Overexpression of Arabidopsis ABF3 gene enhances tolerance to drought and cold in transgenic lettuce (Lactuca sativa)

Abscisic acid (ABA) plays an important role in environmental stress responses of higher plants during vegetative growth via regulating the expression of numerous stress-responsive genes. The gene ABF3 encodes a transcription factor for the expression of ABA-responsive genes. Here we report the transformation of lettuce (Lactuca sativa L. cv. Chongchima, leaf type) with ABF3 derived from Arabidopsis using Agrobacterium tumefaciens-mediated system and characteristics of the transgenic plants including responses to drought and cold stress. Transgenic plants could be successfully obtained using a two-step selection/regeneration procedure with 10.8% of transformation efficiency. Of the tested nine transgenic lines eight gave 3:1 segregation ratio in the T1 progenies of self-pollinated T0 transgenic plants, suggesting single copy integration of the transgene. One line gave 1:1 ratio, suggesting integration of more than one copy in this line. The result of Southern blot analysis of T1 progenies showed that the ABF3 transgene was stably integrated into the genome of transgenic plants. Northern blot analysis confirmed that the ABF3 was highly expressed in T1 progenies of transgenic plants. Transgenic plants showed normal growth in terms of morphologies of whole plant and seed. The transgenic plants showed higher tolerances than wild-type plants against drought as well as cold stress.