dry weight but increased the shoot dry weight per centimeter of stem. Irrigation with water at 5 °C reduced stem length of cabbage seedlings 40%, but use of water at 10 and 15 °C did not. Both shoot and root dry weights were increased by irrigation with water at 10 °C. These results demonstrate that irrigation with cold water provides an effective method for improving the quality of plug-grown seedlings.

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Effects of Day Length and Light Intensity on Growth of Barley IV. Genetically Controlled Variation in Response to Photoperiod

Australian Journal of Biological Sciences ◽

10.1071/bi9660517 ◽

1966 ◽

Vol 19 (4) ◽

pp. 517 ◽

Cited By ~ 8

Author(s):

D Aspinall

Keyword(s):

Floral Development ◽

Stem Elongation ◽

Dry Weight ◽

Day Length ◽

Common Mechanism ◽

Hordeum Vulgare L ◽

Floral Organogenesis ◽

Shoot Dry Weight ◽

Long Day ◽

Wide Range

Apical growth, floral development, stem elongation, tillering, and dry weight at ear emergence were compared for 10 varieties of barley (Hordeum vulgare L.) growing in a range of photoperiods. All the varieties could be described as quanti. tative long. day plants but there was a wide range of response to the photoperiod. In all the varieties and over all photoperiods, apical primordium production was linked with floral organogenesis, suggesting a common mechanism of photoperiodic influence on the two proce~es. The control of internode elongation, however, varied between different varieties, commencing at a much earlier stage of floral organogenesis in some varieties than in others. Tillering appeared to be controlled more by the amount of energy available for photosynthesis than by any photoperiodic process, and this was also an important factor in shoot dry weight at ear emergence.

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Mitigation of Salt Stress in Lettuce (Lactuca sativa L. var. Crispa) by Seed and Foliar 24-epibrassinolide Treatments

HortScience ◽

10.21273/hortsci.47.5.631 ◽

2012 ◽

Vol 47 (5) ◽

pp. 631-636 ◽

Cited By ~ 24

Author(s):

Melek Ekinci ◽

Ertan Yildirim ◽

Atilla Dursun ◽

Metin Turan

Keyword(s):

Salt Stress ◽

Lactuca Sativa ◽

Electrolyte Leakage ◽

Mineral Content ◽

Dry Weight ◽

Nutrient Content ◽

Fresh Weight ◽

Shoot Dry Weight ◽

Negative Effect ◽

Almost All

The objective of this study was to determine the effect of 24-epibrassinolide (24-EBL) applications on growth, chlorophyll, and mineral content of lettuce (Lactuca sativa L. var. Crispa) grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Lettuce seedlings were treated with seed and foliar 24-EBL applications at different concentrations (0, 1, 2, and 3 μM). Salinity treatments were established by adding 0, 50, and 100 mm of sodium chloride (NaCl) to a base complete nutrient solution. Results showed that salt stress negatively affected the growth and mineral content of lettuce plants. However, seed and foliar applications of 24-EBL resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher stem diameter than the control under salt stress. Salinity treatments induced significant increases in electrolyte leakage of plant, but foliar 24-EBL application reduced leaf electrolyte leakage and has determined lower values of leaf electrolyte leakage than non-treated ones. In regard to nutrient content, it can be inferred that 24-EBL applications increased almost all nutrient content in leaves and roots of lettuce plants under salt stress. Generally, the greatest values were obtained from 3 μM 24-EBL application. Treatments of 24-EBL alleviated the negative effect of salinity on the growth of lettuce.

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Responsiveness of Three Tayota (Sechium edule) Types to Gibberellic Acid Treatment

HortScience ◽

10.21273/hortsci.33.3.494b ◽

1998 ◽

Vol 33 (3) ◽

pp. 494b-494

Author(s):

J. P. Morales-Payan

Keyword(s):

