A novel QTL associated with tolerance to cold-induced seed cracking in the soybean cultivar Toyomizuki.

Low temperatures after flowering cause seed cracking (SC) in soybean. Previously, we reported that proanthocyanidin accumulation on the dorsal side of the seed coat, controlled by the locus, may lead to cracked seeds; and that homozygous alleles at the locus confer SC tolerance in the line Toiku 248. To discover new genes related to SC tolerance, we evaluated the physical and genetic mechanisms of SC tolerance in the cultivar Toyomizuki (genotype ).

A pubescence color gene enhances tolerance to cold-induced seed cracking in yellow soybean.

In yellow soybean, severe cold weather causes seed cracking on the dorsal side. Yellow soybeans carry the or allele of the locus and have a yellow () or pigmented ( ) hilum. We previously isolated an additional allele, designated as , of the locus, and reported that yellow soybeans with the genotype may be tolerant to cold-induced seed cracking.

Identification and validation of quantitative trait loci associated with seed yield in soybean.

In soybean [ (L.) Merrill], the genetic analysis of seed yield is important to aid in the breeding of high-yielding cultivars. Seed yield is a complex trait, and the number of quantitative trait loci (QTL) involved in seed yield is high.

A major gene for tolerance to cold-induced seed coat discoloration relieves viral seed mottling in soybean.

In yellow soybeans, inhibition of seed coat pigmentation by RNA silencing of genes is suppressed by low temperature and a viral suppressor, resulting in 'cold-induced seed coat discoloration' and 'seed mottling', respectively. Differences exist in the degree of cold-induced seed coat discoloration among Japanese yellow soybean cultivars; for example, Toyomusume is sensitive, Toyohomare has some tolerance, and Toyoharuka is highly tolerant. In this study, we compared the degree of seed mottling severity due to soybean mosaic virus (SMV) among these three soybean cultivars.

Suppression of RNA-dependent RNA polymerase 6 in tomatoes allows potato spindle tuber viroid to invade basal part but not apical part including pluripotent stem cells of shoot apical meristem.

RNA-dependent RNA polymerase 6 (RDR6) is one of the key factors in plant defense responses and suppresses virus or viroid invasion into shoot apical meristem (SAM) in Nicotiana benthamiana. To evaluate the role of Solanum lycopersicum (Sl) RDR6 upon viroid infection, SlRDR6-suppressed (SlRDR6i) 'Moneymaker' tomatoes were generated by RNA interference and inoculated with intermediate or lethal strain of potato spindle tuber viroid (PSTVd). Suppression of SlRDR6 did not change disease symptoms of both PSTVd strains in 'Moneymaker' tomatoes.

Occurrence and tolerance mechanisms of seed cracking under low temperatures in soybean (Glycine max).

In soybean, occurrence of, or tolerance to, seed cracking under low temperatures may be related to the presence or absence, respectively, of proanthocyanidin accumulation in the seed coat dorsal region. Soybean seeds sometimes undergo cracking during low temperatures in summer. In this study, we focused on the occurrence and tolerance mechanisms of low-temperature-induced seed cracking in the sensitive yellow soybean cultivar Yukihomare and the tolerant yellow soybean breeding line Toiku 248.

Accumulation of proanthocyanidins and/or lignin deposition in buff-pigmented soybean seed coats may lead to frequent defective cracking.

Defective cracking frequently occurs in buff-pigmented soybean seed coats, where proanthocyanidins accumulate and lignin is deposited, suggesting that proanthocyanidins and/or lignin may change physical properties and lead to defective cracking. In the seed production of many yellow soybean (Glycine max) cultivars, very low percentages of self-pigmented seeds are commonly found. This phenomenon is derived from a recessive mutation of the I gene inhibiting seed coat pigmentation.

Method for selection of soybeans tolerant to seed cracking under chilling temperatures.

In Hokkaido, northern Japan, soybean [Glycine max (L.) Merr.] crops are damaged by cold weather.

