In vitro plant regeneration from immature cotyledon explants of macadamia (Macadamia tetraphylla L. Johnson)

Abstract

The macadamia tree, an Australian native, is highly valued for its nuts. Macadamia improvement programs so far have relied on conventional breeding and selection. The production of improved cultivars required to meet future demands could be accelerated by the application of modern biotechnological techniques, but this requires an efficient and reproducible regeneration system that has not yet been established for macadamia. We report here shoot regeneration from immature cotyledon explants of macadamia. Adventitious buds were induced on the cotyledon explants from fruits collected at 140 and 190 days after full bloom (DAFB) on MS medium supplemented with either 10 or 15 microM TDZ. The addition of 2% coconut milk (CM) to 10 microM TDZ containing media resulted in enhanced adventitious bud induction from 190 DAFB explants. Further shoot development from the induced buds was depressed in media containing TDZ + CM; the addition of 0.001 microM IAA to this combination doubled shoot development, from 1.9-3.9 shoots per explant. The transfer of bud clumps to media supplemented with 8.8 microM BA alone or in combination with either 0.14 microM GA(3) or 0.001 microM IAA significantly increased shoot production from the previously induced explants by 1.5-2 times of that observed in TDZ + CM medium. Histological examinations revealed that shoot regeneration was primarily by organogenesis originating from cells on or just below the cut surfaces of explants.

RESPUESTAS MORFOGÉNICAS EN LA PROPAGACIÓN in vitro DE NOGAL PECANERO (Carya illinoinensis [Wangenh] K. Koch)

“…No obstante, en el presente estudio, la posición de la hoja en el tallo no marcó diferencia por tratarse de plantas absence of light during this stage is more convenient, according to what was indicated in the study carried out in Anacardium occidentale L. by Aliyu (2005), who obtained shoots of explants developed in a culture medium with AC, under conditions of darkness. Mulwa and Bhalla (2006) obtained similar results during the initiation of explants of cotyledons of macadamia under conditions of darkness. In avocado, the increment of radiation had no effect on the sprouting of explants (De la Viña et al, 2001).…”

Improved method of in vitro regeneration in Leucaena leucocephala — a leguminous pulpwood tree species

“…TDZ has been used for multiple shoot induction from cotyledonary nodes of Populus (Russell and McCown, 1986), Quercus robur L. (Chalupa, 1988), Cercis Canadensis (Yusnita et al, 1990) and Dalbergia sissoo (Pradhan et al, 1998). TDZ also has been used for shoot regeneration from immature cotyledon explants of Macadamia (Mulwa and Bhalla, 2006) and Poplar (Cseke et al, 2007). Urtubia et al (2008) reported improved shoot regeneration from hypocotyls slices of Prunus, when TDZ was combined with IBA as compared to TDZ alone in the regeneration medium.…”

Influence of kinetin on in vitro rooting and survival of banj oak (Quercus leucotrichophora L.)

“…It was able to induce maximum number of shoots per explant (4.5 shoots/basal segment) with maximum average shoot length (2.32 cm), maximum average length of longest shoot (4.22 cm) and maximum average number of leaves (5.25) ( Table 2). The induction of multiple shoots from the cotyledonary nodes of seedlings in response to BA has also been reported earlier (Purohit et al, 2002a) as well as in other tree species, including Alnus glutinosa L., Gaertn (Perinet and Lalonde, 1983), Pterocarpus marsupium Roxb (Tiwari et al, 2004), Albizia odoratissima L.f. (BENTH) (Rajeshweri and Paliwal, 2006); Macadamia tetraphylla (Mulwa and Bhalla, 2006); Pterocarpus santalinus L.f. (Rajeshweri and Paliwal, 2008) and Aegle marmelos (Nayak et al, 2007). BA was followed by 2-ip which was able to produce average number of shoots per basal segments up to 3.17.…”