2.1 Centre of diversity and domestication
It is likely that modern pineapple originated in pre-Columbian times in South America; a mutation for seedlessness and selection for large fruit size, increased sweetness and juiciness and improved flavour occurred over time (Purseglove, 1972). Chronicles of European explorers have described and mentioned pineapple domestication in parts of South America and in the Caribbean. Pineapples were already a part of the diet of the Native Americans before the arrival of Columbus (Collins 1960). Two hypotheses on the possible origin of pineapple have been stated in Bartholomew et al (2003); the first hypothesis by Bertoni in 1919 suggested that pineapples were domesticated by the Tupi-Guarani Indians from A. comosus var. ananassoides who carried them during their migration northward to the Antilles, northern Andes and Central America. This hypothesis has been quoted in a number of reviews on crop origins (Purseglove 1972; Bartholomew et al. 2003).
The second hypothesis by Leal and Antoni (1981) as stated in Bartholomew et al. (2003), suggested that the genus could have originated and located in an area within 10°N-10°S latitude and 55°-75°W longitude. They also suggested that south eastern Brazil could have been a secondary centre of origin and distribution (Purseglove 1972; Bartholomew et al. 2003). Purseglove (1972) suggested that modern pineapples could have originated in the Parana-Paraguay river drainage area because of the occurrence of seeded relatives in the wild [A. bracteatus, A. ananassoides (Bak.) L. B. Smith, A. erectifolius L. B. Smith and Pseudananas sagenarius (Arudda) Camargo] (Purseglove 1972).
Following the discovery of pineapple in South America, it was soon dispersed into other regions of the world by travellers and seafarers. Pineapple was introduced into the Philippines, Hawaii and Guam during the early 16th Century by the Spaniards, and reached India and the east and west coasts of Africa by 1548. In 1594, pineapple plants were reported growing in China and by 1655 in South Africa. Pineapple plants were reported in Europe in 1650 and pineapple fruits were being produced in Holland in 1686. It was not until 1719 that pineapple plants were successfully established in England in greenhouses (Purseglove 1972; Bartholomew et al. 2003).
In 1777, Captain James Cook planted pineapples on the Society Islands, Friendly Islands and elsewhere in the South Pacific. However, it was not until 1885 that the first sizeable plantation of 5 acres (2 ha) was established in Oahu (Purseglove 1972). In 1838, Lutheran missionaries imported pineapple plants from India into Brisbane, Australia. Pineapple was grown on a small scale and in a scattered manner for some time and the fruit was sold locally in Queensland. In Australia, the commercial pineapple industry was established in 1924 and a canning plant was established at Rockhampton and Cairns in 1946. Later cultivation areas increased in size to cater to the fresh market and canning industry. Post war pineapple production increased and replaced some sugarcane cultivation areas in Queensland (Collins 1960; Morton 1987).
The successful dispersion of pineapple on a world-wide basis can be attributed to its ability to tolerate drought and the relative ease with which vegetative propagules can establish under cultivated conditions (Collins 1960; Purseglove 1972). Pineapple is currently grown commercially over a wide range of latitudes from approximately 30°N to 30°S (Hayes 1960; Purseglove 1972; Bartholomew & Kadzimin 1977; Medina & Garcia 2005).
2.2 Commercial uses
Pineapple is cultivated predominantly for its fruit that is consumed fresh or canned. The fruit is a good source of manganese and contains significant amounts of vitamins C and B1 (for more information on nutrients refer to Table 4, Section 5.4). Approximately 95% of canned pineapple comes from the cultivar Smooth Cayenne. Pineapple is used as an ingredient in a variety of foods including pizzas, condiments, sweets, savouries, cakes, pastries, yoghurt, punches, ice creams etc (Purseglove 1972; Bartholomew et al. 2003; Rohrbach et al. 2003; Medina & Garcia 2005).
Pineapple contains the proteolytic enzyme bromelain, which is used as a meat- tenderising agent and for medicinal purposes. It has been reported to have valuable biological properties such as interfering with the growth of malignant cells, inhibiting platelet aggregation, fibrinolytic and anti-inflammatory action, enhancing drug absorption and removing skin (debridement) (Gailhofer et al. 1998; Mynott et al. 1999; Hale et al. 2005). Pineapple leaf juice is used as a purgative (agent that cleanses the bowel), emmenagogue (agent that induces menstrual bleeding) and vermifuge (agent that expels intestinal worms) (Leal & Coppens d'Eeckenbrugge 1996; Coppens d'Eeckenbrugge & Leal 2001). Pineapple products have also been marketed as a ‘digestive aid’ in health food stores.
