Genomics of Female Flowering ans Seed Yield in Jatropha Curcas L

Abstract

Increased demand of fossil fuels has raised an interest towards culling an alternate and promising renewable source of energy. Jatropha curcas L., a non-edible energy crop of the family euphorbiaceae, has showed potential to provide feedstock for biodiesel due to its high oil content (42%) in the seed. The stumbling roadblock for commercialization of Jatropha based biodiesel production is low seed yield per inflorescence which is governed by low ratio of female to male flowers (1:25-30). Exogenous application of cytokinin was done on floral meristems to increase the female to male flower ratio and seed yield. It increased female flowers (~8-fold) and number of fruits (~3-fold) however, decrease in fruiting and seed size/weight was reduced. Thus, current study was under taken with the following objectives; (1) deciphering molecular cues for floral transitions and female flowering in Jatropha (2) deciphering molecular components of cytokinin on flowering and source-sink relationship of Jatropha. newlineComparative genomic and gene expression profiling was done at floral developmental stages (vegetative to reproductive, differentiation of floral buds into male/female and transition towards female flowering) of Jatropha. CRY2,CUC2, PIN1, TAA1 and CKX1 genes were identified for female flowering and SUP gene for transition of female flower. Further, RNA-seq based comprehensive transcriptome sequencing of inflorescence meristems (treated with cytokinin) and control (untreated inflorescence meristems) at time-intervals of 15 and 30 days, was performed. Through KEGG annotation, metabolic pathways were mapped to photosynthesis, carbon fixation, carbohydrate metabolism and nitrogen metabolism. These pathways were upregulated post cytokinin treatment (15 days) however, after 30 days, genes involved in these pathways were observed to be downregulated. We observed significant downregulation of genes FBP, SBP, GS, GDHandAGPase genes weredownregulated post 30 days of cytokinin treatment.