Exploring the Natural Variation for Seedling Traits and Their Link with Seed Dimensions in Tomato

Abstract

The success of germination, growth and final yield of every crop depends to a large extent on the quality of the seeds used to grow the crop. Seed quality is defined as the viability and vigor attribute of a seed that enables the emergence and establishment of normal seedlings under a wide range of environments. We attempt to dissect the mechanisms involved in the acquisition of seed quality, through a combined approach of physiology and genetics. To achieve this goal we explored the genetic variation found in a RIL population of Solanum lycopersicum (cv. Moneymaker) x Solanum pimpinellifolium through extensive phenotyping of seed and seedling traits under both normal and nutrient stress conditions and root system architecture (RSA) traits under optimal conditions. We have identified 62 major QTLs on 21 different positions for seed, seedling and RSA traits in this population. We identified QTLs that were common across both conditions, as well as specific to stress conditions. Most of the QTLs identified for seedling traits co-located with seed size and seed weight QTLs and the positive alleles were mostly contributed by the S. lycopersicum parent. Co-location of QTLs for different traits might suggest that the same locus has pleiotropic effects on multiple traits due to a common mechanistic basis. We show that seed weight has a strong effect on seedling vigor and these results are of great importance for the isolation of the corresponding genes and elucidation of the underlying mechanisms.

Quantitative trait locus mapping associated with earliness and fruit weight in tomato

“…Similar associations were also obtained between DFST and DFTT with WS, which suggested that seed weight showed a positive effect on the development time of sympodial units formed after the floral transi- tion due to gene linkage. In this regard, similar effects caused by the seed size and weight in tomato seedlings were reported by Khan et al (2012), who concluded that effects on seedling growth were due to the genetic variation in the amount of food reserve (starch) and maternal effects. In addition to seed weight, various factors such as the number of leaves produced before the first inflorescence, length of floral development, light intensity and temperature have been reported to affect the floral transition (Dieleman and Heuvelink, 1992;Samach and Lotan, 2007;Sumugat et al, 2010).…”

“…Recently in tomato, several studies have reported the influence of epistasis on fruit shape, locule number, seed size and fruit weight during the process of domestication (Lippman and Tanksley, 2001; van der Knaap et al, 2002;Khan et al, 2012). In few studies have the epistatic interactions between the components of earliness and fruit weight been examined, and it is equally unclear if tomato earliness is controlled by a single genetic mechanism or something more complex.…”

Cross-Talk Between Sporophyte and Gametophyte Generations Is Promoted by CHD3 Chromatin Remodelers inArabidopsis thaliana

“…It has previously been shown that seed size is positively correlated with growth of the seedling primary root (Elwell et al 2011;Khan et al 2012). One possible explanation for how reduced seed size increases penetrance of the pickle root phenotype is that the derepression of embryonic master regulators that occurs in pkl seedlings (Henderson et al 2004;Li et al 2005) is more likely to result in adoption of the pickle root phenotype in slower-growing roots.…”

“…It should be noted, however, that although our data demonstrate that manipulation of seed size is sufficient to alter penetrance of the pickle root phenotype, our data do not preclude the possibility that loss of PKR2 enhances pickle root penetrance in small seeds via a mechanism that acts in addition to the effect on seed size. It has previously been shown that seed size is positively correlated with growth of the seedling primary root (Elwell et al 2011;Khan et al 2012). One possible explanation for how reduced seed size increases penetrance of the pickle root phenotype is that the derepression of embryonic master regulators that occurs in pkl seedlings (Henderson et al 2004;Li et al 2005) is more likely to result in adoption of the pickle root phenotype in slower-growing roots.…”

Healthy and sustainable diets for future generations

“…Seed quality and supply impact the volume and nutritional value of the crops 13. Seed systems in Africa are generally underdeveloped, with the majority of smallholder farmers procuring seed through informal systems, and therefore commercial seed companies making only minor contributions 14.…”