Background: Identifying biomass-related genes to meet the increasing demand for food supply is important approach for agricultural and scientific efforts. In this study, we employed the Full-length cDNA Over-eXpressing gene hunting system (FOX hunting system) to identify biomass-related genes through ectopic expression of Arabidopsis thaliana full-length cDNA in bird&rsquo;s-foot trefoil (Lotus corniculatus). 
 
Methods: A total of 66 FOX superroot lines (FSLs) from Lotus corniculatus cv. Viking were transferred in vermiculite after two weeks in half-strength Murashige and Skoog (MS) medium. These FSLs were then grown in a growth chamber for four weeks, during which their plant length and root length were measured. High biomass lines were selected from this group. FSL #83 and #121 were then grown for an additional four months in a greenhouse until they reached maturity, at which point they were evaluated for their agronomic traits.&nbsp; 
 
Result: Out of the 66 analyzed FSLs, 15 displayed superior growth characteristics in plant length and total root length. Arabidopsis cDNA, categorized into genes related to various functions such as membrane transport, photosystems, phytohormone synthesis, amino acid synthesis and unknown genes, was introduced into these lines. Two lines were grown to maturity in the greenhouse and their agronomic traits were analyzed in detail. FSL #83 expressed brassinosteroid biosynthetic pathway gene (CPD) led to significant differences in internode length, number of stems, number of flowers and above-ground dry matter weight compared to non-transgenic Super-growing roots (SR). On the other hand, FSL #121 expressed Asparaginyl-tRNA synthetase (SYNC1) gene exhibited increases in plant length and the number of stem nodes.

Exploration of Biomass-related Genes in the FOX-superroot Lines of Lotus corniculatus and its Impact on Agronomic Traits