Germplasm Enhancement and Breeding Strategies for Crop Quality in Japan

Abstract

Rice is the staple food for most Asians. Breeding efforts at the national and international levels have resulted in high-yielding varieties with resistance/tolerance to biotic and abiotic constraints. Consequently Asia has enjoyed rice self-sufficiency in recent years. Now in some countries over-production of rice has occurred, partly because of reduced rice consumption. For instance, in 1962 Japan had a per capita rice consumption of 118.3 kg and then this rapidly declined to about 60kg in 2003. Imbalances between production and consumption in rice and other crops have promoted a paradigm shift of breeding objectives oriented from producers to consumers. Germplasm enhancement (pre-breeding) and breeding strategies now focus on a broad range of crop and food qualities, which are closely associated with industrial and processing properties and human health and nutrition. In particular, physiological functions of chemical compounds involved in crop products are being studied as a part of breeding programs. Diverse plant genetic resources and advances in plant genome research have contributed to successful breeding strategies to improve and manage crop and food quality. Recent progress in germplasm enhancement and breeding strategies for quality improvement of rice, wheat, soybean and sweet potato in Japan is discussed.     

Legume Forage Quality

Abstract

Legume forage quality research is now concerned not only with nutritive value of forage for ruminant animals, but the impact of these nutrients on environmental quality. If we are to move to a more sustainable agriculture worldwide, more legumes must be incorporated into animal production systems. The goal of forage legume breeders is to tailor legume nutritive value to the needs of the consuming animals. A generalized priority list for legume nutritive value research includes high fiber digestibility, low anti-quality compounds, appropriate condensed tannins, reduced nonprotein nitrogen, and high sulfur amino acids. Although breeders have regularly found a wide range in forage quality within a given legume species, very few varieties with proven forage quality advantages have been released. Yield and persistence issues have dominated forage legume breeding. Improvement in forage quality often is linked to a reduction in yield and/or persistence, and also frequently results in complex genotype X environment interactions. Transgenic technology has almost limitless potential for improving legume forage quality and environmental quality, but only if the public can be convinced that transgenics are an acceptable risk. Structural and functional roles of legume plant cell walls and their relationships to forage quality are poorly understood. Research on the basic processes of forage legume growth and the relationships between growth and forage composition should result in the development of more accurate simulation models, and transgenic technology can provide us with the tools to understand these basic processes.     

Mycorrhizal Associations and Their Manipulation for Long-Term Agricultural Stability and Productivity

Summary

Mycorrhizae refer to an association (largely symbiotic) between plants and fungi that colonize the cortical root tissue of most agricultural crops during the period of active plant growth. The contribution of these symbioses to plant growth and soil fertility maintenance has been well-recognized for past several years. In spite of these benefits to agriculture, at present, the realization of the full potential of these fungi has not yet been reached. It must also be recognized that recent research on the possible application of the mycorrhizal symbiosis in agriculture has revealed many gaps in knowledge of fungal biology and ecology. Scientific knowledge on the role of these fungi in plant development and protection, soil stabilization, aggregate formation and creation of nutrient reserves is still limited. For efficient use and manipulation of these fungal symbioses for long-term agricultural stability and productivity, our understanding of their physiology, function and interactions with existing crops and environmental conditions should be improved. Besides, effects of different agronomic practices, application of chemical fertilizers and pesticides on their ecology and function should be elucidated before their successful utilization in agriculture.

This paper presents information on the morphology of different my-corrhizal fungi, their physiology and functions. Methods presently used to produce mycorrhizal inocula, their application in the field, problems to be resolved for their massive exploitation and future research needs have also been described. References have been selected to explain the recent advances in our understanding on these beneficial fungi.     

Allelopathic Effects of Some Volatile Substances from the Tomato Plant

Summary

The allelopathic effects of chemical substances released from the tomato plant (Lycopersicon esculentum Mill.) were investigated on various receptor plants. Bioassays under controlled conditions in a growth chamber showed that germination and seedling growth of Lactuca sativa and growth of Vitis were reduced when grown near tomato plants. It was also observed that when plants were grown in a U-tube pot with tomato plant, the tomato roots excreted allelochemicals that inhibit growth of tested species. To identify the phytotoxic compounds from tomato plant, a GC/MS method was employed. Forty compounds, such as trans-2-hexenal, a-terpineol, linalool, phenylace-taldehyde, methylsalicylic acid and tetradecanoic acid were identified from the essential oil of tomato plants. The volatile substances from leaves inhibited seed germination and seedling growth of receptor plants in laboratory tests. Inhibitory response varied with the concentration of compounds. These findings suggest that the tomato plant may have an interesting allelopathic potential.     

