scholarly journals Gibberellins and Heterosis in Crops and Trees: An Integrative Review and Preliminary Study with Brassica

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 139
Author(s):  
Karen P. Zanewich ◽  
Stewart B. Rood
Keyword(s):  
Shoot Growth ◽  
Seedling Emergence ◽  
Physiological Role ◽  
Hybrid Vigor ◽  
Physiological Basis ◽  
F1 Hybrid ◽  
Multiple Processes ◽  
Total Plant ◽  
Hybrid Seedling ◽  
Preliminary Study

Heterosis, or hybrid vigor, has contributed substantially to genetic improvements in crops and trees and its physiological basis involves multiple processes. Four associations with the phytohormone gibberellin (GA) indicate its involvement in the regulation of heterosis for shoot growth in maize, sorghum, wheat, rice, tomato and poplar. (1) Inbreds somewhat resemble GA-deficient dwarfs and are often highly responsive to exogenous GA3. (2) Levels of endogenous GAs, including the bioeffector GA1, its precursors GA19 and GA20, and/or its metabolite GA8, are higher in some fast-growing hybrids than parental genotypes. (3) Oxidative metabolism of applied [3H]GAs is more rapid in vigorous hybrids than inbreds, and (4) heterotic hybrids have displayed increased expression of GA biosynthetic genes including GA 20-oxidase and GA 3-oxidase. We further investigated Brassica rapa, an oilseed rape, by comparing two inbreds (AO533 and AO539) and their F1 hybrid. Seedling emergence was faster in the hybrid and potence ratios indicated dominance for increased leaf number, area and mass, and stem mass. Overdominance (heterosis) was displayed for root mass, leading to slight heterosis for total plant mass. Stem contents of GA19,20,1 were similar across the Brassica genotypes and increased prior to bolting; elongation was correlated with endogenous GA but heterosis for shoot growth was modest. The collective studies support a physiological role for GAs in the regulation of heterosis for shoot growth in crops and trees, and the Brassica study encourages further investigation of heterosis for root growth.

Compensatory Responses of Common Cocklebur (Xanthium strumarium) and Velvetleaf (Abutilon theophrasti) to Partial Shading

Weed Science ◽  
1993 ◽  
Vol 41 (4) ◽  
pp. 541-547 ◽  
Author(s):  
Emilie E. Regnier ◽  
S. Kent Harrison
Keyword(s):  
Leaf Area ◽  
Shade Tolerance ◽  
Shoot Growth ◽  
Branch Length ◽  
Dry Weight ◽  
Xanthium Strumarium ◽  
Leaf Angle ◽  
Petiole Length ◽  
Partial Shading ◽  
Total Plant

Lower leaves of greenhouse-grown common cocklebur and velvetleaf were shaded to 5% of full light over a 12-d period while upper leaves remained exposed to full light to determine weed foliar and branching responses to partial shading similar to that encountered in soybean crops. Shading increased lower leaf senescence and specific leaf area, and decreased branch length and number of second-order leaves in both species compared to unshaded controls. Common cocklebur branched more extensively along the lower portion of its stem than velvetleaf under both shaded and unshaded conditions. Upper leaves of partially shaded velvetleaf were held in a more perpendicular position to the light source beginning 3 days after treatment (DAT) compared to upper leaves of unshaded plants. Shading of lower leaves caused an increase in upper (unshaded) leaf area beginning 3 and 6 DAT in velvetleaf and common cocklebur, respectively. Petiole length of upper leaves also increased in response to shading in both species. Total plant dry weight at 12 DAT was unaffected by shading in velvetleaf but was reduced 10% by shading in common cocklebur. While common cocklebur maintained greater lower shoot growth in the presence of shade than velvetleaf, there was a greater change in upper leaf angle by velvetleaf in response to shading than by common cocklebur. These results support previous field observations of apparent greater shade tolerance of common cocklebur compared to velvetleaf and indicate that both species have the ability to compensate for shading of lower leaves by altering upper shoot growth.

