12-JHSB-CmPP16 - 643_JHSB_80_5.ps 10:33 am Page 643 Journal of Horticultural Science Biotechnology(2005 80(5 643649 Differential expression of

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Differential expression of CmPP16 homologues in pumpkin ( Curcurbita maxima ), winter squash ( C. moschata ) and their interspecific hybrid By R. ATHANASIADOU 1, 3 , A. N. POLIDOROS 1 , G. MERMIGKA 2 , I. NIANIOU-OBEIDAT 2 and A. S. TSAFTARIS 1,2* 1 Institute of Agrobiotechnology, Center for Research and Technology Hellas, 6th Km. Charilaou-Thermis Rd., P.O. Box 361, 57001 Thermi, Greece 2 Department of Genetics and Plant Breeding, School of Agriculture, Aristotle University of Thessaloniki, P.O. Box 261, 54124 Thessaloniki, Greece (e-mail: [email protected]) (Accepted 13 June 2005) SUMMARY Grafting is used in vegetable production as an alternative to highly toxic, broad-spectrum soil disinfectants such as methyl bromide and to avoid soil-borne biotic and abiotic stresses. However, deterioration in valuable qualitative characters of the scion occurs in specific graft combinations, such as melon to pumpkin, which makes this environmental-friendly approach less desirable. Understanding the reasons for rootstock-scion incompatibility, and the role of the rootstock, could help to alleviate this problem. We therefore examined the level of expression of CmPP16, a pumpkin ( Cucurbita maxima ) phloem protein that mediates RNA transport from the rootstock into scion tissue, in different pumpkin and squash ( C. moschata ) varieties and in a pumpkin ± squash interspecific hybrid. All are currently in use as rootstocks in grafted melon, watermelon and cucumber production. Our data revealed that two different genetic loci, CmPP16-1 and CmPP16-2 , which encode CmPP16 proteins, are expressed in pumpkin and squash, but not in melon. Pumpkin stems accumulated much higher levels of CmPP16 transcripts than squash or interspecific hybrid stems, while in roots CmPP16 -expression was higher in squash. The pumpkin cultivar with the highest levels of expression of CmPP16 was the worst rootstock for melon, suggesting a role for CmPP16 in determining scion quality. Our results, if confirmed in additional varieties and species, may provide an effective way to screen for suitable rootstocks in grafted vegetable production. M ost cultivated cucurbits (melon, cucumber and watermelon) are highly susceptible to soil-borne diseases that currently are mainly controlled by highly toxic broad-spectrum soil disinfectants such as methyl bromide. As the use of methyl bromide is to be eliminated during 2005, grafting of good quality but disease-sensitive scions onto resistant rootstocks is an alternative means to improve the agronomic characteristics of crops with a concomitant decrease in chemical use. In addition, automation of grafting (Kurata, 1994) and the combination of micropropagation and micrografting (Sapountzakis and Tsaftaris, 2002; Grigoriadis et al ., 2005) have been applied successfully to a number of plant species as an efficient way to decrease the production costs of grafted vegetables. Nevertheless, it has been reported that genotypic variation in rootstocks affects growth and productivity of the scion (Zijlstra et al ., 1994) and that, specifically for pumpkin- melon heterografts, some rootstock-scion combinations
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This note was uploaded on 09/13/2010 for the course DGPB 024e taught by Professor Alexiospolidoros during the Spring '10 term at Aristotle University of Thessaloniki.

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12-JHSB-CmPP16 - 643_JHSB_80_5.ps 10:33 am Page 643 Journal of Horticultural Science Biotechnology(2005 80(5 643649 Differential expression of

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