Mutation of the Rice Narrow leaf1 Gene, Which Encodes a Novel Protein, Affects Vein Patterning and Polar Auxin Transport

Abstract

The size and shape of the plant leaf is an important agronomic trait. To understand the molecular mechanism governing plant leaf shape, we characterized a classic rice (Oryza sativa) dwarf mutant named narrow leaf1 (nal1), which exhibits a characteristic phenotype of narrow leaves. In accordance with reduced leaf blade width, leaves of nal1 contain a decreased number of longitudinal veins. Anatomical investigations revealed that the culms of nal1 also show a defective vascular system, in which the number and distribution pattern of vascular bundles are altered. Map-based cloning and genetic complementation analyses demonstrated that Nal1 encodes a plant-specific protein with unknown biochemical function. We provide evidence showing that Nal1 is richly expressed in vascular tissues and that mutation of this gene leads to significantly reduced polar auxin transport capacity. These results indicate that Nal1 affects polar auxin transport as well as the vascular patterns of rice plants and plays an important role in the control of lateral leaf growth.

NAL1 allele from a rice landrace greatly increases yield in modern indica cultivars

“…Through high-resolution mapping, we identified SPIKE, which influences TSN and FLW. Transgenic analysis revealed that SPIKE was identical to Nal1, which affects vein patterning in leaves and polar auxin transport (23). SPIKE, identified from natural variation, is a unique allele from tropical japonica, whereas nal1, identified from a mutant line, is a loss-of-function mutation.…”

Arabidopsis phosphatidylinositol monophosphate 5-kinase 2 is involved in root gravitropism through regulation of polar auxin transport by affecting the cycling of PIN proteins

“…Auxin transport assay was performed according to previous description [76]. Ten-mm root segments were cut from 6-day-old WT and pip5k2 seedlings, and aligned root apices were used for measurement of the polar auxin transport.…”

Natural Variation in the Flag Leaf Morphology of Rice Due to a Mutation of the NARROW LEAF 1 Gene in Oryza sativa L.

“…Notably, the deletion of two amino acids in exon 1 resulted in a phenotype similar to that of the null mutant, with a 50% reduction in the width and length of the leaf (Jiang et al 2015). Compared to a deletion in exon 1, a 10-amino-acid deletion in exon 4 had a milder effect: it reduced the blade width by 37% and the blade length by 13% (Qi et al 2008). The Phulba allele, which produces a truncated protein consisting of only exon 1 (type V), resulted in a phenotype similar to that of the H-type allele (type IV9), which appeared to have no obvious defects ( Figure 6).…”

“…NAL1 was highly expressed in the vascular bundle, especially in the phloem (Qi et al 2008), and its expression peaked at the P3 stage when the small vascular bundle formed. Therefore, its main effect appears to be on the formation of vascular bundles, especially small vascular bundles, which subsequently affect leaf width and morphology.…”

“…NAL1 was originally isolated as a gene affecting vascular patterns in a study on a classic dwarf mutant with a narrow leaf (Qi et al 2008) and was later shown to affect WFL, total spikelet number per panicle, photosynthetic rate, and chlorophyll content (Chen et al 2012;Fujita et al 2013;Takai et al 2013;Zhang et al 2014). NAL1 encodes a plant-specific protein, and the nal1 mutant with an in-frame deletion of 10 amino acids in exon 4 showed reduced basipetal polar auxin transport and fewer longitudinal veins, compared with wild type (Qi et al 2008). A recent analysis of mutant rice with a NAL1 null allele implied that NAL1 is also involved in control of the cell cycle and cell division from the initial stage of leaf development onward (Jiang et al 2015).…”