RESUMO
The incorporation of new sophisticated phenotyping technologies within a crop improvement program allows for a plant breeding strategy that can include selections for major root traits previously inaccessible due to the challenges in their phenotype assessment. High-throughput precision phenotyping technology is employed to evaluate root ontogeny and progressive changes to root architecture of both novel amphiploid and introgression lines of Festulolium over four consecutive months of the growing season and these compared under the same time frame to that of closely related perennial ryegrass (L. perenne) varieties. Root imaging using conventional photography and assembled multiple merged images was used to compare frequencies in root number, their distribution within 0-20 and 20-40 cm depths within soil columns, and progressive changes over time. The Festulolium hybrids had more extensive root systems in comparison with L. perenne, and this was especially evident at depth. It was shown that the acquisition of extensive root systems in Festulolium hybrids was not dependent on the presence of an entire Festuca genome. On the contrary, the most pronounced effect on root development within the four Festulolium populations studied was observed in the introgression line Bx509, where a single small genome sequence from F. arundinacea had been previously transferred onto its homoeologous site on the long arm of chromosome 3 of an otherwise complete L. perenne genome. This demonstrates that a targeted introgression-breeding approach may be sufficient to confer a significant improvement in the root morphology in Lolium without a significant compromise to its genome integrity. The forage production of Bx509 was either higher (months 1-3) or equivalent to (month 4) that of its L. perenne parent control demonstrating that the enhanced root development achieved by the introgression line was without compromise to its agronomic performance.
RESUMO
Increasing the extractable sugar yield from perennial crops is one strategy to generate renewable fuels such as bio-ethanol. Lolium perenne L. (perennial ryegrass) can contain significant (>30% dry matter) water-soluble sugars in the form of polymeric fructan which is readily extracted, broken down and fermented to bio-ethanol. A population of L. perenne generated from four parents which differed in water-soluble carbohydrate (WSC) content was subjected to multiple rounds of selection and recombination on the basis of early spring WSC content to produce a high WSC, and a low WSC population. A control population was generated by selecting the same number of plants at random. The alleles present at six candidate gene loci were analysed before and after selection and correlated to WSC content. Significant differences in the allele frequency of L. perenne soluble-acid invertase1:4 were observed between the three populations with one haplotype significantly associated with the high WSC C2S+ population (after three rounds of selection and two rounds of recombination). Moreover, WSC content was also associated with biomass accumulation. Thus, in addition to a 2.84-fold increase in WSC yield, the C2S+ population also had 1.48-fold more biomass per plant, resulting in 3.9-fold higher WSC yield per plant than the control population.
