Elemental and biochemical markers of stigma receptivity in sunflower
2014
Sharma, Basudha | Bhatla, S. C.
Stigma development in sunflower is accompanied with an accumulation of calcium (33 %), potassium (37 %) and boron (62 %) in mature stigma as compared to stigma at bud stage, thereby demonstrating their essential roles in attaining receptivity. Membrane-bound calcium accumulation is enhanced on the pellicle and is also evident in the cytoplasm accompanying stigma maturation. Total soluble carbohydrate content increases in the staminate stage (55 %) as compared to bud stage. Glucose and fructose are the major monosaccharides and their contents are maximum in the staminate stage. Total lipid content also increases with the passage of stigma development. Erucic acid (22:1) is expressed specifically in the bud and staminate stages. A variation in the contents of triacylglycerides and free fatty acids, and expression of fatty acyl esterases in mature stigma have been correlated with biochemical events associated with signalling mechanisms. Lastly, enhanced expression of two hydrolytic enzymes, namely β-1,3 glucanase and fatty acyl ester hydrolase, has been observed to correlate with stigma maturation. Present findings, thus, provide new information on the structural and biochemical changes marking various signalling events associated with successful pollen–stigma interaction.
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