Compositions and methods for mediating plant stomatal development in response to carbon dioxide and applications for engineering drought tolerance in plants

1. A method for:

increasing the number of stomatal cores corn oared to the total number of cells, or increasing the stomatal density, stomatal index and/or stomatal size, in a plant, plant part, a plant organ, a plant leaf;

up-regulating or increasing carbon dioxide (CO2) and/or water exchange in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

decreasing the water use efficiency of a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

decreasing or desensitizing the carbon dioxide (CO2) sensitivity of a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

upregulating or increasing carbon dioxide (CO2) and/or water exchange in a guard cell, a root cell, a stomatal lineage stage-specific rev, a plant leaf, a plant organ, a plant part or a plant;

increasing the uptake of CO2 in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

decreasing drought tolerance in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant; or

increasing the heat resistance or tolerance, optionally increasing the heat resistance or tolerance, under conditions of drought or increased atmospheric carbon dioxide;

comprising:

decreasing the expression and/or activity of:

(1) a nucleic acid encoding an ATSBT5.2-like protein; or

(2) an ATSBT5.2-like protein;

wherein the ATSBT5.2-like protein comprises:

a) the amino acid sequence as set forth in SEQ ID NO: 5, and

wherein the decreasing of expression and/or activity of the ATSBT5.2-like protein, is by:

introducing to a guard cell, root cell, stomatal lineage stage-specific cell, plant leaf, plant organ, plant part or plant a nucleic acid encoding a heterologous antisense nucleotide, interfering RNA, or microRNA that targets the ATSBT5.2-like protein-encoding nucleic acid sequence; and,

expressing the heterologous antisense nucleotide, interfering RNA, or microRNA, in the guard cell, root cell, stomatal lineage stage-specific cell, plant leaf, plant organ, plant part or plant,

or introducing to a guard cell, root cell, stomatal lineage stage-specific cell, plant leaf, plant organ, plant part or plant a heterologous antisense nucleotide, interfering RNA or microRNA that targets the ATSBT5.2-like protein-encoding nucleic acid sequence

wherein the heterologous antisense nucleotide, interfering RNA or microRNA comprises a nucleotide sequence having at least about 11, 12, 13, 14, 15, 16, 17, 18, or 19 or more consecutive nucleotides of a nucleotide sequence encoding the sequence of SEQ ID NO:5, or the complement thereof;

thereby:

increasing the number of stomatal pores compared to the total number of cells, or increasing the stomatal density, stomatal index and/or stomatal size, in a plant, plant part, a plant organ, a plant leaf;

up-regulating or increasing carbon dioxide (002) and/or water exchange in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

decreasing the water use efficiency of a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

decreasing or desensitizing the carbon dioxide (CO2) sensitivity of a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

upregulating or increasing carbon dioxide (CO2) and/or water exchange in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

increasing the uptake of CO2 in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant;

decreasing drought tolerance in a guard cell, a root cell, a stomatal lineage stage-specific cell, a plant leaf, a plant organ, a plant part or a plant; or

increasing the heat resistance or tolerance, optionally increasing the heat resistance or tolerance under conditions of drought or increased atmospheric carbon dioxide.

2. The method of claim 1 , wherein the ATSBT5.2-like protein-expressing nucleic acid is operably linked to a plant expressible promoter, an inducible promoter, a constitutive promoter, a root specific promoter, a stomatal lineage stage-specific cell specific promoter, a guard cell specific promoter, a drought-inducible promoter, a stress-inducible promoter or a guard cell active promoter.

3. The method of claim 1 , wherein the plant is, or the guard cell, plant cell, plant part or plant organ, is isolated and/or derived from:

(i) a dicotyledonous or monocotyledonous plant;

(ii) wheat, oat, rye, barley, rice, sorghum, maize or corn, tobacco, a legume, a lupins, potato, sugar beet, pea, bean, soybean or soy, a cruciferous plant, a cauliflower, rape (or rapa or canola), cane (sugarcane), flax, cotton, palm, sugar beet, peanut, a tree, a poplar, a lupin, a silk cotton tree, desert willow, creosote bush, winterfat, balsa, ramie, kenaf, hemp, roselle, jute, or sisal abaca; or,

(iii) a species from the genera Anacardium, Arachis, Asparagus, Atropa, Avena, Brassica, Citrus, Citrullus, Capsicum, Carthamus, Cocos, Coffea, Cucumis, Cucurbita, Daucus, Elaeis, Fragaria, Glycine, Gossypium, Helianthus, Heterocallis, Hordeum, Hyoscyamus, Lactuca, Linum, Lolium, Lupinus, Lycopersicon, Malus , Man[iota]hot, Majorana, Medicago, Nicotiana, Olea, Oryza, Panieum, Pannisetum, Persea, Phaseolus, Pistachia, Pisum, Pyrus, Prunus, Raphanus, Ricinus, Secale, Senecio, Sinapis, Solanum, Sorghum, Theobromus, Trigonella, Triticum, Vicia, Vitis, Vigna or Zea.

4. The method of claim 1 , wherein the ATSBT5.2-like protein-expressing nucleic acid is a gene, a cDNA or an mRNA.