Table 1.
Effects of genetic modification of auxin response genes on plant traits.
| Gene | Pathway of Auxin Response | Detail of the Modification Traits | Type of Regulation | Species | References |
|---|---|---|---|---|---|
| 1. Changes of the apical dominance | |||||
| OsIAA1 | CTAR | Decreased plant height, loose plant architecture, reduced inhibition of root elongation to auxin treatment | Overexpression | Oryza sativa | [140] |
| SlIAA15 | CTAR | Reduced apical dominance, increased lateral root formation, and decreased fruit set | Down-regulated | Solanum lycopersicum | [141] |
| ARF7/ARF19 | CTAR | Thin and short florescence stems, enhanced apical dominance, and reduced and delayed lateral root formation | Double mutant | Arabidopsis | [142,143] |
| VvIAA19 | CTAR | Faster growth including root elongation and earlier floral transition | Overexpression | Arabidopsis | [144] |
| 2. Root architecture and growth | |||||
| EgrIAA4 | CTAR | Inhibition of primary root elongation, lateral root emergence and gravitropism | Overexpression | Arabidopsis | [145] |
| SlIAA27 | CTAR | Root development alternations | Silencing | Solanum lycopersicum | [146] |
| MtARF2, 3, and 4 | Non-TAR | Reduced primary and lateral root length, but increased lateral root density | Simultaneous knockdown | Medicago truncatula | [147] |
| 3. Stem characteristics modification | |||||
| PttIAA3 | CTAR | Changes of secondary xylem development | Overexpressing mutant gene | Populus tremula × P. tremuloides | [148] |
| SlIAA9 | CTAR | Including enhanced hypocotyl/stem elongation, increased leaf vascularization, and reduced apical dominance | Silencing | Solanum lycopersicum | [149] |
| GhARF2 | Non-TAR | Inhibited fiber cell elongation but promoted initiation | Overexpression | Gossypium hirsutum | [150] |
| 4. Modification of leaf traits | |||||
| CgARF1 | CTAR | Increased leaf senescence and decreased chlorophyll content. | Overexpression | Arabidopsis and Nicotiana benthamiana | [151] |
| SlARF3/ETT | TAR | Decreased density of epidermal pavement cells and reduced density of trichomes of leaves and shoot xylem cells | Silencing | Solanum lycopersicum | [152] |
| e2fc | TAR | Reductions in ploidy levels of mature leaves | Silencing | Arabidopsis | [80] |
| 5. Modification of flower and fruit traits | |||||
| RhIAA16 | CTAR | Promoted petal abscission | Silencing | Rosa chinensis | [153] |
| RsIAA33 | TAR | Inhibited the reproductive growth and promoted taproot thickening and development | Silencing | Raphanus sativus | [154] |
| MdIAA26 | CTAR | Promoted the accumulation of anthocyanin in calli | Overexpressing | Malus domestica | [155] |
| FaARF4 | Non-TAR | Flowering earlier | Overexpression | Fragaria vesca | [156] |
| SlARF4 | Non-TAR | Accumulated starch at early stages of fruit development and enhanced chlorophyll content and photochemical efficiency. | Silencing | Solanum lycopersicum | [157] |
| SlARF5/MP | TAR | Seedless fruits following emasculation | Silencing | Solanum lycopersicum | [158] |
| OsAFB6 | CTAR | Promoted inflorescence meristem development and increased panicles size and grain yield | Overexpression | Oryza sativa | [20] |
| SlARF6A | CTAR | Increased chlorophyll contents, accumulated starch and soluble sugars, and inhibited fruit ripening and ethylene production | Overexpression | Solanum lycopersicum | [159] |
| PTRE1 | CTAR | short siliques and arrested embryogenesis | Mutant | Arabidopsis | [160] |
| BnaA9.ARF18 | Non-TAR | Increased seed weight and silique length | Mutant | Brassica napus | [161] |
| FveARF8 | CTAR | Larger fruit | Mutant with FveRGA1 | Fragaria x ananassa | [162] |
| SlARF10 | Non-TAR | Improved accumulation of starch, fructose, and sucrose in fruit | Overexpression | Solanum lycopersicum | [163] |
| 6. Response to environmental stress | |||||
| MdIAA9 | CTAR | Increased tolerance to osmotic stresses. | Overexpression | N. tabacum | [22] |
| OsIAA18 | CTAR | Enhanced salt and drought tolerance | Overexpression | Oryza sativa | [18] |
| VvIAA18 | CTAR | Improved salt tolerance | Overexpression | N. tabacum | [164] |
| MdIAA24 | CTAR | Increase drought resistance and cadmium tolerance. | Overexpression | Malus domestica | [21] |
| OsIAA20 | TAR | Enhanced drought and salt tolerance, increased stomatal closure, and reduced the rate of water loss | Overexpression | Oryza sativa | [19] |
| SlARF4 | Non-TAR | Enhanced resistance to water stress and rehydration ability | Knockdown | Solanum lycopersicum | [165] |
| CsARF5/MP | TAR | Enhanced the cold stress tolerance | Overexpression | Cucumis sativus | [166] |
| ABP1 | Non-TAR | Changes of root and hypocotyl growth and bending, lateral root and leaf development, bolting, as well as response to heat stress | Gain-of-function alleles | Arabidopsis | [167] |
| ABP1 | Non-TAR | Higher root slanting angles, longer hypocotyls, agravitropic roots and hypocotyls, aphototropic hypocotyls, and decreased apical dominance. | Heterozygous abp1/ABP1 insertion mutant | Arabidopsis | [124] |
| ABP1 | Non-TAR | Severe retardation of leaf growth | Knockdown | Arabidopsis and N. tabacum | [101] |
| ABP1 | Non-TAR | Changes in leaf growth rate or form, the cell size in certain regions of the leaf was altered | Overexpression | Arabidopsis | [168] |
| TMK1 | Non-TAR | Hypocotyl elongation | Double mutant | Arabidopsis | [168] |