I wonder if seedless watermelons are the “fruit” of genetic engineering. And, if so, how come no one is complaining, right? I guess until any side effects appear, we’ll all just enjoy this genetically altered fruit.
Also, are baby carrots and baby corns natural? I mean, they are both miniature (baby) and yet fully mature to eat. Is this man’s doing, as well?
They’re genetically modified in that they were crossbred to produce an unnatural plant. There was no splicing, merely a careful selection of mating partners.
In other news, all of the food you eat and most of the clothes you wear is the product of similar genetic modification. As are you, to a much, much lesser extent. (Assuming your parents consciously chose each other as mating partners, that is.)
Yes the are natural. Yes they are gentically selected (engineered in one sense) as all are all food crops.
Seedless watermelons are hybrids which have undeveloped seeds. Not “genetic engineering” except in the sense that mankind has been engaging in for centuries - selectively controlling the reproduction of plants and animals to obtain desireable characteristics.
Baby corn is simply corn which has been harvested before it’s mature. Some varieties work better for this purpose than others - how to grow your own:
http://eesc.orst.edu/agcomwebfile/garden/vegetable/babycorn.html
You will have to clarify what you mean when you say “genetic engineering”.
Seedless watermelons are triploid, that is to say, they have three sets of chromosomes (3X) rather than the normal two (2X). This makes them sterile, which is why they don’t produce seed. To get the triploid seed that grows into the triploid plant, you have to cross a diploid (2X) plant with a tetraploid (4X) plant. To get a tetraploid plant, you must treat normal diploid seedlings with colchicine, which doubles the number of chromosomes.
Is this genetic engineering? You tell me. There’s no foreign DNA or gene splicing or vector bacteria involve. All the DNA in seedless watermelon comes only from watermelon, there’s just more of it. Yet you still had to manipulate the plants in order to get them to that state.
Other food plants that were produced the same way, using aneuplody (meaning there’s an odd number of sets of chromosomes) include bananas and, IIRC, seedless grapes. The wild banana is a seed pod filled with seeds about the size of ping pong balls. Many other domesticated plants, including strawberrys, have more sets of chromosomes than the “natural” wild plants, because, as a general rule, plants with extra chromosome sets tend to make larger fruits.
Aneuploidy is the term applied when you have a single (or two) extra or missing chromosomes. If you have entire extra sets of chromosomes, the term used is polyploidy. Plants are quite tolerant of this and other strange genomic phenomena, so you can observe it quite often. One of the more obvious effects of polyploidy in plants, aside from seedlessness, is increased size so it’s is often a desirable trait. Off the top of my head, not only seedless watermelon, and the aforementioned bananas and seedless grapes, but also crops like potatoes, sugarcane, and wheat are polyploid.
Baby carrots are bigger carrots chopped into pieces and rounded off. I’d say this is very much “man’s doing.”
http://www.rgj.com/news/stories/html/2002/06/24/17556.php
(For you nitpickers, I know there’s a true miniature called the Nantes variety but have never encountered one in real life, just the Imperator variety.)
You could take an apple tree, graft on different types of apple branches and get red, yellow and green apples growing on the same tree.
Natural? Yes. We’re natural. Lest you believe humans are exempt from nature. Nature isn’t 'everything that humans don’t do".
Engineered? Guess in the broadest sense, it is an ‘engineered’ tree.
Watermelons, lettuce, plants. We breed them, graft them, etc. I think Granny Smith apples are named for the Granny who created them.
I think I read in ‘Guns Germs & Steel’ that as corn evolved, it took it quite some time before it reached the size we think of as “normal”. So in some sense, the baby ones are the normal ones, and the large kind are freakish.
Baby corn is just that - corn cobs that have not yet matured. You could try planting baby corn, but nothing will happen. The kernels aren’t ripe yet. If you wait for baby corn to grow and ripen and mature, it looks just like ordinary corn.
You are so right. Sorry. I’ve been working with human genetics for too long. I’ve forgotten some of this terminology.
Anyway, I wanted to add that polyploidy is not unusual among plants in the wild. New species often arise from hybrids this way - two closely related plants hybridize, producing a normally sterile offspring. The offspring then undergoes some event that doubles its chromosome number, and boom, it’s fertile. Then, over time, the species can gradually lose some or all of the redundant genetic material. One of my professors demonstrated that this was exactly the way in which a new species arose in a certain habitat he was studying.
