Role of Proline and Glycinebetaine in Improving Chilling Stress Tolerance in Sugarcane Buds at Sprouting

Sugarcane shows reduced crop stand under suboptimal conditions, the main reason amongst others is sensitivity of bud tissue to temperature fluctuations. The aim of these studies was to monitor the time course changes in some physiological and histological attributes and possible roles of proline and glycinebetaine (GB) in mitigating the effect of chilling stress in the sprouting nodal buds of sugarcane. Chilling stress reduced bud fresh and dry weights, led to the generation of H2O2, reduced the tissue levels of K+ and Ca2+; nonetheless, osmolytes synthesis was enhanced in a time course manner. As for the histological changes, chilling stress restricted and delayed the formation of new bud leaves and their expansion, which was mainly, because of reduction in the number and area of mesophyll cells and poor development of vascular bundles. The pretreatment of bud chips with proline and GB substantially reduced the production of H2O2, improved the synthesis of soluble sugars and protected the developing tissues from chilling stress effects. Correlation matrix indicated that pretreatment with proline and GB reduced H2O2 generation, improved the K+ and Ca2+ nutrition, levels of free proline, GB and soluble sugars thus improving chilling resistance in sugarcane buds. (c) 2010 Friends Science Publishers