Inheritance of a pectate lyase mediated soft rot resistance in crosses between transgenic potato lines of cv. désirée andS. tuberosum cultivars
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Expression of the pectate lyase (PL) isoenzyme 3 in transgenic potato lines of cv. Désirée mediates an enhanced resistance of tuber tissue toErwinia carotovora (Ec) soft rot due to a pre-activation of plant defence mechanisms. Therefore, theSolanum tuberosum cvs Agave and Adretta with a moderate level of soft rot resistance were crossed with such PL-expressing potato lines. The resulting progenies were assessed with respect to plant/tuber characteristics over a period of four years and then tested for PL3-expression as well as for soft rot resistance. 71% of the selected progeny lines exhibited a stable production of the PL3 enzyme. Statistical analysis revealed differences between the transgenic and the non-transgenic progeny concerning the soft rot resistance of tuber tissue. Compared with the PL-inactive progeny, extension of Ec-rotting on the wound surface of PL-transgenic potatoes was diminished on average by 51.8%. Similarly, the degree of cell lysis caused by bacterial maceration was significantly (P<0.05) reduced in tuber tissue of PL-expressing progeny lines. The latter also revealed an enhanced PPO and PAL activity in their tuber tissue indicating an active plant defence. It is concluded therefore that the PL-mediated soft rot resistance introduced into potatoes by means of molecular techniques is heritable.
Additional keywordsBreeding disease resistance Erwinia carotovora Solarium tuberosumL. transgenic plants phenylalanine ammonia-lyase polyphenol oxidase
cauliflower mosaic virus
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