Plants seem to be generally much more tolerant of extra chromosomes than we are. Polyploid plants are often larger and more robust than their “normal” relatives.
So…natural? It’s certainly not entirely artifical. It happens all the time. I guess the difference is whether the polyploid strains happened on their own or were encouraged by humans. You’d have to research that on a plant-by-plant basis, which is beyond my expertise.
Not lose, but transform. There is selection pressure to maintain existing gene functions, but with two copies of everything, one copy is maintained while the other can mutate to acquire other functions. There’s lots of evidence for this type of ancient polyploidization and subsequenct rediploidization in both wild and cultivated plant species.
A couple of examples of natural polyploidy:
Redwood (Sequoia sempervirens) is naturally hexaploid. Of course, it’s fertile (i’ve read that highly polyploid plant mutants are the only fertile ones). This was one of the primary reasons that redwood were split from the Giant sequoia (Sequoiadendron giganteum). Not to mention seed development (one year in redwood, two in sequoia), and sequoia cones continue growing for many years, as well as other reasons.
Oxalis pes caprae (Bermuda buttercup) occurs in California in a pentaploid sterile form. Like the seedless watermelon it doesn’t produce viable seeds, but it reproduces like mad and is considered invasive (it makes use of its tendency to form bulbils and runners and it spreads FAST). We have this in our garden here and we never can get rid of it. But it’s pretty enough so we let it stay (it fortunately dies back after winter rains stop so it’s not a nuisance and it does a fantastic job at covering up a very ugly side yard we haven’t landscaped yet).
Fertile strains of O. pes caprae are the diploid and tetraploid populations. The pentaploid populations are thought to be hybrid crosses of the diploid and tetraploid strains.
Cite? I’m not challenging you, I just like to read about weird plant genomes.
From this DOC file:
http://www.npwrc.usgs.gov/resource/2000/APRS/lit/Oxalis%20pes-caprae.doc
Interestingly O. pes-caprae is also a host for Broomrape (Orobanche) in Greek vineyards
Your link doesn’t work for me. Oh well.
As a further example of the unseen hand of man in “natural” crops, my Biology textbook said that broccoli, cauliflower, kale, Brussels sprouts, lettuce, and I think cabbage too were all developed from a single plant species by selective breeding and cultivation.
Not lettuce, but cabbage, cauliflower, broccoli, brussel sprouts, kohlrabi, and kale are all members of the same species Brassica oleracea. They are taxonomically differentiated by assigning them to different varietal forms:
[ul]
[li] Brassica oleracea var. acephala (kale)[/li][li] Brassica oleracea var. botrytis (cauliflower)[/li][li] Brassica oleracea var. capitata (cabbage)[/li][li] Brassica oleracea var. gemmifera (brussel sprouts)[/li][li] Brassica oleracea var. gongylodes (kohlrabi)[/li][li] Brassica oleracea var. italica (broccoli)[/li][/ul]
Lettuce is Lactuca sativa. This also has different varietal forms, such as for iceberg or Romaine, but the taxonomic differentiation is not as clear.
Here is the body of the text. I highlighted the polyploidy bits:
Oxalis pes-caprae L. (Oxalidaceae)
Bermuda Buttercup
Description. Perennial, somewhat succulent; stems 10-20 cm long, erect but subterranean, fleshy, producing white to light brown bulbs near the base and above the roots. Leaves in a basal rosette, compound, petiolate, with 3 leaflets, leaflets 10-30 mm mm long, green, often spotted, usually obcordate, folding lengthwise at night. Flowers 3-20, bisexual, radial, in an umbel, the peduncle 10-30 cm long. Sepals 5, distinct, lanceolate to oblong, petals 5, 15-25 mm long, somewhat united at the base, yellow, stamens 10, in two sets, five long and 5 short, the filaments pilose; ovary superior, with 5 locules, 5 style branches. In California flowering from February to May, but not producing seeds (plants in California apparently sterile). (Munz 1959, Ornduff 1993, Valentine 1968, Webb et al 1988).
Synonym= Oxalis cernua Thunberg.
