A LARGE-SCALE GENE INVENTORY AT EARLY STAGES OF MICROSPOROGENESIS IN Brassica rapa

¹ Plant Science, University of Manitoba, Winnipeg, MB, R3T2N2, Canada

² Vegetable Crops, UCDavis, CA 95616, USA

Plant microsporogenesis plays an essential role in sexual reproduction, providing the opportunity for gene manipulation to induce male sterility as an important tool for crop improvement. Using a genetic male sterile line of B. rapa, we isolated living meiocytes and tetrads in large quantities for gene profiling through the Sequence-Related Amplified Polymorphism (SRAP) technique. More than 400 fragments amplified differentially in cDNA samples from meiocytes and tetrads were sequenced, of which 290 sequences were found to have counterparts in Arabidopsis matching 268 unique genes. Most of these genes with known proteins were classified by function in four main classes: 1) cell division related; 53 sequences matching 46 unique genes in Arabidopsis; 2) transcription and translation related; 67 sequences matching 60 unique genes; 3) chromosome and cell matrix dynamic proteins, 19 sequences matching 18 genes; and 4) kinases and phosphates, 13 sequences matching 12 genes. We validated the origin of these meiocyte-specific genes by RT-PCR after designing 15 pairs of primers based on 15 of these sequences. Most of these genes expressed differentially or only during microsporogenesis. Additionally our survey served to assign function to many other genes whose function remained unidentified in Genbank, being listed as “hypothetical protein” genes. The manipulation of these genes could be explored to create a universal type of male sterility in plants.