Functional conservation of MADS-box factors controlling floral organ identity in rice and Arabidopsis

Abstract

Studies on MADS-box genes in Arabidopsis and other higher eudicotyledonous flowering plants have shown that they are key regulators of flower development. Since Arabidopsis and monocotyledonous rice are distantly related plant species it is interesting to investigate whether the floral organ identity factors have been conserved in their functions, and if not, to understand the differences. Arabidopsis and rice are very suitable for these studies since they are both regarded as models for plant functional genomics. Both their genomes are sequenced and tools are available for the analysis of gene function. These developments have accelerated experiments and increased our knowledge on rice gene function. Therefore it is the right moment to perform a comparative analysis on MADS-box factors controlling floral organ identity as reported in this review.

Functional Analysis of All AGAMOUS Subfamily Members in Rice Reveals Their Roles in Reproductive Organ Identity Determination and Meristem Determinacy

“…Similarly, rice DEF/GLO orthologs have been shown to determine the identity of second and third whorl floral organs (B-function), whereas SQUA-like MADS box genes are more likely required to influence FM identity rather than having a true A function, although further analysis will be required (reviewed in Kater et al, 2006). Recessive A-function mutants, clearly showing identity defects in first-and second-floral whorl organs, have thus far been reported only in Arabidopsis, and probably only a BC model can be applied to other model core eudicots (Schwarz-Sommer et al, 2003;Causier et al, 2010).…”

“…Among the four AG subfamily genes of rice, MADS3, MADS13, and MADS58 regulate also FM determinacy, whereas MADS21 seems not to play important functions during flower development. The MADS domain proteins shown in this model might interact with SEP-like and/or AGL6-like MADS domain proteins providing E-function (Favaro et al, 2002;Kater et al, 2006;Ohmori et al, 2009;Cui et al, 2010;Li et al, 2010;Li et al, 2011a), which for simplicity are not shown in this scheme.…”

Genetic and Epigenetic Alteration among Three Homoeologous Genes of a Class E MADS Box Gene in Hexaploid Wheat

“…These SEP genes can form heterochimeric protein complexes with the products of the class A, B, C, and D genes that regulate identity acquirement of sepals, petals, stamens, carpels, and ovules (Honma and Goto, 2001;Pelaz et al, 2001;Favaro et al, 2003). In rice, five class E MADS box genes have been identified: Os MADS1, Os MADS5, Os MADS24 (identical to Os MADS8), Os MADS34 (identical to Os MADS19), and Os MADS45 (identical to Os MADS7) (Kater et al, 2006;. These rice class E genes can be separated into two groups: one consists of Os MADS1, Os MADS5, and Os MADS34, and the other consists of Os MADS24 and Os MADS45.…”

“…Analysis of the ABCDE genes in monocot species, such as rice (Oryza sativa), suggests that the ABCDE model could essentially be extended to monocots, except for the role of the class A genes (Kater et al, 2006;. Transgenic rice expressing antisense RNA of the class B gene Os MADS4 shows alteration of stamens into a carpel-like organ (Kang et al, 1998).…”

Phenotypic Characterization and Genetic Mapping of An Open-hull Sterile Mutant in Rice

“…As with other members of the grass family, rice inflorescence is organized in spikelets, each consisting of two sterile lemmas, two rudimentary glumes, and a floret which has one carpel, six stamens, two lodicules, and lemma and one palea (Kyozuka et al 2000;Bommert et al 2005;Kater et al 2006). The glumes, lemma and palea are modified leaves that enclose the reproductive parts of the flower and found only in the grass.…”