Genetic Variability for Osmotic Adjustment in Pollen Grains and its Association with Field Tolerance to Moisture Stress in Maize Inbred Lines

Drought severely affects gametophytic development in maize. To explore pollen tolerance to drought stress, the pollen grains of 16 inbred lines were subjected to osmotic stress (without and with osmolyte; 10 mM CaCl₂) under in vitro conditions. The effect of stress was observed as a measure of intrinsic osmotic adjustment (OA) and induced OA. Evaluation of inbreds for drought tolerance in field indicated significant differences for sensitivity drought index (SDI) among the lines. The Δ¹³ surrogate trait indicated genotypic differences for drought tolerance. Significant negative correlation was observed between pollen OA and SDI values; and positive correlation between pollen OA and Δ¹³ values, suggesting correspondence in drought tolerance between pollen and sporophyte. The superoxide dismutase isozyme expression also indicated the overlap drought tolerance mechanism. Thus, the present study provides an insight into overlapping behaviour regarding stress response mechanism of pollen grains and plants.