Geographic distribution. A native of southern Africa, Bermuda buttercup has become naturalized in Great Britain, Mediterranean Europe, California, Chile, Australia, and New Zealand. (Chapman 1991, Galil 1968, Michael 1964, Munz 1959, Ornuduff 1987, Valentine 1968, Webb et al 1988).
Bermuda buttercup was first reported (as O. cernua) in the early 20th century as a weed in orchards (Robbins 1940). It has been reported from Santa Cruz Island (Junak et al. 1997) and occurs throughout most California coastal counties (Anonymous 1998, Ornduff 1993).
Reproductive and vegetative biology. Oxalis pes-caprae is heterostylous and self-incompatible (Ornduff 1974, 1987). Populations in South Africa are tristylous (composed of three different floral forms with style and stamen lengths corresponding to 3 different levels). **Sexual populations are either diploid or tetraploid, but a sterile, pentaploid race is believed derived from diploid X tetraploid hybrids. Although sexual plants can be weedy, the sterile pentaploid is apparently the only race that has become widespread outside of South Africa **(Michael 1964, 1965, Ornduff 1987), spreading entirely by bulblets formed at the base of the succulent stem (Galil 1968, Peirce 1973, Putz 1994).
Seeds of the diploid and tetraploid forms require a light stimulus for germination, which is enhanced by warm, moist conditions and require light (Marshall 1987, Peirce 1973). The primary mode of reproduction, however, are bulbs produced by subterranean stems.
In the presence of spring rains, bulbs of the sterile pentaploid produce roots and young shoots within 4 to 6 weeks (Lane 1984). Each bulb develops two different subterranean stem systems, one vertical, the other horizontal (Galil 1968). The vertical stem gives rise to the aerial shoot system and may also produce axillary buds that develop into bulbs. The horizontal stem grows laterally by means of contractile roots. At maturity the horizontal stem becomes a storage organ (water, nutrients) and develops a terminal bulb immediately above the roots. Both kinds of stems can develop adventitious roots (Galil 1968), especially if damaged or cut by disturbance (e.g., plowing, digging). Mature plants may produce up to 20 bulblets, most of which are dispersed from the parent plant at the end growing season (Galil 1964, 1968, Putz 1994). Bulbs are sensitive to freezing, but can persist for more than 3 years in a vegetative condition if kept dry (Marshall 1987). Cultivation and redistribution of soils are the most prevalent means of bulb dispersal (Galil 1968, Paspatis 1985), but birds and and mole rats (in South Africa) also disperse the bulbs (Galil 1967, Young 1958).
Bermuda buttercup has been found to be toxic to livestock (Rekhis 1994).
Ecological distribution. Bermuda buttercup occurs in cultivated and fallow fields, irrigation ditches, along roadsides, and open sites (Galil 1968, Hildreth and Agamalian 1985, Munz 1959, Ornduff 1993).
Weed status. Oxalis pes-caprae is not considered a serious weed in agricultural or horticultural practice, at least at a global level (not listed by Holm et al. 1977), nor is it considered a noxious weed by the State Dept. of Food and Agriculture (Anonymous 1996). It is not listed for the United States in Lorenzi and Jeffery (1987).
Microbial pathogens. No literature was found that reported microbial pathogens of Oxalis pes-caprae.
Insect pathogens. The noctuid moth, Klugeana philoxalis, selectively feeds on bermuda buttercup and has been recommended as a biocontrol in South Africa (Kluge and Claasens 1990).
Herbicide control. Hildreth and Agamalian (1985) recommended the use of oxyflourflen in California artichoke fields. The most effective long-term treatment was found to be associated with initial appearnace of shoots from single bulbs. Other herbicide treatments, including 2,4-D and glyphosate, have been evaluated but their use was inneffective at levels considered to be safe for cultivated grapes and other perennial crops (Marshall 1987, Michael 1965, Paspatis 1985).
Other control methods. Bermuda buttercup is a host to broomrape (Orobanche sp.), which selectively infests herbaceous plants in Greek vineyards (Paspatis 1985).
Literature Cited
Anonymous. 1996. Exotic pest plants of greatest ecological concern in California as of August 1996. California Exotic Pest Plant Council. 8 pp.
