Pollen tube growth promotion by MrX from pistils

WENGIER, D. L.; MAZZELLA, M. A.; MCCORMICK, S.; MUSCHIETTI, J. P.

MAr del Plata, Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Higher plants depend on pollen tube growth for the delivery of male gametes to the embryo sac. Upon arrival to the stigma, pollen grain hydrates and produces a structure that grows through the female tissue directionally to the ovules. This growth is regulated positively and negatively by numerous factors such as proteins in the extracellular matrix, low molecular weight compounds, nutrients, ions, etc; this suggests an active communication between female and male tissues. In this context, we purified and characterized MrX, a small molecular weight compound from pistils that specifically dephosphorylates the receptor kinase LePRK2 in tomato pollen plasma membrane. To determine the physiological effects of MrX on pollen grains, in vitro pollen tube growth experiments were done in the presence of a purified fraction of MrX. Tube length was determined on 1- and 3-hour-germinated pollen grains. Results show that pollen tube length increased in a dose-dependent manner. Indeed, after 3 hour of germination, concentrations as low as 0.0003 Abs280nm/microliter induced a statistically significant increase in pollen tube length when compared to pollen grains incubated with a non-active fraction. Our observations suggest that communication between female and male tissues through MrX and LePRK2, results in growth stimulation from the onset of pollen tube development.