Soybean (Glycine max [L.] Merr.) shoots systemically control arbuscule formation in mycorrhizal symbiosis

The roots of soybean ( Glycine max [L.] Merr.) establish symbiosis with nodule-inducing rhizobia and arbuscular mycorrhizal (AM) fungi. The existing nodules systemically suppress subsequent nodule formation, a phenomenon known as autoregulation. Grafting experiments revealed that some forms of autoregulation are controlled by the shoot. In the present study, we examined shoot-controlled regulation of AM fungal colonization using a reciprocal grafting technique. Ten-day-old seedlings of wild-type soybean cv. Enrei and its hypernodulating mutant En6500 were cut below the cotyledons and the shoots were grafted to self or reciprocal roots. Grafted seedlings were inoculated with Bradyrhizobium japonicum and Gigaspora rosea and grown in a glasshouse for 60 days. The arbuscule abundance of the En6500 (shoot)/En6500(root) graft was 1.5-fold higher than that of the Enrei/Enrei graft. In grafts between Enrei and En6500, an increased arbuscule abundance was detected only when En6500 was used as the shoot. The arbuscule abundance of Enrei/En6500 when Enrei was used as the shoot was comparable to that of Enrei/Enrei. The intensity of AM fungal colonization was lower in Enrei/En6500 than in the other grafting treatments. From the results obtained, we suggest that soybean shoots systemically control arbuscule formation in both AM symbiosis and nodule formation.     

AFLP Analysis of Genetic Diversity in Indian Soybean [Glycine max (L.) Merr.] Varieties

AFLP technique was used to assess genetic diversity in 72 soybean varieties under cultivation in India. Selected 12 AFLP primer pairs produced 1319 products of which 1257 were polymorphic (95%). Wide variations were observed for the number of amplification products, percent polymorphism and average polymorphism information content (PIC). The Jaccard's similarity indices (J) based on the AFLP profiles of the 72 soybean varieties were subjected to UPGMA cluster analysis. The dendrogram generated revealed four major clusters, which were strongly supported by the high bootstrap values obtained from analyses of 1000 bootstrap samples. In addition, the Mantel's test for cophenetic correlation with r = 0.955 indicated very good fit of the varieties to a group in the cluster analysis. Some correspondence between the clustering pattern and the pedigree, place of release or target area of the variety was observed. Overall moderately high genetic diversity was observed which appears to be due to the higher genetic diversity prevalent in 12 of the varieties included in three diverse clusters and was indicative of the need to include more diverse germplasm in the soybean improvement programs.     

Analysis of regulation site and manner of abundant nodulation in a soybean (Glycine max (L.) Merr.) cultivar,kitantusunte, using grafting techniques

To characterize the regulation site and manner of the abundant nodulation in the soybean (Glycine max (L.) Merr.) cv. Kitamusume, three grafting eperiments were carried out as follows: reciprocal wedge grafting and inter-cultivar approach grafting between Kitamusume and a normal nodulating cultivar, Toyosuzu, as well as wedge grafting of scions of the supernodulating mutant En6500 onto either Kitamusume or Toyosuzu rootstock. In the reciprocal wedge grafting, the number of nodules per shoot dry weight and average weight per nodule in the grafted plants were consistent with those exhibited by the genotype of their rootstocks. Approach grafting did not affect the number of nodules per shoot dry weight on either side of the inter-cultivar approachgrafted plant. Although grafting of the mutant scion resulted in the loss of the autoregulatory response from the roots of both cultivars, difference in the number of nodules per g shoot dry weight still remained between the two cultivars. These results suggested that the abundant nodulation in Kitamusume is controlled by the root in a non-systemic manner and is independent of the autoregulation mechanism.     

