Estimation of the number of loci involved in the inheritance of resistance to Phytophthora palmivora (Butl.) Butl. in the leaves of Theobroma cacao L.

Abstract

Comparisons of theoretical and observed distributions indicated that resistance to necrosis caused by Phytophthora palmivora within leaf tissues of Theobroma cacao clone ICSl was influenced by a minimum of five unlinked heterozygous loci. The frequency of infection at the leaf surface was not linked to necrotic spread and did not adequately fit the expected progeny distributions. It is argued that this lack of fit was possibly the result of gene effects of differing magnitude influencing the observed variation in leaf surface infection rate, although other factors such as epistasis may be important.

Improvement of cocoa tree resistance to Phytophthora diseases

“…Like many other agronomic traits, resistance to Phytophthora exhibits a continuum of phenotypic variations in the species T. cacao, suggesting the implication of several genes. A polygcnic control of resistance has already been suggested by several authors (Blaha and Lotode, 1976;Enriquez and Salazar, 1980;Rodriguez et al, 1985;Warren, 1994;Enriquez and Soria, 1996;. also showed that genetic factors involved in resistance in the field were additive.…”

A simple detached leaf assay provides rapid and inexpensive determination of pathogenicity of Pythium isolates to ‘all year round’ (AYR) chrysanthemum roots

“…In addition to the presence/absence of necrosis giving an indication of pathogenicity, the rates of necrosis development and the proportion of positive bioassays have also been found to give some indication of both the amount of host resistance and/or the virulence of individual pathogen isolates in detached plant part assays on other host species (Borecki & Millikan, 1969; Gooding et al. , 1981; Pettitt & Pegg, 1994; Warren & Pettitt, 1994). In this study, all known pathogenic isolates tested gave positive necrosis reactions in detached leaves, and the indications are that isolates with low virulence may also be indicated by low incidences of leaf infection and slower rates of necrosis, although further investigation would be required to firmly establish this.…”

Hemodynamics study of a multilayer stent for the treatment of aneurysms

“…MS can overcome drawbacks which brought by covered stent (CS), providing a new idea in the treatment of AAA involving the branch artery. Polydorou et al [5] reported that 9 patients with MS got 100% technical successes between December 2006 and November 2009; Fossaceca et al [6] followed-up six patients who were treated by MSs for peripheral artery aneurysms from September 2010 to May 2011. Totally 12 stents were used, technical successes were achieved by 100%; Giampaolo et al [2] reported that a 60-year-old man presenting a celiac trunk aneurysm refused open surgical repair and then was treated with a MS to reduce the strength of vortex and induce thrombosis, after 12 month it confirmed that the thrombosis was formed in the sac without impairment of the main branches.…”