Allelopathy in Agroecosystems in Spain

Summary

This paper reviews the effects of allelopathic interactions in agroecosystems in Spain on plant physiological activity and their ecological advantages. The phenological stage of growth of donor plants and the effective allelochemicals in the soil solution while studying the role of phenolic compounds were highlighting. Finally possible future prospects and conclusions regarding weed control by allelochemi-cals under integrated crop management strategies are discussed.     

Plant Parasitic Nematodes in Rice-Wheat Based Cropping Systems in South Asia

Summary

Rice-wheat based cropping systems in South Asia are among the most highly evolved production systems in the world. The productivity growth of these systems in South Asia is declining due to several factors including the biotic stresses of plant parasitic nema-todes. This article reviews the research on rice and wheat nematodes in a cropping systems perspective and identifies nematodes that have wide host ranges and are greatly influenced by the crop rotations and sequences. These polyphagous nematodes can cause significant damage to rice and (or) wheat crops, either alone or in combination with other microorganisms. The research projects on pest management in the region lack inter-disciplinarity and it is important for nematologists to become integral members of interdisciplinary teams on improving the productivity and sustainability of the rice-wheat cropping systems.     

Ethylene

Abstract

Ethylene is a simple gaseous hormone that is involved in many aspects of plant growth and development. Two physiological responses that are commonly controlled by ethylene, fruit ripening and flower senescence, have been given the most significant attention in terms of crop improvement using the tools of modern plant molecular biology and biotechnology. Fortunately, the wealth of research on ethylene biosynthesis and signaling pathway has been providing tools for the genetic control of ethylene effects. Today, manipulation of ethylene biosynthesis and signaling is one of the most promising approaches to improve crops through genetic engineering. In this review we will discuss current status and future directions of transgenic techniques to control ethylene effects with a primary focus on flower senescence.     

New approaches concerning the utilization of natural amendments in cadmium phytoremediation

Different vegetal biomass resources such as Picea abies bark, Castanea sativa chestnuts shell and Asclepias syriaca plant were considered to provide a source of natural bioactive compounds, which can be properly used in several directions such as: plant growth regulators and amendments in bioremediation. Having in mind a complex processing biomass technology, these raw materials are used in a first step to separate bioactive compounds by an aqueous extraction. The obtained extracts containing polyphenols were tested in germination tests to evaluate their influence on cadmium bioaccumulation in oat plant (Avena sativa). It was observed that the mentioned extracts modulated cadmium bioaccumulation, photosynthesizing pigments biosynthesis, plant growth and its development depending on metal ion concentration (5, 12.5, 25 mg/L), and extracts composition determined by vegetal raw material and their total polyphenols content (130, 122, 114 mg/L related to gallic acid). FTIR spectra and histo-anatomical cross section of the roots certify that P. abies bark and A. syriaca plant extracts amendments stimulated cadmium bioaccumulation, promoting the translocation of heavy metals to the aerial part of the plant, meanwhile chestnuts shell extract reduced the mobility of cadmium determining in situ inactivation of heavy metal ions.     

Increasing Crop Competitiveness to Weeds Through Crop Breeding

Abstract

Increasing the ability of crops to compete against weeds, through either enhancing crop tolerance or crop interference to weeds, provides an attractive addition to current weed control practices and could be an integral component of weed management systems. Research has shown that considerable variability exists among crop culti-vars with respect to their ability to compete with weeds. Despite this evidence, directed research on competitive crops has been minimal. Reasons for this lack of emphasis in plant breeding programs include the effectiveness of current weed management with tillage and herbicides, and the lack of easily identifiable crop characteristics that are indicative of weed competitiveness. Expanded knowledge of specific crop-weed interactions would facilitate crop competitiveness to weeds through either crop management practices or plant breeding. Plant breeders need basic and applied information to identify favorable crop-weed competitive traits in order to enhance or incorporate those traits into crop cultivars. Accelerated research on weed competitive crops should lead to more economical, effective, and feasible integrated weed management programs for all crops.     

