Morphological and Anatomical Investigations on Old Home x Farmingdale 333 / Pyrus elaeagrifolia in Vitro Micrografts

Hatice Dumanoğlu,Aysun Çelik,Nurhan H Büyükkartal,Saeed Dousti

doi:10.15832/tbd.65549

Abstract

In this study, the possibility of creation of a specific pear rootstock combination by micrografting was investigated. Two genotypes; ‘Old Home x Farmingdale 333’ ( Pyrus communis L.) which is a clonal semi dwarf pear rootstock resistant to fireblight and pear decline, and Pyrus elaeagrifolia known as tolerant to Fe-chlorosis, salinity and drought stresses were used to obtain a clonal, semi dwarf and tolerant to the stresses pear rootstock combination. In vitro P. elaeagrifolia seedlings were used as rootstock, and in vitro shoots of ‘OH x F 333’ were used as semi dwarf interstock. Cleft grafting was applied in micrografts. Grafted seedlings were cultured on Murashige and Skoog basal medium with ½ strength of macronutrients for 8 weeks. Cultures were incubated under white fluorescent light, 16 h per day. However, complete darkness was applied for 1 or 2 weeks at the beginning of incubation for the darkness treatments. Graft take success in the control treatment was significantly higher (97.9%) than darkness treatments (90.5% and 82.5%, respectively). Ultrastructural observations with transmission electron microscope revealed that dividing cambial initials reached to 2-3 layers and new xylem and phloem elements distinctly differentiated in transversal sections of the graft union after 8 weeks of micrografts in the control and dark treatments. The results indicated that a successful graft union formation occurred. To the best of our knowledge, this is the first report of in vitro micrografting on Pyrus elaeagrifolia Pallas.

Highlights

Native Mediterranean Pyrus species P. elaeagrifolia Pallas which has habitat ranging from Turkey to Southeastern Europe and Ukraine (Bell 1990), is a potential pear rootstock in areas where lime, salt and drought are limiting factors for growing many Pyrus species (Lombard & Westwood 1987; Matsumoto et al 2006)
Very high graft take success was obtained in the micrografts of ‘OHxF 333’ / P. elaeagrifolia seedlings
Nunes et al (2005) reported that in vitro micrografting techniques offer the potential for effective propagation of high quality genetic material in a short time under controlled and aseptic conditions

Summary

Introduction

Native Mediterranean Pyrus species P. elaeagrifolia Pallas which has habitat ranging from Turkey to Southeastern Europe and Ukraine (Bell 1990), is a potential pear rootstock in areas where lime, salt and drought are limiting factors for growing many Pyrus species (Lombard & Westwood 1987; Matsumoto et al 2006). Scions of cultivars (Pyrus communis L.) grafted on P. elaeagrifolia grow vigorously similar to pear seedlings causing a long juvenile period. This problem could be overcome by using a dwarf or semi dwarf clonal Pyrus interstocks such as ‘OHxF 333’ on P. elaeagrifolia. It is known that interstocks may reduce vegetative growth and enhance reproductive growth of the tree. Such double-worked plants have two unions, one between the rootstock and interstock and one between the interstock and the scion. Production of grafted-rootstock plants using conventional techniques takes time for at least more than one year considering the growth time of rootstock lines (Elivar & Dumanoğlu 1999)

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