Os12g0189500

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Annotated Information

Function

The increase in IAA content was strongly correlated with the expression of putative IAA biosynthesis genes, OsYUC9, OsYUC11 and OsTAR1, measured by quantitative reverse transcriptase polymerase chain reaction. These results confirm the importance of the tryptophan aminotransferase/YUCCA pathway in this system. All three genes were expressed in endosperm; expression of OsYUC11 appeared to be confined to endosperm tissue. Phylogenetic analysis indicated that OsYUC11 and AtYUC10 belong to a separate clade of YUCCAs, which do not have orthologues outside the Angiosperms. This clade may have evolved with a specific role in endosperm. Expression of tryptophan decarboxylase in developing rice grains did not correlate with IAA levels, indicating that tryptamine is unlikely to be important for IAA synthesis in this system. In light of these observations, we hypothesize that IAA production in developing rice grains is controlled via expression of OsTAR1, OsYUC9, OsYUC11 and that IAA may be important during starch deposition in addition to its previously suggested role early in grain development.

Expression

Quantitative RT–PCR results for OsYUC3, OsYUC 9, OsYUC 11, OsYUC 12, OsYUC 14, OsTAR1, OsTAR2 and OsTDC1. Total RNA was extracted using a Qiagen RNeasy Kit. Reaction tubes were prepared using a CAS-1200 Robotic liquid-handling system, Qiagen. Each tube contained 250 ng RNA per 25 μL reaction and a final primer concentration of 0.5 μM. Amplification was carried out using a Qiagen QuantiTect SYBR Green RT–PCR kit in a Corbett Research Rotor-Gene 3000 thermocycler fitted with a 72-tube rotor for 45 cycles. Expression was calculated relative to reference genes UBC using ROTORGENE software (Qiagen) . Melt curve analysis confirmed that a single product was obtained for each gene amplified. Results shown are the means ± the standard error of three biological replicates and two technical replicates. Comparison of the expression of YUCCA, TAA/TAR and TDC orthologues during grain/seed development .

Evolution

• Phylogenetic tree of Trp decarboxylases and sequence homologues: sequences were obtained by BLASTp search of proteomes of Rice (Os), Arabidopsis (At), Sorghum (Sb) and Poplar (POPTR) . In addition, sequences of experimentally characterized TDCs from Catharanthus roseus (CatroTDC), Camptotheca acuminata (CaTDC1, CaTDC2), Ophiorrhiza pumila (OpTDC), TyDCs from Papaver somniferum (PapsoTYDC1, PapsoTYDC2) and Petroselinum crispum (PetcrTYD) and phenylacetaldehyde synthases from Petunia hybrida (PetuniaPAAS) and Rosa hybrid cultivar (RosaPAAS) were included. The tree was rooted with the putative TDC/TyDC from Chlamydomonas reinhardtii (Cre01.g028423). Multiple sequence alignments were carried out using MUSCLE (Edgar 2004); trees were constructed using PROTDIST and FITSCH； bootstrapping was conducted using SEQBOOT .
• Phylogenetic tree of FMOs from rice (Os), Arabidopsis (At), Selaginella (Smoe), Physcomitrella (Ppls) and Chlamydomonas (Cr/Cre). Human FMOs, translated Pinus cDNAs and four sequences from bacteria, representing the most closely related proteins to YUCCA from outside the plant kingdom were also included. Multiple sequence alignments were carried out using MUSCLE (Edgar 2004); trees were constructed using PROTDIST and FITSCH bootstrap values for major branches are indicated. Scale bar indicates 0.1 amino acid substitutions persite. Examination of the expression of YUCCA in developing seeds using both RT–PCR and microarray data indicated that OsYUC11 and AtYUC10 appeared to be specific to, and highly expressed in, endosperm tissue. These two proteins are orthologues of each other and also of ZmYUC, which appears to be important for IAA synthesis in developing maize kernels.

Labs working on this gene

• Department of applied biological science, Al-Ghad International AppliedMedical Science University, Jeddah, Saudi Arabia