Antifungal activity toPhytophthora infestans of sesquiterpenoids from infected potato tubers

Summary The sesquiterpenes 2-(1',2'-dihydroxy-1'-methylethyl)-6,10-dimethyl-spiro-[4,5]dec-6-en-8-on (1) and its 2'-O-β-d-glucopyranoside (2) were isolated from the stress zones of potato tubers infected withPhoma foveata andFusarium spp., and rishitin and solavetivone from tuber slices inoculated withErwinia carotovora. The influence of these compounds, and of the naturally occurring plant sesquiterpenoids abscisic acid, cedrol and farnesol, on the mycelial growth ofPhytophthora infestans were tested on agar plates using a defined medium. All sesquiterpenoids suppressed the growth of the pathogen, except for1 and its glucoside2 which induced a slight, however significant, growth stimulation. Compounds1 and2 could not be isolated fromE. carotovora orP. infestans-inoculated tuber tissue.     

Recent Advances in Marker-Assisted Selection for Drought Tolerance in Pearl Millet

Abstract

Pearl millet [Pennisetum glaucum (L.) R. Br.] is the staple cereal of the hottest, driest areas of the tropics and subtropics. Drought stress is a regular occurrence in these regions, making stress tolerance an essential attribute of new pearl millet cultivars. Recent breeding research has mapped several quantitative trait loci (QTLs) for components of grain and stover yield per se, as well as yield maintenance, under terminal drought stress conditions. We report here the evaluation of these QTLs as possible selection criteria for improving stress tolerance of an elite hybrid cultivar. Initial evaluations, based on hybrids made with topcross pollinators bred from lines selected directly from the mapping population, indicated an advantage to the QTL-based topcross hybrids. This advantage seemed to be related to a particular plant phenotype that was similar to that of the drought tolerant parent of the mapping population. Subsequent evaluations were based on testcross hybrids of drought tolerance QTL introgression lines in the background of the drought-sensitive parent of the mapping population, H 77/833-2. These introgression lines were bred by limited marker-assisted backcrossing of a putative major drought tolerance QTL into H 77/833-2 from the mapping population’s drought tolerant parent. Several of these QTL introgression lines had a significant positive general combining ability for grain yield under terminal stress and significantly out-yielded testcross hybrids made with the original recurrent parent both in unrelieved terminal drought stress and in gradient stress evaluations.     

Auxin,Cytokinin and Ab sei sic Acid

Abstract

Auxin, cytokinin, and abscisic acid (ABA) are important plant hormones that regulate many growth and developmental processes. In recent years, a number of genes involved in the metabolic and signaling pathways for auxin, cytokinin and ABA have been cloned and characterized. With organ-and tissue-specific or conditionally active gene promoters, it has become possible to manipulate concentrations of plant hormones in planta to create commercially desirable traits. Seedless fruit production and the extension of shelf life of green produce and ornamental plants are two successful examples of manipulating concentrations of these hormones in planta. In this review, we will focus our discussion on the effects of the over-or under-expression of genes involved in the biosynthetic and catabolic pathways of these hormones with an emphasis on their potential applications in ornamental crops.     

The Level of Mesenchymal-Epithelial Transition Autophosphorylation is Correlated with Esophageal Squamous Cell Carcinoma Migration

