Cloning and Characterization of a Putative TAC1 Ortholog Associated with Leaf Angle in Maize (Zea mays L.)

BACKGROUND: Modifying plant architecture to increase photosynthesis efficiency and reduce shade avoidance response is very important for further yield improvement when crops are grown in high density. Identification of alleles controlling leaf angle in maize is needed to provide insight into molecular mechanism of leaf development and achieving ideal plant architecture to improve grain yield. METHODOLOGY/PRINCIPAL FINDINGS: The gene cloning was done by using comparative genomics, and then performing real-time polymerase chain reaction (RT-PCR) analysis to assay gene expression. The gene function was validated by sequence dissimilarity analysis and QTL mapping using a functional cleaved amplified polymorphism (CAP). CONCLUSIONS: The leaf angle is controlled by a major quantitative trait locus, ZmTAC1 (Zea mays L. Leaf Angle Control 1). ZmTAC1 has 4 exons encoding a protein with 263 amino acids, and its domains are the same as those of the rice OsTAC1 protein. ZmTAC1 was found to be located in the region of qLA2 by using the CAP marker and the F(2:3) families from the cross between Yu82 and Shen137. Real-time PCR analysis revealed ZmTAC1 expression was the highest in the leaf-sheath pulvinus, less in the leaf and shoot apical meristem, and the lowest in the root. A nucleotide difference in the 5'-untranslated region (UTR) between the compact inbred line Yu82 ("CTCC") and the expanded inbred line Shen137 ("CCCC") influences the expression level of ZmTAC1, further controlling the size of the leaf angle. Sequence verification of the change in the 5'-UTR revealed ZmTAC1 with "CTCC" was present in 13 compact inbred lines and ZmTAC1 with "CCCC" was present in 18 expanded inbred lines, indicating ZmTAC1 had been extensively utilized in breeding with regard to the improvement of the maize plant architecture

Common and distinct mechanisms underlying the establishment of adaxial and abaxial polarity in stamen and leaf development

Establishment of adaxial-abaxial polarity is essential for lateral organ development. A stamen consists of a bilaterally symmetrical anther and a radial filament. Using a rice mutant, rod-like lemma, in which establishment of adaxial-abaxial polarity is compromised, we found that stamen patterning is likely to be achieved by a unique regulatory mechanism: rearrangement of adaxial-abaxial polarity in the anther, and abaxialization in the filament. These regulations are not found in leaf development. Here, we discuss similarities and differences between the stamen and the leaf in the mechanisms underlying the establishment of adaxialabaxial polarity. In addition, we propose the idea that the process of establishing adaxial-abaxial polarity in lateral organs is likely to be divided into two phases: a meristem-dependent, followed by a meristem-independent phase. In stamen development, the transition between these two phases is clearly observed as the rearrangement of expression patterns of the adaxial and abaxial marker genes