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The initiation of intracellular infection of legume roots by symbiotic rhizobia bacteria and arbuscular mycorrhiza (AM) fungi is preceded by the induction of calcium signatures in and around the nucleus of root epidermal cells. Although a calcium and calmodulin-dependent kinase (CCaMK) is a key mediator of symbiotic root responses, the decoding of the calcium signal and the molecular events downstream are only poorly understood. Here, we characterize Lotusjaponicus cyclops mutants on which microbial infection was severely inhibited. In contrast, nodule organogenesis was initiated in response to rhizobia, but arrested prematurely. This arrest was overcome when a deregulated CCaMK mutant version was introduced into cyclops mutants, conferring the development of full-sized, spontaneous nodules. Because cyclops mutants block symbiotic infection but are competent for nodule development, they reveal a bifurcation of signal transduction downstream of CCaMK. We identified CYCLOPS by positional cloning. CYCLOPS carries a functional nuclear localization signal and a predicted coiled-coil domain. We observed colocalization and physical interaction between CCaMK and CYCLOPS in plant and yeast cell nuclei in the absence of symbiotic stimulation. Importantly, CYCLOPS is a phosphorylation substrate of CCaMK in vitro. Cyclops mutants of rice were impaired in AM, and rice CYCLOPS could restore symbiosis in Lotus cyclops mutants, indicating a functional conservation across angiosperms. Our results suggest that CYCLOPS forms an ancient, preassembled signal transduction complex with CCaMK that is specifically required for infection, whereas organogenesis likely requires additional yet-to-be identified CCaMK interactors or substrates. BiFC | map-based cloning | plant-microbe symbiosis | protein phosphorylation | protein-protein interaction

Identification of forage legumes well adapted to the southeastern United States is complicated by climatic, soil, and biotic factors. Among the pests that impact forage legume persistence are root-knot nematodes (RKNs) (Meloidogyne spp.). We hypothesized that legumes native to the region should have higher levels of resistance to RKN species that are common in this region due to long-term natural selection pressure. The objective of this research was to evaluate the response of 10 southeastern U.S. native legumes to M. arenaria (Neal) Chitwood race 1, M. incognita (Kofoid and White) Chitwood race 3, and M. javanica (Treub) Chitwood. Legumes were grown in Cone-tainers in a greenhouse for 3 wk, inoculated with a given RKN isolate, and after an additional 9 wk were uprooted and evaluated for root galling and nematode egg mass production responses. The level of root galling and egg mass production varied among native legumes, but in general was lower than previously observed on introduced legumes. Desmodium paniculatum (L.) DC., Galactia regularis (L.) Britton et al., and Centrosema virginianum (L.) Benth. varied among the three RKN species in their root galling and egg mass production responses. The accession of D. incanum DC. used was immune to all three RKN isolates, and could be a potential source of RKN resistance genes. The perennial native legumes evaluated all had either a fleshy taproot or a strong rhizome system.

Intercropping is the simultaneous cultivation of more than one crop species on the same piece of land and is regarded as the practical application of basic ecological principles such as diversity, competition and facilitation. Field experiments were carried out on a sandy loam soil and a sandy soil in Denmark over three consecutive cropping seasons including dual grain legume (pea, faba bean and lupin)-barley intercropping as compared to the respective sole crops (SC). Yield stability of intercrops (IC) was not greater than that of grain legume SC, with the exception of the IC containing faba bean. Faba bean and lupin had lower yield stability than pea and fertilized barley. However, the different IC used environmental resources for plant growth up to 50% (LER = 0.91-1.51) more effectively as compared to the respective SC, but with considerable variation over location, years and crops. The SC performance supported the interspecific interactions within the IC stand. On the sandy loam 13% greater grain yield of pea cv. Agadir (520 g[m.sup.-2]) was observed as compared to cv. Bohatyr. Faba bean and lupin yielded similarly (340 g[m.sup.-2]) in the sandy loam soil, with decreasing yields on the sandy soil (320-270g[m.sup.-2]). Nitrogen fixation was very constant in grain legume SC over species and location, varying from 13.2 to 15.8g N[m.sup.- 2], being lowest in peas and highest in faba bean and lupin. The intercropped grain legumes increased the proportion of plant N derived from [N.sub.2]-fixation by on average 10-15% compared to the corresponding SC. However, especially lupin was suppressed when intercropping, with a reduced [N.sub.2]-fixation from 15 to 5-6g N[m.sup.- 2]. The IC were particularly effective at suppressing weeds, capturing a greater share of available resources than SC. Weed infestation in the different crops was comparable; however, it tended to be the highest in sole cropped faba bean, lupin and unfertilized barley, where the application of urea to barley reduced the weed infestation by around 50%. Reduction in disease was observed in all IC systems compared to the corresponding SC, with a general disease reduction in the range of 20-40%. For one disease in particular (brown spot on lupin) disease reduction was almost 80% in the IC. Intercropping practices offer many advantages but improved understanding of the ecological mechanisms associated with planned spatial diversity, including additional benefits with associated diversity, is needed to enhance the benefits achieved. Key words: intercropping, grain legumes, cereals, yield advantage, resource use, nitrogen fixation, leaf diseases, weeds, grain quality