Seed Coat Cracking of Soybean (Glycine max [L.] Merr.) After Soaking and Cooking

Seed coat cracking after soaking (SCAS) and after cooking (SCAC) are unfavorable traits associated with soybeans for food uses, such as cooked and seasoned beans (nimame) and fermented steamed beans (natto) because they cause an inferior appearance of the products and clogging of the production lines. The variation and causes of SCAS and SCAC among cultivars have not yet been clarified, but if they are determined genetically, genetic modification could be possible. Cultivars showed considerable variations in SCAS and SCAC. Significantly positive seasonal correlations of SCAS (Spearman's rank correlation coefficient, ρ = 0.518) and of SCAC (ρ = 0.681) were observed among recombinant inbred lines (RILs) derived from the cross between cultivars Nattoshoryu and Hyokeikuro 3. Quantitative trait locus (QTL) analyses and statistical analyses using generalized linear models showed that QTLs for SCAS (qSCAS1 , qSCAS2 , and qSCAS3 ) and SCAC (qSCAC1 and qSCAC2 ) were located on chromosomes 4 (linkage group [LG]: C1), 6 (LG: C2), and 8 (LG: A2) of the RILs. Interactions between QTLs were also observed. SCAS and SCAC are traits controlled by QTLs, which could provide significant insight into their causes and mechanisms. These undesirable characteristics could be improved through breeding.     

Lead-Induced Histological and Ultrastructural Changes in the Leaves of Soybean (Glycine max (L.) Merr.)

The seedlings of the soybean ( Glycine max. (L.) Merr.) cv. Polan were investigated by subjecting them to water culture for a period of 14 d. To the Knop nutrient solution, lead was added as PbCl₂ at four concentrations: 0, 10, 20 and 40 mg dm⁻³. Observations of soybean leaf tissues were carried out by light microscopy, transmission electron microscopy and scanning electron microscopy. The Pb levels used in the present study reduced the area of cotyledons and leaf blades of the soybean plants. Pb-induced changes in the leaf epidermis structure involved a reduction in the cell size, more abundant wax coating, and an increase in the number of stomata and trichomes per unit area with simultaneous reduction in the size of the guard cells. The lead treatment resulted in the reduction in the thickness of the leaf blades, reduction in the area of xylem and phloem in the vascular bundles and in the diameter of the xylem vessels. Under Pb stress, the leaf mesophyll cells were characterized by the presence of altered chloroplasts with a reduced lamellar system and multidirectional pattern of the thylakoid system. Burst stroma of the thylakoid system and cracked chloroplast envelopes were also observed. The importance of the increase in the number of stomata and trichomes for plants under the metal stress was examined.     

Classification and Characteristic of Maturity Groups of Chinese Landraces of Soybean [Glycine max (L.) Merr.]

To link Chinese soybean classification with the world soybean maturity group system suggested by American researchers, 264 soybean landraces from China and 48 varieties of 13 soybean maturity groups from the United States (US) were tested under the natural and extended day-length at Nanjing, China. Based on comparing Chinese with the US soybeans in days to maturity, Chinese soybean landraces were classified into maturity group (MG) 000, 00, 0, I, II,..., IX, which only MG X might not exist in China. Chinese soybean landraces in each of MG 0, I, II and III revealed large variation in days to flowering and were almost grown in all eco-regions in China. These four maturity groups were further divided into eight sub-groups according to the variation in days to flowering and geographical distribution of soybeans of the same maturity group. The geographic distribution of soybean maturity groups in China was also presented in this paper. This study should be significant for soybean researchers in the world to understand the whole feature of Chinese soybean landraces germplasm.     

Soybean (Glycine max (L.) Merr.) yield and disease incidence with potassium fertilization

Abstract

Six cultivars and three lines of soybean (Glycine max (L.) Merr.) were planted at two locations in Delaware in 1974 and 1975. Potassium fertilizer (KCl) at 0, 56, or 223 kg/ha actual K was added to the soil and the plants were evaluated for seed yield and incidence of gray‐moldy and purple‐stained seed.

