Tryptophan deficiency affects organ growth by retarding cell expansion in Arabidopsis

Abstract

SummaryTryptophan (Trp) is an essential amino acid required not only for protein synthesis but also for the production of many plant metabolites, including the hormone auxin. Mutations that disrupt Trp biosynthesis result in various developmental defects in plant organs, but how Trp affects organ growth and development remains unclear. Here, we identify an Arabidopsis mutant, small organ1 (smo1/trp2-301), which exhibits a reduction in the size of its aerial organs as a result of the retardation of growth by cell expansion, rather than by the retardation of growth by cell proliferation. smo1/trp2-301 contains a lesion in TSB1 that encodes a predominantly expressed Trp synthase b-subunit, and is allelic with trp2 mutants. Further analyses show that in trp2 leaf cells, the nuclear endoreduplication is impaired and chloroplast development is delayed. Furthermore, cell expansion and leaf growth in trp2 can be restored by the exogenous application of Trp, but not by auxin, and the general protein synthesis is not apparently affected in trp2 mutants. Our findings suggest that the deficiency in Trp or its derivatives is a growth-limiting factor for cell expansion during plant organogenesis.

Plastidial Glyceraldehyde-3-Phosphate Dehydrogenase Deficiency Leads to Altered Root Development and Affects the Sugar and Amino Acid Balance in Arabidopsis

“…Using a nonlethal deficiency mutant, a crucial role for His homeostasis in root meristem maintenance has been demonstrated (Mo et al, 2006). Also, it has been shown that Trp deficiency produces retardation of aerial organ development by affecting cell expansion in Arabidopsis (Jing et al, 2009). By reducing the content of Ser in gapcp double mutant roots, a drastic arrest of its development was observed.…”

Tryptophan-dependent auxin biosynthesis is required for HD-ZIP III-mediated xylem patterning

“…It has been previously shown that tryptophan synthase mutants can be rescued by externally supplied L-tryptophan (L-Trp) (Jing et al, 2009;Last et al, 1991;Last and Fink, 1988;Müller and Weiler, 2000). We therefore examined trp2-12 mutants grown on medium supplied with 10 μM L-Trp and found that the mutant phenotypes, including phloem unloading and xylem patterning defects, were completely rescued (supplementary material Fig.…”

The glycolytic enzyme, phosphoglycerate mutase, has critical roles in stomatal movement, vegetative growth, and pollen production in Arabidopsis thaliana

“…Therefore, an alternative hypothesis is that the severe retardation of plant growth and the reticulate leaf phenotypes in ipgam double mutants are not due to reduced energy provision but rather to altered aromatic acid metabolism. Several reticulate leaf mutants have been characterized recently, including cue1 (Voll et al , 2003), ven3 and ven6 (Molla-Morales et al , 2011), and trp2 (Jing et al , 2009). Analysis of these mutants suggests that mesophyll development is restricted and amino acid biosynthesis is impaired.…”