The barren stalk2 Gene Is Required for Axillary Meristem Development in Maize.

The diversity of plant architecture is determined by axillary meristems (AMs). AMs are produced from small groups of stem cells in the axils of leaf primordia and generate vegetative branches and reproductive inflorescences. Previous studies identified genes critical for AM development that function in auxin biosynthesis, transport, and signaling.

vanishing tassel2 encodes a grass-specific tryptophan aminotransferase required for vegetative and reproductive development in maize.

Auxin plays a fundamental role in organogenesis in plants. Multiple pathways for auxin biosynthesis have been proposed, but none of the predicted pathways are completely understood. Here, we report the positional cloning and characterization of the vanishing tassel2 (vt2) gene of maize (Zea mays).

Developmental disaster1: A novel mutation causing defects during vegetative and inflorescence development in maize (Zea mays, Poaceae).

Axillary meristems, which give rise to branches and flowers, play a critical role in plant architecture and reproduction. To understand how axillary meristems initiate, we have screened for mutants with defects in axillary meristem initiation to uncover the genes controlling this process. These mutants, called the barren class of mutants in maize (Zea mays), have defects in axillary meristem initiation during both vegetative and reproductive development.

BARREN INFLORESCENCE2 interaction with ZmPIN1a suggests a role in auxin transport during maize inflorescence development.

Polar auxin transport, mediated by the PIN-FORMED (PIN) class of auxin efflux carriers, controls organ initiation in plants. In maize, BARREN INFLORESCENCE2 (BIF2) encodes a serine/threonine protein kinase co-orthologous to PINOID (PID), which regulates the subcellular localization of AtPIN1 in Arabidopsis. We show that BIF2 phosphorylates ZmPIN1a, a maize homolog of AtPIN1, in vitro and regulates ZmPIN1a subcellular localization in vivo, similar to the role of PID in Arabidopsis.

Suppressor of sessile spikelets1 functions in the ramosa pathway controlling meristem determinacy in maize.

The spikelet, which is a short branch bearing the florets, is the fundamental unit of grass inflorescence architecture. In most grasses, spikelets are borne singly on the inflorescence. However, paired spikelets are characteristic of the Andropogoneae, a tribe of 1,000 species including maize (Zea mays).

Genetic and physical interaction suggest that BARREN STALK 1 is a target of BARREN INFLORESCENCE2 in maize inflorescence development.

Organogenesis in plants is controlled by polar auxin transport. In maize (Zea mays), barren inflorescence2 (bif2) encodes a co-ortholog of the serine/threonine protein kinase PINOID (PID), which regulates auxin transport in Arabidopsis. In this paper, we report that the basic helix-loop-helix transcription factor BARREN STALK1 (BA1) is a putative target of BIF2, revealing a previously unknown function of BIF2 in the nucleus.

barren inflorescence2 Encodes a co-ortholog of the PINOID serine/threonine kinase and is required for organogenesis during inflorescence and vegetative development in maize.

Organogenesis in plants is controlled by meristems. Axillary meristems, which give rise to branches and flowers, play a critical role in plant architecture and reproduction. Maize (Zea mays) and rice (Oryza sativa) have additional types of axillary meristems in the inflorescence compared to Arabidopsis (Arabidopsis thaliana) and thus provide an excellent model system to study axillary meristem initiation.

Identification and characterization of PiORP1, a Petunia oxysterol-binding-protein related protein involved in receptor-kinase mediated signaling in pollen, and analysis of the ORP gene family in Arabidopsis.

Oxysterol-binding proteins (OSBPs) and oxysterol-binding-protein related proteins (ORPs) are encoded by most eukaryotic genomes examined to date; however, they have not yet been characterized in plants. Here we report the identification and characterization of PiORP1, an ORP of Petunia inflata that interacts with the cytoplasmic kinase domain of a receptor-like kinase, named PRK1, of P. inflata.

Petunia phospholipase c1 is involved in pollen tube growth.

Although pollen tube growth is essential for plant fertilization and reproductive success, the regulators of the actin-related growth machinery and the cytosolic Ca2+ gradient thought to determine how these cells elongate remain poorly defined. Phospholipases, their substrates, and their phospholipid turnover products have been proposed as such regulators; however, the relevant phospholipase(s) have not been characterized. Therefore, we cloned cDNA for a pollen-expressed phosphatidylinositol 4,5-bisphosphate (PtdInsP2)-cleaving phospholipase C (PLC) from Petunia inflata, named Pet PLC1.

Identification of the pollen determinant of S-RNase-mediated self-incompatibility.

Many flowering plants have adopted self-incompatibility mechanisms to prevent inbreeding and promote out-crosses. In the Solanaceae, Rosaceae and Scrophulariaceae, two separate genes at the highly polymorphic S-locus control self-incompatibility interactions: the S-RNase gene encodes the pistil determinant and the previously unidentified S-gene encodes the pollen determinant. S-RNases interact with pollen S-allele products to inhibit the growth of self-pollen tubes in the style.

S-RNase-mediated self-incompatibility.

The Solanaceae, Rosaceae, and Scrophulariaceae families all possess an RNase-mediated self-incompatibility mechanism through which their pistils can recognize and reject self-pollen to prevent inbreeding. The highly polymorphic S-locus controls the self-incompatibility interaction, and the S-locus of the Solanaceae has been shown to be a multi-gene complex in excess of 1.3 Mb.