Optimizing Early Flowering and Pre-selection for Short Juvenile Period in Olive Seedlings

Abstract

<jats:p>In recent years, the juvenile period of olive seedlings has been reduced by diverse forcing and pruning-formation techniques, but it is still a major drawback for breeding. Plant height at the time when seedlings are transplanted to the field has been found effective for obtaining earlier flowering, but the value of this parameter varies widely among olive breeding programs. We evaluated different transplant dates, taking into account mean plant height and age, with the aim of determining the optimum parameters for achieving early flowering and easy plant management and, at the same time, for the early elimination of genotypes with a long juvenile period. A mean seedling height of ≈100 cm at the time of planting in the field provided the best results in terms of shortening the juvenile period and facilitating handling of the seedlings. For all dates tested, seedling height at transplanting was effective as a pre-selection criterion for the early elimination of genotypes with long juvenile periods, with slight improvement in effectiveness with advancing transplant date.</jats:p>

De Novo Assembly and Functional Annotation of the Olive (Olea europaea) Transcriptome

“…During the transition from juvenile to adult, a maturation gradient is developed in plants from the basal parts formed by juvenile apical meristems, to the upper parts formed by adult meristems. 10,42–44 Thus, we generated a cDNA library using RNA extracted from actively growing buds and four cDNA collections using RNA extracted from buds containing active or inactive (dormant) buds (Table 1). In addition, in woody plants, a minimum distance from the roots to the apical meristems, measured as number of nodes rather than length, is required to get the juvenile-to-adult phase transition, suggesting that juvenility signals coming from the roots are involved in the process.…”

“…9 Therefore, new cultivars adapted to the new trends in olive growing, i.e. shorter juvenile periods, 10 tree architecture suitable for hedgerow orchards and mechanical harvesting, 11 or increased oil content and organoleptic profiles tailored to different markets, 12 are needed. 11 …”

Early selection for yield in robusta coffee based on juvenile growth traits

“…Indirect selection for yield based on early stage growth traits has been effectively applied in the improvement of olives (Moreno-Alías et al, 2010) and kola (Akpertey et al, 2017). Similarly, in Robusta coffee, selection indices for vigour, moisture stress tolerance and yield using quantitative traits (stem diameter, number of laterals, span and height) have been shown to be successful (Walyaro and Van Der Vossen, 1979;Anim-Kwapong et al, 2011).…”

Transcriptomic time-series analysis of early development in olive from germinated embryos to juvenile tree

“…Despite its relevance, the genetic control of the early steps of tree development has received little attention. In practical terms, the study of the genetic changes in normal olive-tree development is relevant to breeders seeking to shorten the unproductive juvenile period [ 1 ]. Understanding the molecular basis of these characteristics and improving the efficiency of such breeding programs require the development of genomic information and tools.…”