Agrobacterium-Mediated Sequential Transformation of Sri Lankan Citrus Species by Flowering Locus T (FT) and VlmybA2

Abstract

Sri Lankan Citrus spp are important fruit crops with high potential for expanded production. Reduced long juvenile period would be an attractive breeding output for growers. Early flowering local Citrus was attempted through genetic transformation by Flowering LocusT (FT). VlmybA2 was used as a potential visual marker. Seedlings of commercially available Citrus were transformed at 3 days and 9 months of germination. Citrus nobilis (Jamanaran) plants transformed by 35S: VlmybA2 were shorter compared to those transformed by 35S:FT and control. Purple pigmentation was only evident in Nasnaran (Citrus madurensis) seedlings which could not survive after acclimatization. Putative 35S:FT Nasnaran produced very early axially buds bylO days. Fifty five percent of putative 35S:FT Jamanaran plants initiated axillary shoots by 12 weeks while there were no axillary buds in control or 35S:FT until 16 weeks. Early axillary buds and, the highest number of branches (13) and leaves (82) in putative 3SS:FT could be signs of manipulated flowering time. As all purple plants of putative 35S: VlmybA2could not survive, VlmybA2 is not suitable as a visual marker. According to our results, sequential whole plant transformation is effective in altering plant structure. Further experiments with replicated putative transgenic plants through vegetative propagation for morphological and molecular analysis are aimed to check if 35S: FT can induce early flowering in local Citrus.