scholarly journals Combined S1-TC-RRS with consideration of cms and dihaploids in maize

Genetika ◽  
2012 ◽  
Vol 44 (1) ◽  
pp. 69-79
Author(s):  
Jelena Vancetovic ◽  
Dragana Ignjatovic-Micic ◽  
Sofija Bozinovic ◽  
Nenad Delic ◽  
Zoran Camdzija
Keyword(s):  
Seed Production ◽  
Inbred Lines ◽  
Maize Breeding ◽  
Selection Cycle ◽  
Breeding Populations ◽  
Per Se ◽  
Variety Protection ◽  
Short Time ◽  
Selection Of

Herein, we present the combined S1-HS-RRS method using inbred testers (S1-TC-RRS) as a long-term maize breeding program, which increases the frequency of favorable alleles and maintains genetic variability in two genetically opposite populations. The method improves two different genetic sources simultaneously, where S1 families, developed by selfing phenotypically superior plants from both breeding populations are crossed with opposite inbred testers for specific combining ability selection, accompanied by selection of S1 families per se. A certain percentage of the evaluated S1 families is used for the next TC-RRS selection cycle. Maternal haploids from the selected S1 lines of each cycle of S1-TC-RRS can serve to produce elite 100% homozygous inbred lines (dihaploids) in a short time, which decreases the time and expenses of the selection cycle and influence the efficiency of seed production, as well as, variety protection rights. This elite lines than can be converted to CMS versions (paternal haploids), for the seed production, which lowers the costs of it.

Evaluation of U.S. inbred lines with expired plant variety protection for mid-altitude tropical maize breeding

Euphytica ◽  
2020 ◽  
Vol 216 (3) ◽  
Author(s):  
Mateus Cupertino-Rodrigues ◽  
Thanda Dhliwayo ◽  
Samuel Trachsel ◽  
Rui Guo ◽  
Felix San Vicente
Keyword(s):  
Inbred Lines ◽  
Tropical Maize ◽  
Maize Breeding ◽  
Plant Variety Protection ◽  
Plant Variety ◽  
Variety Protection

scholarly journals Efficiency of the backcrossing method in dihaploid maize breeding

2019 ◽  
Vol 2 (2) ◽  
pp. 24-32
Author(s):  
M. E. Mikhailov
Keyword(s):  
Chromosome Doubling ◽  
Doubled Haploids ◽  
Breeding Cycle ◽  
Parental Line ◽  
Initial Material ◽  
Maize Breeding ◽  
Selection Cycle ◽  
Number Of Cycles ◽  
Dh Lines ◽  
Short Time

The doubled haploid (DH) lines, obtained by doubling the haploid genome, are now widely used in breeding many crops, since they allow to transfer gene variants to the homozygous state in a short time. However, the advantages of doubled haploids are not fully utilized in maize breeding. The present work is devoted to the evaluation of the backcrossing method efficiency and to further development of the original schemes of creating highly productive homozygous maize lines on the basis of DH lines originating from an interline F1 hybrid. Rf7 and Ku123 maize lines were used as the initial material. The breeding cycle consisted of producing haploid plants in the selected genotype (matroclinic haploidy using an inducer), subsequent chromosome doubling (colchicine‑induced or spontaneous), followed by multiplication of the doubled haploids for obtaining a new set of DH lines. In the first cycle, the DH lines were obtained from the F1 hybrid (Rf7 × Ku123), while in the subsequent cycles they were obtained from the genotypes obtained by crossing a DH line selected from the previous cycle with F1, P1 or P2. Three cycles of selection for productivity were performed, and in 2017 the DH lines obtained in all cycles were simultaneously tested in the field. The breeding progress was estimated by the increase in the first ear productivity compared to the best parent Rf7 (103.9 g per plant in 2017). The first selection cycle resulted in 43 DH lines obtained on the basis of the F1 hybrid. Productivity of the best line rk‑5 amounted to 112.5 g per plant. Three lines (rk‑6, rk‑5 and rk‑22) selected for the next cycle were further crossed with F1 or with the parental line Rf7. The second selection cycle yielded three series containing 41, 49 and 16 lines, while productivity of the best genotypes was 121.2, 117.0 и 107.1 g per plant, respectively. The third cycle included populations of 24 and 8 lines obtained through backcrosses with Rf7 and Ku123 lines, respectively. The best genotypes in these series had productivity of 135.6 and 97.7 g per plant. As a result of selection, the obtained rk‑433 line had a productivity 30.5% higher than that of the best parent Rf7. The progress averaged 10.2% per cycle. In maize breeding using doubled haploids it is promising to use backcrosses of the selected DH lines with the initial material or with F1. Thanks to such an approach, a noticeable progress can be reached with a small number of cycles including from 20 to 50 DH lines.