Anthracnose, caused by the fungus Colletotrichum lindemuthianum, is considered a major constraint in the production of common bean (Phaseolus vulgaris L.). This study aimed to evaluate, in a backcross plant-breeding program, the efficiency of selecting plants resistant to anthracnose using marker-assisted selection (MAS) for two resistance genes, Co-5 and Co-42 derived from the resistance source G2333 based on the linked PCR based markers SAB3 and SAS13. The amplification of both markers was compared using DNAs extracted with two techniques, alkaline extraction, which is a fast, and inexpensive method for high throughput screening; versus a proteinase K based miniprep extraction, which is more time consuming but provides more DNA. To further evaluate the effectiveness of the markers in selecting for resistance, we compared the marker genotypes and observed phenotypes for 266 plants from eight backcross families inoculated with a field isolate of anthracnose. The Co-5 gene and SAB3 proved to be useful and the markers associated with Co-5 and Co-42 could be pyramided to give added levels of anthracnose resistance.

Two important race groups of the stem nematode, Ditylenchus dipsaci, an obligatory polyphagous endoparasite, attack the bean, Vicia faba. Morphological differences have been found in the two groups and there were corresponding differences in faba bean disease symptoms. Agreement has been found between RAPD and phenotypic characteristics in the nematodes. Variation between D. dipsaci species in populations involved with V. faba was low. No strong correlation was found between geographical origin and morphological or molecular characteristics.

Red clover (Trifolium pretense L.) is an important forage legume grown in the USA, Canada, and northern and eastern Europe. The effects of root rot resistance of six improved cultivars and three regionally adapted ecotypes on forage and seed yield under typical production systems in Wisconsin and Oregon, respectively, were measured. The relationship of cultivar flowering capacity to seed yield was also measured. The objectives of this study were to: (i) determine the benefits of using improved cultivars instead of locally adapted ecotypes in Wisconsin forage production systems; (ii) determine whether selection for root rot resistance in Wisconsin benefits seed production systems in Oregon; and (iii) identify strategies to increase seed yields in cultivars with improved persistence and high forage yields. Forage and seed yields were inversely related in all improved cultivars except Kenland, which had lower forage yield than the other improved cultivars and the same yield as the three local Wisconsin and Oregon ecotypes. The local ecotypes produced the highest seed yield because of a greater flower producing capacity than improved cultivars following spring forage removal. Seed yield was highly associated with the number of flowers produced by late July (r = 0.87; P ≤ 0.002). Selection for root rot resistance in Wisconsin did not benefit seed production in Oregon. Improvement in seed yield capacity of cultivars with high forage yield may be possible by selecting for rapid flowering after spring forage removal in the western Oregon seed production region., Most red clover cultivars are bred for frequent clipping in hay and silage systems or for grazing. An important factor for successful red clover forage and seed production is the [...]

Byline: R. Modgil (1), U. Mehta (1) Keywords: Chick pea; Mung bean; Pigeon pea; Phytic acid; Saponin; Trypsin inhibitor activities; Antinutritional factors; Insect infestation Abstract: Effect of bruchid infestation on selected antinutritional factors, saponin, phytic acid and trypsin inhibitor activities, of three (mung bean, chickpea and pigeon pea) legumes stored for six months was studied. The three antinutritional factors, saponin, phytic acid and trypsin inhibitor activity (TIA), increased with increased storage period. Saponin, phytic acid and trypsin inhibitor activity values were significantly lower in control samples compared to stored infested samples. The difference between the contents of antinutritional factors were significant (p Author Affiliation: (1) Department of Food Science and Nutrition, CCS HAU, 125 004, Hisar, India Article History: Registration Date: 26/05/2006 Received Date: 06/02/1996 Accepted Date: 06/06/1997

Arcelin, a seed protein discovered in wild Phaseolus vulgaris L. accessions, gives high levels of resistance to the Mexican Bean Weevil [MBW; Zabrotes subfasciatus (Boheman)]. Five arcelin variants have been described. To better understand to genetic control of arcelin and MBW resistance, an inheritance study was conducted. Bioassay tests for insect response, and biochemical tests to detect the presence-absence of arcelin, were performed on the same individual seed. Accessions G12952 (arc-4) and G02771 (arc-5) had the highest level of resistance to MBW with no adults emerging from infested seed. Resistance was also found in G12882 (arc-1) and G12866 (arc-2), while G12922 (arc-3) and the commercial cultivar, Pijao, were susceptible to the insect. The genetic study confirmed that all arcelin variants were inherited as a single dominant gene based on biochemical evaluations for presence-absence of arcelin. Nevertheless, in bioassay tests with MBW, only crosses with arc-1 and arc-5 showed a single, completely dominant gene mode of inheritance, with the presence of arcelin being highly associated with resistance to the insect. For arc-1 and arc-5, biochemical tests can be reliably used to select for MBW resistance. For arc-2, a combination of biochemical and bioassay tests is needed. As arc-4 segregated few resistant individuals, and arc-3 gave only intermediate to susceptible offspring, the use of these two arcelin variants is not recommended in a routine resistance breeding program. Electrophoretic patterns and bioassay tests of F [sub1] and F [sub2] generations showed that arc-5 and arc-1 variants are inherited as a single unit and are codominant.