Background:The MET receptor is a critical member of cancer-associated RTKs and plays an important role in different biological activities, including differentiation, migration, and cell proliferation. Methods:In this study, novel MET inhibitors were introduced and applied on esophageal squamous carcinoma cell line KYSE-30, and the level of proliferation and migration, as well as the activated form of MET receptor protein were assessed in the examined cells. The human KYSE-30 cell line was cultured according to ATCC recommendations. The mRNA level of the MET gene was measured in the examined cell line using the quantitative RT-PCR assay. Cytotoxicity evaluation test was performed at different concentrations of heterocyclic anti-MET compounds (i.e. D1, D2, D5, D6, D7, and D8). Finally, the capability of these compounds in MET receptor inhibition was evaluated using the migration assay and Western blot. All experiments were performed in triplicate and repeated three times with similar results. Results:Cell growth and proliferation were significantly inhibited (p ≤ 0.05) by all the above-mentioned compounds. Moreover, the majority of compounds significantly prevented the cell migration (p ≤ 0.05) and inhibited MET autophosphorylation. Interestingly, the level of phosphorylated MET was significantly correlated with KYSE-30 cell migration. Conclusion:The obtained data introduced and confirmed the biological activities of the mentioned novel compounds in KYSE-30 cells and proposed that the therapeutic inhibition of MET with these compounds may be a powerful approach for inhibiting cancer cell migration and proliferation although some structural optimizations are needed to improve their inhibitory functions. Key Words: c-MET, Esophageal squamous cell carcinoma, Receptor tyrosine kinases     

Regulation of C/N Interaction in Model Plant Species

Summary

Carbon (C) and nitrogen (N) metabolisms are two major metabolic pathways which have been intensively studied in plants. Both N and C metabolisms are tightly linked in numerous plant biochemical pathways. Therefore the C to N ratio has to be carefully regulated to ensure proper functioning of the huge metabolic network. In order to maintain a viable C/N status under a large range of growth conditions plants have evolved complex mechanisms to regulate the delicate network of these two major assimilatory pathways. C and N metabolisms are both highly regulated. We will present the current knowledge on the regulation of N and C metabolisms by sugars and N metabolites. Players involved in these regulatory processes are just starting to be uncovered and possible signaling molecules involved in these regulations as well as known or potential candidate regulatory genes willbe discussed.     

Improving the Nutritional Value of Cool Season Food Legumes

Abstract

Cool season food legumes such as pea, lentil, chickpea, faba bean, grasspea and lupin have been consumed in animal and human diets since domestication and have been cultivated for over 9000 years. Due to their nutritional value they continue to make up a substantial portion of diets in developing countries worldwide. Seeds are composed of protein, starch, fiber, lipids, vitamins and minerals as well as several antinutritional compounds. Protein and starch combined account for 50-75% of seed mass. Similar amounts of protein and starch are present in each species and range from 15-40% and 35-53%, respectively. Fiber accounts for 1-22% of the seed mass. Chickpea is quite variable for fiber content, but faba bean, grasspea and lupin all contain approximately 15% fiber while pea and lentil have substantially lower levels, 4-8%. Protein composition is deficient in the sulfur amino acids, methionine and cysteine, but contains adequate levels of lysine making the legumes an excellent dietary complement to cereals. As a result these crops have been produced and consumed together for centuries. Despite the high nutritional value of these crops, they contain several antinutritional factors (ANF) such as phytic acid, protease inhibitors, heamagglutinins, tannins, alkaloids, raffinose oligosaccharides and antigenicity factors at relatively low levels. These compounds serve important roles in pest resistance or plant survival, but reduce digestibility and palatability when consumed. Genetic analysis of the antinutritional factors has shown that many of the ANFs are controlled by single genes and has allowed geneticists to reduce accumulation of the ANFs, thereby improving nutritional value. Legumes will continue to serve as the primary source of protein in areas of the world where meat is not readily available. Continued research toward a better understanding of the genetic control of legume quality will give geneticists the opportunity to improve the dietary value of these crops.     

Developing a Fluorescent Hybrid Nanobiosensor Based on Quantum Dots and Azoreductase Enzyme for Methyl Red Monitoring

Background:Azo dyes are the most widely used synthetic colorants in the textile, food, pharmaceutical, cosmetic, and other industries, accounting for nearly 70% of all dyestuffs consumed. Recently, much research attention has been paid to efficient monitoring of these hazardous chemicals and their related metabolites because of their potentially harmful effect on environmental issues. In contrast to the complex and expensive instrumental procedures, the detection system based on the QDs with the superior optochemical properties provides a new era in the pollution sensing and prevention. Methods:We have developed a QD-enzyme hybrid system to probe MR in aqueous solutions using a fluorescence quenching procedure. Results:The azoreductase enzyme catalyzed the reduction of azo group in MR, which can efficiently decrease the FRET between the QDs and MR molecules. The correlation between the QDs photoluminescence recovery and MR enzymatic decolorization at the neutral phosphate buffer permitted the creation of a fluorescence quenching-based sensor. The synthesized biosensor can be used for the accurate detection of MR in a linear calibration over MR concentrations of 5-84 μM, with the LOD of 0.5 μM in response time of three minutes. Conclusion:Our findings revealed that this fluorometric sensor has the potential to be successfully applied for monitoring a wide linear range of MR concentration with the relative standard deviation of 4% rather than the other method. Key Words: Azoreductase, Methyl red, Quantum dots     

