Vavilov’s Series of the “Green Revolution” Genes

One hundred years ago N.I. Vavilov formulated the Law of homologous series in hereditary variability. Among the broad range of examples that encouraged N.I. Vavilov to make this important generalization, homologous series in plant height variability were mentioned. In the current review, we compare data collected over the century on genetic basis and molecular mechanisms behind the series in plant height variability with the stress on “Green revolution” genes. Application of fertilizers boosted redirection of artificial selection from tall-growing varieties to those with reduced height. The sources of GA-sensitive and GA-insensitive reduced height (Rht) genes in wheat and rice first were involved in crosses in Japan and China. The commercially valuable alleles of the Rht genes were spread broadly in varieties released in 1960s all over the world. Results of genetic studies into inheritance of the Rht genes are summarized for rice and wheat (together with further Triticeae crops–barley and rye). Three orthologous series of reduced plant height genes have been found within Triticeae tribe species and rice: (1) wheat Rht12 and rye Ddw1; (2) wheat Rht-B1/D1 and barley Dwf2; (3) barley denso/sdw1 and rice sd1. Molecular and cell mechanisms underlying plant reduced height are considered with focus on metabolic pathways regulated by commercially valuable alleles of Rht genes: GA-insensitive Rht-B1/D1 and GA-sensitive sd1, denso/sdw1, Rht8, Rht12, Rht18, Ddw1. Overall, in spite of similar metabolic pathways, the certain genes conferring variability for plant height are often distinct, resulting in existence of several “short” orthologous series of genes rather than one series through different cereal taxa.