Table 2.

Drought tolerant gene that has been tested in rice.

Gene Action	Gene	Promoter	Transformation	Phenotype	References
Genes Encoding Enzymes That Synthesize Osmotic and Other Protectants
Arginine decarboxylase	ADC	CaMV35S	Biolistic	Reduction in chlorophyll loss under water deficiency	[79]
Polyamine synthesis	ADC	Ubi-1	Agrobacterium	Improved drought tolerance by producing higher levels of putrescine and spermine synthesis.	[16]
abscisic acid Metabolism	CaMV35SP	DSM2	Agrobacterium	Oxidative and drought stress resistance and increase of the xanthophylls and non-photochemical quenching.	[80]
Amino acid metabolism	OsOAT	Ubi1	Agrobacterium	Improve drought tolerance and increase seed setting	[77]
Reactive oxygen species scavenging	OsSRO1c	Ubi1	Agrobacterium	Oxidative stress tolerance and stomata closure regulation	[81]
Protoporphyrinogen oxidase	PPO	-	Agrobacterium	Less oxidative damage, and drought tolerance	[82]
Trehalose synthesis	OsTPS1	Actin1	Agrobacterium	Tolerance of rice seedling to drought, cold, and high salinity	[83]
Trehalose synthesis	TPSP	Ubi1	Agrobacterium	Cold, salt and drought tolerance expressed by chlorophyll fluorescence	[78]
Proline synthesis	P5CS	Act1	Agrobacterium	Resistance to water and salinity stress	[84]
Proline synthesis	P5CS	AIPC	Biolistic	Increased biomass production under salinity and drought stresses	[76]
Late Embryogenesis Abundant (LEA) Related Genes
LEA protein gene	HVA1	Actin1	Agrobacterium	Cell membrane stability, higher leaf relative water content (RWC) and increase in growth under drought stress.	[73]
	HVA1	Actin1	Agrobacterium	Drought and salinity tolerance	[85]
	HVA1	Actin 1	Biolistic	Increased drought tolerance and salinity stress.	[86]
	OsLEA3-1	rice LEA3-1	Agrobacterium	Drought resistance for grain yield under field conditions	[71]
	OsLEA3-2	CaMV35S	Agrobacterium	Drought resistance and increase grain per panicle	[70]
Various Regulatory Genes
Transcription factor	ABF3	Ubi1	Agrobacterium	Improved salinity and drought tolerance	[87]
	AP37	OsCc1	Agrobacterium	Improve growth performance under drought stress	[88]
	OsbZIP23	Ubi1	Agrobacterium	Wide spectrum to salt and drought tolerance and improvement in yield.	[89]
	OsbZIP72	CaMV35S	Agrobacterium	Drought resistance and ABA sensitivity	[90]
	DREB1 or OsDREB1	CaMV 35S	Agrobacterium	Tolerance to water deficient, low-temperature and high-salt stresses	[91]
	DREB2	rd29A	Agrobacterium	Improve grain yield under drought stress	[92]
	HvCBF4	Ubi1	Agrobacterium	Tolerance to drought, high-salinity, and low-temperature.	[93]
Harpin protein	Hrf1	CaMV 35S	Agrobacterium	Drought resistance through ABA signalling and antioxidants, and stomata closure regulation	[94]
Jasmonate and ethylene-responsive factor 1	JERF1	CaMV35S	Agrobacterium	Drought resistance	[95]
Ethylene-responsive factor 1	TSRF1	-	Agrobacterium	Enhances the osmotic and drought tolerance	[96]
RING finger protein	OsCOIN	CaMV35S	Agrobacterium	Cold, salt and drought tolerance	[97]
Stress/zinc finger protein	OsiSAP8	-	Agrobacterium	Tolerance to salt, drought and cold stress	[98]
Protein degradation (E3 ubiquitin ligase)	OsRDCP1	CaMV35S	Agrobacterium	Improved tolerance to drought stress	[99]
	OsSDIR1	Ubi1	Agrobacterium	Stomata regulation under drought stress	[100]