Potassium application was related to a decrease in yield in one year at one location but had no significant effect in the other year or at the other location. Cultivars differed in yield over the two years, with Kent, Cutler 71, and York having the most consistent yield in this study. The pathogen incidence was not affected by potassium application in contrast to earlier studies with soybeans grown in aluminum cylinders with a partially restricted soil volume. In this study, gray‐moldy and purple‐stain was highest in short season cultivars and higher at Georgetown than at Newark.

Use of soybean cultivars resistant to diseases as well as maintaining adequate soil potassium levels should reduce high levels of disease.     

Dynamic chloroplast pigments concentration in leaves of soybean ( Glycine max [L.] Merr.) under reduced tillage

The objectives of this experiment were to determine the chloroplast pigments dynamics of soybean leaves during the growth stages under different tillage systems, which can be a major factor limiting yield of soybean. The greatest differences between the photosynthetic productivity parameters of the investigated soybean were determined from reproductive stages (R2 and R3?–?4). The chlorophyll a, chlorophyll a/b and carotenoids content under CT, DH and NT were greater in the reproductive stages (R2 and R3?–?4) than in the early stages (V3?–?4 and R1). The concentration dynamics of chlorophyll b and chlorophyll a/b was very similar in all growth stages and under all tillage systems in the 2-yr average. The increased drought stress in 2003 was likely critical in the observed lower seed yields in 2003. The yield of soybean was significantly lower under NT than CT and DH treatments in both years. The relationship between the soybean yield and chloroplast pigments concentration is strongly influenced by external factors. In the 2-yr average the soybean yield was considerably affected by the years and tillage systems. Statistical analysis showed a very significant relationship between chlorophyll pigments content, but photosynthetic parameters investigated did not correlate with soybean yield.     

干旱及复水条件下草甘膦对抗草甘膦大豆幼苗渗透调节物质和莽草酸含量的影响

为探明干旱胁迫及复水条件下不同剂量草甘膦对抗草甘膦大豆(RR1)幼苗叶片渗透调节物质、莽草酸(shikimic acid, SA)含量及根系活力的影响,采用盆栽试验,在大豆的第3复叶期进行水分胁迫5d和除草剂草甘膦处理,研究RR1幼苗叶片可溶性蛋白(soluble protein, SP)、可溶性糖(soluble sugar, SS)、游离脯氨酸(free praline, FP)、莽草酸(shikimic acid, SA)含量和根系活力(RA)的变化。结果表明,干旱胁迫前期RR1叶片的SP含量随草甘膦剂量的增加呈先升高后降低趋势,0.46kg/hm2叶片SP的含量最高,胁迫后期SP含量随草甘膦剂量的增加而降低;SS、FP和SA含量随草甘膦剂量的增加和胁迫时间的延长而增加,RA随草甘膦剂量的增加和胁迫时间的延长而降低。复水12d后,不同剂量草甘膦处理的各指标均有所恢复。干旱条件下,经草甘膦处理的RR1叶片的SP含量和RA低于草甘膦在正常水分条件下的处理,而SS、FP和SA含量相反。相关性分析表明,FP和SA含量与草甘膦剂量的相关关系最明显;而SS和SA含量与干旱胁迫时间的相关关系最明显。说明正常水分条件下,草甘膦对RR1幼苗造成的伤害经过一段时间后有所缓解;干旱胁迫加剧了草甘膦对RR1幼苗叶片渗透调节物质、莽草酸含量和根系活力的影响。抗草甘膦大豆主要通过积累FP、SS和SA对草甘膦和干旱胁迫做出响应。     

