Plant development and reproduction
Gene modification to produce plants more suitable for high-density orchards can be performed both on cultivars and rootstocks (Table 3.1). Plants with an extensive root system and/or with reduced water consumption or changes in canopy architecture, dwarf and semi-dwarf canopy, with short and numerous shoots, could increase orchard density and improve plant performance. At present, reduction of plant size is achieved by using mainly dwarfing rootstocks and, in a few cases, by using spur varieties, selected by clonal selection or among seedling population. Both dwarfing rootstocks and spur varieties are available for only a few species and graft compatibility often presents a problem. Biotechnology techniques may contribute to the creation of dwarfing rootstocks and dwarf varieties either by somaclonal variation (better if in combination with gamma irradiation treatments) or by genetic engineering to modify hormone activity or light receptors. in vitro cultures treated with ionising radiation frequently produce shoots modified in their growth which maintain this characteristic also in the field. More interesting, however, is a transformation approach with some already available genes. Both phytohormone, or phytohormone- like and phytochrome genes seem to be good candidates in modifying plant architecture, particularly in response to different light conditions. Phytohormones are recognised as modulators of growth and differentiation in plants, since their levels can influence the growth rate such as branching, apical dominance, flowering, sex determination, regrowth and rest period. Since their synthesis is linked to light quality, modifying genes for hormone synthesis or for light receptors (phytocromes), some interesting modifications should be expected.Table 3.1 Genetic modification of fruit crops for plant development and reproduction | |||||||||||||
Fruit crop |
Technique |
Alien gene(s) |
System/Plasmid or selective agents |
Origin of plant material |
Modification in planta |
Authors |
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Apple (Malus X domestica) M26 rootstock |
T |
RiT-DNA |
A.rh. |
Microcutting |
Increased rooting ability and altered morphology |
Lambert and Tepfer 1992 |
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Apple (Malus X domestica) cv Granny Smith |
T |
Ipt |
A.t. |
Leaf segment |
Bushy phenotype |
Trifonova et al. 1994 |
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Apple (Malus X domestica) (M26) rootstock |
T |
rolA |
A.t. |
Leaf |
Altered morphology |
Holefors et al. 1998 |
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Apple (Malus X domestica) (M26) rootstock |
T |
rolB |
A.t. |
Leaf |
Rooting capacity |
Welander et al. 1998; Zhu et al. 2001 |
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Banana (Musa spp AAA group) |
S.V |
– |
– |
Meristem |
Dwarfism, abnormal leaves colour of pseudostem; ploidy change |
Hawang 1986; Hawang and Ko 1987; Reuveni et al. 1985; Stover 1987; Stover and Buddenhagen 1986 |
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Banana (Musa spp AAB group) |
S.V |
– |
– |
Meristem |
Flower and leaf abnormalities |
Ramcharan et al. 1985; Vuylsteke et al. 1988 |
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Blackberry (Rubus laciniatus) |
S.V |
– |
– |
Shoot tips |
Thornyness, dwarf phenotypea |
Swartz et al. 1983 |
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Blackberry (Rubus fruticosus) |
S.V. |
– |
Tissue culture |
Buds |
Thornless |
Hall et al. 1986 |
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Citrange troyer (C. sinensis X Poncirus trifoliata) and Orange (C. sinensis) cv Tarocco |
T |
rolABC |
A.t. |
Internodes |
Altered morphology |
Gentile et al. 1999 |
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Clementine (Citrus clementine) |
S.V |
– |
– |
Nucellus |
Thornlessness |
