Mohanpuria, PrashantGursimran Kaur2021-02-092021-02-092020Gursimran Kaur (2020). Genetic transformation of guava (Psidium guajava L.) with RNAi construct for fruit fly [Bactrocera dorsalis (Hendel)] resistance (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810161055Guava (Psidium guajava L.) is one of the most nutritious fruit due to its abundance in antioxidants, tannins, vitamins A, C and minerals. But its production is severely affected by fruit fly [Bactrocera dorsalis (Hendel)] infestation. There is no fruit fly resistant guava germplasm reported so far globally. RNAi approach against fruit fly provides an attractive approach to overcome this devastating problem. Here we report generation of marker-free RNAi guava lines of cv. Allahabad Safeda targeting ecdysone receptor (ECR) gene of fruit fly through in planta genetic transformation. For floral dip method, completely developed closed bud and bud with calyx split were used and effects of different dipping time in infiltration medium were observed. Dipping time for more than 10 seconds led to necrosis of floral buds and pre-mature flower drop. For floral drop method, different amount of dropping inoculum on bud with calyx split and open flower were used. Dropping 4-6 drops of Agrobacterium inoculum led to necrosis and flower drop, while dropping 1-2 drops of inoculum found optimum led to development of subsequent guava fruits. RNAi cassette integration was detected in transformed guava lines through PCR using gene specific and vector specific primers. No transformants were obtained with floral dip method in guava, but floral drop transformation showed a higher transformation efficiency of 4.95% with bud with calyx split stage of guava used as explant. The present optimized, efficient floral drop transformation method will be very useful for genetic manipulation of guava.EnglishThesis