缺磷胁迫下草甘膦对抗草甘膦大豆幼苗光合作用和叶绿素荧光参数的影响1

为探明缺磷胁迫下草甘膦对抗草甘膦大豆（RR1）幼苗叶片光合作用和叶绿素荧光参数的影响,采用溶液培养方法,在大豆长出真叶时进行缺磷胁迫,第二复叶完全展开时进行草甘膦处理,5d后测定各生理指标。结果表明, 相对于正常供磷条件的清水处理,缺磷胁迫下4.98 mL/L草甘膦处理的大豆叶片净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）、最大荧光（Fm）、PSⅡ最大光化学效率（Fv/Fm）、PSⅡ的有效量子产量［Y(Ⅱ)］、PSⅡ非调节性能量耗散的量子产量［Y(NO)］、最大电子传递速率（ETRmax）和半饱和光强（Ik）均呈下降趋势。而气孔限制值（Ls）、叶绿素a（Chl a）、叶绿素b（Chl b）、叶绿素a/b（Chl a/b）、类胡萝卜素（Car）、总叶绿素（Chl）含量和PSⅡ调节性能量耗散的量子产量［Y(NPQ)］均呈升高趋势。说明缺磷胁迫条件下喷施草甘膦显著降低了抗草甘膦大豆的光合速率。缺磷引起的气孔因素可能是导致RR大豆光合速率下降的主要原因,而光合速率的下降导致其PSⅡ反应中心的开放程度降低,活性减弱,参与CO2固定的电子较少,光化学效率较低。     

不同种植密度下丛枝菌根真菌对玉米磷吸收的影响

【目的】利用土著丛枝菌根真菌(arbuscular mycorrhizal fungi,AM真菌)与作物形成互惠互利的共生关系提高作物对土壤磷的利用效率是解决农业生产中磷供需矛盾的主要途径之一,本研究在大田玉米不同种植密度条件下,研究AM真菌对玉米根系的侵染及磷吸收作用,为揭示集约化玉米高效获取磷的机理提供理论依据。【方法】以大田作物玉米的两种种植密度(5104 plants/hm2和9104 plants/hm2)体系为研究对象,在田间原位埋设PVC管装置,通过测定菌丝生长室中的菌丝密度和有效磷耗竭来确定不同种植密度体系条件下AM真菌对玉米磷吸收的作用。【结果】相对于低密度种植群体,高密度群体显著降低了玉米拔节期土壤有效磷的耗竭量,同时增加了玉米地上部的磷含量,即磷吸收效率,增幅达20%; 在玉米拔节期,增加种植密度使根际的根外菌丝生物量(菌丝密度)降低了4%,而非根际土壤中的根外菌丝生物量(菌丝密度)增加了37%; 高密度玉米种植密度群体中AM真菌的根外菌丝对土壤有效磷耗竭的贡献增加了22%。【结论】集约化玉米生产中土著AM真菌依然帮助植株从土壤中吸收有效磷; 高密度体系下玉米对磷的吸收更加依赖于AM真菌。高密度种植增加AM真菌对玉米的侵染、 根外菌丝量和对土壤有效磷的吸收。     

Influence of Mercury on Soybean Plants (Glycine max L.) at Low pH

The influence of Hg on soybean plants under different pH conditions and Hg concentrations was studied. Growth inhibition by Hg was higher in roots than the upper part of the plant, but was highly dependant on pH condition. Growth inhibition of roots was observed when Hg concentration was higher than 1 mg Hg L⁻¹ for pH 4.0 and 5 mg Hg L⁻¹ for pH 6.0. Using ²⁰³Hg as a radioactive tracer, the amount of Hg (1 mg Hg L⁻¹) uptake in root was found to be about 1.5 times higher at pH 4.0 than that at pH 6.0; suggesting that Hg when highly accumulated at the lower pH induced inhibition of root growth. Decreased amounts of Hg due to evaporation during the plant growth were very low, but were higher at pH 6.0 than that at pH 4.0. There was hardly any translocation of Hg from roots to the upper parts through the stem within 24 h.     

