Search

Leaf elongation rate (LER) is a key component of forage grass dry matter yield. Leaf lamina initiate rapid expansion during the winter at a time that coincides with lengthening days but this extension is not associated with any large environmental shifts such as an increase in light intensity or temperature. The rate increase precedes any anatomical indication of floral initiation in apical meristems (double ridge formation) by around 2–3 weeks. We measured LER in a perennial ryegrass (Lolium perenne L.) pair-cross mapping family that has been extensively mapped with more than 1,200 SNP markers generated by Illumina’s Infinium platform. These have been anchored to the seven Lolium linkage groups as defined by Triticeae nomenclature with seven micro-satellite markers originally developed by ViaLactia Biosciences. Measurements were made in the winter/spring during extending day length, after full natural vernalisation. The plants’ leaves were beginning to expand rapidly with leaf extension rates varying between approximately 0.4 mm and 1.1 mm h−1. We obtained a significant correlation between LER and both apical meristem elongation and ear emergence (the date at which inflorescences emerge above the flag-leaf ligule) measured in two separate seasons. A QTL for LER was revealed with a peak some distance away from the major floral initiation and ear emergence date QTL on linkage group 7. This is the first evidence of genetic linkage that determines the often observed association between LER in herbage grasses in the spring with floral initiation determined in large part by the action of Arabidopsis flowering initiation gene homologues, Flowering Time Locus (FT) and Constans (CO).

A fast neutron (FN)-mutagenised population was generated in Pisum sativum L. (pea) to enable the identification and isolation of genes underlying traits and processes. Studies of several phenotypic traits have clearly demonstrated the utility of the resource by associating gene deletions with phenotype followed by functional tests exploiting additional mutant sources, from both induced and natural variant germplasm. For forward genetic screens, next generation sequencing methodologies provide an opportunity for identifying genes associated with deletions rapidly and systematically. The application of rapid reverse genetic screens of the fast neutron mutant pea population supports conclusions on the frequency of deletions based on phenotype alone. These studies also suggest that large deletions affecting one or more loci can be non-deleterious to the pea genome, yielding mutants that could not be obtained by other means. Deletion mutants affecting genes associated with seed metabolism and storage are providing unique opportunities to identify the products of complex and related gene families, and to study the downstream consequences of such deletions.