The duration of the life cycle is associated with C-value and affects reproductive features in the Fabeae, the tribe with largest genomes in Fabaceae

Abstract

The amount of DNA per nucleus, usually expressed in terms of the amount within a haploid chromosome set (C-value), is known to have significant impacts on morphological and physiological features in plants. Among these features, C-value influences replication time and hence duration of the whole cell cycle, as well as sizes of cells. The Fabeae tribe of the family Leguminosae (Fabaceae) is remarkable in having both annual and perennial species and the largest C-values in the family. Polyploidy is rare in this tribe. This work aims to study the correlation between annuality/perenniality, C-value and some morphological characteristics of reproductive organs, such as the number of pollen grains, ovules, flowers per inflorescence as well as pollen and flower size, in annual and perennial species within the tribe Fabeae (Vicieae). The average C-value of perennials is statistically significantly higher than of annuals. Compared with perennials, annuals are mostly characterized by single- or few-flowered inflorescences and fewer ovules per carpel independently of flower size. All floral characteristics exhibit a range of intraspecific variation thus complicating the estimation of precise impact of C-value on phenotype. Features of the reproductive system in the Fabeae are therefore partly correlated with C-value, most probably mediated through the interaction between ecological adaptation of species with their life cycle duration.