Morphological and physiological analysis of cleistogamy in barley (<i>Hordeum vulgare</i>)

Abstract

We previously reported that cleistogamy/chasmogamy (CL/CH) of barley ( Hordeum vulgare L.) is controlled by either two tightly linked genes or one gene with multiple alleles. To clarify the morphological and physiological mechanisms of barley CL, we analysed the lodicule size and auxin response of two cultivars whose CL/CH was controlled by two different genes, cly1 and Cly2 . In both cases, lodicules of the CL parent were smaller than those of the CH parent. Analyses of lodicule size and flowering phenotype of f 1 plants and segregation analyses of the mapping population indicated that lodicule size co‐segregated with the flowering phenotype. Indole‐3‐acetic acid (IAA) and other synthetic auxins, such as 2,4‐dichlorophenoxyacetic acid, induced abnormal flowering in CH ears, in which florets remained open for a few days instead of the normal hour or so, but not in CL ears. This auxin effect also co‐segregated with the flowering phenotype. Analyses of auxin‐related compounds in the floret organs revealed that the anther contained high levels of IAA, whereas indole‐3‐carboxylic acid, a putative decarboxylated metabolite of IAA, accumulated only in lodicules of CH plants just at flowering. These results indicate that lodicule size and auxin response are pleiotropic effects of the CL gene, which may play a role in auxin response or metabolism.