Submitted to: Protocols for Micropropagation of Selected Economically-Important Horticultural Plant
Publication Type: Book / Chapter
Publication Acceptance Date: March 5, 2011
Publication Date: September 25, 2012
Citation: Reed, B.M., De Noma, J.S., Wada, S., Postman, J.D. 2012. Micropropagation of pear (Pyrus sp). In: M. Lambardi, E.A. Ozudogru, and S.M. Jain (eds.) Protocols for Micropropagation of Selected Economically-Important Horticultural Plant. Springer, NY:Humana Press. p.554. Interpretive Summary: This chapter describes how to establish shoot tip cultures, produce multiple plants, root the plants and prepare them for growth in the greenhouse. The great genetic variation in pears makes micropropagation challenging. New shoots are collected from dormant shoots forced in the greenhouse or from grafted shoots. Clean shoots are recovered after testing for contaminants . Although pear species and cultivars are cultured on several well known media, Murashige and Skoog (MS) is the most commonly used. Our studies showed higher concentrations of calcium chloride, potassium phosphate and magnesium sulfate than MS medium produces better growth. Pear shoots are often difficult to root, but there are several techniques that are effective for many types. Pears shoot cultures can be stored at 1-4°C for as long as 4 years or in liquid nitrogen for decades.
Technical Abstract: Establishment of shoot tip cultures, proliferation, rooting, and acclimatization of the resulting plantlets are all elements of micropropagation. The great genetic variation in Pyrus (pear)makes micropropagation challenging for many genotypes. Initiation of shoots is most successful from forced dormant shoots or from scions grafted on seedling rootstocks to impose juvenility. Clean shoots are recovered after testing for contaminants at the initiation stage on ½ strength Murashige and Skoog 1962 medium (MS) at pH 6.9 for one week. Although pear species and cultivars are cultured on several well known media, MS is the most commonly used. Our studies showed that multiplication and growth of shoots is best on pear medium with higher concentrations of calcium chloride, potassium phosphate and magnesium sulfate than MS medium and 4.4 µM (1 mg/L) N6 benzyladenine (BA). Pear shoots are often recalcitrant to rooting; however a 15 sec. dip in 10 mM indole-3-butyric acid (IBA) or naphthalene acetic acid (NAA) and planting on basal medium with no plant growth regulators is effective for many genotypes. Pears shoots store well at 1-4°C for as long as 4 years without reculture. Cryopreservation protocols are available for long-term storage of pear shoot tips. Acclimation of in-vitro rooted or micrografted shoots in a mist bed follows standard procedures.