Pyramiding of Meloidogyne hapla resistance genes in potato does not result in an increase of resistance

High levels of resistance against Meloidogyne hapla have been identified in wild species of tuber-bearing potatoes, but only QTL with partial effects have been identified so far in back crosses with cultivated potato. This study was designed to test if pyramiding of two previously identified resistance genes, R Mh-tar and R Mh-chc A, will result in improved or even an absolute level of resistance. R Mh-tar and R Mh-chc A introgressed from the wild tuber-bearing potato species Solanum tarijense and Solanum chacoense were combined in a segregating diploid Solanum tuberosum population. With the aid of AFLP markers, descendants from this segregating population were classified into four groups, carrying no R gene, with only R Mh-tar , with only R Mh-chc A and a group with the pyramided R Mh-tar and R Mh-chc A. Upon inoculation with M. hapla isolate Bovensmilde, the group containing only R Mh-chc A showed a decline of 88% in average number of developed egg masses compared to the group without R Mh-chc A and R Mh-tar . The group of genotypes containing only R Mh-tar , but not R Mh-chc A, showed a decline of 55% in the number of developed egg masses compared to the group without R Mh-chc A and R Mh-tar . Unfortunately, the latter effect of R Mh-tar was not significant. The effect of both loci, R Mh-tar and R Mh-chc A combined, did not further reduce the number of egg masses compared to the level of R Mh-chc A alon

Resistance Breeding in Apple at Dresden-Pillnitz

Resistance breeding in apple has a long tradition at the Institute of Fruit Breeding now Julius Kuehn-institute in Dresden-Pillnitz. The breeding was aimed at the production of multiple resistance cultivars to allow a more sustainable and environmentally friendly production of apple. In the last decades a series of resistant cultivars (Re®-cultivars) bred in Dresden-Pillnitz has been released, ‘Recolor’ and ‘Rekarda’ in 2006. The main topic in the resistance breeding programme was scab resistance and the donor of scab resistance in most cultivars was Malus x floribunda 821. Due to the development of strains that are able to overcome resistance genes inherited by M. x floribunda 821 and due to the fact that single resistance genes can be broken easily, pyramiding of resistance genes is necessary. Besides scab, fire blight and powdery mildew are the main disease for which a pyramiding of genes is aspired in Pillnitz. Biotechnical approaches are necessary for the early detection of pyramided resistance genes in breeding clones. This paper will give an overview of the resistance breeding of apple in Pillnitz and the methods used

Criteria For Expanding The Sales Tax Base: Services and Exemptions

This brief focuses on issues associated with the sales tax base and discusses the criteria and factors that should be considered in deciding which services to add to the sales tax base and which sales tax exemptions to eliminate or add

Collateral, Financial Arrangements and Pareto Optimality

The existence of collateral requirements to guarantee repayment on issued securities reduces in general the efficiency of competitive equilibria. The general equilibrium analysis is presented in a world where reputation plays no role, and the lender always expects a future payment equal to the future market value of provided collateral. In this context I show that collateral requirements result in two distinct problems for efficiency. I argue that two financial arrangements, tranching and financial pyramiding, arise in developed capital markets in response to the challenges posed by collateral requirements. If these arrangements are sufficiently developed, then the pareto efficiency of competitive equilibria is restored, even in the presence of collateral requirements.Collateral, Pareto Optimality, Financial Arrangements, Tranching, Financial Pyramiding.

Pyramiding 2.0: Exaptation of the Pyramiding Approach to Recruit New Idea Contributors for a Virtual Ideas Competition

When searching for user innovations, the identification of so called ‘technology lead users’ is one of the most important tasks. However, scientific literature indicates that the present measures to search and to recruit new members imply high spreading losses. As a con-sequence we develop the “Pyramiding 2.0” approach. Building on existing literature we develop a theory-motivated approach for systematically recruiting participants for a crowdsourcing environment with the help of a virtual social network. This paper describes our reasons for using the pyramiding approach and elaborates on the supposed benefits that an adaption of the pyramiding search within an online setting implies. Our findings confirm the assumption that the pyramiding 2.0 approach can be successfully applied to recruit new idea contributors for a virtual ideas competition. Moreover, our results show that pyramiding can be applied within a virtual social network, thereby expanding existing literature within the field of pyramiding

