Origin and relationships of New Zealand chestnut (Castanea sp.Fagaceae) selections reflect patterns of graft failure
Oraguzie, NC and Paterson, AM and McNeil, DL, Origin and relationships of New Zealand chestnut (Castanea sp.Fagaceae) selections reflect patterns of graft failure, Plant Systematics and Evolution, 218, (3-4) pp. 193-204. ISSN 0378-2697 (1999) [Refereed Article]
Graft failure that occurs in the clonal propagation of chestnuts is a practical problem which has arisen in recent years. Several hypotheses have been put forward to explain reasons for the failure but none have focused on origin and relationships of cultivars. This study was carried out to determine whether relationships of New Zealand chestnut selections and their origin reflect patterns of graft failure within the selections. Two different character data sets, random amplified polymorphic DNA (RAPD) and morpho-nut, were employed for the analyses of the relationships between the chestnut selections. Four different analyses were done to generate trees depicting the relationships of the selections. These were: morpho-nut character, RAPD character, taxonomic congruence (combination of morpho-nut and RAPD trees), and character congruence (combination of morpho-nut and RAPD data sets). When graft failure data were mapped onto the majority rule consensus tree constructed from character congruence analysis, it was found that self graft incompatibility was reflected in the origin and relationships of the chestnut selections. Information on the affinities of the chestnut selections to introduced chestnut species showed that the selections that were mostly implicated in graft failure which are from the North Island had affinities with the Castanea crenata species. But the selections (from the South Island) that were placed with Castanea sativa as well as hybrids ('1002' and '1007' from the North Island) of Castanea mollissima and C. crenata had no failed grafts. This finding indicates that graft failure in New Zealand chestnut selections does not occur by chance but is dependent on the origin and/or evolutionary history of the selections.