Poster: Reproductive development

Abs # 709: PIRL1 and PIRL9, novel intracellular LRR proteins, are required for pollen development in Arabidopsis

Presenter:	Vernon, Daniel M, Contact Author
Authors	Forsthoefel, Nancy R (A)   Geiser, Heidi A (A)   Vernon, Daniel M (A)
Affiliations:	(A): Whitman College

PIRLs (Plant Intracellular Ras-group-related LRRs) are an intriguing plant-specific class of leucine-rich repeat proteins related to intracellular signal transduction LRRs from animals and fungi. To determine the functions of these previously uncharacterized proteins, we are carrying out a systematic reverse-genetic study of the 9 Arabidopsis PIRLs. Here we describe knockout analysis of the closely-related PIRL1 and PIRL9 genes. Pirl1 and pirl9 T-DNA insertion lines were identified, homozygotes isolated, and knockout status confirmed by RT-PCR. Mutant alleles displayed normal Mendelian segregation and homozygotes did not exhibit obvious developmental defects. To investigate possible functional redundancy, we attempted to construct pirl1;pirl9 double mutants. Double mutant progeny could not be recovered, suggesting either early lethality or gametophytic transmission failure of the double mutant allele combination. Selfed pirl1;pirl9 heterozygotes did not produce aborted or abnormal seeds, ruling out the possibility of sporophytic embryo lethality. PCR genotyping of progeny from reciprocal crosses between wild-type and pirl1;pirl9 carriers indicated that the pirl1;pirl9 allele combination failed to transmit specifically via the male gametophyte. Scanning electron microscopy of pollen produced by pirl1-/-;pirl9+/- and pirl1-/+,pirl9-/- individuals revealed that ~50% of the pollen was severely malformed, a phenotype frequency consistent with the predicted meiotic segregation of the double mutant allele combination. PIRL1 & PIRL9 therefore have redundant roles essential for male gametophyte function. These novel LRR proteins likely take part in intracellular signaling, transport, or regulatory processes crucial for pollen development. -Supported by USDA grant 2002350412304