Table 2 - Biology Online

Table 2

- Mechanisms underlying plant resilience to water deficits: prospects for water-saving agriculture

Table 2. Recent achievements in improving drought tolerance in crops through genetic engineering

Gene/enzyme	Organism of origin	Target plant	Effect	Author
Functional proteins
Superoxide dismutase (MnSOD)	Nicotiana plumbaginifolia	Alfalfa	Better performance in the field under drought	McKersie et al. (1996)
HVA1 (group 3 Lea gene)	Barley	Rice	Constitutive expression leads to protein accumulation in leaves and roots and improved recovery after drought and salt stress	Xu et al. (1996)
Myo-inositol O-methyltransferase (IMT1)	Mesembryanthemum crystallinum	Tobacco	Enhanced photosynthesis protection and increased recovery under drought, through the accumulation of D-ononitol.	Sheveleva et al. (1997)
Trehalose-6-P synthase, Trehalose-6-P phosphatase	Bacteria	Tobacco	Better photosynthetic efficiency and higher dry weight under drought stress	Pilon-Smiths et al. (1998)
HVA1 (group 3 Lea gene)	Barley	Wheat	Constitutive expression (ubiP) improved biomass productivity and water use efficiency under water-stress	Sivamani et al. (2000)
Aldose/aldehyde reductase (MsALR)	Alfalfa	Tobacco	Detoxification effect (reduced amounts of reactive aldehydes derived from lipid peroxidation) leading to tolerance to multiple stresses, including drought	Oberschall et al. (2000)
NADP-malic enzyme	Maize	Tobacco	Drought avoidance phenotype through decreased stomatal conductance and increased fresh weight per unit water consumed. Growth and rate of development similar to wild type	Laporte et al. (2002)
Fusion gene with Trehalose-6-P synthase and Trehalose-6-P phosphatase (TPSP) regulated by ABA inducible promoter or small subunit rbcS promoter	E. coli	Rice	Sustained plant growth and reduced photo-oxidative damage under drought and other abiotic stresses. Improved photosynthetic activity also under non-stress conditions.	Garg et al. (2002)
Mannitol-1-phosphate dehydrogenase (mtlD)	E. coli	Wheat	Improved drought tolerance with mannitol accumulation at a concentration insufficient for osmotic adjustment	Abebe et al. (2003)
Aquaporin NtAQP1	Tobacco	Tobacco	Over-expression of NtAQP increased membrane permeability for CO₂ and water, and increased leaf growth	Uehlein et al. (2003)
Regulatory proteins
Calcium dependent protein kinase (OsCDPK7)	Rice	Rice	Over-expression of OsCDPK7 led to induced expression of a glycine rich protein (salT) and LEA proteins (rab16A, wsi18) under stress. Increased salt and drought-tolerance.	Saijo et al. (2000)
CBF1 (DREB1B) (driven by P35SCaMV)	Arabidopsis	Tomato	Increased resistance to water-stress, but dwarf phenotype. Higher levels of proline than controls, and faster closure of stomata under water stress. Higher catalase activity and lower (McAinsh et al., 1996), with or without stress	Hsieh et al. (2002)

The genes used were originated from plants or bacteria and accounted for various cellular responses ending up in increased drought tolerance.

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Table 2 - Mechanisms underlying plant resilience to water deficits: prospects for water-saving agriculture

Table 2
- Mechanisms underlying plant resilience to water deficits: prospects for water-saving agriculture