The Emergence of Corporate Pyramids in China

We examine the pyramidal ownership structure of a large sample of newly listed Chinese companies controlled by local governments or private entrepreneurs. Both types of the owners use layers of intermediate companies to control their firms. However, their pyramiding behaviors are likely affected by different property rights constraints. Local governments are constrained by the Chinese laws prohibiting free transfer of state ownership. Pyramiding allows them to credibly decentralize their firm decision rights to firm management without selling off their ownership. Private entrepreneurs are constrained by their lack of access to external funds. Pyramiding creates internal capital markets that help relieving their external financing constraints. Our empirical results support these conjectures. Local governments build more extensive corporate pyramids when they are less burdened with fiscal or unemployment problems, when they have more long-term goals, and when their firm decisions are more subject to market and legal disciplines. The more extensive pyramids are also associated with smaller "underpricing" when the firms go public. Entrepreneur owners construct more complex corporate pyramids when they do not have a very deep pocket - as indicated by whether they are among the top-100 richest people in China.Pyramidal Ownership, Decentralization, China

The Emergence of Corporate Pyramids in China

We examine the pyramidal ownership structure of a large sample of newly listed Chinese companies controlled by local governments or private entrepreneurs. Both types of the owners use layers of intermediate companies to control their firms. However, their pyramiding behaviors are likely affected by different property rights constraints. Local governments are constrained by the Chinese laws prohibiting free transfer of state ownership. Pyramiding allows them to credibly decentralize their firm decision rights to firm management without selling off their ownership. Private entrepreneurs are constrained by their lack of access to external funds. Pyramiding creates internal capital markets that help relieving their external financing constraints. Our empirical results support these conjectures. Local governments build more extensive corporate pyramids when they are less burdened with fiscal or unemployment problems, when they have more long-term goals, and when their firm decisions are more subject to market and legal disciplines. The more extensive pyramids are also associated with smaller "underpricing" when the firms go public. Entrepreneur owners construct more complex corporate pyramids when they do not have a very deep pocket - as indicated by their personal wealth.

Pyramiding of Ryd2 and Ryd3 conferring tolerance to a German isolate of Barley yellow dwarf virus-PAV (BYDV-PAV-ASL-1) leads to quantitative resistance against this isolate

Barley yellow dwarf virus (BYDV) is an economically important pathogen of barley, which may become even more important due to global warming. In barley, several loci conferring tolerance to BYDV-PAV-ASL-1 are known, e.g. Ryd2, Ryd3 and a quantitative trait locus (QTL) on chromosome 2H. The aim of the present study was to get information whether the level of tolerance against this isolate of BYDV in barley can be improved by combining these loci. Therefore, a winter and a spring barley population of doubled haploid (DH) lines were genotyped by molecular markers for the presence of the susceptibility or the resistance encoding allele at respective loci (Ryd2, Ryd3, QTL on chromosome 2H) and were tested for their level of BYDV-tolerance after inoculation with viruliferous (BYDV-PAV-ASL-1) aphids in field trials. In DH-lines carrying the combination Ryd2 and Ryd3, a significant reduction of the virus titre was detected as compared to lines carrying only one of these genes. Furthermore, spring barley DH-lines with this allele combination also showed a significantly higher relative grain yield as compared to lines carrying only Ryd2 or Ryd3. The QTL on chromosome 2H had only a small effect on the level of tolerance in those lines carrying only Ryd2, or Ryd3 or a combination of both, but the effect in comparison to lines carrying no tolerance allele was significant. Overall, these results show that the combination of Ryd2 and Ryd3 leads to quantitative resistance against BYDV-PAV instead of tolerance

Market Based, Segregated Exchanges with Default Risk

This paper studies a competitive general equilibrium model with default and endogenous collateral constraints. Even though all collateralized contracts are allowed, the possibility and desirability of trade in spot markets (or the equivalent trade in ex ante asset backed securities) creates externalities, as spot prices (or security prices) and the bindingness of collateral constraints interact. We show that if agents are allowed to contract ex ante on market fundamentals determining the state-contingent spot price, over and above contracting on true underlying states of the world, then competitive equilibria with bundled securities and commodities and with endogenous collateral constraints are equivalent with Pareto optima. Examples show that it is possible to have multiple market fundamentals in equilibrium. Equivalently, it is possible for there to be segregation into distinct competitive securities exchanges with endogenous (positive and negative) entry fees. Fees accrue to borrowers who are otherwise collateral constrained.default; endogenous collateral; externalities; segregated exchanges; Walrasian equilibrium; limited commitment; financial crises