The natural aging-related biochemical changes in the seeds of two legume varieties stored for 40 years

Abstract

This study was carried out to evaluate the effect of long-term natural aging on germinability and several biochemical characteristics regarding antioxidative response of both dry and germinating two different clover (Trifolium repens and Trifolium pratense) seeds stored for 40 years. The percent germination of the seeds was monitored for 7 days. The activities of catalase, peroxidase, superoxide dismutase, lipid peroxidation, H₂O₂ levels, and phenolic matter content were tested on 0, 1st, 3rd, and 7th days of germination. On the 7th day of germination, the germination ratios of the old T. repens and T. pratense seeds were 32 and 17%, while freshly harvested seeds showed 99 and 96% germination on the 4th day, respectively. The long-term aging caused an important increase in lipid peroxidation levels of the old dry seeds. Total phenolic content was high in the old dry seeds of T. repens compared with those of T. pratense. Remarkably, the long-term aging caused an important decrease in H₂O₂ content and the activities of catalase and peroxidase enzymes, but an increase in activity of superoxide dismutase in both the old dry seeds. The decreases in germinability of the old legume seeds were well correlated with the increasing level of lipid peroxidation and the decreasing activities of peroxidase and catalase. During the germination of the legume seeds, a noticeable increase was determined only in peroxidase activity in two types of the old seeds, while catalase activity decreased. However, the other biochemical parameters studied did not significantly change between the germinating old seeds and their freshly harvested controls.     

Effect of land degradation on soil microbial biomass in a hilly area of south Sumatra,Indonesia

We investigated the impact of land-use changes on the soil biomass at several soil sites in Indonesia under different types of land-use (primary forest, secondary forest, coffee plantation, traditional orchard, and deforested area), located within a small geographical area with similar parent material and climatic conditions. Various parameters of soil microbial biomass (biomass C, biomass N, content of anthrone-reactive carbohydrate carbon, and soil ergosterol content) were examined. Our results suggested that the removal of the natural plant cover did not cause any appreciable decrease in the amount of microbial biomass; on the contrary it led to a short-time increase in the amount of microbial biomass which may be due to the availability of readily decomposable dead roots and higher sensitivity to the decomposition of residual litter in recently deforested soils. However, the amount of microbial biomass tended to decrease in proportion to the duration of the land history in coffee plantation soils. This may be ascribed to the effect of the loss of available substrates associated with soil erosion in the long term. Lower ergosterol contents in recently deforested areas reflected a reduction in the amount of fungal biomass which may be due to the destruction of the hyphal network by the slash and burn practice. On the other hand, the higher soil ergosterol content at the sites under bush regrowth indicated that microbial biomass was able to recover rapidly with the occurrence of a new plant cover.     

Effects of suni-bug (Eurygaster spp.) damage on semolina properties and spaghetti quality characteristics of durum wheats (Triticum durum L.)

Effects of suni-bug (Eurygaster spp.) damage on semolina properties and spaghetti quality characteristics of durum wheats (Triticum durum L.) were investigated. The semolinas obtained from sound (control), medium damage (around 20%) and high damage (around 40%) samples of five durum wheat cultivars (cvs. Diyarbakir, Firat, Ege, Svevo and Zenith) were processed into spaghetti. As the bug damage level increased, Glutograph stretch values of all cultivars decreased significantly probably due to deteriorative effects of bug damage on gluten quality. Glutograph relaxation values and gluten spread values of the damaged samples were considerably higher compared to those of sound samples in all cultivars, due to proteolytic degradation. The breaking force of the uncooked spaghetti samples decreased significantly with increasing bug damage level indicating that they were susceptible to breakage and not suitable for handling, packaging and shipment. Panel tests indicated significant deterioration in sensory properties (stickiness, firmness and bulkiness) generally at the medium damage level.     

A new ZTL-type F-box functions as a positive regulator in disease resistance: VIGS analysis in barley against powdery mildew

In our previous studies, we found a new Zeitlupe (ZTL) type F-box protein which is expressed at a higher level upon avirulent pathogen infection (Bozkurt et al., 2007). F-box proteins mark the proteins to be degraded through 26S proteasome system by ubiquitination. Since the information on the role of ubiquitin mediated proteolysis in disease responses is advancing rapidly, we sought to understand the way which F-box functions in resistance response as part of ubiquitin–proteasome pathway. Interestingly, in response to silencing of this F-box gene via BSMV mediated virus induced gene silencing (VIGS) method, barley plants lost resistance towards avirulent pathogen race. The Pallas-01 line having Mla1 R-gene showed hyphae formations when inoculated with avirulent powdery mildew race, Bgh103, after 4-fold silencing. This observation suggests that F-box protein functions as a positive regulator in powdery mildew disease mechanism and broadens the function of ZTL-type F-box proteins, previously known to have roles only in circadian clocks, flowering time control, and phytochrome pathway.