Characterization of dwarf and narrow leaf (<i>dnl-4</i>) mutant in rice

Abstract

Height and leaf morphology are important agronomic traits of the major crop plant rice (<i>Oryza sativa</i>). In previous studies, the <i>dwarf and narrow leaf</i> genes (<i>dnl1, dnl2</i> and <i>dnl3</i>) have identified in rice. Using the <i>Ac</i>/<i>Ds</i> knockout system, we found a new dwarf and narrow leaf (dnl) mutant and identified mutated gene. The <i>dnl-4</i> mutant showed reduced plant height and leaf blade width compared to the wild type, and increased leaf inclination. The morphological defects of the mutant were caused by the suppressed expression of the <i>DNL-4</i> gene, which encodes a pfkB carbohydrate kinase protein. These results suggest that <i>DNL-4</i> expression is involved in modulating plant height and leaf growth. Furthermore, <i>DNL-4</i> expression also affects productivity in rice: the <i>dnl-4</i> mutant exhibited reduced panicle length and grain width compared with the wild type. To understand <i>DNL-4</i> function in rice, we analyzed the expression levels of leaf growth-related genes, such as <i>NAL1, NAL7</i>, and <i>CSLD4</i>, in the <i>dnl-4</i> mutant. Expression of <i>NAL1</i> and <i>NAL7</i> was downregulated in the <i>dnl-4</i> mutant compared to the wild type. The observation that <i>DNL-4</i> expression corresponded with that of <i>NAL1</i> and <i>NAL7</i> is consistent with the narrow leaf phenotype of the <i>dnl-4</i> mutant. These results suggest that <i>DNL-4</i> regulates plant height and leaf structure in rice.