Improving oxidative stability and release behavior of docosahexaenoic acid algae oil by microencapsulation.

BACKGROUND: Spray-dried docosahexaenoic acid algae oil (DHA AO) microcapsules were prepared using whey protein isolate and glucose syrup (WPI + GS), or sodium starch octenylsuccinate and glucose syrup (SSOS + GS), or whey protein isolate and lactose (WPI + L). The effect of the formulations on encapsulation properties, oxidative protection and in vitro oil release pattern of the resulting microencapsulates was investigated. RESULTS: A high encapsulation efficiency of over 98% of DHA AO was obtained for microcapsules with all three wall materials. Among the wall materials, SSOS + GS exhibited a better micro-particulation ability reflected by more uniform size and smoother surface of the formed microcapsules and no agglomerates. DHA AO microcapsules with all the wall materials showed good protection of the oil from oxidation during storage with an increasing order of WPI + GS, SSOS + GS and WPI + L. Moreover, microencapsulation significantly increased the release of DHA AO in the intestinal phase of the in vitro digestion process with an increasing order of SSOS + GS, WPI + GS and WPI + L, indicating the increased stability of the oil in the highly acidic gastric environment and the enhanced lipid digestibility in the small intestine. CONCLUSIONS: The results suggest that it is possible to transform a highly oxidizable liquid functional food ingredient such as DHA AO into a stable and easy-to-handle solid powder through spray drying with properly selected wall materials. © 2020 Society of Chemical Industry.

High Salt Tolerance of a Bradyrhizobium Strain and Its Promotion of the Growth of Stylosanthes guianensis.

Salinity is a serious limiting factor for the growth of rhizobia. Some rhizobia are tolerant to salt stress and promote plant growth, but the mechanisms underlying these effects are poorly characterized. The growth responses and osmoprotectants in four Bradyrhizobium strains were examined under salt stress in this study. Two-dimensional electrophoresis (2-DE) and mass spectrometry were conducted to investigate protein profiles in rhizobia exposed to salt stress. Subsequently, salt tolerance in stylo (Stylosanthesguianensis) inoculated with rhizobia was further detected in hydroponics. Results showed that the Bradyrhizobium strain RJS9-2 exhibited higher salt tolerance than the other three Bradyrhizobium strains. RJS9-2 was able to grow at 0.35 M NaCl treatment, while the other three Bradyrhizobium strains did not grow at 0.1 M NaCl treatment. Salt stress induced IAA production, and accumulation of proline, betaine, ectoine, and trehalose was observed in RJS9-2 but not in PN13-1. Proteomics analysis identified 14 proteins regulated by salt stress in RJS9-2 that were mainly related to the ABC transporter, stress response, and protein metabolism. Furthermore, under saline conditions, the nodule number, plant dry weight, and N concentration in stylo plants inoculated with RJS9-2 were higher than those in plants inoculated with PN13-1. These results suggest that the tolerance of RJS9-2 to salt stress may be achieved by the coordination of indole-3-acetic acid (IAA) production, osmoprotectant accumulation, and protein expression, thus promoting stylo growth.

Alterations of growth, antioxidant system and gene expression in Stylosanthes guianensis during Colletotrichum gloeosporioides infection.

Anthracnose caused by Colletotrichum gloeosporioides is one of the most destructive fungal diseases of many plants, including stylo (Stylosanthes spp.), which is an important tropical forage legume. Although C. gloeosporioides-caused anthracnose is the major constraint limiting the growth and yield of stylo, little information is available regarding the responses of stylo during the infection process of this pathogen. This study investigated the changes in growth, the antioxidant system and gene expression in stylo in response to C. gloeosporioides treatment. Negative effects of C. gloeosporioides were observed in inoculated stylo plants, as reflected by the formation of necrotic disease lesions and the decrease in shoot fresh weight. Reactive oxygen species (ROS) accumulation increased in stylo leaves during the C. gloeosporioides infection process. The activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX) and glutathione reductase (GR), as well as the concentrations of the antioxidant compounds ascorbate (AsA) and glutathione (GSH), increased in leaves under C. gloeosporioides treatment. Furthermore, transcriptional analysis showed that the expression of stress response genes, including NADPH oxidase (Nox), thioredoxin (Thi), pathogenesis related genes (PR1 and PR5), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), chalcone synthase (CHS) and chitinase (Cht), was differentially enhanced in stylo leaves by C. gloeosporioides. Taken together, this study provides novel information regarding the alterations during the infection process of C. gloeosporioides in stylo at the levels of antioxidant system and gene expression.

Polymorphism analysis in identification of genetic variation and relationships among Stylosanthes species.