The stems and leaves of the pineapple plant are a source of fibre, which can be processed into paper. Fibres are approximately 60cm in length, white and easily dyed. The cloth made from pineapple fibre is known as ‘pina cloth’ and was in use as early as 1571. Even today in the Philippines small scale cottage industries make high quality clothes from pineapple fibre (Collins 1960; Purseglove 1972; Montinela 1991; Coppens d'Eeckenbrugge & Leal 2001). Pineapple fibre has potential in paper production and the development of low density polyethylene composites (Fujishige et al. 1977; Fujishige & Tsuboi 1978; George et al. 1993). Parts of the pineapple plant are used for silage and hay for cattle feed. Processing wastes in the form of shell, core materials and centrifuged solids from juice production are used as animal feed. Alcoholic beverages can also be made from the juice (Purseglove 1972; Stanley & Ishizaki 1979; Bartholomew et al. 2003). World pineapple production reached 15.5mt in 2004, with Asia contributing 50% and Americas contributing 31.6% (Table 1) (FAO 2005). The international fresh-pineapple market (approximately 670,000 t) is dominated by Costa Rica, the Philippines and the Cote d`Ivoire (FAO 2005).
|Country||Area (ha)||Production (t)|
*Data compiled from FAO (2005) (FAO 2005).
2.3 Cultivation in Australia
Although all Ananas species are found in Australia according to the latest taxonomic classification (Coppens d'Eeckenbrugge & Leal 2003), their distribution is limited except for A. comosus var. comosus (cultivated pineapple) (Sanewski & Scott 2000):
- A. ananassoides (A. comosus var. ananassoides), A. parguazensis (A. comosus var. parguazensis), A. fritzmuelleri (A. comosus var. bracteatus) and Pseudananas sagenarius (A. macrodontes) are located only at Maroochy Research Station, Queensland; and
- A. nanus (A. comosus var. ananassoides), and A. bracteatus (A. comosus var. bracteatus) are sometimes found in nurseries or home gardens as ornamental plants mainly in Queensland. A cultigen of A. comosus var. erectifolius is being assessed by a few pineapple growers in Queensland for the production of cut flowers (Sanewski & Scott 2000).
Various factors like temperature, rainfall, location, soil type, drainage and nutrient requirements influence pineapple plant development and production in managed ecosystems (agricultural). Relative to other pineapple producing areas in the world, Australia (south east Queensland) is unusually far from the equator, with pineapple crops subject to strong seasonal influences. Sinclair (1993) stated that climatic conditions of south east Queensland is less than optimal for pineapple cultivation. Therefore the optimal climatic conditions for pineapple cultivation prescribed by Neild and Boshell (1976) do not apply to Australia.
A temperature range of 18°C to 32°C is most favourable for pineapple cultivation (Bartholomew et al. 2003). In Queensland the summers are warm to hot (19°C to 30.3°C) and wet, while the winters are cool (6°C to 20.5°C) and comparatively dry (Wassman 1990; Bureau of Meteorology 2007). Plant growth decreases rapidly at mean temperatures below 15°C or above 32°C (Neild & Boshell 1976). In Queensland, low temperatures occur from May to October and potentially inhibit growth during the mid winter (Glennie 1981; Wassman 1990). Plants do not tolerate frost but temperatures have been reported to drop below 0°C for short periods in the pineapple growing areas of south east Queensland. Prolonged cold periods (0°C) will affect plant growth (destroy canopy), delay maturity and cause the fruit to be more acid (Swete Kelly & Bartholomew 1993). In Australia, Smooth Cayenne can initiate reproductive development below 10°C, however fruit formation is drastically affected and will eventually impact on the harvest dates. High (above 35°C) and low (below 10°C) temperatures affect fruit development and retard growth (Purseglove 1972; Bartholomew & Criley 1983; Py et al. 1987; Malezieux et al. 1994).
Pineapple plants are most productive under dry environments where low rainfall is supplemented by irrigation in well-drained soils. Pineapple performs well in relatively low water regimes; it requires as much as 5cm of water per month from rain or irrigation (an annual rainfall of 115cm during spring and autumn) (Black 1962; Purseglove 1972; Py et al. 1987). In Queensland the average rainfall varies from 102-358cm annually. Annual rainfall ranges from 102-165cm in the pineapple growing belt of Queensland (Collins 1960; Black 1962).