Germination Ecology of Milkweedvine (Morrenia odorata)

Weed Science ◽  
1984 ◽  
Vol 32 (6) ◽  
pp. 781-785 ◽  
Author(s):  
Megh Singh ◽  
Nagi Reddy Achhireddy
Keyword(s):  
Seed Germination ◽  
Osmotic Stress ◽  
Root Growth ◽  
Seedling Growth ◽  
Shoot Growth ◽  
Seedling Emergence ◽  
Germination Percentage ◽  
Planting Depth ◽  
Germination Ecology ◽  
Optimum Ph

The germination of milkweedvine (Morrenia odorataLindl. ♯3MONOD) seed at 20 or 25 C was unaffected by a 12-h photoperiod. The 12-h photoperiod, however, decreased germination by 50% at 15 C. No germination occurred at 35 C regardless of photoperiod. By alternating 35 C for 12 h with 20 C for 12 h, the germination percentage was 57%. Seedling growth was maximum at alternating temperatures of 30/20 C. Optimum pH for germination and seedling growth was 7 and germination did not occur at pH levels below 6. Seed germination declined steadily at osmotic stress below −0.12 MPa; no germination occurred at −0.5 MPa. Seedling growth was not influenced by osmotic stress down to −0.18 MPa. Germination percentages of seeds kept under aerated water and nonaerated water were similar, but the seedling growth was greater in aerated water. Seedling emergence was maximum from depths of 0.5 to 2.5 cm, but no seedling emerged from 0 or 10 cm. Planting depth was negatively correlated (r = −0.7) with shoot growth but positively correlated (r = +0.98) to root growth.

Photoinhibition in indica and japonica subspecies of rice (Oryza sativa) and their reciprocal F1 hybrids

2001 ◽  
Vol 28 (4) ◽  
pp. 299 ◽  
Author(s):  
Demao Jiao ◽  
Benhua Ji
Keyword(s):  
Protein Synthesis ◽  
Oryza Sativa ◽  
Xanthophyll Cycle ◽  
Intrinsic Factor ◽  
D1 Protein ◽  
Physiological Role ◽  
F1 Hybrids ◽  
Protein Synthesis Inhibitor ◽  
Physiological Basis ◽  
Maternal Line

Photoinhibitory performance and its physiological basis have been studied in Oryza sativa L. subspecies indica and japonica, and their reciprocal F1 hybrids. The results demonstrate that the japonica ssp. was usually more tolerant to photoinhibition, indicated by higher maintaining capacity of D1 protein (less degradation), higher induced superoxide dismutase (SOD) activity and longer duration of the activity. Compared with japonica, the indica ssp. was more sensitive to photoinhibition, and exhibited more degradation of D1 protein and a much larger xanthophyll pool. A statistically significant positive correlation exists between D1 protein content and Fv/Fm, PSII activity and Pn during photoinhibition (r2 = 0.98, 0.93, 0.95, respectively, P < 0.01). This result further supported the hypothesis that D1 protein encoded by plastid genes might play an important physiological role in the mechanism of photoinhibition. This hypothesis is also enhanced by the fact that the capacity of D1 protein synthesis mediated the components and cycle of xanthophyll and non-photochemical quenching in treatment with streptomycin, a D1 protein synthesis inhibitor, while the xanthophyll cycle had a photoprotective role for D1 protein and Fv/Fm in treatment with DDT, a xanthophyll cycle inhibitor. The photoinhibition of reciprocal F1 hybrids between japonica and indica is mainly intermediate, but somewhat inclined to the maternal line. This demonstrates that the basic feature of photoinhibition was controlled by the interaction of an intrinsic factor, D1 protein encoded by plastid genes, with the xanthophyll cycle, as well as SOD, controlled by nuclear genes. Since the response to photoinhibitory treatment of indica–japonica F1 hybrids seems to depend on female parents, we propose to select and use photoinhibition-tolerant varieties as female parents for generation of photoinhibition-tolerant hybrids.

