N-Acylanilines, Herbicide−CHA Chimera, and Amino Acid Analogues as Novel Chemical Hybridizing Agents for Wheat (Triticum aestivum L.)

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. N-Acylaniline derivatives, namely, ethyl 4'-fluoro oxanilate (1) and ethyl 4'-trifluoromethyl oxanilate (2) containing halogen atoms in the para position of the aryl ring and substituted amide linkage (-CO-NH-) in the acyl side chain induced >98% spikelet sterility on three genotypes of wheat, namely, PBW 343, HD 2046 and HD 2733, at 1500 ppm. The active moieties were incorporated in the form of herbicide-CHA chimera and amino acid analogues using glycine and alanine as templates. The target activity was made more selective by synthesizing chimeric structure of herbicide (2,4-dichlorophenoxyacetic acid and dalapon) and the most active CHA templates, namely, 4- fluoroanilinyl and beta-ethoxycarbonyl moieties. Among herbicide-CHA chimera ethyl 2',4'-dichlorophenyl oxalate (14) induced 79.11% male sterility, whereas benzyl methyl 2-oxo-3-azaadipate (20) was the best, inducing 73.87% male sterility in HD 2733, among amino acid analogues. The CHAs were found to modify the reproductive biology to ensure cross-pollination in the cleistogamous wheat flowers, increasing the probability for the development of hybrids.