Narcissus and Daffodil

Production of Narcissus bulbs 103
Mutation breeding of narcissus was reported by Misra (1990). Two narcissus
cultivars flowered early without leaves, after exposure to gamma radiation. Rahi
et al. (1998) carried out experiments with N. tazetta ‘Paper White’ in which bulbs
were exposed to gamma radiation and then planted in normal or alkaline soil.
The performance of irradiated plants in the alkaline soil indicated possibilities for
selecting salt-resistant strains.
D.O. Sage (personal communication) is developing a transformation system
for narcissus as a possible route to cultivar development. Transgenic callus of
narcissus ‘Golden Harvest’ has been produced, carrying a selectable marker and
reporter gene, and attempts are being made to regenerate plants from it. Work
will then concentrate on ‘clean’ transformation technologies for producing transgenic
narcissus ultimately without selectable marker and reporter genes. The technology
should then be able to approach pest and disease control by introducing
resistance genes to otherwise acceptable cultivars.
Future uses of narcissus plants may require breeding for characteristics such as
alkaloid or essential oil content, which have not apparently so far been attempted.
Whatever the goals of narcissus breeding, there is a need to conserve genetic
material for future use. Because of the huge numbers of commercial cultivars
there is a danger that historical but valuable parent cultivars may be lost, while the
loss of wild species (and potentially useful subspecific taxa) through over-collecting
or habitat destruction has already begun (see Chapter 3, this volume). Historic
cultivars and wild types need to be conserved. Koopowitz (1986) has discussed
the wider implications of conserving amaryllids, including the need for a large
number of each to represent the variation of the gene pool meaningfully, long
generation times, specialised cultural requirements and the widespread occurrence
of virus diseases.
As well as improving narcissus cultivars, narcissus genes may be useful in the
production of other transgenic plants. Booth (1957, 1963) studied carotenoids in
narcissus, finding the coronas to be among the richest sources of carotene. Rice
contains neither β-carotene (provitamin A) nor its precursors, and Burkhardt et al.
(1997) transformed rice by microprojectile bombardment with a cDNA coding for
phytoene synthesis from narcissus.
Narcissus propagation
A major problem with commercial narcissus breeding is the long time – 15–20
years – needed to build up adequate stocks beginning with one bulb and using
natural multiplication, about 1.6-fold per annum, by which it takes about 16 years
to go from one to 1000 bulbs (Rees, 1969). Micropropagation is almost certain to
be required, perhaps followed by a low-cost macro-propagation method, such as
chipping combined with optimised field production, once reasonable numbers of
bulbs have been produced (Hanks and Rees, 1979). Propagation from seed is also
considered.
Micropropagation
Whereas macropropagation techniques such as chipping are simple and require
minimal facilities, in many cases they will not produce the multiplication rates