Isolation and characterization of two tightly linked catalase genes from castor bean that are differentially regulated

Two catalase genes,cat1 andcat2, have been isolated from the castor bean genome. They were located in the same direction on a chromosome at a distance of 2.4 kb,cat1 being on the downstream side ofcat2. The two genes contained introns at the same positions except that one of the 7 introns incat1 is missing incat2 and the corresponding introns differed in size and sequence between the two genes. The translated regions of the two genes had the same number of nucleotides and exhibited 81.3% nucleotide sequence identity. In addition to introns, the nucleotide sequences of the 5-and 3-flanking regions are highly divergent between the two genes. In etiolated seedlings,cat1 mRNA was present abundantly in endosperms and cotyledons and only in a small amount in roots. Thecat1 mRNA could not be detected in hypocotyls. By contrast,cat2 mRNA is most abundant in hypocotyls and roots, while endosperms and cotyledons contained only low levels ofcat2 mRNA. Although neithercat1 norcat2 mRNA could be detected in dry seeds, both mRNAs showed temporal accumulation in the endosperm in response to germination. These results suggest that expression of two tightly linked catalase genes of castor bean,cat1 andcat2, are differentially regulated during development.     

Induction of Polysome Formation in Sweet Potato Root Tissue in Response to Wounding

We determined the effects of yolk water-soluble protein (YSP) on bone resorption. YSP potently suppressed osteoclastogenesis from bone marrow-derived precursor cells driven by tumor necrosis factor-α (TNF-α). YSP (200 μg/ml) abolished the formation of tartarate-resistant acid phosphatase (TRAP)-positive osteoclasts. Furthermore, TNF-α induced TRAP activity was greatly inhibited by YSP (100 μg/ml) treatment. Our results suggest that YSP has therapeutic potential for bone-erosive diseases.     

A Putative Receptor Protein Kinase Gene in Ipomoea trifida

We have characterized a cDNA clone, IRK1, for a putative receptorkinase from a stigma cDNA library of Ipomoea trifida. IRK1 proteincontains an extracellular receptor-like domain and the consensussequences diagnostic of serine/threonine protein kinase. Boththe pattern of gene expression and the results of RFLP analysisindicate that the IRK1 gene is not primarily involved in theself-incompatibility system of Ipomoea. (Received October 16, 1995; Accepted April 10, 1996)     

Differential in Situ Expression of Three ABA-Regulated Genes of Rice, RAB16A, REG2 and OSBZ8, during Seed Development

The spatial and temporal expression patterns of three ABA-regulatedgenes of rice in the developing seeds of wild type and embryonicmutants were studied by in situ hybridization. By the use ofan embryo-less mutant, we found that the expression of thesegenes in the aleurone layers was independent of embryonic tissues. (Received August 24, 1998; Accepted January 23, 1999)     

RICE SALT SENSITIVE3 binding to bHLH and JAZ factors mediates control of cell wall plasticity in the root apex

Plasticity of root growth in response to environmental cues and stresses is a fundamental characteristic of plants, in accordance with their sessile lifestyle. This is linked to the balance between plasticity and rigidity of cells in the root apex, and thus is coordinated with the control of cell wall properties. However, mechanisms underlying such harmonization are not well understood, in particular under stressful conditions. We have recently demonstrated that RICE SALT SENSITIVE3 (RSS3), a nuclear factor that mediates restrictive expression of jasmonate-induced genes, plays an important role in root elongation under saline conditions. In this study, we report that loss-of-function of RSS3 results in changes in cell wall properties such as lignin deposition and sensitivity to a cellulose synthase inhibitor, concomitant with altered expression of genes involved in cell wall metabolism. Based on these and previous phenotypic observations of the rss3 mutant, we propose that RSS3 plays a role in the coordinated control of root elongation and cell wall plasticity in the root apex.