A quantitative study of the effects of gibberellic acid on the growth of Festuca arundinacea

1968 ◽  
Vol 19 (2) ◽  
pp. 221 ◽  
Author(s):  
DG Morgan
Keyword(s):  
Gibberellic Acid ◽  
Festuca Arundinacea ◽  
Dry Matter ◽  
Growth Analysis ◽  
Shoot Growth ◽  
Plant Weight ◽  
Matter Production ◽  
Whole Plant ◽  
Total Plant ◽  
Net Assimilation

Single plants of Festuca arundinacea (cv. S170) were treated with gibberellic acid (GA) and the sequence of effects on the growth of the whole plant and of various organs followed by means of growth analysis. The first effect of GA was to change the distribution of dry matter between shoot and root and between tillers within the shoot without affecting total plant weight. Shoot growth was increased and resulted in a larger amount of photosynthetic tissue with a higher net assimilation rate; total plant weight increased as a consequence of these effects. The significance of these results in interpreting previous work on the effects of GA on dry matter production in grasses and other plants is discussed.

scholarly journals Night Interruption Lighting Is Beneficial in the Production of Plugs of Dahlia `Sunny Rose'

HortScience ◽  
2000 ◽  
Vol 35 (7) ◽  
pp. 1244-1246
Author(s):  
Garry Legnani ◽  
William B. Miller
Keyword(s):  
Shoot Growth ◽  
Physiological State ◽  
Dry Weight ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Fibrous Root ◽  
Shoot Dry Weight ◽  
Total Plant ◽  
Short Days ◽  
Foliar N Concentration

Experiments were conducted to evaluate effects of photoperiod on growth and dry-weight partitioning in Dahlia sp. `Sunny Rose' during both seedling (plug) production and subsequent production in 10-cm pots. Plugs were grown under short days [9-hour natural photosynthetic photon flux (PPF)] or long days (same 9-hour PPF plus a 4-hour night interruption with incandescent light). Total plant dry weight was unaffected by photoperiod; however, long days (LD) inhibited tuberous root development and increased shoot dry weight, fibrous root dry weight, leaf area, shoot length, and number of leaf pairs. Long days reduced plug production time by ≈1 week compared with short days (SD). Following transplanting to 10-cm pots, shoot growth and foliar development were superior under LD. There was no effect of photoperiod on foliar N concentration. The superior growth of LD plugs following transplanting can be attributed to the plant being in a physiological state conducive to shoot expansion instead of storage.

scholarly journals Exploitation of Hybrid Vigor for Identification of Promising Sorghum F1 Hybrid for High Grain Yield and Resistance to Sorghum Midge

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Massaoudou Hamidou ◽  
Oumarou Souleymane ◽  
Mahamadou Salifou ◽  
Malick N. Ba ◽  
Issoufou Kapran ◽  
...  
Keyword(s):  
Grain Yield ◽  
Grain Sorghum ◽  
Hybrid Vigor ◽  
Cereal Crop ◽  
F1 Hybrid ◽  
The World ◽  
Improvement Programs ◽  
Parental Lines ◽  
Sorghum Production ◽  
Better Than

Sorghum is the second most grown cereal crop in Niger. However, sorghum production in the country is dominated by indigenous cultivars with low productivity. Productivity in grain sorghum has been achieved in developing countries around the world using hybrids. This study was conducted to evaluate heterosis in F1 sorghum hybrids for grain yield and resistance to midge. Fifty F1 sorghum hybrids were evaluated for grain yield and resistance to midge. Variation for grain yield, midge resistance, and flowering time was observed. The magnitude of better parent heterosis for grain yield and resistance to midge varied significantly among hybrids. Four hybrids combined high better parent heterosis for both grain yield and resistance to midge while eight hybrids were better than their better parent for resistance to midge. These hybrids performed well for grain yield and/or resistance to midge. Therefore, the parental lines involved in these hybrids can be advanced for commercial hybrids production or used in sorghum improvement programs.

scholarly journals Hybrid mimics and hybrid vigor in Arabidopsis

2015 ◽  
Vol 112 (35) ◽  
pp. E4959-E4967 ◽  
Author(s):  
Li Wang ◽  
Ian K. Greaves ◽  
Michael Groszmann ◽  
Li Min Wu ◽  
Elizabeth S. Dennis ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Recurrent Selection ◽  
Hybrid Vigor ◽  
F1 Hybrids ◽  
Parent Plant ◽  
F1 Hybrid ◽  
Altered Expression ◽  
Cell Numbers ◽  
Seed Industry ◽  
Vegetative Biomass

