Transgenic banana cv. Rasthali (AAB, Silk gp) harboring Ace-AMP1 gene imparts enhanced resistance to Fusarium oxysporum f.sp. cubense race 1

• Development of Fusarium resistant transgenic banana cv. Rasthali with Ace-AMP1 gene is described.
• Embryogenic cell suspensions were transformed with the Ace-AMP1 gene.
• Of the 148 original transformants 10 lines are Southern confirmed.
• Tolerant lines were selected after root challenging with Foc1 isolate in pots.
• The findings may help in reviving the most favored cultivar facing extinction.

Banana cultivar Rasthali (AAB, Silk gp) is one of the favored varieties known for its flavor and keeping quality in southern India. The cultivar is affected by Fusarium wilt which has reached serious proportions, almost wiping it out. Highly regenerative embryogenic cell suspensions of cultivar Rasthali were developed using male floral meristems. Agrobacterium strain LB4404 harboring binary vector pCAMBIA2301 with a gene encoding antimicrobial peptide (Ace-AMP1) cloned from onion seeds driven by CaMV35S promoter and nos terminator was used in transformation. Embryogenic cells were transformed with the gene and 148 putative transformants were developed. Molecular characterization of transformants demonstrated that 20 plants were PCR positive and the transgenes had been stably integrated into the banana genome in ten lines and expression of the gene was confirmed by ELISA and Western blot in them. Transformants were root challenged with Fusarium oxysporum f.sp. cubense race1 (Foc) in earthen pots and observed over a period of six months. External symptoms appeared after 4–5 months and by 6 months plants showed only 0–20% of PDI and 38–48% VDI as compared to untransformed control plants which showed severe disease symptoms (100%) within three months and died. Significantly higher AMP protein content in transgenic lines was negatively correlated and higher root colonization was positively correlated with disease symptoms. Six transgenic lines were selected for field evaluation.