QTLs for oil yield components in an elite oil palm (Elaeis guineensis) cross

Increased modern farming of superior types of the oil palm, Elaeis guineensis Jacq., which has naturally efficient oil biosynthesis, has made it the world’s foremost edible oil crop. Breeding improvement is, however, circumscribed by time and costs associated with the tree’s long reproductive cycle, large size and 10–15 years of field testing. Marker-assisted breeding has considerable potential for improving this crop. Towards this, quantitative trait loci (QTL) linked to oil yield component traits were mapped in a high-yield population. In total, 164 QTLs associated with 21 oil yield component traits were discovered, with cumulative QTL effects increasing in tandem with the number of QTL markers and matching the QT+ alleles for each trait. The QTLs confirmed all traits to be polygenic, with many genes of individual small effects on independent loci, but epistatic interactions are not ruled out. Furthermore, several QTLs maybe pleiotropic as suggested by QTL clustering of inter-related traits on almost all linkage groups. Certain regions of the chromosomes seem richer in the genes affecting a particular yield component trait and likely encompass pleiotropic, epistatic and heterotic effects. A large proportion of the identified additive effects from QTLs may actually arise from genic interactions between loci. Comparisons with previous mapping studies show that most of the QTLs were for similar traits and shared similar marker intervals on the same linkage groups. Practical applications for such QTLs in marker-assisted breeding will require seeking them out in different genetic backgrounds and environments

Controlled Term Rewriting

International audienceMotivated by the problem of verification of imperative tree transformation programs, we study the combination, called controlled term rewriting systems (CntTRS), of term rewriting rules with con- straints selecting the possible rewrite positions. These constraints are specified, for each rewrite rule, by a selection automaton which defines a set of positions in a term based on tree automata computations. We show that reachability is PSPACE-complete for so-called monotonic CntTRS, such that the size of every left-hand-side of every rewrite rule is larger or equal to the size of the corresponding right-hand-side, and also for the class of context-free non-collapsing CntTRS, which transform Context-Free (CF) tree language into CF tree languages. When allowing size-reducing rules, reachability becomes undecidable, even for flat CntTRS (both sides of rewrite rules are of depth at most one) when restricting to words (i.e. function symbols have arity at most one), and for ground CntTRS (rewrite rules have no variables). We also consider a restricted version of the control such that a position is selected if the sequence of symbols on the path from that position to the root of the tree belongs to a given regular language. This restriction enables decision results in the above cases

Autowrite: A Tool for Checking Properties of Term Rewriting Systems

International audienceAutowrite is an experimental tool written in Common Lisp for checking properties of TRSs. It was initially designed to check sequentiality properties of TRSs. For this purpose, it implements the tree automata constructions used in [J96,DM97,DM98,NT99] and many useful operations on terms, TRSs and tree automata (unfortunaletly not all yet integrated into the graphical interface)

Deciding fundamental properties of right-(ground or variable) rewrite systems by rewrite closure

Abstract. Right-(ground or variable) rewrite systems (RGV systems for short)are term rewrite systems where all right hand sides of rules are restricted to be either ground or a variable. We define a minimal rewrite extension R of the rewriterelation induced by a RGV system R. This extension admits a rewrite closurepresentation, which can be effectively constructed fro

Layered transducing term rewriting system and its recognizability preserving property

A term rewriting system which effectively preserves recognizability (EPR-TRS) has good mathematical properties, In this paper, a new subclass of TRSs, layered transducing TRSs (LT-TRSs) is defined and its rccognizability preserving property is discussed. The class of LT-TRSs contains some EPR-TRSs, e.g., {f(x)-f(g(x))} which do not belong to any of the known decidable subclasses of EPR-TRSs. Bottom-up linear tree transducer, which is a well-known computation model in the tree language theory, is a special case of LT-TRS. We present a sufficient condition for an LT-TRS to be an EPR-TRS. Also reachability and joinability are shown to be decidable for LT-TRSs