Identification and expression profiling of HvMADS57 and HvD14 in a barley tb1 mutant

MADS-box genes interact with TB1 to regulate plant organ morphogenesis. In rice, OsMADS57 interacts with OsTB1 to control OsD14 transcription. In this study, we aimed to determine the relationships among these genes in barley. We identified a natural mutant of HvTB1 (tb1) formed by a C?A transition at position 230, which resulted in a premature stop codon. We cloned the HvMADS57 and HvD14 genes and studied their expression in the tb1 mutant. The results showed that HvMADS57 is a MIKCc -type MADS-box gene, and the expression levels of both HvMADS57 and HvD14 were significantly reduced in the tb1 mutant when compared to those in the wildtype gene. These results indicate that, HvMADS57 regulates plant growth and development by interacting with HvTB1 to suppress the transcription of HvD14 in barley which is similar to the relationships among the orthologs of these genes in rice.

Origination and selection of ABCDE and AGL6 subfamily MADS-box genes in gymnosperms and angiosperms

BACKGROUND: The morphological diversity of flower organs is closely related to functional divergence within the MADS-box gene family. Bryophytes and seedless vascular plants have MADS-box genes but do not have ABCDE or AGAMOUS-LIKE6 (AGL6) genes. ABCDE and AGL6 genes belong to the subgroup of MADS-box genes. Previous works suggest that the B gene was the first ABCDE and AGL6 genes to emerge in plant but there are no mentions about the probable origin time of ACDE and AGL6 genes. Here, we collected ABCDE and AGL6 gene 381 protein sequences and 361 coding sequences from gymnosperms and angiosperms and reconstructed a complete Bayesian phylogeny of these genes. In this study, we want to clarify the probable origin time of ABCDE and AGL6 genes is a great help for understanding the role of the formation of the flower, which can decipher the forming order of MADS-box genes in the future. RESULTS: These genes appeared to have been under purifying selection and their evolutionary rates are not significantly different from each other. Using the Bayesian evolutionary analysis by sampling trees (BEAST) tool, we estimated that: the mutation rate of the ABCDE and AGL6 genes was 2.617 × 10-3 substitutions/site/million years, and that B genes originated 339 million years ago (MYA), CD genes originated 322 MYA, and A genes shared the most recent common ancestor with E/AGL6 296 MYA, respectively. CONCLUSIONS: The phylogeny of ABCDE and AGL6 genes subfamilies differed. The APETALA1 (AP1 or A gene) subfamily clustered into one group. The APETALA3/PISTILLATA (AP3/PI or B genes) subfamily clustered into two groups: the AP3 and PI clades. The AGAMOUS/SHATTERPROOF/SEEDSTICK (AG/SHP/STK or CD genes) subfamily clustered into a single group. The SEPALLATA (SEP or E gene) subfamily in angiosperms clustered into two groups: the SEP1/2/4 and SEP3 clades. The AGL6 subfamily clustered into a single group. Moreover, ABCDE and AGL6 genes appeared in the following order: AP3/PI → AG/SHP/STK → AGL6/SEP/AP1. In this study, we collected candidate sequences from gymnosperms and angiosperms. This study highlights important events in the evolutionary history of the ABCDE and AGL6 gene families and clarifies their evolutionary path.