Genotypic Variation for Morphological Traits in a White Clover Mapping Population Evaluated Across Two Environments and Three Years

Abstract

Phenotypic measurements of plants growing in swards are often confounded by a combination of environmental variation and experimental error. Genetic analysis allows plant scientists to decipher genomic regulation control of key traits, informing breeding strategies and enabling marker‐aided breeding. Our research objective was to estimate genotypic variation for a range of key aboveground morphological traits in a white clover (Trifolium repens L.) F1 mapping population evaluated over 3 yr across two contrasting New Zealand environments in mixed sward conditions. Significant (P < 0.05) genotypic variation for internode length, node number, stolon branching, and stolon thickness was observed, both within individual environments and also across environments and years. There was also significant (P < 0.05) genotypic variation within the population for herbage growth within seasons and across years at the Palmerston North site, which was related to the morphological characters. The potential genetic variation was also characterized by repeatability estimated within individual environments and across environments and years. Analysis of progeny performance across years within a site indicated significant (P < 0.05) genotype × year interaction for most of the morphological traits and mean seasonal growth. There was also significant (P < 0.05) genotype × environment × year interaction for some traits. The significant and large genotype × environment interactions emphasized the importance of trials conducted across multiple environments and years in perennials such as white clover. Genotypes with positive correlation between herbage growth and stolon branching, a trait associated with vegetative persistence, were identified. An interesting observation was the range of diverse phenotypes within the population, the result of a simple pair cross between two morphologically and genetically distinct parents. When extended to include a marker analysis, these trait data will provide for a more thorough understanding of the genetic architecture and control of these pivotal economic traits in white clover and their response to change in environment.

Anthocyanin leaf markings are regulated by a family of R2R3‐MYB genes in the genus Trifolium

“…These data were combined with existing MP2 SSR data and a parental consensus linkage map was estimated (Griffiths et al ., ) and visualised using MapChart 2.2 (Voorrips, ). Vby and Vrl were scored in a T. repens population (MP3) comprised of F 1 full‐sib progeny derived from a hand‐pollinated reciprocal pair‐cross of a genotype each of cv ‘Grasslands Kopu II’ ( Vrl, Vby ) and cv ‘Grasslands Crusader’ as described (Jahufer et al ., ). The population ( n = 92) was screened with SSRs to generate a parental consensus linkage map using JoinMap ® 3.0 (Van Ooijen & Voorrips, ).…”

Achievements and Challenges in Improving Temperate Perennial Forage Legumes

“…There is extensive variation for yield potential in diverse and elite white clover populations (Aasmo Finne et al, 2000a;Jahufer et al, 2013), even within full-sib progenies. As an indirect measure of yield potential, leaf size is a useful, readily measured trait (Caradus and Chapman, 1998), with recent research demonstrating the ability to automate estimation of clover yield using a combination of digital imaging and point analysis (Chen et al, 2010).…”

“…Yield responses of white clover genotypes or populations may largely interact with cropping environments (Jahufer et al, 2013). They can also be inconsistent across contrasting conditions of plant density, type of grass companion and exploitation regime (Table 4), with important implications on breeding strategies.…”

“…In white clover, QTL discovery for traits has included spaced plant morphogenesis in an F 2 inbred population in the absence of grass competition and grazing , seed yield on spaced plants ( Barrett et al, 2005b), salt tolerance (Wang et al, 2010), and stolon diameter, stolon number, and internode length (Zhang et al, 2010). White clover full-sib pair cross mapping populations have been assessed for aerial and root morphological characters (Jahufer et al, 2008;Jahufer et al, 2013) but have not yet had QTL discovery reported. Qualitative trait maps have also been developed (Barrett et al, 2005b;Casey et al, 2010;Tashiro et al, 2010;Wang et al, 2010), identifying independent loci controlling leaf colour, self-compatibility, and in the related species T. semipilosum a single gene resistance to root nematode infection.…”

Evaluation of Egyptian Clover (Trifolium alexandrinum L.) Germplasm through Redundancy Analysis for Forage Yield and Its Components

“…Generally, forage yield per se has low heritability; therefore, its improvement can be achieved by selection for other traits that individually or synergistically determine forage yield (Naeem et al, 2006; Vasiljevic´ et al, 2006; Hussain et al, 2015). In comparison with forage yield, components such as plant height, leaf area, single plant dry biomass, internodal length, number of leaflets stem −1 , stem diameter, stem number, and stem density affect total forage yield (Naeem et al, 2006; Ranjbar, 2008; Kapoor et al, 2011; Jahufer et al, 2013; Hussain et al, 2015). The percentage of emergence and seedling vigor can contribute to better stand establishment, seedling competitiveness in the sward, and result in a higher forage yield (DeHaan et al, 2001; Fraser et al, 2004; Taylor, 2008; Leger and Baughman, 2015; Rauf et al, 2015).…”