Exudation of an allelopathic substance lepidimoide from seeds during germination

Lepidimoide promotes growth of the cockscomb hypocotyl. It is exuded from germinating seeds of various plant species into their culture environment. The mode of exudation of lepidimoide from seeds into the culture solution, using sunflower and buckwheat seeds, was studied in relation to seed germination. In the dry seeds, about 75% of the lepidimoide was found in the seed coat and about 25% in the kernel. Upon water imbibition it was released into the culture solution. However, the quantity of lepidimoide detected in the seed exudate was more than three times the total amount in dry and imbibed seeds, suggesting that lepidimoide was also produced de novo in the seeds and subsequently released. When seed coats or kernels were imbibed separately, the quantity of lepidimoide released from the seed coats into the culture solution was much the same as that in the dry seeds, but the amount of lepidimoide detected in the exudate of kernels was about 16 times that in the dry kernels. These results suggest that lepidimoide, already present in dry seeds, as well as that newly produced in the kernels following imbibition, was released into the environment.     

苦荞叶肉细胞原生质体的分离纯化及瞬时转化

高效分离原生质体是遗传转化、细胞融合和再生培养的基础性工作。该实验以苦荞(Fagopyrum tartaricum)品种‘榆6-21’的叶肉细胞为材料,研究了酶类组合、甘露醇浓度、酶解时间以及离心速度对苦荞叶肉细胞原生质体分离纯化的影响。结果表明:酶解液组成为1.5%纤维素酶R-10+0.5%离析酶R-10+0.5mol/L甘露醇+20mmol/L MES+20mmol/L KCl+10mmol/L CaCl2+0.1%牛血清白蛋白,以第5~7片真叶为材料,用胶带纸撕去叶片下表皮后,25℃黑暗酶解4h,以900r/min离心收集,可以获得高质量的原生质体,原生质体产量可达6×106个/g,活力达到90%以上;用双荧光素酶报告基因载体检测原生质体的转化效率,以分离纯化的苦荞叶肉细胞原生质体为受体,将双荧光素酶报告基因载体与其混合后,在终浓度为20%PEG4000介导下,黑暗转化20min,可以检测到较高活性的萤火虫荧光素酶和海肾荧光素酶,证明双荧光素酶报告载体可成功转化到原生质体中。研究结果为苦荞原生质体瞬时转化及遗传操作提供了技术基础。     

Anther culture and androgenetic plant regeneration in buckwheat (Fagopyrum esculentum Moench)

Anther culture for haploid induction of buckwheat was studied over a period of five years. Approximately 24,000 anthers were isolated and cultured on different culture media. The regeneration capacity was generally very low. Data are presented for experiments that included 7278 anthers on which 99 calluses were formed and 20 buds regenerations were noted. Regeneration occurred most readily on gellan-gum solidified media, with 90 g l^-1 maltose, 2.5 mg l^-1 BA, 0.5 mg l^-1 IAA, and preferably in darkness. Haploid cells, as established by chromosome counts, were observed in eight regenerants. Several abnormalities of pollen development in vitro were detected. Starch presence in pollen as a possible sign of androgenic capacity was studied. Microspores in uninucleate and early binucleate stages contained only proplastids, while in adult pollen grains a number of amyloplasts were present.Abbreviations BA benzyladenine - IAA indole-3-acetic acid - 2,4 D-2,4-dichloro-phenoxyacetic acid - IBA indole-3-butyric acid - 2iP 6- c,c-dimethylallylaminol-purine - NAA -naphthalene acetic acid     

High-quality Fagopyrum esculentum genome provides insights into the flavonoid accumulation among different tissues and self-incompatibility

Common buckwheat (Fagopyrum esculentum) and Tartary buckwheat (Fagopyrum tataricum), the two most widely cultivated buckwheat species, differ greatly in flavonoid content and reproductive mode. Here, we report the first high-quality and chromosome-level genome assembly of common buckwheat with 1.2 Gb. Comparative genomic analysis revealed that common buckwheat underwent a burst of long terminal repeat retrotransposons insertion accompanied by numerous large chromosome rearrangements after divergence from Tartary buckwheat. Moreover, multiple gene families involved in stress tolerance and flavonoid biosynthesis such as multidrug and toxic compound extrusion (MATE) and chalcone synthase (CHS) underwent significant expansion in buckwheat, especially in common buckwheat. Integrated multi-omics analysis identified high expression of catechin biosynthesis-related genes in flower and seed in common buckwheat and high expression of rutin biosynthesis-related genes in seed in Tartary buckwheat as being important for the differences in flavonoid type and content between these buckwheat species. We also identified a candidate key rutin-degrading enzyme gene (Ft8.2377) that was highly expressed in Tartary buckwheat seed. In addition, we identified a haplotype-resolved candidate locus containing many genes reportedly associated with the development of flower and pollen, which was potentially related to self-incompatibility in common buckwheat. Our study provides important resources facilitating future functional genomics-related research of flavonoid biosynthesis and self-incompatibility in buckwheat.     

