Effect of local stress induction on resistance-related enzymes in cucumber seeding

Endophytic Pseudomonas fluorescens promotes changes in the phenotype and secondary metabolite profile of Houttuynia cordata Thunb

The interactions between microbes and plants are governed by complex chemical signals, which can forcefully affect plant growth and development. Here, to understand how microbes influence Houttuynia cordata Thunb. plant growth and its secondary metabolite through chemical signals, we established the interaction between single bacteria and a plant. We inoculated H. cordata seedlings with bacteria isolated from their roots. The results showed that the total fresh weight, the total dry weight, and the number of lateral roots per seedling in the P. fluorescens-inoculated seedlings were 174%, 172% and 227% higher than in the control seedlings. Pseudomonas fluorescens had a significant promotional effect of the volatile contents compared to control, with β-myrcene increasing by 192%, 2-undecanone by 203%, decanol by 304%, β-caryophyllene by 197%, α-pinene by 281%, bornyl acetate by 157%, γ-terpinene by 239% and 3-tetradecane by 328% in P. fluorescens-inoculated H. cordata seedlings. the contents of chlorogenic acid, rutin, quercitin, and afzelin were 284%, 154%, 137%, and 213% higher than in control seedlings, respectively. Our study provided basic data to assess the linkages between endophytic bacteria, plant phenotype and metabolites of H. cordata to provide an insight into P. fluorescens use as biological fertilizer, promoting the synthesis of medicinal plant compounds.

Beneficial Effects of Endophytic Fungi from the Anoectochilus and Ludisia Species on the Growth and Secondary Metabolism of Anoectochilus roxburghii

Endophytic fungi possess favorable effects on their host plants, including disease-resistance improvement, secondary metabolite induction, and growth promotion. It is therefore a promising and sustainable strategy to utilize endophytic fungi for the quality improvement of medicinal herbs or important crops. In our study, a collection of 277 strains of endophytic fungi were isolated from Anoectochilus and Ludisia orchids. Two strains J162 and J211 can be symbiotically cocultured with the tissue culture seedlings of Anoectochilus roxburghii, a popular medicinal and edible plant in southern China. Both strains can significantly enhance the biomass of A. roxburghii and induce the biosynthesis and accumulation of its active ingredients, including flavonoids, kinsenoside, and polysaccharides. J162 and J211 were further identified as Chaetomium globosum and Colletotrichum gloeosporioides based on multilocus phylogenetic analysis. Immunocytochemical staining indicated that J162 and J211 mainly colonized the intercellular gap of xylem parenchyma cells of A. roxburghii roots without obvious harm. In addition, quantitative real-time polymerase chain reaction showed that the expression of three growth-related genes, namely, uracil phosphoribosyl transferase, amino acid transmembrane transporter, and maturase K, were significantly altered in A. roxburghii plants when treated with J162 and J211. In conclusion, the two strains are highly beneficial microbial resources for the growth and accumulation of active ingredients of A. roxburghii in agricultural cultivation.

28-homobrassinolide alters protein content and activities of glutathione-s-transferase and polyphenol oxidase in raphanus sativus L. Plants under heavy metal stress

OBJECTIVES

The application of brassinosteroids (BRs), the plant steroidal hormones, results in an increased tolerance toward stress and thus helps improving the yield of crop plants. The present study was carried out to investigate the effect of 28-homobrassinolide (28-HBL) on the protein content as well as activities of antioxidant enzymes viz., glutathione-s-transferase (GST) and polyphenol oxidase (PPO) in radish plants grown under Cadmium (Cd) and Mercury (Hg) metal stress.

MATERIALS AND METHODS

Shoots of 60 and 90 days old radish plants, grown under Cd and Hg metal stress (0, 0.5, 1.0, 1.5 mM) and given the presowing treatment of 28-HBL (0, 10(-7), 10(-9), 10(-11) M) to seeds for 8 h, were analyzed for protein content and GST and PPO enzyme activities.

