A major challenge faced by today’s white clover breeder is how to manage
resources within a breeding program. It is essential to utilise these
resources with sufficient flexibility to build on past progress from
conventional breeding strategies, but also take advantage of emerging
opportunities from molecular breeding tools such as molecular markers and
transformation. It is timely to review white clover breeding strategies. This
background can then be used as a foundation for considering how to continue
conventional plant improvement activities and complement them with molecular
breeding opportunities.
In this review, conventional white clover breeding strategies relevant to the
Australian dryland target population environments are considered. Attention is
given to: (i) availability of genetic variation,
(ii) characterisation of germplasm collections,
(iii) quantitative models for estimation of
heritability, (iv) the role of multi-environment trials
to accommodate genotype-by-environment interactions, (v)
interdisciplinary research to understand adaptation to dryland environments,
(vi) breeding and selection strategies, and
(vii) cultivar structure. Current achievements in
biotechnology with specific reference to white clover breeding in Australia
are considered, and computer modelling of breeding programs is discussed as a
useful integrative tool for the joint evaluation of conventional and molecular
breeding strategies and optimisation of resource use in breeding programs.
Four areas are identified as future research priorities:
(i) capturing the potential genetic diversity among
introduced accessions and ecotypes that are adapted to key constraints such as
summer moisture stress and the use of molecular markers to assess the genetic
diversity, (ii) understanding the underlying
physiological/morphological root and shoot mechanisms involved in water
use efficiency of white clover, with the objective of identifying appropriate
selection criteria, (iii) estimation of quantitative
genetic parameters of important morphological/physiological attributes to
enable prediction of response to selection in target environments, and
(iv) modelling white clover breeding strategies to
evaluate the opportunities for integration of molecular breeding strategies
with conventional breeding programs.
Conventional breeding strategies to enhance the sustainability of Musa biodiversity conservation for endemic cultivars