scholarly journals Using the best linear predictor (BLP) in the selection between and among half-sib progenies of the CMS-39 maize population

1997 ◽  
Vol 20 (4) ◽  
pp. 683-690
Author(s):  
Cleso Antônio Patto Pacheco ◽  
José Ivo Ribeiro Júnior ◽  
Cosme Damião Cruz
Keyword(s):  
Variance Component ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
The Other ◽  
Linear Predictor ◽  
Selection Cycle ◽  
Maize Population ◽  
Best Linear Predictor ◽  
Selection Of

Data of corn ear production (kg/ha) of 196 half-sib progenies (HSP) of the maize population CMS-39 obtained from experiments carried out in four environments were used to adapt and assess the BLP method (best linear predictor) in comparison with to the selection among and within half-sib progenies (SAWHSP). The 196 HSP of the CMS-39 population developed by the National Center for Maize and Sorghum Research (CNPMS-EMBRAPA) were related through their pedigree with the recombined progenies of the previous selection cycle. The two methodologies used for the selection of the twenty best half-sib progenies, BLP and SAWHSP, led to similar expected genetic gains. There was a tendency in the BLP methodology to select a greater number of related progenies because of the previous generation (pedigree) than the other method. This implies that greater care with the effective size of the population must be taken with this method. The SAWHSP methodology was efficient in isolating the additive genetic variance component from the phenotypic component. The pedigree system, although unnecessary for the routine use of the SAWHSP methodology, allowed the prediction of an increase in the inbreeding of the population in the long term SAWHSP selection when recombination is simultaneous to creation of new progenies.

scholarly journals B73 and related inbred lines in maize breeding

Genetika ◽  
2005 ◽  
Vol 37 (3) ◽  
pp. 245-252 ◽  
Author(s):  
Milisav Stojakovic ◽  
Goran Bekavac ◽  
Nenad Vasic
Keyword(s):  
Grain Yield ◽  
Inbred Lines ◽  
Mean Value ◽  
Yield Potential ◽  
Maize Breeding ◽  
Serbia And Montenegro ◽  
Maize Hybrids ◽  
Hybrid Production ◽  
The Mean ◽  
Per Se

Inbred lines B73 and Mol7 or some versions thereof are the most commonly used parental pair in the development of medium late and late maize hybrids in Serbia and Montenegro. Because of the ever-increasing importance of line B73 in maize hybrid production, we chose several B73-type lines and a few unrelated lines and crossed them. Using the pedigree method, progenies were developed up to the S6 generation. The grain yield potential of test crosses with Mo 17 inbred tester, as well as ear length, number of grain rows per ear and 1,000-grain mass of lines per-se were tested. Among the new inbred lines related to B73, line 260277/2 distinguished itself by a high potential for grain yield when crossed with Mo 17. Inbred lines 260465/1, 260362/1, 260747/4, 260357/13, 260151/2 and 260156/2 had a significantly longer ear than the mean value of all progenies. Compared with progeny mean, lines 260341/7, 260317/4, 260277/2 and 260187/2 had significantly more grain rows per ear, while 260362/1, 260130/5, 260277/2, 260151/2 and 260187/2 had a significantly larger 1,000-grain mass.

scholarly journals Time is money. Waiting costs explain why selection favors steeper time discounting in deprived environments.

2019 ◽  
Author(s):  
Hugo Mell ◽  
Nicolas Baumard ◽  
Jean-Baptiste André
Keyword(s):  
Time Horizon ◽  
Behavioural Syndrome ◽  
Muscular Tissue ◽  
Risk Averse ◽  
Time Discounting ◽  
Time Horizons ◽  
Per Se ◽  
Short Time ◽  
Evolutionarily Stable