F1 hybrids can outperform their parents in yield and vegetative biomass, features of hybrid vigor that form the basis of the hybrid seed industry. The yield advantage of the F1 is lost in the F2 and subsequent generations. In Arabidopsis, from F2 plants that have a F1-like phenotype, we have by recurrent selection produced pure breeding F5/F6 lines, hybrid mimics, in which the characteristics of the F1 hybrid are stabilized. These hybrid mimic lines, like the F1 hybrid, have larger leaves than the parent plant, and the leaves have increased photosynthetic cell numbers, and in some lines, increased size of cells, suggesting an increased supply of photosynthate. A comparison of the differentially expressed genes in the F1 hybrid with those of eight hybrid mimic lines identified metabolic pathways altered in both; these pathways include down-regulation of defense response pathways and altered abiotic response pathways. F6 hybrid mimic lines are mostly homozygous at each locus in the genome and yet retain the large F1-like phenotype. Many alleles in the F6 plants, when they are homozygous, have expression levels different to the level in the parent. We consider this altered expression to be a consequence of transregulation of genes from one parent by genes from the other parent. Transregulation could also arise from epigenetic modifications in the F1. The pure breeding hybrid mimics have been valuable in probing the mechanisms of hybrid vigor and may also prove to be useful hybrid vigor equivalents in agriculture.

Genetic Techniques in Flatfish Culture

1976 ◽  
Vol 33 (4) ◽  
pp. 1088-1093 ◽  
Author(s):  
C. E. Purdom
Keyword(s):  
Fish Farming ◽  
Inbred Lines ◽  
Hybrid Vigor ◽  
Fish Culture ◽  
Common Phenomenon ◽  
F1 Hybrid ◽  
Hybrid Production ◽  
Environmental Component ◽  
Genetic Techniques ◽  
Selection For

Selection for improved growth rate does not appear to be feasible in flatfish because the environmental component of variation is very large. Selection for other characters has not been studied. The development of inbred lines, and their use in F1 hybrid production, seems warranted in fish farming if only as a means of avoiding inbreeding depression of fitness. Gynogenesis may be a practical means for accelerating the rate of inbreeding in fish. Induced triploidy is a potentially useful technique in fish culture in that it prevents sexual maturation and limits the depression of growth associated with this. Hybridization is a common phenomenon among fish and can lead to a form of hybrid vigor. Its application in fish culture may be limited by marketing problems where fish are sold under a specific name.

Influence of Seedbed Tilth on Emergence and Root and Shoot Growth of Seedlings of Some Crops

1985 ◽  
Vol 21 (1) ◽  
pp. 59-65 ◽  
Author(s):  
R. S. Malik ◽  
B. S. Jhorar ◽  
I. S. Dahiya
Keyword(s):  
Soil Moisture ◽  
Root Growth ◽  
Shoot Growth ◽  
Soil Moisture Content ◽  
Seedling Emergence ◽  
High Moisture ◽  
High Soil Moisture ◽  
Root And Shoot Growth ◽  
Growth Of Seedlings ◽  
Zone Temperature

SUMMARYWheat (Triticum aestivum), mustard (Brassica juncea), gram (Cicer arietinum) and barley (Hordeum vulgare) seedlings were raised in soils of different tilth created in microplots during 1981 and 1982. Amplitude in diurnal seed-zone temperature and soil moisture content increased with tilth coarseness. At low soil moisture levels, seedling emergence of wheat and mustard decreased with increasing clod size while that of gram and barley increased. These effects were not significant at high soil moisture levels. Shoot growth of all the crops was higher under coarse tilth than under fine tilth at both moisture levels. Root growth of wheat and mustard decreased with increasing clod size while that of gram and barley increased, at both moisture levels. Mustard had the highest seedling emergence at the low moisture level. Seedling emergence and shoot growth were higher under high moisture than under low moisture for all crops. Root growth varied depending upon the type of crop.

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