Influence of mold growth on the pressure drop in aerated solid state fermentors

The measurement of pressure drop(DeltaP) across an aerated fermentation bed is proposed as alternative on-line sensor for the qualitative and, in some cases, quantitative, macroscopic changes in a static solid state fermentor. An increase in the DeltaP is correlated with the evolution of the different phases of Aspergillus niger growth: germination, vegetative growth, limitation, and sporulation, we observed in the microscope. For the case where the support is not modified during the fermentation and the water content remains constant, i.e., a synthetic resin (Amberlite IRA-900), the gas phase permeability of the bed is directly related to the biomass content. For example, the permeability of the bed is reduced to 5% of the initial value when biomass attains 21 mg dry biomass/g dry support. Biomass was appropriately predicted from the DeltaP measurements in an independent test. Experiments with different initial sucrose solution concentrations showed that biomass could not be produced beyond a certain level (21.5 mg dry biomass/g dry support) which suggests steric limitations. For the case of wheat bran and cane bagasse, the increase in DeltaP was related qualitatively to the evolution in the growth and the morphology of the mold . (c) 1993 Wiley & Sons, Inc.     

应用常压水解法从脱脂米糠中制取肌醇

本文论述了应用常压水解从脱脂米糠制取肌醇的方法.用稀盐酸浸渍米糠,控制pH3—4,选用碳酸氢钠作沉淀剂,以稀植酸溶解菲汀,过滤,阳离子交换,减压浓缩得到植酸。取50—60％浓度的植酸,以1:1加入到一缩二乙二醇中,在130—150℃温度下水解,肌醇水解率在75—95％以上(以植酸汁).     

Characterization of the growth and sporulation behavior of Penicillium roquefortii in solid substrate fermentation by material and bioenergetic balances

When Pencillium roquefortii is grown on two kinds of buckwheat, exhibiting a low [0.85 g water/g dry matter (DM), buckwheat A] and a high [1.5 g water/g initial dry matter (IDM), buckwheat B] water content, a marked difference in the mode of development of the fungus is observed. Material balances for buckwheat A show that growth does not stop because of nutrient exhaustion. Analysis of water balance shows that active growth proceeds with a permanent limitation by the turgor potential which disappears when the water activity of the substrate is close to 0.96, thus arresting growth. This limitation causes intensive water excretion from the system due to the lowering of the water activity of the substrate. The water content of the mycelium thus decreases from 79% at the beginning of the cultivation to 74% when the growth stops. This is linked to a substantial oxidative metabolism and a high sporulation efficiency, close to 0.85. The spores obtained have a low dry weight and a reduced nitrogen content. In the case of buckwheat B, the active growth is shown to stop because of available mineral nitrogen depletion. No significant decrease in the water activity of the substrate is found during the protein synthesis, and the turgor potential remains high at the end of this period. Culture proceeds with new wall synthesis; the sporulation efficiency remains high and the spores obtained exhibit a high dry weight and a high nitrogen content. The bioenergetic balances show that the P/O ratio varies with the kind of substrate used; its value is close to 1.56 for the low water medium and to 2.21 for the high one. The ATP yield Z is always close to 1, and fungal development occurs with limitations of both anabolism and catabolism on buckwheat B and only of anabolism and catabolism on buckwheat B and only of anabolism on buckwheat A.     

A method for determining binding kinetics applied to thiamine-binding protein

A rapid and simple method for assaying the binding activity of thiamine-binding protein is described. By this assay method, the binding characteristics of rice bran thiamine-binding protein have been evaluated with [14C]thiamine as ligand. Analysis of these data by Scatchard plot resulted in linear plots giving a dissociation constant (Kd) for thiamine of 0.55 microM and a maximum binding (Bmax) of 14.5 pmol of ligand bound/microgram of protein. Thiamine binding to the binding protein was time dependent and reached equilibrium at approximately 20 min. The Kob was 0.18 min-1 and the k1 was 1.25 X 10(5) min-1 M-1. Reversibility of thiamine binding at equilibrium was completed at 60 min with a k2 value of 0.052 min-1. The Kd calculated from the reverse rate constant was 0.42 microM. These results indicated that this binding assay method was substantially reliable and accurate.     

Effectiveness of beta-exotoxin ofBacillus thuringiensis var.thuringiensis on the ability ofMeloidogyne sp. from brinjal (Solanum melongena L.) to survive

Beta-exotoxin produced byBacillus thuringiensis var.thuringiensis grown in the acid hydrolysates of wheat and rice brans caused 95% and 85% mortality respectively ofMeloidogyne sp. as against 72% of β-exotoxin produced on farm yard manure within 7 days. Acid hydrolysate of wheat or rice bran and solid farm yard manure proved to be the best media for growth ofB. thuringiensis var.thuringiensis.     

Changes in moisture content,mycoflora and aflatoxin content of rice bran during storage

The changes in moisture content, storage mycoflora and aflatoxin B₁ (AFB₁) in bran from untreated or raw rice (Rr) and parboiled rice (Pbr) stored in small lots in polyethylene bags were studied at 15-day intervals up to 60 days, using five lots of each type of bran. Deterioration was more rapid with reference to all the three parameters, in Rr bran compared to Pbr bran, the former becoming completely overgrown and caked with fungi by the end of 60 days.Aspergillus flavus was the dominant fungus in Pbr bran, whereasA. candidus andTrichoderma viride were abundant in Rr bran. The frequency of incidence as well as concentration of AFB₁ increased with storage time in both types of bran, but the rate of increase as well as overall concentration were much higher in Rr bran. Thus raw rice bran is unsuitable for prolonged storage.Abbreviations AFB₁ aflatoxin B₁ - MC moisture content - Pbr parboiled rice - Rr raw rice