Comparative analysis of the inverted repeat of a chalcone synthase pseudogene between yellow soybean and seed coat pigmented mutants.

In soybean, the I gene inhibits pigmentation over the entire seed coat, resulting in yellow seeds. It is thought that this suppression of seed coat pigmentation is due to naturally occurring RNA silencing of chalcone synthase genes (CHS silencing). Fully pigmented seeds can be found among harvested yellow seeds at a very low percentage.

Seed coat pigmentation in transgenic soybean expressing the silencing suppressor 2b gene of Cucumber mosaic virus.

Soybean expressing the Cucumber mosaic virus 2b gene manifests seed coat pigmentation due to suppression of endogenous RNA silencing but no other morphological abnormality. This gene may help prevent transgene silencing. RNA silencing is an important mechanism for gene regulation and antiviral defense in plants.

A pair of transposons coordinately suppresses gene expression, independent of pathways mediated by siRNA in Antirrhinum.

Our knowledge is limited regarding mechanisms by which transposable elements control host gene expression. Two Antirrhinum lines, HAM2 and HAM5, show different petal colors, pale-red and white, respectively, although these lines contain the same insertion of transposon Tam3 in the promoter region of the nivea (niv) locus encoding chalcone synthase. Among 1000 progeny from HAM5 grown under the preferred conditions for the Tam3 transposition, a few showed an intermediate petal color between HAM2 and HAM5.

Suppressive mechanism of seed coat pigmentation in yellow soybean.

In soybean seeds, numerous variations in colors and pigmentation patterns exist, most of which are observed in the seed coat. Patterns of seed coat pigmentation are determined by four alleles (I, i(i), i(k) and i) of the classically defined I locus, which controls the spatial distribution of anthocyanins and proanthocyanidins in the seed coat. Most commercial soybean cultivars produce yellow seeds with yellow cotyledons and nonpigmented seed coats, which are important traits of high-quality seeds.

Accumulation of Potato spindle tuber viroid-specific small RNAs is accompanied by specific changes in gene expression in two tomato cultivars.

To better understand the biogenesis of viroid-specific small RNAs and their possible role in disease induction, we have examined the accumulation of these small RNAs in potato spindle tuber viroid (PSTVd)-infected tomato plants. Large-scale sequence analysis of viroid-specific small RNAs revealed active production from the upper portion of the pathogenicity and central domains, two regions previously thought to be underrepresented. Profiles of small RNA populations derived from PSTVd antigenomic RNA were more variable, with differences between infected Rutgers (severe symptoms) and Moneymaker (mild symptoms) plants pointing to possible cultivar-specific differences in small RNA synthesis and/or stability.

Endogenous RNA interference of chalcone synthase genes in soybean: formation of double-stranded RNA of GmIRCHS transcripts and structure of the 5' and 3' ends of short interfering RNAs.

In yellow soybean, seed coat pigmentation is inhibited via endogenous RNA interference (RNAi) of the chalcone synthase (CHS) genes. Genetic studies have shown that a single dominant gene, named the I gene, inhibits pigmentation over the entire seed coat in soybean. We previously isolated a candidate for the I gene from the yellow soybean genome with the I/I genotype, and designated it GmIRCHS.

Variation of GmIRCHS (Glycine max inverted-repeat CHS pseudogene) is related to tolerance of low temperature-induced seed coat discoloration in yellow soybean.

In yellow soybean, seed coat pigmentation is inhibited by post-transcriptional gene silencing (PTGS) of chalcone synthase (CHS) genes. A CHS cluster named GmIRCHS (Glycine max inverted-repeat CHS pseudogene) is suggested to cause PTGS in yellow-hilum cultivars. Cold-induced seed coat discoloration (CD), a commercially serious deterioration of seed appearance, is caused by an inhibition of this PTGS upon exposure to low temperatures.

Molecular mechanism of seed coat discoloration induced by low temperature in yellow soybean.

Seed coat pigmentation is inhibited in yellow soybean. The I gene inhibits pigmentation over the entire seed coat. In yellow soybean, seed coat discoloration occurs when plants are exposed to low temperatures after the onset of flowering, a phenomenon named 'cold-induced discoloration (CD)'.

