Quantitative Structure−Activity Relationship Analysis as a Tool To Evaluate the Mode of Action of Chemical Hybridizing Agents for Wheat (Triticum aestivum L.)

Augmentation of wheat production calls for introduction of wheat hybrids in cultivation. In the absence of viable alternative technology of hybrid wheat development, chemical induction of male sterility mediated technology based on chemical hybridizing agents (CHAs) holds a great potential. The QSAR method was applied to two families of CHAs in the N-acylanilines and pyridone class of chemistry. The models for each CHA family gave good correlation between the variations in log percent of male sterility and the steric−electrostatic properties of the sets. QSAR analysis has revealed a direct relationship of the Swain−Lupton constant F p and molecular mass but an inverse relationship of MR, ES, and Swain−Lupton resonance constant R in influencing the bioactivity in the N-acylanilines. QSAR analysis of four parent families consisting of two training sets each of pyrid-2-ones and prid-4-ones revealed the positive contributions of field effect exemplified by the Swain−Lupton field constant (F) and the negative contributions of the molar refractivity (MR) of aromatic substituents in all but one training set. The QSAR models also indicated that increased steric bulk at the 4-position on the phenyl ring is associated with enhanced activity. These leads will be useful in explaining the CHA binding fit in the macromolecular receptor site. Keywords: Chemical hybridizing agents; mode of action; N-acylanilines; pyridones; anilides; quantitative structure−activity relationship; wheat