Growth and metal uptake of edamame [Glycine max (L.) Merr.] on soil amended with biosolids and gypsum

ABSTRACT

Although biosolids are a rich source of plant nutrients, there is concern about the potential heavy metal uptake by crops grown on biosolid-amended soils. This study was conducted to determine the effects of limed or composted biosolids and flue gas desulfurization gypsum (FGDG) on edamame growth, nodule development, and metal uptake. Two consecutive crops of edamame were grown on 40 and 80 T ha^?1 biosolid-amended soil with and without 10 T ha^?1 FGDG. Biosolids with or without FGDG did not reduce biomass, nodules, or grain yields in the first harvest and increased yields of all three tissues in the second harvest. Lead and cadmium concentrations in grain and biomass were below the instrument detection limits. Copper, manganese, and zinc were within the ranges normally found in soybean grain. In this pot study, biosolids and FGDG did not reduce edamame growth or increase grain metal concentrations to levels of concern.     

Effect of liming using a partial mixing technique on reductions in the seed cadmium levels for soybeans (Glycine max (L.) Merr.) under field conditions

To reduce the availability of soil cadmium (Cd) to soybeans (Glycine max (L.) Merr.), we employed a liming by partial mixing (PM) technique in two drained paddy fields on Gray Lowland soils, which had 0.1 mol L^–1 hydrochloric acid-extractable Cd concentrations as high as 1.08 and 1.40 mg kg^–1. Among the different application methods tested, PM application (PM2) using a width of 20 cm and a depth of 20 cm was found to be most appropriate for reducing the seed Cd concentration and to obtain the optimum yield at Site A. Under PM2, a liming rate of 38% of that for broadcast incorporated into the surface 15 cm layer (Bc) was suitable to reduce the seed Cd concentration at Site A, whereas the lime rate with PM2 was set at 50% of that for Bc (PM2-50) at Site B due to the higher availability of soil Cd. The root system was limited within the range of lime and fertilizer application for PM2 as well as PM2-50; thus, the lime and fertilizer were supplied successfully to the rooting zone. The soil pH value was lower under PM2 at Site A and PM2-50 at Site B compared with Bc, whereas the seed Cd concentration was lower for PM2 and PM2-50. This may be explained by the intensive uptake of calcium and magnesium with PM2 as well as PM2-50. The seed Cd concentration in the cultivar “Ryuhou” at the target pH of 6.5 was approximately 30% lower with PM2-50 than Bc at Site B. In addition, the average seed Cd concentrations in one cultivar and two lines, characterized by the lower Cd uptake with higher retention in roots and higher accumulation in leaves, were approximately 40% lower compared with “Ryuhou.” Thus, the combination of liming with PM2-50 at the target pH of 6.5 and a low-Cd cultivar (or lines) minimized the seed Cd concentration. The highest seed Cd concentration was found in the first year of soybean cultivation, which was considered to be caused by the release of Cd from organic nitrogen compounds during the nitrogen mineralization process.     

Warm temperatures or drought during seed maturation increase free alpha-tocopherol in seeds of soybean (Glycine max [L.] Merr.)

Soybean seeds are an important source of dietary tocopherols, but like seeds of other dicotyledonous plants, they contain relatively little alpha-tocopherol, the form with the greatest vitamin E activity. To evaluate potential effects of environmental stress during seed maturation on tocopherols, soybeans were raised in greenhouses at nominal average temperatures of 23 degrees C or 28 degrees C during seed fill, with or without simultaneous drought (soil moisture at 10-25% of capacity), during normal growing seasons in 1999 (cvs. Essex and Forrest) and 2000 (cvs. Essex, Forrest, and Williams). Total free (nonesterified) tocopherols increased slightly in response to drought in Essex and Forrest. All three lines responded to elevated temperature and, to a lesser extent, drought with large (2-3-fold) increases in alpha-tocopherol and corresponding decreases in delta-tocopherol and gamma-tocopherol. The results suggest that weather or climate can significantly affect seed tocopherols. It may be possible to breed for elevated alpha-tocopherols by selecting for altered plant response to temperature.     