In the subtropical areas of southern Queensland elevation and aspect are of particular importance in deciding the site for pineapple cultivation (Black 1962). Therefore most pineapple plants are planted on hillsides to escape frost. Pineapples thrive well when planted on a north-easterly aspect where they receive the maximum amount of sunlight and warmth (Bartholomew et al. 2003). Slopes of nearly 40% are farmed with medium sized equipment in Queensland although soil erosion can be an issue (El-Swaify et al. 1993; Ciesiolka et al. 1995).
Pineapple plants require sandy soils and good drainage to prevent water logging and therefore purpose built raised beds on slopes are utilised. Well drained loamy soil with high organic matter and a pH of 4.5-6.5 is best for pineapple cultivation (Morton 1987; Bartholomew et al. 2003). The soils along the coastal regions of Queensland vary from sands, sandy loams, basaltic red loams, clayey loams, gravely loams and gravely clay-loams. The dark brown and reddish-brown basaltic and sandy loams are considered ideal for pineapple production (Collins 1960; Morton 1987).
2.3.1 Commercial propagation
Two cultivars of A. comosus are grown commercially in Australia: a spiny leaved small fruit type ‘Queen’ and smooth-leaved medium fruit type ‘Cayenne’ (Collins 1960). In Queensland, clonal selection began in 1950 when 100 plants were selected from commercial fields. Four clones of Smooth Cayenne (C8, C10, C13 and C30) along with Hawaiian clone ‘Champaka F180’ were eventually released into the industry in 1975. Other clones selected by private growers and established include ‘Ripley Queen’, ‘Alexander’ and McGregor’ obtained from the cultivar ‘Queen’ (Duke 1997). After 20 years of breeding and testing, the Queensland Department of Primary Industries released a dual purpose cultivar named the ‘Queensland Cayenne’ in 1975 (Loison-Cabot 1987; Morton 1987; Coppens d'Eeckenbrugge et al. 1997; Sanewski 1998). Other cultivars bred for the fresh fruit market include Mareeba Sweet, Mareeba Gold, Golden circle premium gold and Bethonga Gold which characteristically have low acid levels and true pineapple taste (QMPI&F 2007). ‘Aus-Jubilee’ is a new variety of pineapple (at its first stage of commercialisation) selected for its high sugar, vitamin C content (twice that of Smooth Cayenne), aromatic flavour, firm flesh and colour (Botella et al. 2000; Medina & Garcia 2005; DAFF 2007a).
2.3.2 Scale of cultivation
Pineapples are grown on a small scale relative to other crops, mainly because only the tropical and sub tropical regions of Queensland provide suitable (though sub optimal) climatic conditions for cultivation. In Queensland, pineapples are grown (up to 40 km inland) over a 1,500 km narrow coastal strip along the eastern seaboard from Cairns in the north to Brisbane in the southeast (Sinclair 1993). The most northerly plantations are at Mossman in Far North Queensland and the most southerly are at Dayboro (just north-west of Brisbane); Rollingstone near Townsville and Atherton tablelands in the north, Yeppoon in central Queensland and Sunshine coast and Caboolture in the south are other important pineapple cultivation areas in Queensland (refer Figure 1 below) (QMPIF 2007). The majority of plantations are in Wamuran and Caboolture approximately 100 km north of Brisbane. Small commercial fields are also located in the Northern Territory, northern New South Wales and central Western Australia (Reid 1990). Pineapple canning centres are located in Yeppoon, Bundaberg, Mary Valley, Gympie, Nambour, the Glasshouse Mountains area and Brisbane (Collins 1960).
Figure 1. Map taken from Australian, States and Territories Map (2007) (Australia, State, Teritory & Local Governments Portal). Location of places on the map is only to give a broad idea of pineapple cultivation areas in Queensland.
