P 09 Genetic transformation of two local Citrus species by Flowering Locus T (FT) and VlmybA2

Abstract

There is a necessity for genetic improvement of local Citrus species to meet the national requirement and to exploit the potential export market. Delayed flowering is a main barrier for Citrus genetic improvement and seedling derived crop cultivation. Therefore, we attempted to improve two local Citrus species for early flowering through transformation by Agrobacterium bearing 35S:Flowering Locus T (FT), and 35S: VJmybA2 for enhancement of ornamental value by induction of purple pigmentation. We followed the seedling transformation as an efficient alternative method. Purple pigmentation was clear on putative VlmybA2 seedlings of Nasnaran (Citrus madurensis) after 2 weeks of transformation, but they could not survive. Only one axillary shoot was observed in a putative chimeric 35S.FT seedling out of seedlings after 4 weeks of transformation. Above plant could not survive during acclimatization. Significantly lowest plant height was observed in putative VlmybA2 Jamanaran (Citrus nobilis)) plants. Purple pigmentation was not evident in them. Auxin production may be altered in 35S: VlmybA2 plants resulting in lowest plant height. Inter nodal length, number of nodes and number of leaves were significantly reduced in putative 35S.FTplants by 3 months of transformation. Fifty five percent of putative 35S: FT plants produced axillary shoots while there were no axillary buds in control or 35S: VlmybA2 plants after 4 months of transformation. Early axillary buds and reduced intermodal lengths in putative 35S.FT could be signs of early flowering in Citrus. FT being a mobile signal for flowering induction, there is a possibility that the protein produced at base of the plant due to transformation could move upward for axillary bud initiation. Our results indicate that there is a potential in 35S.FT to alter the plant growth and structure. This experiment is being continued through morphological and molecular analysis to determine the effect of FT on early flowering.