A Regulatory Hierarchy of the Arabidopsis Branched-Chain Amino Acid Metabolic Network

Xing, Anqi

doi:10.1105/tpc.17.00186

Cited by 52 publications

(52 citation statements)

References 64 publications

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“…While most plant enzymes involved in amino acid biosynthesis have been characterized (Radwanski and Last, ; Galili, ; Maeda and Dudareva, ; Coruzzi et al ., ; Galili et al ., ), it remains to be studied how plants maintain amino acid homeostasis in planta (Zhu and Galili, ; Angelovici et al ., , ; Xing and Last, ) and control overall plant physiology. This study provides genetic evidence that the model plant A. thaliana synthesizes tyrosine mainly via the arogenate pathway.…”

Section: Discussionmentioning

confidence: 99%

Imbalance of tyrosine by modulating TyrA arogenate dehydrogenases impacts growth and development of Arabidopsis thaliana

et al. 2019

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L-Tyrosine is an essential aromatic amino acid required for the synthesis of proteins and a diverse array of plant natural products; however, little is known on how the levels of tyrosine are controlled in planta and linked to overall growth and development. Most plants synthesize tyrosine by TyrA arogenate dehydrogenases, which are strongly feedback-inhibited by tyrosine and encoded by TyrA1 and TyrA2 genes in Arabidopsis thaliana. While TyrA enzymes have been extensively characterized at biochemical levels, their in planta functions remain uncertain. Here we found that TyrA1 suppression reduces seed yield due to impaired anther dehiscence, whereas TyrA2 knockout leads to slow growth with reticulate leaves. The tyra2 mutant phenotypes were exacerbated by TyrA1 suppression and rescued by the expression of TyrA2, TyrA1 or tyrosine feeding. Low-light conditions synchronized the tyra2 and wild-type growth, and ameliorated the tyra2 leaf reticulation. After shifting to normal light, tyra2 transiently decreased tyrosine and subsequently increased aspartate before the appearance of the leaf phenotypes. Overexpression of the deregulated TyrA enzymes led to hyper-accumulation of tyrosine, which was also accompanied by elevated aspartate and reticulate leaves. These results revealed that TyrA1 and TyrA2 have distinct and overlapping functions in flower and leaf development, respectively, and that imbalance of tyrosine, caused by altered TyrA activity and regulation, impacts growth and development of Arabidopsis. The findings provide critical bases for improving the production of tyrosine and its derived natural products, and further elucidating the coordinated metabolic and physiological processes to maintain tyrosine levels in plants.

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Section: Discussionmentioning

confidence: 99%

Imbalance of tyrosine by modulating TyrA arogenate dehydrogenases impacts growth and development of Arabidopsis thaliana

et al. 2019

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“…Isopropylmalate synthase (IPMS, EC 2.2.3.13) catalyzes condensation of 3-methyl-2-oxobutanoate and acetyl-CoA, resulting in 2-isopropylmalate [40]. ALS and IPMS work together to maintain homeostasis of Val and Leu [60]. While ALS affects the flux of Val and Leu into their pathways, IPMS regulates their partitioning.…”

Section: Candidate Genes Associated With Grain Starch As Revealed By mentioning

confidence: 99%

Genome-wide association study reveals that different pathways contribute to grain quality variation in sorghum (Sorghum bicolor)

Kimani

Zhang

et al. 2020

BMC Genomics

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Background: In sorghum (Sorghum bicolor), one paramount breeding objective is to increase grain quality. The nutritional quality and end use value of sorghum grains are primarily influenced by the proportions of tannins, starch and proteins, but the genetic basis of these grain quality traits remains largely unknown. This study aimed to dissect the natural variation of sorghum grain quality traits and identify the underpinning genetic loci by genomewide association study. Results: Levels of starch, tannins and 17 amino acids were quantified in 196 diverse sorghum inbred lines, and 44 traits based on known metabolic pathways and biochemical interactions amongst the 17 amino acids calculated. A Genome-wide association study (GWAS) with 3,512,517 SNPs from re-sequencing data identified 14, 15 and 711 significant SNPs which represented 14, 14, 492 genetic loci associated with levels of tannins, starch and amino acids in sorghum grains, respectively. Amongst these significant SNPs, two SNPs were associated with tannin content on chromosome 4 and colocalized with three previously identified loci for Tannin1, and orthologs of Zm1 and TT16 genes. One SNP associated with starch content colocalized with sucrose phosphate synthase gene. Furthermore, homologues of opaque1 and opaque2 genes associated with amino acid content were identified. Using the KEGG pathway database, six and three candidate genes of tannins and starch were mapped into 12 and 3 metabolism pathways, respectively. Thirty-four candidate genes were mapped into 16 biosynthetic and catabolic pathways of amino acids. We finally reconstructed the biosynthetic pathways for aspartate and branched-chain amino acids based on 15 candidate genes identified in this study. Conclusion: Promising candidate genes associated with grain quality traits have been identified in the present study. Some of them colocalized with previously identified genetic regions, but novel candidate genes involved in various metabolic pathways which influence grain quality traits have been dissected. Our study acts as an entry point for further validation studies to elucidate the complex mechanisms controlling grain quality traits such as tannins, starch and amino acids in sorghum.

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“…They are, first and foremost, the building blocks for proteins. They are also the precursors of many primary and secondary metabolites involved in core metabolic functions as well as in plant protection against biotic and abiotic stresses (Fait et al , ; Angelovici et al , ; Galili et al , ; Xing and Last, ). The function of the FAA pool at the end of desiccation is not clear.…”

Section: Introductionmentioning

confidence: 99%

The complex response of free and bound amino acids to water stress during the seed setting stage in Arabidopsis

et al. 2020

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Free amino acids (FAAs) and protein-bound amino acids (PBAAs) in seeds play an important role in seed desiccation, longevity, and germination. However, the effect that water stress has on these two functional pools, especially when imposed during the crucial seed setting stage is unclear. To better understand these effects, we exposed Arabidopsis plants at the seed setting stage to a range of water limitation and water deprivation conditions and then evaluated physiological, metabolic, and proteomic parameters, with special focus on FAAs and PBAAs. We found that in response to severe water limitation, seed yield decreased, while seed weight, FAA, and PBAA content per seed increased. Nevertheless, the composition of FAAs and PBAAs remained unaltered. In response to severe water deprivation, however, both seed yield and weight were reduced. In addition, major alterations were observed in both FAA and proteome compositions, which indicated that both osmotic adjustment and proteomic reprogramming occurred in these naturally desiccation-tolerant organs. However, despite the major proteomic alteration, the PBAA composition did not change, suggesting that the proteomic reprogramming was followed by a proteomic rebalancing. Proteomic rebalancing has not been observed previously in response to stress, but its occurrence under stress strongly suggests its natural function. Together, our data show that the dry seed PBAA composition plays a key role in seed fitness and therefore is rigorously maintained even under severe water stress, while the FAA composition is more plastic and adaptable to changing environments, and that both functional pools are distinctly regulated.

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A Regulatory Hierarchy of the Arabidopsis Branched-Chain Amino Acid Metabolic Network

Cited by 52 publications

References 64 publications

Imbalance of tyrosine by modulating TyrA arogenate dehydrogenases impacts growth and development of Arabidopsis thaliana

Imbalance of tyrosine by modulating TyrA arogenate dehydrogenases impacts growth and development of Arabidopsis thaliana

Genome-wide association study reveals that different pathways contribute to grain quality variation in sorghum (Sorghum bicolor)

The complex response of free and bound amino acids to water stress during the seed setting stage in Arabidopsis

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