Modulation of intracellular proline levels affects flowering time and inflorescence architecture in Arabidopsis

Abstract

We reported previously that the plant oncogene rolD anticipates and stimulates flowering in Nicotiana tabacum, and encodes ornithine cyclodeaminase, an enzyme catalysing the conversion of ornithine to proline. To investigate on the possible role of proline in flowering, we altered the expression of AtP5CS1, encoding the rate-limiting enzyme of proline biosynthesis in plants. Accordingly we characterized a mutant line containing a T-DNA insertion into AtP5CS1 and introduced in Arabidopsis thaliana AtP5CS1 under the control of the CaMV35S promoter. As expected homozygous p5cs1 mutants behaved as late flowering. In addition p5cs1 mutants exhibited a shorter size and contained lower levels of proline, compared to wild type. 35S-P5CS1 plants, manifested, early in development, overexpression of P5CS1 and accumulation of proline, leading to early flowering, both under long- and short-day conditions. Later in development, down-regulation of P5CS1 occurred in 35S-P5CS1 leaves, leading to proline reduction, and, in turn, impaired bolting and stunted growth. Salt-stress restored expression of P5CS1 and proline accumulation in P5CS1-transformed plants, as well as rescuing growth. Our data suggest that proline plays a key role in flower transition, bolting and coflorescence formation.

Proline accumulation and transcriptional regulation of proline biothesynthesis and degradation in Brassica napus

“…Recently, characterization of AtP5CS1-overexpressing and AtP5CS1 knock-out Arabidopsis mutants led to the proposal that proline plays a key role in flower transition, bolting and coflorescence formation (20). Moreover, AtP5CS2 was found to be one of the four early targets of CONSTANS (21).…”

The relationship of proline content and metabolism on the productivity of maize plants

“…Furthermore, during flower, embryo and other developmental processes it may support the energetic needs of rapidly dividing or elongating cells. 3,19 Proline was found to be the most abundant amino acid in mature and germinated Arabidopsis pollen, accounting for 60-65% of the free amino acid pool. 20 Water stress at maize tassel initiation showed a greater influence on proline, ABA levels and yield than that at anthesis.…”

Short Term Effect of He-Ne Laser on Jatropha curcas Leaf Development and Amino Acid Biosynthesis: More Insights in Developmental Genetics of Oil Producing Plants

“…Plants engineered to accumulate proline exhibit the ability to tolerate salinity, oxidative and drought stress (Hong et al, 2000). Proline has strong influence on plant developmental processes including cell division, embryo development, and flowering (Mattioli et al, 2008). It also promotes the formation of proline-rich cell wall linker proteins in the plasmalemma that are responsible for cell wall maintenance and stress-induced fortification (Stein et al, 2011).…”