A novel major quantitative trait locus controlling seed development at low temperature in soybean (Glycine max).

Low temperature is among the critical environmental factors that limit soybean production. To elucidate the genetic basis for chilling tolerance and identify useful markers, we conducted quantitative trait loci (QTL) analysis of seed-yielding ability at low temperature in soybean (Glycine max), using artificial climatic environments at usual and low temperatures and recombinant inbred lines derived from a cross between two contrasting cultivars in terms of chilling tolerance. We identified a QTL of a large effect (LOD > 15, r (2) > 0.

Functional analysis of soybean genes involved in flavonoid biosynthesis by virus-induced gene silencing.

Virus-induced gene silencing (VIGS) is a powerful tool for functional analysis of genes in plants. A wide-host-range VIGS vector, which was developed based on the Cucumber mosaic virus (CMV), was tested for its ability to silence endogenous genes involved in flavonoid biosynthesis in soybean. Symptomless infection was established using a pseudorecombinant virus, which enabled detection of specific changes in metabolite content by VIGS.

Dose-dependent hypocholesterolemic actions of dietary apple polyphenol in rats fed cholesterol.

The dose-dependent hypocholesterolemic and antiatherogenic effects of dietary apple polyphenol (AP) from unripe apple, which contains approximately 85% catechin oligomers (procyanidins), were examined in male Sprague-Dawley rats (4 wk of age) given a purified diet containing 0.5% cholesterol. Dietary AP at 0.

Structural features of GmIRCHS, candidate of the I gene inhibiting seed coat pigmentation in soybean: implications for inducing endogenous RNA silencing of chalcone synthase genes.

Most commercial soybean varieties have yellow seeds due to loss of pigmentation in the seed coat. The I gene inhibits pigmentation over the entire seed coat, resulting in a uniform yellow color of mature harvested seeds. We previously demonstrated that the inhibition of seed coat pigmentation by the I gene results from post-transcriptional gene silencing (PTGS) of chalcone synthase (CHS) genes.

Patterning of virus-infected Glycine max seed coat is associated with suppression of endogenous silencing of chalcone synthase genes.

Most commercial Glycine max (soybean) varieties have yellow seeds because of loss of pigmentation in the seed coat. It has been suggested that inhibition of seed coat pigmentation in yellow G. max may be controlled by homology-dependent silencing of chalcone synthase (CHS) genes.

Isolation of a subfamily of genes for R2R3-MYB transcription factors showing up-regulated expression under nitrogen nutrient-limited conditions.

Plant R2R3-MYB transcription factors are encoded by more than 100 copies of genes. In this study, we attempted to isolate some members of the R2R3-MYB superfamily involved in regulation of nitrogen fixation in legumes. A library of 300 recombinant plasmid clones containing the R2R3-MYB fragments of the superfamily was screened by differential hybridization to isolate R2R3-MYB genes whose expression was up-regulated under nitrogen nutrient-limited conditions.

Sequence divergence at chalcone synthase gene in pigmented seed coat soybean mutants of the Inhibitor locus.

Seed coat color in soybeans is determined by the I (Inhibitor) locus. The dominant I allele inhibits seed coat pigmentation, and it has been suggested that there is a correlation between the inhibition of pigmentation by the I allele and chalcone synthase (CHS) gene silencing in the seed coat. Analysis of spontaneous mutations from I to i has shown that these mutations are closely related to the deletion of one of the CHS genes (designated ICHS1).

New pollen-specific receptor kinases identified in tomato, maize and Arabidopsis: the tomato kinases show overlapping but distinct localization patterns on pollen tubes.

We previously characterized LePRK1 and LePRK2, pollen-specific receptor kinases from tomato (Muschietti et al., 1998). Here we identify a similar receptor kinase from maize, ZmPRK1, that is also specifically expressed late in pollen development, and a third pollen receptor kinase from tomato, LePRK3.