Lotus japonicus HAR1 regulates root morphology locally and systemically under a moderate nitrate condition in the absence of rhizobia.

The local and long-distance signaling pathways mediated by the leucine-rich repeat receptor kinase HAR1 suppress root branching and promote primary root length in response to nitrate supply. The root morphology of higher plants changes plastically to effectively absorb nutrients and water from the soil. In particular, legumes develop root organ nodules, in which symbiotic rhizobia fix atmospheric nitrogen in nitrogen-poor environments.

Spatial regulation of resource allocation in response to nutritional availability.

It is critical for a living organism to appropriately allocate resources among its organs, or within a specific organ, because available resources are generally limited. For example, in response to the nutritional environment of their soil, plants regulate resource allocation in their roots in order to plastically change their root system architecture (RSA) for efficiently absorbing nutrients. However, it is still not understood why and how RSA is adaptively controlled.

LARGE GRAIN Encodes a Putative RNA-Binding Protein that Regulates Spikelet Hull Length in Rice.

Grain size is a key determiner of grain weight, one of the yield components in rice (Oryza sativa). Therefore, to increase grain yield, it is important to elucidate the detailed mechanisms regulating grain size. The Large grain (Lgg) mutant, found in the nonautonomous DNA-based active rice transposon1 (nDart1)-tagged lines of Koshihikari, is caused by a truncated nDart1-3 and 355 bp deletion in the 5' untranslated region of LGG, which encodes a putative RNA-binding protein, through transposon display and cosegregation analysis between grain length and LGG genotype in F2 and F3.

A gain-of-function Bushy dwarf tiller 1 mutation in rice microRNA gene miR156d caused by insertion of the DNA transposon nDart1.

A non-autonomous DNA transposon in rice, nDart1, is actively transposed in the presence of an autonomous element, aDart1, under natural conditions. The nDart1-promoted gene tagging line was developed using the endogenous nDart1/aDart1 system to generate various rice mutants effectively. While the dominant mutants were occasionally isolated from the tagging line, it was unclear what causes dominant mutations.

A mutable albino allele in rice reveals that formation of thylakoid membranes requires the SNOW-WHITE LEAF1 gene.

Active DNA transposons are important tools for gene functional analysis. The endogenous non-autonomous transposon, nDart1-0, in rice (Oryza sativa L.) is expected to generate various transposon-insertion mutants because nDart1-0 elements tend to insert into genic regions under natural growth conditions.

Examination of transpositional activity of nDart1 at different stages of rice development.

As a useful tool to elucidate gene functions, a rice transposon tagging line has been developed using an active endogenous DNA transposon, nDart1. It was highly desirable to evaluate the transposition timing and frequency of the nDart1 elements during rice development to facilitate the generation of an efficient mutant isolation system. Comparison of the detected new insertions at different stages of rice development by transposon display analysis demonstrated that the last heading tiller carry a higher number of nDart1 elements than the main culm.

A rice mutant displaying a heterochronically elongated internode carries a 100 kb deletion.

We have isolated a recessive rice mutant, designated as indeterminate growth (ing), which displays creeping and apparent heterochronic phenotypes in the vegetative period with lanky and winding culms. Rough mapping and subsequent molecular characterization revealed that the ing mutant carries a large deletion, which corresponds to a 103 kb region in the Nipponbare genome, containing nine annotated genes on chromosome 3. Of these annotated genes, the SLR1 gene encoding a DELLA protein is the only one that is well characterized in its function, and its null mutation, which is caused by a single base deletion in the middle of the intronless SLR1 gene, confers a slender phenotype that bears close resemblance to the ing mutant phenotype.

Composition and structure of the centromeric region of rice chromosome 8.

Understanding the organization of eukaryotic centromeres has both fundamental and applied importance because of their roles in chromosome segregation, karyotypic stability, and artificial chromosome-based cloning and expression vectors. Using clone-by-clone sequencing methodology, we obtained the complete genomic sequence of the centromeric region of rice (Oryza sativa) chromosome 8. Analysis of 1.

Physical maps and recombination frequency of six rice chromosomes.

We constructed physical maps of rice chromosomes 1, 2, and 6-9 with P1-derived artificial chromosome (PAC) and bacterial artificial chromosome (BAC) clones. These maps, with only 20 gaps, cover more than 97% of the predicted length of the six chromosomes. We submitted a total of 193 Mbp of non-overlapping sequences to public databases.