Oat Antioxidants

Oat (Avena sativa L.) is a source of many compounds that exhibit antioxidant activity. Vitamin E (tocols), phytic acid, phenolic compounds, and avenanthramides are the most abundant antioxidants in oat, and flavonoids and sterols are also present. These antioxidants are concentrated in the outer layers of the kernel. Several in vitro tests have been used to evaluate antioxidant activity of oat extracts. A few examples show that an oat-containing diet boosted the antioxidant capacity of serum or meat in animals. Avenanthramides may be a plant defense response, as these compounds are induced in oat leaves by rust spores or elicitors. Antioxidants function in helping to maintain the stability of processed oat products, and oat can stabilise oils and fats against rancidity. Possible future research should be aimed at increasing antioxidants by plant breeding and through a nutritional genomics approach. Additionally, we need to acquire knowledge about the bioavailability and function of antioxidants in human and animal systems. Methods for fractionation of oat to produce antioxidant co-products along with other high-value components should also be studied.     

Insecticidal properties of Mentha species: A review

In view of the environmental, food-safety and health related issues associated with the application of chemical insecticides, growing emphasis is being laid on insect-pest control through plant resources. Mentha (mint) is one of the most common herb which has been known for its medicinal and aromotherapeutic properties since ancient times and in the last few decades, its insecticidal potential has also been investigated. The present review consolidates studies concerning insecticidal activity of Mentha against various stored grain pests and vectors. Insecticidal properties of different Mentha species are commonly inherent in its essential oils or plant extracts which is correlated with their chemical composition. Insect/pest control potential of various Mentha species has been evaluated by conducting adulticidal, larvicidal and growth/reproduction inhibition bioassays. Fumigant and repellent activity of Mentha essential oil has been studied against several stored grain pests (Tribolium castaneum, Sitophilus oryzae, Acanthoscelides obtectus, etc.) and vectors. Nevertheless, studies exploring larvicidal and growth/reproduction regulatory activity of Mentha, are relatively less. Among the vectors, mosquitocidal activity of several Mentha essential oils and their constituents is established. However, the studies directed towards formulation or product development and performance assessment in actual field conditions are lacking. Hence, although a ground has been set based on the lab scale research investigations, field studies on these aspects are warranted to ensure wide scale application.     

Genotypic Variation of Stomatal Conductance in Relation to Stomatal Density and Length in Rice (Oryza sativa L.)

Abstract

Stomatal conductance (g_s) is an important trait responsible for the genotypic difference in gas diffusion for photosynthesis and transpiration in rice (Oryza sativa L.). We measured g_s, stomatal density and stomatal length (guard-cell length) at two weeks before heading for 64 accessions from a rice diversity research set of germplasm (RDRS) and for three high-yielding cultivars (HYC) under field conditions. Considerable variations in g_s, and stomatal length were observed among varieties in RDRS, and it was considered that RDRS covers the species diversity of the stomatal characteristics in rice. When it was compared among the varieties with similar plant earliness, g_s was higher in HYC than in most varieties of RDRS. Stomatal density did not correlate with g_s, and there was a negative correlation between stomatal density and stomatal length. However, noticeable variance existed in the latter relation, where HYC exhibited a higher stomatal density and slightly shorter stomatal length than RDRS. High g_s in HYC is attributable to their high stomatal density and moderate specific stomatal conductance (g_s / stomatal density) while the high-g_s varieties in RDRS tended to have a lower stomatal density and higher specific stomatal conductance. Stomatal length is related to specific stomatal conductance, but there are remarkable differences between these traits. Specific stomatal conductance in HYC has not reached the upper limit for their stomatal size, which raises a possibility of further improvement of HYC in g_s.