Table 4.
Genes responsible for amino acid synthesis.
| Amino acid | Key precursors | Key enzymes | Genes in Arabidopsis | References |
|---|---|---|---|---|
| Glutamate | 2-oxoglutarate; Glutamine |
Amino transferases; glutamate synthase (GOGAT): two forms- ferredoxin (Fd) and NADH |
44 putative genes Fd form: GLU1, GLU2 NADH form: GLT |
Liepman and Olsen, 2004; Forde and Lea, 2007 |
| Glutamine | Glutamate | Glutamine synthase: two forms—plastidic (GS1) and cytoplasmic (GS2) | GS1 form: one gene; GS2 form: five genes |
Forde and Lea, 2007; Gaufichon et al., 2016 |
| Asparagine | Glutamine and Aspartate | Asparagine synthase | asnB gene; ASN gene family (ASN1, ASN2, ASN3) | Arabidopsis Genome Initiative, 2000; Gaufichon et al., 2010 |
| Histidine | Ribose-5-phosphate | Eight enzymes | PRATP/CH, ProFAR-I, IGPS, HPP, HDH- single copy genes; ATP-PRT, IGPD, HPA-duplicated genes | Rees et al., 2009; Ingle, 2011 |
| Leucine | Pyruvate 2-oxoisovalerate |
Acetohydroxyacid synthase (AHAS) enzyme Isopropylmalate synthase (IPMS), isopropylmalate isomerase (IPMI), and isopropylmalate dehydrogenase (IPMDH) |
AHAS gene IPMS: IPMS1, IPMS2, IPMI LSU1 IPMI SSU1 IPMI SSU2, IPMI SSU3, IPMDH gene |
Singh and Shaner, 1995; Calder, 1995; Xing and Last, 2017; Knill et al., 2009 |
| Valine | Pyruvate 2-oxoisovalerate |
Acetohydroxyacid synthase (AHAS) enzyme Amino transferase |
AHAS gene Single gene |
Singh and Shaner, 1995; Calder, 1995; Xing and Last, 2017; Knill et al., 2009 |
| Isoleucine | 2-ketobutyrate | Acetohydroxyacid synthase (AHAS) enzyme | AHAS gene | Singh and Shaner, 1995 |
| Alanine | Pyruvate and glutamate | Alanine aminotransferases | Eight genes | Parthasarathy et al., 2019 |
| Phenylalanine Tyrosine |
Chorismate Prephenate Arogenate |
Chorismate mutase (CM), Prephenate aminotransferase Phenylalanine synthesis: Arogenate dehydratase Tyrosine synthesis: Arogenate dehydrogenase |
CM: AtCM1, AtCM2, AtCM3, AtPPA-AT gene Six genes (ADT1, ADT2, ADT3, ADT4, ADT5, ADT6) Two genes (TyrA1, TyrA2) |
Tzin and Galili, 2010; Dudareva et al., 2011 |
| Tryptophan | Chorismate Anthranillite |
Anthranilate synthase (AS) Anthranilate phosphoribosyltransferase (PAT1), indole-3-glycerol phosphate synthase (IGPS), tryptophan synthase alpha (TS a), phosphoribosylanthranilate isomerase (PAI), and tryptophan synthase beta (TS b) |
Three genes (ASa1, ASa2, ASb1) and seven putative genes (two Asa and five ASb genes) PAT1, IGPS, TSa, three genes (PAI1, PAI2, PAI3) and two genes (TSb1 and TSb2) |
Tzin and Galili, 2010; Parthasarathy et al., 2018 |
| Aspartate | Oxaloacetate and glutamate | Aspartate aminotransferase (AspAT) | Five genes: AspAT1, AspAT2, AspAT3, AspAT4, AspAT4, AspAT5 | Han et al., 2021 |
| Methionine, Threonine, Isoleucine Lysine | Aspartate L-aspartate-4-semialdehyde |
Aspartate kinase (AK) Methionine, threonine and isoleucine synthesis: homoserine dehydrogenase (HSD) Lysine synthesis: dihydrodipicolinate synthase (DHDPS) |
Five genes Two genes Two genes |
Vauterin and Jacobs, 1994; Vauterin et al., 1999; Craciun et al., 2000; Sarrobert et al., 2000; Galili, 2011 |