The BAM1/BAM2 Receptor-Like Kinases Are Important Regulators ofArabidopsisEarly Anther Development

Abstract

Anther development involves the formation of several adjacent cell types required for normal male fertility. Only a few genes are known to be involved in early anther development, particularly in the establishment of these different cell layers. Arabidopsis thaliana BAM1 (for BARELY ANY MERISTEM) and BAM2 encode CLAVATA1-related Leu-rich repeat receptorlike kinases that appear to have redundant or overlapping functions. We characterized anther development in the bam1 bam2 flowers and found that bam1 bam2 anthers appear to be abnormal at a very early stage and lack the endothecium, middle, and tapetum layers. Analyses using molecular markers and cytological techniques of bam1 bam2 anthers revealed that cells interior to the epidermis acquire some characteristics of pollen mother cells (PMCs), suggesting defects in cell fate specification. The pollen mother-like cells degenerate before the completion of meiosis, suggesting that these cells are defective. In addition, the BAM1 and BAM2 expression pattern supports both an early role in promoting somatic cell fates and a subsequent function in the PMCs. Therefore, analysis of BAM1 and BAM2 revealed a cell-cell communication process important for early anther development, including aspects of cell division and differentiation. This finding may have implications for the evolution of multiple signaling pathways in specifying cell types for microsporogenesis.

Viability and Action of CPL Lectin on <i>in Vitro</i> Germinability of Pollen Grains of <i>Malpighia emarginata</i> DC.—(Malpighiaceae)

“…Other authors [35][36][37] also found that RLK lectins appear to control the development of pollen development by regulating the endothecium, middle lamella and tapetum.…”

The Rice Basic Helix-Loop-Helix Transcription Factor TDR INTERACTING PROTEIN2 Is a Central Switch in Early Anther Development

“…In Arabidopsis, SPOROCYTELESS (SPL)/NOZZLE is required for sporogenous cell formation, and BARELY ANY MERISTEM1 (BAM1) and BAM2 promote somatic cell fate by limiting the expression of SPL. In spl mutants, sporogenous cell generation is impaired, and bam1 bam2 mutants produce extra pollen mother cells at the expense of adjacent somatic cells (Schiefthaler et al, 1999;Yang et al, 1999;Hord et al, 2006;Liu et al, 2009).…”

A Tale of Two Systems: Peptide Ligand-Receptor Pairs in Plant Development

“…Other LRR-RLKs, BARELY ANY MERISTEM (BAM) receptors close to CLV1, have also been suggested to regulate SAM homeostasis by promoting stem cell maintenance . Unlike CLV1, they are broadly expressed and control various developmental processes Hord et al 2006). BAM can directly bind to CLE9, which has been shown to be specifically expressed in stomatal lineage cells (Shinohara et al 2012).…”