High-tech cabbages standing tall

Press, 8 May 1985, Page 20

High-tech cabbages standing tall

By

HOWARD BEZAR,

of the Crop Research Division,

D.5.1.R., Lincoln.

Biotechnology will be one of the areas of investment in science being discussed at the Beehive this week as the Science and Technology Summit debates how the science dollar can be spent to best effect.

Biotechnology has been a boom area for venture capital in the United States and Europe over the last few years. The business world has been slightly hesistant, more recently, as they have come to realise that nature takes its own time and may not deliver the return on investment as quickly as they would like. “Biotechnology” is the buzz word given to the new technologies developed in the 70s which allow biologists to manipulate plant and animal matter genetically in ways hitherto only dreamed of. Such exciting new drugs as interferon, which can be manufactured by bacteria, have emerged; primitive animals are being cloned; plants are being crossed in exciting ways which suggest the long dreamed of plants, with potatoes on the roots and tomatoes on the tops, may be closer than we think. While the new science has been quietly finding its way into laboratories in New Zealand over the last five years, one scientist at the Crop Research Division, Lincoln, has used one of the techniques which are peripheral to the new “biotechnology” and made a major breakthrough in crossing closely related members of the Brassica or cabbage family which have

never been successfully crossed before.

The project began six years ago when D.S.I.R. staff were discussing the breakdown of the aphid resistance that had occurred in'one of their commercial forage rape cultivars. No source of durable resistance to aphids was known to the Crop Research scientists, but they knew that rape's close relative, the kale/cabbage group of Brassicas, had this durable resistance. "Wouldn’t it be great if they could be crossed and we could transfer the source of resistance.” was their cry.

Dr Hanif Quazi, a geneticist on the staff, thought that it would be worth trying the new technique of embryo culture to see if any of the immature embryos which formed after pollination between the two species could be rescued before they normally aborted. He set about crossing the two members of the Brassica nupus family, forage rape and oilseed rape, with two members of the Brassica oleaceae family kale and broccoli. He then carefully rescued the newly-formed embryos just before they aborted and placed them in test tubes where, under special conditions, they were nurtured in the hope that they would continue to grow and develop. It may have been beginners luck, or perhaps, more charitably, his care for attention to detail, but whatever it was, Dr Quazi came up with a true hybrid almost immediately. The hybrid withstood

several tests of authenticity’ — that it has characteristics from both parents. Although it looked like its female parent, an oilseed rape plant, it had the whitecoloured flower of its male parent. The hybrid also had 28 chromosomes, midway between the 38 and 18 of the two parents. The work could easily have stopped here as Dr Quazi found he could select after several generations of self-pollination of the hybrid, a white flowered oilseed rape (they are normally yellow) with an oil content significantly higher than those in commerce. However, he chose to continue exploring the bounds of possibility and found that his first hybrid was compatible when crossed with both its parents and, in fact, could be used as a bridge to transfer various genes, or genetically controlled characters, from one species to the other. His list of characters successfully transferred between the two species is now progressively growing:

• white flowers from broccoli to rape; • curly leaf character from kale to rape; • cabbage aphid resistance from kale to rape; • atrazine resistance from rape to kale.

The last two are of particular importance because, as all farmers know, cabbage aphids can very quickly devastate a crop of rape. Atrazine, a weedkiller of major agricultural importance, cannot be used to kill weeds in kale. However, Dr Quazi now has

both a kale and a broccoli with good resistance to atrazine. The work has only just been fully verified with field trials during recent weeks in which the new rape with resistance to cabbage aphid has been grown outdoors for the first time. It was a great success. All the other rape cultivars grown in the paddock were decimated by the cabbage aphid while Dr Quazi’s new rape stood proudly undamaged, still growing vigorously. While the work is being written up for publication overseas, word is beginning to spread and considerable interest created. The work will now turn in a number of directions. Other D.S.I.R. breeders will take Dr Quazi’s material for use in developing new commercial cultivars of oilseed rape, forage rape, kales

and broccoli etc. Dr Quazi will continue to see if he can begin work with turnips, another member of the Brassica family (camestris), and swedes which are the same family as the rapes.

If he can transfer the root disease resistance from swedes and turnips back to the kale; cabbage and the rape family this will be of major international significance. Not only are the cabbage family major vegetable crops on heavy soils and subject to root diseases, but oilseed rape is expanding rapidly as a crop worldwide, bringing with it problems of accumulating root diseases.

Another direction in which the work will undoubtedly progress will be through overseas biotechnologists and plant breeders who may buy the New Zealand “high tech.”