Navarro et al. 1985 |
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Colt rootstock (P. avium X P. pseudocerasus) |
T |
RiT-DNA |
A.rh. |
Roots |
Hairy root phenotype |
Gutierrez-Pesce et al. 1998; Rugini and Gutierrez-Pesce 1999 |
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Colt rootstock (P. avium X P. pseudocerasus) |
T |
PhyA |
A.t. |
Stem |
light perception light perception |
Negri et al. 1998; Muleo and Iacona 1998 and Iacona 1998 |
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Grape (Vitis vinifera) cv Koshusanjaku |
T |
RiT-DNA |
A.rh. |
Leaf embryogenic calli |
Ri phenotype Increase root mass |
Nakano et al. 1994 |
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Grape (Vitis vinifera) cv Parodok Magaracha |
S.V. |
– |
Gamma irradiation |
Tetraploids |
Kuksova et al. 1997 |
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Kiwi fruit (Actinidia deliciosa) male (cv GTH) and female
(cv Hayward) |
T |
rolABC |
A.t. |
Leaf discs |
Altered morphology (Hairy root phenotype) |
Rugini et al. 1991; Rugini et al. 2000b |
|||||||
Kiwi fruit (Actinidia deliciosa) female (cv Hayward) |
T |
rolB |
A.t |
Leaf discs |
Normal phenotype |
Rugini and Mariotti 1992 |
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Kiwi fruit (A. deliciosa), cvs: Hayward, Abbot, Matsua and Bruno |
T |
RiT-DNA |
A.rh.IFO14555, A5, ArM123, A13 |
Petiole |
(Adventitious buds) |
Yamakawa and Chen 1996 |
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Kiwi fruit (Actinidia deliciosa) |
T |
RiT-DNA |
A.rh. NIAES 1724 |
Hypocotils |
Hairy root phenotype |
Yazawa et al. 1995 |
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Kiwi fruit (Actinidia deliciosa) |
T
|
OSH1 |
A.t. |
Leaf |
Dwarf |
Kusaba et al. 1995 |
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Kiwi fruit (A. kolomikta) |
T |
rolC |
A.t. |
Leaf |
Altered morphology |
Firsov and Dolgov 1997 |
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Mexican lime (C. aurantifolia) |
T |
RiT-DNA |
A.rh. |
Internode |
Perez and Ochoa 1998 |
Perez and Ochoa 1998 |
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Papaya (Carica papaya L.) |
T |
Ri-TDNA |
A.rh. |
Hairy root phenotype |
Hairy root phenotype |
Rugini et al. 1994 |
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Papaya (Carica papaya L.) |
T |
rol genes |
A.rh. |
Petiole leaf |
Hairy root phenotype |
Cabrera-Ponce et al. 1996 |
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Peach (Prunus persica) |
T |
Ipt |
A.t. |
Zygotic embryos |
Compact habit |
Hammerschlag and Smigocki 1998 |
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Pear (Pyrus communis) |
S.V |
– |
– |
Protoplasts |
Leaf morphology, rootability |
Ochatt 1987 |
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Persimmon (Diospiros kaki) |
T |
RiT-DNA |
A.rh. |
Stem of micropropagated shoots |
Altered morphology |
Tao et al. 1994 |
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Plum rootstock (MRS2/5) |
T |
RiT-DNA |
A. rh |
Transgenic roots |
Altered morphology |
Rugini and Gutierrez-Pesce 1999 |
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Red raspberry (Rubusideaus) | T | Hpt, SAMase | A.t. | Leaf and petiole | Altered morphology | Mathews et al. 1995 | |||||||
(Rubus laciniatus and Robus ursinus loganobaccus) | S.V. | – | – | Meristem callus | Thornlessness | McPheeters and Skirvih 1983; Hall et al. 1986 | |||||||
Strawberry (Fragaria X Ananassa) cv Calypso | T | rolC | A.t. | A.t. | Compact habit | Mazzara et al. 1998 | |||||||
Strawberry (Fragaria X ananassa) | T | rolABC | A.t. | Leaf stipule | Compact habit | Lolletti 1999 | |||||||
Trifoliate Orange (P. trifoliata) | T | RiT-DNA | A.rh. 1724 | Epicotyl | Altered morphology (reduced geotropism) | Kaneyoshi and Kobayashi 1999 | |||||||
Trifoliate Orange (P. trifoliata) | T | rolC | A.t. | Epicotyl | Altered morphology | Kaneyoshi and Kobayashi 1999 |