Influence of Mercury on Soybean Plants (Glycine max L.) at Low pH

The influence of Hg on soybean plants under different pH conditions and Hg concentrations was studied. Growth inhibition by Hg was higher in roots than the upper part of the plant, but was highly dependant on pH condition. Growth inhibition of roots was observed when Hg concentration was higher than 1 mg Hg L^?1 for pH 4.0 and 5 mg Hg L^?1 for pH 6.0. Using ²⁰³Hg as a radioactive tracer, the amount of Hg (1 mg Hg L^?1) uptake in root was found to be about 1.5 times higher at pH 4.0 than that at pH 6.0; suggesting that Hg when highly accumulated at the lower pH induced inhibition of root growth. Decreased amounts of Hg due to evaporation during the plant growth were very low, but were higher at pH 6.0 than that at pH 4.0. There was hardly any translocation of Hg from roots to the upper parts through the stem within 24 h.     

Potassium fertilization effects on isoflavone concentrations in soybean [Glycine max (L.) Merr.

Soybean isoflavone concentrations vary widely, but the contribution of soil fertility and nutrient management to this variability is unknown. Field experiments from 1998 to 2000 on soils with low to high exchangeable potassium (K) concentrations evaluated K application and placement effects on isoflavone concentrations and composition of soybean in various tillage and row-width systems. Soybean seed yield and concentrations of daidzein, genistein, glycitein, leaf K, and seed K were measured. Significant increases in daidzein, genistein, and total isoflavone were observed with direct deep-banded K or residual surface-applied K on low-K soils. Positive effects of K fertilization on isoflavones were less frequent on medium- to high-testing K soils. Both individual and total isoflavones were often positively correlated with seed yield, leaf K, and seed K on low-K soils. Appropriate K management could be an effective approach to increase isoflavone concentrations for soybeans produced on low- to medium-K soils.     

Nitrogen accumulation in soybean [Glycine max (L.) Merr.] is increased by manure compost application in drained paddy fields as a result of increased soil nitrogen mineralization

The application of manure compost is an effective way to increase soybean [Glycine max (L.) Merr.] yield and nitrogen (N) fertility in drained paddy fields. We investigated changes in soil N mineralization during soybean cultivation using reaction kinetics analysis to determine the contribution of increased N mineralization after manure compost application (at a rate of 0 to 6?kg?m^?2) on N accumulation and seed yield of soybean under drained paddy field conditions. The seed yield and N accumulation decreased markedly in the second and third year of the experiment, but soil N mineralization increased in both years. No decrease in soil N mineralization occurred even after two soybean crops. Soil N availability was not the main cause of decreased soybean yield in the second and third years. The differences in plant aboveground N content between plots with and without manure compost was similar to the increase in N mineralization caused by manure compost application in the second and third years. The application of 6?kg?m^?2 of manure compost increased the amount of ureide-N and nitrate-N in soybean in the third year. Our results suggest that manure compost application increases soil N mineralization and soybean N₂ fixation, resulting in increased N accumulation and seed yield. However, the soybean yield remained less than 300?g?m^?2 in the second and third years (i.e., below the yield in the first year) at all levels of manure compost application due to the remarkable decrease of N accumulation in the second and the third crops.     

Physical mapping and candidate gene prediction of branch number on the main stem in soybean [Glycine max (L.) Merr.]

Genetic Resources and Crop Evolution - Branch number on the main stem (BNMS) is an important factor that affects crop plant architecture and yield in soybean [Glycine max (L.) Merr.]. With the aim...     

Assessment of phenotypic and molecular diversity in soybean [Glycine max (L.) Merr.] germplasm using morpho-biochemical attributes and SSR markers

Genetic Resources and Crop Evolution - Soybean is a high-nutritional crop that provides a sustainable source of dietary protein and edible oil for human consumption and animal diet. In this...