Australia exported 1t canned fresh fruit to Hong Kong and East Timor during 2004/05 (Rohrbach et al. 2003; QDPI 2007). Pineapple production reached 139kilo t (kt) worth $44m in 1999/00, while in 2004/05 production decreased to 110kt (worth $37m) and 104kt respectively (DAFF 2007b). Table 2 indicates the pineapple yield in t/ha and the number of hectares under cultivation during 2001-05 in Queensland.
|Year||Production '000 in t||Bearing area in '000 ha||Yield t/ha|
^ data subject to sampling variability between 10% and 25%; *Data compiled from Australian Bureau of Statistics Agricultural Commodities, Australia ABS (2007) (ABS 2007)
Details of pineapple production during 2004/05 in Queensland are given in Table 3.
|Statistical Region||'000 t|
|Wide Bay-Burnett||^ 17.6|
- nil or rounded to zero (includes null cells); ^ data subject to sampling variability between 10% and 25%; * data subject to sampling variability between 25% and 50%; Data compiled from ABS (2007) (ABS 2007)
As indicated in Table 3, in 2004-05, most of the pineapples produced in Queensland came from the Moreton, Brisbane and Fitzroy areas (ABS 2007). Since pineapples are not propagated using seeds, there is no seed industry in Australia. There are no commercial plantings of GM pineapples in Australia, however field trials of GM pineapple plants modified to control flowering and ripening (DIR027/2002) and to reduce black heart (DIR028/2002) have been approved.
2.3.3 Cultivation practices
Pineapples are perennials and are cultivated throughout the year mainly by use of vegetative propagules like crowns, slips, hapas or suckers (Purseglove 1972; Bartholomew et al. 2003). These vegetative propagules are desiccation tolerant and can be stored and survive detached from the parent plant for up to 6 months depending on the prevailing conditions. All plant materials designated for vegetative propagation are treated with fungicides and insecticides prior to planting (Coppens d'Eeckenbrugge & Leal 2001). In Queensland, it takes 24 months in the tropics to 36 months in the cool subtropical environment for the propagales to establish into plants and provide fruits (Bartholomew et al. 2003). Soils are cleared of large rocks, and trees, and conventional or minimum tillage is carried out to eliminate weeds before planting. Fertilisers (nitrogen, potassium and phosphorous) are applied to the soil before planting. In pineapple plantations high levels of nutrients are supplemented to maintain good levels of growth (Nightingale 1942a; Morton 1987; Bartholomew et al. 2003).
The type of planting material determines the planting depth; crowns, propagules and plantlets are most sensitive to deep planting and are usually buried at a depth of 5-10cm; slips, hapas and suckers are planted at a depth of 10-15cm. Exposure to sun helps control butt rot in these structures. Drip and overhead irrigation systems are used to apply water and fertilisers. Weeds are controlled to avoid serious damage and impedance to plant growth; in Queensland, special attention is given to clump grasses and vines, which are problematic. Mulches are also used to block weed growth in planting beds (Coppens d'Eeckenbrugge & Leal 2001; Bartholomew et al. 2003). Planting is usually done manually with a traditional short handled narrow bladed hoe (Coppens d'Eeckenbrugge & Leal 2001). Quality of planting is best when hand planted, compared to machines, which damage the growing point of the planting material (Coppens d'Eeckenbrugge & Leal 2001; Bartholomew et al. 2003).
Typical plant densities for Smooth Cayenne range from 29,000 to 86,000 plants per hectare (Bartholomew et al. 2003). Densities are usually based on the intensity of agricultural practices and planned use of the fruit. Plants are planted in single rows or on beds of 2-4 rows with adequate space (80cm) for walking to carry out all field activities. Inter row (between 2 rows) distance is usually approximately 35cm to 40cm (Morton 1987; Coppens d'Eeckenbrugge & Leal 2001; Bartholomew et al. 2003).
Control of flowering
Natural flowering is a major problem and occurs during the months of May and June in plants that are approximately a year old and weigh >500g. In order to avoid uneven natural flowering, artificial induction with chemicals is common in commercial practices, a process called ‘forcing’ (Botella et al. 2000). Application of ethylene and ethylene-releasing chemicals like ethepon or etacelasil are used to induce flowering (Burg & Burg 1966; Kuan et al. 2005). Auxins like naphthalene acetic acid and acetylene are also effective forcing agents (Gowing & Leeper 1959). Ethylene applied as a pressurized spray late in the evening or at night permits uptake through the stomata (Bartholomew & Criley 1983). In Queensland, ethylene is applied either once or twice as a saturated solution in water. Activated charcoal is also added to enhance absorption of ethylene. Personal protective equipment is required to avoid exposure of workers to the highly combustible gas (Bartholomew et al. 2003).
