Variations in Calcium Requirements for In Vitro Shoot Culture among Potato Cultivars

Tissue cultures offer an accurate system for the evaluation of nutrient deficiency studies for immobile nutrients such as calcium. Calcium is an important plant nutrient and its role in plant growth and development is well known. In our previous studies, we have reported that a calcium deficiency to in vitro shoot cultures causes damage to potato shoot subapical expanding cells resulting in shoot tip necrosis and development of axillary shoots. This study was conducted using only potato cultivar Dark Red Norland and shoot tip injury occurred when the media Ca was below 300 µM. The standard MS media for shoot cultures contains 3000 µM Ca. In the present study we investigated the variability of Ca requirements within potato cultivars Solanum tuberosum L. using an in vitro shoot culture system. Shoot cultures of three potato cultivars were grown in the standard MS media containing Ca concentrations from 50–3000 µM. Shoot tip health and axillary shoots development were evaluated after 20–30 days after transfer. The media calcium concentration varied for each cultivar to first observe (threshhold) Ca deficiency symptoms. For example this threshhold media calcium concentration was about 60 µM for the cultivar Snowden, 275 µM for cultivar Dark Red Norland, and 700 µM for the cultivar Burbank. Our results suggest that there is a genetic variation within potato cultivars for Ca requirement for healthy growth in vitro.