Browsing by Author "Bhalla, Prem L."

Now showing 1 - 2 of 2

Assessment of clonal stability of in vitro regenerated shoots of Macadamia tetraphylla by RAPD analysis
(Egerton University, 2007) Mulwa, Richard M. S.; Bhalla, Prem L.
Macadamia nuts constitute an important part of the world nut industry and are highly valued for their health- promoting properties. Macadamia is an open-pollinated crop that takes 8–12 years to bear fruit when multiplied via seeds. The yield and nut quality in seedling plantations are often highly variable, and grafting is currently the most common method for producing nursery trees with reduced variability. We have previously reported on the tissue-culture propagation of macadamia, and in the present study we assessed the clonal integrity of the regenerated shoots. The RAPD proﬁles of 3 macadamia stock plants and 10 in vitro regenerated lines from each stock plant were analysed to assess the clonal integrity of the shoots regenerated in vitro for micropropagation purposes. The extent of genetic variation between the stock plants and 9 randomly selected seedlings was also assessed. There was no difference in clonal identity between the stock plants and their micropropagated progeny, indicating that clonal micropropagation was possible using enhanced axillary proliferation in macadamia. In contrast, there was a large genetic variation among the seedlings and between the seedlings and stock plants, with genetic distance estimates ranging from 0.121 to 0.637 among seedlings, indicating rampant out-crossing of the macadamia plant.
In vitro plant regeneration from immature cotyledon explants of macadamia (Macadamia tetraphylla L. Johnson)
(Egerton University, 2006-07) Mulwa, Richard M. S.; Bhalla, Prem L.
The macadamia tree, an Australian native, is highly valued for its nuts. Macadamia improvement pro- grams so far have relied on conventional breeding and selec- tion. 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 cotyle- don explants from fruits collected at 140 and 190 days af- ter full bloom (DAFB) on MS medium supplemented with either 10 or 15 µM TDZ. The addition of 2% coconut milk (CM) to 10 µM TDZ containing media resulted in enhanced adventitious bud induction from 190 DAFB ex- plants. Further shoot development from the induced buds was depressed in media containing TDZ + CM; the addi- tion of 0.001 µM IAA to this combination doubled shoot development, from 1.9–3.9 shoots per explant. The trans- fer of bud clumps to media supplemented with 8.8 µM BA alone or in combination with either 0.14 µM GA3 or 0.001 µM IAA significantly increased shoot production from the previously induced explants by 1.5–2 times of that observed in TDZ + CM medium.