Variation in plant sensitivity was observed in the variety Smooth Cayenne to forcing; plants less than 1.0kg in weight and large plants (above 2 kg) are difficult to force. Therefore plants of optimum size (2kg) are recommended for forcing in order to obtain even flowering (Sinclair 1993; Bartholomew et al. 2003). In Queensland, if plants are induced to flower during June, they are ready to be harvested in the first week of March after a period of 274 days; while plants forced to flower during September are harvested in the fourth week of March after a period of 204 days (Malezieux et al. 1994). In sub tropical parts of Queensland it takes 280-300 days from floral induction to harvest (Dodson 1968; Botella et al. 2000; Bartholomew et al. 2003). In Queensland, the average cost to the pineapple industry for natural flowering is estimated at $900,000/year (Botella et al. 2000). Strategies for increasing pineapple yield and fruit size include application of side dressings of nitrogen, phosphorous and potassium 5 times a year (Py et al. 1987; Morton 1987). Morton also reported increase in fruit size with the application of magnesium (Morton 1987).
Harvest, Storage & Transport
Pineapple is a highly perishable fruit; therefore the stage of maturity of the fruit is important in determining quality of the fruit and harvest times. At the time of fruiting it is crucial to cover the fruits to protect them from sun burn/damage (Coppens d'Eeckenbrugge & Leal 2001; Bartholomew et al. 2003). Fruit colour is a good indicator of fruit maturity; as the fruit matures the outer shell gradually changes from green to yellow (Bartholomew et al. 2003). Other fruit quality indices include size, shape, firmness, absence of decay, sunburn, cracks, bruising, internal breakdown and brown spots, gummosis and insect damage. A reliable way of establishing fruit maturity is by determining the ‘flesh brix’ of the fruit, that is, a measure of total solids at each fruit colour stage. A minimum of 12°Brix (12% total soluble solids) and 1% maximum acidity was established by CODEX and FAO/WHO in international trade to guarantee consumer acceptance (Coppens d'Eeckenbrugge & Leal 2001).
In Australia harvest is mechanically assisted and usually undertaken before ripening. Pineapples are harvested and placed in bins for cannery processing. Such collected fruits may be accumulated at roadways for transfer to trucks or loaded directly for transportation to canneries or to a central location for trade (Bartholomew et al. 2003). Once harvested, fruits are susceptible to sunburn and therefore should not be placed in direct sunlight for more than an hour. Fruits for the fresh market are harvested without crowns and a short length of peduncle attached. For the best fruit quality it is preferable to harvest fruits when ripe. To help retain fruit quality cut fruits may be waxed and treated with fungicide to reduce black rot (Paul & Rohrbach 1982; Paul & Rohrbach 1985).
The main issues that affect pineapple fruit quality are damage due to bruising during loading, transportation, unloading and conveying. Air and road transportation up to 2 days does not require refrigeration; however fruit quality is retained and improved if refrigerated after picking. Fruits should be refrigerated at temperatures between 7.1°C to 10°C if they are to be transported for more than 3 days (Bartholomew et al. 2003). Fresh fruits are transported at 15°C from Queensland to other states by rail or road with the major markets being Brisbane, Sydney and Melbourne. Significant quantities are also transported to Adelaide, Perth, Hobart and Darwin. Air transportation of pineapples is mainly to neighbouring countries like New Zealand and Hong Kong (Smith 1993).
Crop rotation & Intercropping
Selection of crops to combine with pineapple cultivation can occur in the form of crop rotation or inter row cropping. This practice has been adopted recently in some parts of the world because it permits use of resources more efficiently during the long production cycle of pineapple and in addition reduces the dependency on one crop and spreads income along the cultivation cycle (Lee 1972). The pineapple crop also offers protection against heavy rain and winds to the intercropped species. In turn growth of the pineapple crop is healthier due to frequent weeding, fertilizer and pesticide application to the inter row crops (Uriza-Avila et al. 2005).
Pineapple cultivation is carried out routinely as a monocrop; as a result the crop is susceptible to many fungal diseases. Recent reports recommend crop rotation in pineapple farms as a means of controlling fungal diseases. Crop rotation using legumes like Canavalia spp. has decreased the incidence of root disease on pineapple in Mexico. However in Australia, crop rotation is not a common practice. After a crop is harvested the remaining plant material is slashed and ploughed and the field remains fallow for a period of time until new vegetative propagales are planted. Inter row cropping in pineapple plantations is gaining importance and popularity; in Queensland oats are intercropped with pineapple (Garth Sanewski1 pers comm). This is mainly due to the beneficial effects of chemicals released from oats, which provide protection to the pineapple roots against fungal pathogens (Cruz et al. 2006). Ratooning is an agricultural practice of harvesting a second or additional crop from an original pineapple plant. Generally in Australia, the plant and one ratoon crop are harvested after approximately 3-4 years (Bartholomew et al. 2003). The original plant is called the ‘plant crop’ while the fruit developed from the lateral, axillary branch attached to the axis of the plant crop is called the ‘first ratoon’. A healthy root system is necessary to produce successful ratoon crops. Ratoon crops are fertilized, irrigated, forced, ripened and harvested in a way similar to the plant crop. The amount of fertilizer used however is reduced. In Queensland pineapple farmers avoid the use of ratoon crops to minimise carryover diseases and prefer to plant new vegetative propagules (Purseglove 1972; Bartholomew et al. 2003).
