| I. Research Notes The genetics of floral development in wheat O. H. FRANKEL and A. M. MUNDAY Division of Plant Industry, C.S.I.R.O., Canberra, Australia " Basal Sterility " in wheat has been studied for a number of years for three principal reasons. Firstly, a progressive series of genotypes differing from each other in the extent of flower abnormalities open possibilities for a study of the hereditary component of morphogenesis. This presumably is the first time such an attempt has been made. Secondly, the work has uncovered the possibility that ancestral genomes, from which hexaploid wheat was built, possessed genetic systems for flower formation which have been replaced and, hence, have become non-functional. This phase of the study, therefore, is designed to shed light on the evolution of gene function in a high polyploid. Thirdly, interactions between genetic and environmental determinants of flower development have been discovered which are being further studied. This report deals only with progress in the first and second phases. Basal sterility is a condition in wheat, so far only found in speltoid mutants, in which flower formation in one or more basal flowers of some or all spikelets is impaired. The degree of flower abnormality varies from loss or reduction of the anterior stamen to complete absence of any flower parts. There is a pattern which is variable within the ear, where the apex tends to be least affected, but is rigid within spikelets, where the next higher flower never is more affected than the lower one, so that only if the basal (the first) flower is affected will the second one be affected, and so on. We had previously shown (Frankel and Fraser 1948) that the normal flower development in vulgare is determined by a single gene closely associated with the gene Q which determines the vulgare characteristics. It is only in the absence of Q, i.e. in speltoids, that basal sterility is found. We have been working with crosses between four speltoids, grading in flower development from almost complete normality to almost complete absence of the first three flowers. |
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