ISHS Acta Horticulturae 692: II International Symposium on Biotechnology of Tropical and Subtropical Species
INCREASED DISEASE RESISTANCE IN PAPAYA BY TRANSFORMING A PATHOGEN-INDUCIBLE STILBENE SYNTHASE GENE |
| Authors: | Y.J. Zhu, C.S. Tang, P. Moore |
| Keywords: | Resveratrol (trans-3,4´,5-trihydroxy-stilbene), genetic transformation, Carica papaya, Phytophthora palmivora |
| Abstract:
Phytoalexins have been shown to be important natural components in the defense of plants against fungal infection. Resveratrol is a major phytoalexin in grapevine. We conducted in vitro pathogen inhibition assays to show that Resveratrol inhibited fungal pathogens of papaya. Resveratrol at 1.0 mM in V8 agar culture medium inhibited mycelia growth of P. palmivora up to 50% of control. The compound was active against P. palmivora as low as 100 µM. Resveratrol was not as effective against the anthracnose pathogen, Colletotrichum gloeosporiodes. We transformed papaya embryogenic cultures with the stilbene synthase gene cloned from grapevine and driven by its own inducible promoter along with the hygromycin resistance or kanamycin resistance gene under the control of a CaMV35S promoter. The presence of transgenes was confirmed by PCR and Southern blot. Twenty lines of transgenic plants were propagated from tissue cultures for greenhouse assays. Transgenic papaya plants were challenged with oomycete pathogen in greenhouse conditions. Data from greenhouse studies showed that the disease level in transgenic plants was reduced to 35% of the disease level in non-transformed control plants. Papaya lines produced with increased resistance to diseases became available for crossing with SunUp to produce hybrids that have resistance to both virus and fungal diseases. | |
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