Gibberellic Acid ◽

Acid Treatment ◽

Stem Elongation ◽

Dry Weight ◽

Growth Stages ◽

Shoot Dry Weight ◽

Sechium Edule ◽

Randomized Design ◽

Practical Standpoint ◽

Gibberellic Acid Treatment

Container experiments were conducted in the Dominican Republic to determine the effects of gibberellic acid applications on the `White', `Green', and `Spiny Green' tayota (Sechium edule) Dominican types. Young plants (25 cm in length) of the three types were sprayed with aqueous solutions of gibberellic acid at rates 0, 50, 100, 150, and 200 parts per million. A completely randomized design with seven replications was utilized. Plant height and shoot dry weight were determined 30 days after treatment and resulting data was subjected to analysis of variance and regression analysis. Gibberellic acid treatment significantly increased tayota shoot dry weight and stem elongation. Both variables responded with similar patterns to gibberellic acid application. A linear regression (Y = 39.82 + 0.214 X, r2 0.95) described stem elongation as a function of gibberellic acid rates. Results show that gibberellic acid can be effectively used in either tayota type to promote early stem elongation. From a practical standpoint, due to the climbing nature of Sechium edulis, rapid stem elongation could be instrumental in a more rapid establishment of the crop vines in the trellis system, as well as to provide the crop with an advantage on weeds competing for light during the usually critical early growth stages.

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Regulation of Polyhydroxybutyrate Synthesis in the Soil Bacterium Bradyrhizobium diazoefficiens

Applied and Environmental Microbiology ◽

10.1128/aem.00757-16 ◽

2016 ◽

Vol 82 (14) ◽

pp. 4299-4308 ◽

Cited By ~ 25

Author(s):

J. I. Quelas ◽

S. Mesa ◽

E. J. Mongiardini ◽

D. Jendrossek ◽

A. R. Lodeiro

Keyword(s):

Carbon Allocation ◽

Dry Weight ◽

Receptor Protein ◽

Extracellular Polysaccharides ◽

Wild Type ◽

Higher Plant ◽

Granule Formation ◽

Content Type ◽

Shoot Dry Weight ◽

Matter Production

ABSTRACTPolyhydroxybutyrate (PHB) is a carbon and energy reserve polymer in various prokaryotic species. We determined that, when grown with mannitol as the sole carbon source,Bradyrhizobium diazoefficiensproduces a homopolymer composed only of 3-hydroxybutyrate units (PHB). Conditions of oxygen limitation (such as microoxia, oxic stationary phase, and bacteroids inside legume nodules) were permissive for the synthesis of PHB, which was observed as cytoplasmic granules. To study the regulation of PHB synthesis, we generated mutations in the regulator genephaRand the phasin genesphaP1andphaP4. Under permissive conditions, mutation ofphaRimpaired PHB accumulation, and aphaP1 phaP4double mutant produced more PHB than the wild type, which was accumulated in a single, large cytoplasmic granule. Moreover, PhaR negatively regulated the expression ofphaP1andphaP4as well as the expression ofphaA1andphaA2(encoding a 3-ketoacyl coenzyme A [CoA] thiolases),phaC1andphaC2(encoding PHB synthases), andfixK2(encoding a cyclic AMP receptor protein [CRP]/fumarate and nitrate reductase regulator [FNR]-type transcription factor of genes for microoxic lifestyle). In addition to the depressed PHB cycling,phaRmutants accumulated more extracellular polysaccharides and promoted higher plant shoot dry weight and competitiveness for nodulation than the wild type, in contrast to thephaC1mutant strain, which is defective in PHB synthesis. These results suggest thatphaRnot only regulates PHB granule formation by controlling the expression of phasins and biosynthetic enzymes but also acts as a global regulator of excess carbon allocation and symbiosis by controllingfixK2.IMPORTANCEIn this work, we investigated the regulation of polyhydroxybutyrate synthesis in the soybean-nodulating bacteriumBradyrhizobium diazoefficiensand its influence in bacterial free-living and symbiotic lifestyles. We uncovered a new interplay between the synthesis of this carbon reserve polymer and the network responsible for microoxic metabolism through the interaction between the gene regulatorsphaRandfixK2. These results contribute to the understanding of the physiological conditions required for polyhydroxybutyrate biosynthesis. The interaction between these two main metabolic pathways is also reflected in the symbiotic phenotypes of soybeans inoculated withphaRmutants, which were more competitive for nodulation and enhanced dry matter production by the plants. Therefore, this knowledge may be applied to the development of superior strains to be used as improved inoculants for soybean crops.

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