RESULTS

Protein content showed decrease in plants given Cd and Hg metal treatment alone, while treatment with 28-HBL enhanced the protein content, suggesting its stress protective role. An increase in the activity of antioxidative enzymes was also observed in plants stressed with heavy metals as well as in those supplemented with 28-HBL.

CONCLUSIONS

In the present investigation, the activity of antioxidative enzymes was found to increase due to metal stress and a further increase was noticed in plants given both metal and 28-HBL treatment, suggesting the stress protective role of 28-HBL via modulating the antioxidative enzymes.

Milk yield responses to changes in milking frequency during early lactation are associated with coordinated and persistent changes in mammary gene expression

Background

The lactating mammary gland responds to changes in milking frequency by modulating milk production. This response is locally regulated and, in dairy cows, the udder is particularly sensitive during early lactation. Relative to cows milked twice-daily throughout lactation, those milked four-times-daily for just the first 3 weeks of lactation produce more milk throughout that lactation. We hypothesized that the milk yield response would be associated with increased mammary cell turnover and changes in gene expression during frequent milking and persisting thereafter. Cows were assigned to unilateral frequent milking (UFM; left udder halves milked twice-daily; right udder halves milked four-times daily) on days 1 to 21 of lactation, followed by twice-daily milking for the remainder of lactation. Relative to udder halves milked twice-daily, those milked four-times produced more milk during UFM; the difference in milk yield declined acutely upon cessation of UFM after day 21, but remained significantly elevated thereafter. We obtained mammary biopsies from both udder halves on days 21, 23, and 40 of lactation.

Results

Mammary cell proliferation and apoptosis were not affected by milking frequency. We identified 75 genes that were differentially expressed between paired udder halves on day 21 but exhibited a reversal of differential expression on day 23. Among those genes, we identified four clusters characterized by similar temporal patterns of differential expression. Two clusters (11 genes) were positively correlated with changes in milk yield and were differentially expressed on day 21 of lactation only, indicating involvement in the initial milk yield response. Two other clusters (64 genes) were negatively correlated with changes in milk yield. Twenty-nine of the 75 genes were also differentially expressed on day 40 of lactation.

Conclusions

Changes in milking frequency during early lactation did not alter mammary cell population dynamics, but were associated with coordinated changes in mammary expression of at least 75 genes. Twenty-nine of those genes were differentially expressed 19 days after cessation of treatment, implicating them in the persistent milk yield response. We conclude that we have identified a novel transcriptional signature that may mediate the adaptive response to changes in milking frequency.

Acute milk yield response to frequent milking during early lactation is mediated by genes transiently regulated by milk removal

Milking dairy cows four times daily (4×) instead of twice daily (2×) during early lactation stimulates an increase in milk yield that partly persists through late lactation; however, the mechanisms behind this response are unknown. We hypothesized that the acute mammary response to regular milkings would be transient and would involve different genes from those that may be specifically regulated in response to 4×. Nine multiparous cows were assigned at parturition to unilateral frequent milking (UFM; 2× of the left udder half, 4× of the right udder half). Mammary biopsies were obtained from both rear quarters at 5 days in milk (DIM), immediately after 4× glands had been milked (experiment 1, n = 4 cows), or 2.5 h after both udder halves had last been milked (experiment 2, n = 5 cows). Affymetrix GeneChip Bovine Genome Arrays were used to measure gene expression. We found 855 genes were differentially expressed in mammary tissue between 2× vs. 4× glands of cows in experiment 1 (false discovery rate ≤ 0.05), whereas none were differentially expressed in experiment 2 using the same criterion. We conclude that there is an acute transcriptional response to milk removal, but 4× milking did not elicit differential expression of unique genes. Therefore, there does not appear to be a sustained transcriptional response to 4× milking on day 5 of lactation. Using a differential expression plot of data from both experiments, as well as qRT-PCR, we identified at least two genes (chitinase 3-like-1 and low-density lipoprotein-related protein-2 that may be responsive to both milk removal and to 4× milking. Therefore, the milk yield response to 4× milking may be mediated by genes that are acutely regulated by removal of milk from the mammary gland.