Individuals exposed to deprivation tend to show a characteristic behavioural syndrome suggestive of a short time horizon. This pattern has traditionally been attributed to the intrinsically higher unpredictability of deprived environments, which renders waiting for long term rewards more risky (i.e. collection risks are high). In the current paper, based on a simple dynamic life history model, we show that a significant portion of individuals’ propensity to discount future rewards might have a completely distinct origin. Upon collecting a resource, individuals have the opportunity to accumulate “capital” (e.g. grow muscular tissue, build a protective shelter, buy a car, etc.), which eventually increases their productivity and/or their chances of survival. As a result, delaying the collection of a resource creates an opportunity cost in the sense that during the waiting time, the benefits otherwise generated by the increment in capital are lost. These forgone benefits are independent of collection risks and constitute waiting costs per se. Using optimal control theory we show that these costs can lead to the evolution of short time horizons even in the complete absence of collection risks. Moreover, assuming diminishing returns to capital, we show that the evolutionarily stable time horizon increases with the amount of capital already owned by individuals. When individuals possess little capital, they have a lot of room to improve their productivity and/or survival, hence they should be impatient to collect resources; that is, their time horizon should be short. On the contrary, when individuals already possess a lot of capital, the benefits of further accumulation are plateauing, hence patience becomes a more profitable strategy and individuals should lengthen their time horizon. This means that individuals get more patient as they age and that people in deprivation, who still have important productive and survival needs that can be satisfied, should have a shorter time horizon. Moreover, beyond time horizon, our model shows that people with little capital should also be more risk averse than the more privileged. Taken together, these results lead us to interpret the behavioral constellation of deprivation in a new way.

Women's Participation in Politics: Ukrainian Case

2014 ◽  
Vol 2013 (3) ◽  
pp. 53-66
Author(s):  
Skovikov Alexey
Keyword(s):  
Political Culture ◽  
Separation Of Powers ◽  
Party Competition ◽  
Political Life ◽  
Ruling Class ◽  
Political Actors ◽  
Women's Participation ◽  
Democratic Transformation ◽  
Selection Of

AbstractThe international practices takes into account the question of women's participation in the political life of modern Ukraine. The selection of the state was due to the dynamic process of democratic transformation - the separation of powers, the formation of multi-party competition among political actors in the electoral process, the activity women in the various institutions of civil society. The position was claimed on the basis of empirical data range of academic institutions and reputable sociological centers, and also interviews with experts who said that the creation of real conditions for self-realization by women's interest in politics is only possible for long term. The process is controversial and caused by political culture, traditions and interests of the ruling class represented mainly by men.

Markets, Technological Change and Economic Growth (The Quaid-i-Azam Lecture)

1994 ◽  
Vol 33 (4I) ◽  
pp. 327-356 ◽  
Author(s):  
Richard G. Lipsey
Keyword(s):  
United States ◽  
Economic Growth ◽  
Developing Countries ◽  
Common Ground ◽  
The United States ◽  
Industrial Countries ◽  
Canadian Institute ◽  
Primary Focus ◽  
Short Time

I am honoured to be invited to give this lecture before so distinguished an audience of development economists. For the last 21/2 years I have been director of a project financed by the Canadian Institute for Advanced Research and composed of a group of scholars from Canada, the United States, and Israel.I Our brief is to study the determinants of long term economic growth. Although our primary focus is on advanced industrial countries such as my own, some of us have come to the conclusion that there is more common ground between developed and developing countries than we might have first thought. I am, however, no expert on development economics so I must let you decide how much of what I say is applicable to economies such as your own. Today, I will discuss some of the grand themes that have arisen in my studies with our group. In the short time available, I can only allude to how these themes are rooted in our more detailed studies. In doing this, I must hasten to add that I speak for myself alone; our group has no corporate view other than the sum of our individual, and very individualistic, views.

Evidence for a single mechanism gating perceptual and long-term memory information into working memory

2020 ◽  
Author(s):  
Sam Verschooren ◽  
Yoav Kessler ◽  
Tobias Egner
Keyword(s):  
Working Memory ◽  
Long Term Memory ◽  
Sources Of Information ◽  
Term Memory ◽  
Source Selection ◽  
Single Mechanism ◽  
Gating Mechanism ◽  
Opening And Closing ◽  
Selection Of

An influential view of working memory (WM) holds that its’ contents are controlled by a selective gating mechanism that allows for relevant perceptual information to enter WM when opened, but shields WM contents from interference when closed. In support of this idea, prior studies using the reference-back paradigm have established behavioral costs for opening and closing the gate between perception and WM. WM also frequently requires input from long-term memory (LTM), but it is currently unknown whether a similar gate controls the selection of LTM representations into WM, and how WM gating of perceptual vs. LTM sources of information relate to each other. To address these key theoretical questions, we devised a novel version of the reference-back paradigm, where participants switched between gating perceptual and LTM information into WM. We observed clear evidence for gate opening and closing costs in both cases. Moreover, the pattern of costs associated with gating and source-switching indicated that perceptual and LTM information is gated into WM via a single gate, and rely on a shared source-selection mechanism. These findings extend current models of WM gating to encompass LTM information, and outline a new functional WM architecture.

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