New strategies for increasing heterozygosity in crops: Vicia faba mating system as a study case

Abstract

Our research assesses the feasibility of using artificial selection on pre-mating floral traits to modify the mating system of faba bean (Vicia faba). This analysis considered two synthetic populations, which were derived from different genetic pools and had undergone five years of multiplication. For these populations, we identified floral and inflorescence traits that influence outcrossing per plant and examined the relative importance of these traits in governing yield. Codominant isozyme loci and the mixed-mating model were used to estimate the multilocus female outcrossing rate. A maternal half-sib design was used to evaluate the additive genetic component of floral and inflorescence traits, yield and yield components. Multiple regression was used to assess the effects of floral and inflorescence traits on outcrossing and yield and components of yield. The two populations exhibited mixing mating. Self-fertilization appears to result from the action of pollinating bees, so that its incidence could be modified by selection on floral and inflorescence traits that affect pollination. Floral and inflorescence traits affected individual differences in outcrossing unequally, with most variation being associated with the numbers of displayed flowers and inflorescences. Variation among plants in reward traits and in shape, although statistically significant, had limited and inconsistent influences on individual differences in outcrossing. Yield and its components varied strongly with aspects of floral display and, to a lesser extent, floral design, except for seed weight. Overall, our results imply that both outcrossing and yield could be enhanced by selection for plants that produce more inflorescences, each with relatively few flowers.

GM Crops, Organic Agriculture and Breeding for Sustainability

“…This can be overcome by increasing recombination through the use of male sterility when available [63], or cisgenesis [13], or by genetic manipulation of flower biology [64][65][66][67].…”

Genetic Vulnerability of Modern Crop Cultivars: Causes, Mechanism and Remedies

“…Varieties developed through mass selection would also have considerable genetic variation because several similar looking plants which are variable for quantitative traits are selected and bulked (Singh, 2002). For instance, the development of synthetic varieties has been effective for increasing yield and stability in faba bean (Vicia faba L.) because heterozygosity is enhanced while at the same time the dangers of genetic vulnerability from varietal uniformity is reduced (Suso et al, 2005). A work in Kenya clearly showed that deliberately maintaining some level of variation in varieties turned out to be an important prerequisite of high grain yield in sorghum grown under drought stress (Haussmann et al, 2000).…”

The role of crop-pollinator relationships in breeding for pollinator-friendly legumes: from a breeding perspective

“…DIAS of traits, such as standard length, width, area, and perimeter, facilitates extensive and detailed phenotypic analyses to describe subtle differences in flower size (Yoshioka et al 2004(Yoshioka et al , 2005. Appropriate software packages can provide more accurate, consistent, and objective measurement for floral traits, such as style length, ovary style angle (for assessment of the mechanical fit to pollinator) or pollen presentation that were impossible or impractical to determine manually (Suso et al 2005a).…”

“…Studies on faba bean have been focused on the analysis of out-crossing within cultivars (Suso et al 2001), and pollen-mediated gene flow between cultivars. Breeding questions include the choice of appropriate procedures for cultivar development that exploit heterosis and maximize yield stability (Metz et al 1993Pierre et al 1996;Carre et al 1998;Suso et al 2005a), and for maintenance of varietal and germplasm purity during seed multiplication .…”

“…The methodological question that arises within this process is: How to elevate out-crossing to increase heterozygosity and recombination potential (Barrett 2008)? Out-crossing, and consequently the level of heterozygosity, would be increased through selection for floral characteristics that enhance its frequency (Abdel-Ghani et al 2003, 2005Suso et al 2005a;Parzies et al 2008;Singh et al 2007). More information on ways in which floral traits influence mating systems is needed for legumes.…”