A total of 148 accessions representing six important species of the genus Stylosanthes, including S. guianensis, S. hamata, S. scabra, S. seabrana, S. macrocephala, and S. capitata, were used to evaluate genetic variation and relationships using sequence-related amplified polymorphism markers. The results showed that the 18 selected primer pairs generated 138 distinct fragments. The fragment sizes ranged from 150 to 2000 bp. Genetic similarity coefficients among the 148 accessions ranged from 0.51 to 0.99, with an average of 0.79. The effective allele number (ne) generated by the 18 primer pairs averaged 1.3552 and ranged from 1.2069 to 1.6080; Nei's gene diversity (He) ranged from 0.1304 to 0.3207, with an average of 0.2070; and Shannon's information index (I) averaged 0.3213 and ranged from 0.2233 to 0.4582. The unweighted pair-group method with arithmetic averages at the 0.69 similarity level separated the 148 accessions into two distinct groups. One group belonged to S. guianensis, and the other group belonged to the non-S. guianensis type. This study verified that Stylosanthes have rich genetic variation, which is an excellent basis for Stylosanthes breeding for new cultivars. This study demonstrates that the SRAP technique is a reliable tool for differentiating Stylosanthes accessions and for discerning genetic relationship among them.

Carex jianfengensis (Carex sect. Rhomboidales, Cyperaceae), a New Species from Hainan, China.

A new species of Carex sect. Rhomboidales, C. jianfengensis, is described and illustrated from Hainan, China. The new species is similar to C. zunyiensis but differs in having involucral bracts sparsely hispid and with ca.1 cm long sheaths; inflorescence with 4 spikes, terminal spike ca. 2.5 cm long, lateral spikes 2-3.5 × 0.7-1 cm; staminate glumes narrowly ovate, ca. 5 mm; pistillate glumes triangular-lanceolate, 5-7 mm; perigynia 6-8 × 3 mm and pubescent on veins; nutlet 4-5 mm long, rhombic-ovoid, trigonous, base with shortly stipitate, apex abruptly contracted into a erect short beak, and not expanding into an annulate orifice.

Genetic analysis of 430 Chinese Cynodon dactylon accessions using sequence-related amplified polymorphism markers.

Although Cynodon dactylon (C. dactylon) is widely distributed in China, information on its genetic diversity within the germplasm pool is limited. The objective of this study was to reveal the genetic variation and relationships of 430 C. dactylon accessions collected from 22 Chinese provinces using sequence-related amplified polymorphism (SRAP) markers. Fifteen primer pairs were used to amplify specific C. dactylon genomic sequences. A total of 481 SRAP fragments were generated, with fragment sizes ranging from 260-1800 base pairs (bp). Genetic similarity coefficients (GSC) among the 430 accessions averaged 0.72 and ranged from 0.53-0.96. Cluster analysis conducted by two methods, namely the unweighted pair-group method with arithmetic averages (UPGMA) and principle coordinate analysis (PCoA), separated the accessions into eight distinct groups. Our findings verify that Chinese C. dactylon germplasms have rich genetic diversity, which is an excellent basis for C. dactylon breeding for new cultivars.

Carex diaoluoshanica (Carex sect. Lageniformes, Cyperaceae), a new species from Hainan, China.

Carex diaoluoshanica, a new species of Carex sect. Lageniformes from Hainan, China, is described and illustrated. The new species is similar to C. breviscapa but differs in having wider leaves with the leaf base gradually narrowed, 5-10 cm long and petiolelike, culms subfiliform, with only two spikes, the lateral female spikes from near the culm base.

Aluminium tolerance and high phosphorus efficiency helps Stylosanthes better adapt to low-P acid soils.

BACKGROUND AND AIMS: Stylosanthes spp. (stylo) is one of the most important pasture legumes used in a wide range of agricultural systems on acid soils, where aluminium (Al) toxicity and phosphorus (P) deficiency are two major limiting factors for plant growth. However, physiological mechanisms of stylo adaptation to acid soils are not understood. METHODS: Twelve stylo genotypes were surveyed under field conditions, followed by sand and nutrient solution culture experiments to investigate possible physiological mechanisms of stylo adaptation to low-P acid soils. KEY RESULTS: Stylo genotypes varied substantially in growth and P uptake in low P conditions in the field. Three genotypes contrasting in P efficiency were selected for experiments in nutrient solution and sand culture to examine their Al tolerance and ability to utilize different P sources, including Ca-P, K-P, Al-P, Fe-P and phytate-P. Among the three tested genotypes, the P-efficient genotype 'TPRC2001-1' had higher Al tolerance than the P-inefficient genotype 'Fine-stem' as indicated by relative tap root length and haematoxylin staining. The three genotypes differed in their ability to utilize different P sources. The P-efficient genotype, 'TPRC2001-1', had superior ability to utilize phytate-P. CONCLUSIONS: The findings suggest that possible physiological mechanisms of stylo adaptation to low-P acid soils might involve superior ability of plant roots to tolerate Al toxicity and to utilize organic P and Al-P.