Poster: Reproductive development

Abs # 343: Decreased accumulation of ATP and mitochondrial ATP synthase subunits in developing pollen of S male-sterile maize

Presenter:	Siripant, May N., aquabele@ufl.edu
Authors	Siripant, May N. (A)   Ortega, Victor M (A)   Chase, Christine D (A)
Affiliations:	(A): University Of Florida

In the S cytoplasmic male sterility (CMS-S) system of maize, expression of mitochondrial open reading frames (orf355-orf17) conditions collapse of developing haploid pollen following the microspore mitosis. The orf17 gene predicts a protein that is 65% identical to the ATP synthase subunit 9 C-terminal membrane domain. Two approaches were used to assess whether ATP synthase function is compromised during the development of CMS-S maize pollen. Indirect measurements of ATP demonstrated a 60-70% reduction of ATP levels in the sterile microspores as compared to normal microspores. Western blot analysis showed decreased accumulation of ATP synthase subunits 4, 6, and 9 in CMS-S microspores as compared to normal microspores. We propose that ATP synthase dysfunction causes a decrease in ATP levels and an increase in mitochondrial matrix pH. These conditions favor opening of the mitochondrial permeability transition pore, resulting in mitochondrial-signaled programmed cell death and pollen collapse.