2.4 Crop Improvement
Pineapple is largely vegetatively propagated. Sexual reproduction is rare in nature because pineapple is self sterile; seeds if produced by self fertilization germinate slowly with low vigour and young seedlings are fragile due to inbreeding depression (Purseglove 1972; Daniela 1999; Bartholomew et al. 2003). However, since pineapple is heterozygous, hybridisation is possible between A. comosus var. comosus and other varieties as mentioned in Section 1. Hybrids are valuable material in pineapple breeding and breeders can generate a wide variety of genotypes. Many important fruit characteristics such as high ascorbic acid and carotene content, low acidity, increase in total soluble solids, size increase and high translucency were obtained by clonal selection (Chan 2006). Small scale hybridization programs aimed at clonal selection of Smooth Cayenne were also carried out during 1970s in Australia (Loison-Cabot 1987; Sanewski 1998; Coppens d'Eeckenbrugge et al. 1997). For more details refer Section 2.3.1.
Conventional breeding has disadvantages due largely to the domination of a single variety Smooth Cayenne in the markets and the low level of molecular diversity between varieties of A. comosus (Duval et al. 2001). This has resulted in poor success in varietal improvements. In addition, hybridization programs are resource intensive; an estimated 15 years is required to produce hybrid varieties (Loison-Cabot 1987; Sanewski 1998).
2.4.2 Genetic modification
A range of useful traits viz improved fruit quality, flowering control, pathogen resistance and herbicide tolerance are being developed using genetic techniques. Attempts have been made by scientists in Australia to inactivate the Polyphenol Oxidase (PPO) gene to reduce or eliminate discolouration (black heart) of the pineapple fruits. The inactivation is expected to reduce or eliminate the discoloration of the fruit pulp (Graham et al. 2000). Fields trials of this GMO have been successfully conducted in Queensland in which the PPO gene expression was reduced. Sripaoraya and co workers (2001, 2006) have successfully transformed the ‘Phuket’ cultivar of pineapple by introducing the herbicide (bialophos) tolerance bar gene (Sripaoraya et al. 2001; Sripaoraya et al. 2006) that are tolerant to commercial herbicide basta and could potentially reduce residual herbicides in the plant and environment.
Flowering control to achieve synchronous natural flowering is another important aim pursued by the Hawaiian Pineapple Genetic Engineering Consortium in collaboration with Queensland Department of Primary Industries (Botella et al 2000). Rohrbach and co workers (2000) and Botella and co workers (2000) have successfully transformed pineapple by down regulating the 1-aminocyclopropane-1-carboxylate (ACC) synthase gene (Botella et al 2000) or over expressing the ACACS2 in pineapple to achieve suppression due to methylation of the same endogenous gene (Trusov & Botella 2006). ACC synthase is a key enzyme responsible for the biosynthesis of ethylene (which can cause early flowering). Preliminary results of field trials conducted in Queensland indicate a low incidence of natural flowering in the both types of GM pineapple (Rohrbach et al. 2000; Botella & Fairbairn 2005; Trusov & Botella 2006).
Nematode types like root knot and reniform and mealby wilt virus are significant pathogens of pineapple. The ban on use of nematicides such as methyl bromide has encouraged scientists to develop transgenic nematode resistant pineapple. Bakhetia’s group at the University of Leeds have successfully developed nematode resistant pineapple plants using anti-feeding defence strategy (Bakhetia et al. 2007). Two Ampeloviruses, Pineapple mealybug wilt associated virus-1 & 2 (PMWaV1 & 2) have been identified in pineapples grown in Hawaii. The coat protein gene PMWaV-2 was introduced into pineapple as an inverted repeat; glass house testing of such modified pineapple produced five putative transgenic lines resistance to the virus (Perez et al. 2006).
1Garth Sanewski Senior Horticulturist at the Queensland Department of Primary Industries & Fisheries Research Station at Nambour, Queensland.