Anonymous. 1998. California county flora database version 2, Santa Barbara Botanic Garden and USDA National Plants Data Center, Santa Barbara and New Orleans. URL = plants.usda.gov
Arnold, T. and B. de Wet. 1993. Memoir 62. Plants of southern Africa: names and distribution. National Botanical Institute, Pretoria. 825 pp.
Chapman, A. 1991. Australian plant name index. K-P. Australian Government Publishing Service, Canberra. pp. 1711-2495.
Galil, J. 1967. On the dispersal of the bulbs of Oxalis cernua Thung. by mole-rats (Spalax ehrenbergi Nehrin). Journal of Ecology 55: 787-792.
Galil, J. 1968. Vegetative dispersal in Oxalis cernua. American Journal of Botany 55: 68- 73.
Hildreth, R. and H. Agamalian. 1985. Control of buttercup oxalis in artichokes with oxyfluorfen. Proceedings, Western Society of Weed Science. 38: 187-195.
Holm, L., D. Plucknett, J. Pancho, and J. Herberger. 1977. The worlds worst weeds: distribution and ecology. University Press of Hawaii, Honolulu. 609 pp.
Junak, S., S. Chaney, R. Philbrick, and R. Clark. 1997. A checklist of vascular plants of Channel Islands National Park. Southwest Parks and Monuments Association, Tucson, AZ. 43 pp.
Kluge, R. and M. Claasens. 1990. Klugeana philoxalis Geertsema (Noctuidae: Cuculliinae), the first potential biological control agent for the weed Oxalis pes-caprae L. Journal of the Entomological Society of Southern Africa. 53: 191-198.
Lane, D. 1984. Factors affecting the development of of populations of Oxalis pes-caprae L. Weed Research 24: 219-225.
Lorenzi, H. and L. Jeffery. 1987. Weeds of the United States and their control. Van Nostrand Company, New York. 355 pp.
Marshall, G. 1987. A review of the biology and control of selected weed species in the genus Oxalis: O. stricta L., O. latifolia H.B.K. and O. pes-caprae L. Crop Protection. 6: 355-364.
Michael, P. 1964. The identity and origin of varieties of Oxalis pes-caprae L. naturalized in Australia. Transactions, Royal Society of South Australia. 88: 167-173.
Michael, P. 1965. Studies on Oxalis pes-caprae L. in Australia. The control of the pentaploid variety. Weed Research 5: 133-140.
Munz, P. 1959. A flora of California. University of California Press, Berkeley. 1681 pp.
Ornduff, R. 1974. Heterostyly in South African plants: a conspectus. Journal of South African Botany. 1: 1-355.
Ornduff, R. 1987. Reproductive systems and chromosome races of Oxalis pes-caprae L. and their bearing on the genesis of a noxious weed. Annals of the Missouri Botanical Garden. 74: 79-84.
Ornduff, R. 1993. Oxalidaceae. pp. 808-809. In Hickman, J. (ed.). The Jepson manual: Vascular plants of California. University of California Press, Berkeley. 1400 pp.
Paspatis, E. 1985. Chemical, cultural and biological control of Oxalis pes-caprae in vineyards in Greece. pp. 27-29. In R. Cavalloro and D. Robinson. (eds). Weed control on vine and soft fruits. Dublin, Ireland.
Peirce, J. 1973. Soursob (Oxalis pes-caprae L.) in Western Australia its life history, distribution, morphological variation and weed potential. Western Australia, Dept. of Agriculture. Technical Bulletin 20. 9 pp.
Putz, N. 1994. Vegetative spreading of Oxalis pes-caprae (Oxalidaceae). Plant Systematics and Evolution. 191: 57-67.
Rekhis, J. 1994. The poisonous plant Oxalis cernua. Veterinary and Human Toxicology. 36: 23.
Robbins, W. 1940. Alien plants growing without cultivation in California. Agricultural Experiment Station. Bulletin 637. University of California, Berkeley. 128 pp.
Valentine, D. 1968. Oxalidaceae. pp. 192-193. In In Tutin et al. 1968. Flora Europaea. Volume 2. Rosaceae to Umbelliferae. Camrbidge University Press, Cambridge. 455 pp.
Webb, C., W. Sykes, and P. Garnock-Jones. 1988. Flora of New Zealand. Volume 4. Naturalized pteridophytes, gymnosperms, dicotyledons. Department of Scientific and Industrial Research, Christchurch. 1365 pp.