The isoleucic acid triad: distinct impacts on plant defense, root growth, and formation of reactive oxygen species

Isoleucic acid (ILA), a branched-chain amino acid-related 2-hydroxycarboxylic acid, occurs ubiquitously in plants. It enhances pathogen resistance and inhibits root growth of Arabidopsis. The salicylic acid (SA) glucosyltransferase UGT76B1 is able to conjugate ILA. Here, we investigate the role of ILA in planta in Arabidopsis and reveal a triad of distinct responses to this small molecule. ILA synergistically co-operates with SA to activate SA-responsive gene expression and resistance in a UGT76B1-dependent manner in agreement with the observed competitive ILA-dependent repression of SA glucosylation by UGT76B1. However, ILA also shows an SA-independent stress response. Nitroblue tetrazolium staining and pharmacological experiments indicate that ILA induces superoxide formation of the wild type and of an SA-deficient (NahG sid2) line. In contrast, the inhibitory effect of ILA on root growth is independent of both SA and superoxide induction. These effects of ILA are specific and distinct from its isomeric compound leucic acid and from the amino acid isoleucine. Leucic acid and isoleucine do not induce expression of defense marker genes or superoxide production, whereas both compounds inhibit root growth. All three responses to ILA are also observed in Brassica napus.

Prairie Dropseed Germination Highest with Warm, Moist Conditions

We tested prairie dropseed (Sporobolus heterolepis) using six different germination treatments and found the best results with cold (40 °F), dry storage followed by direct seeding into a commercial germination mix placed in a 75 °F glass-glazed greenhouse with intermittent mist (5 seconds of mist every 8 minutes), and 600-W high-pressure sodium lighting with a 16-hour daylength. We found commercial laboratory viability analysis from tetrazolium staining did not correspond to germination results. Cold (34 °F), moist (2.3 g seed moistened with 2.5 mL deionized water) treatment, also known as cold conditioning, produced significantly less germination and fewer transplantable seedlings, and is not recommended for prairie dropseed.

Short Communication: Tetrazolium test for evaluating viability of Capsicum annum seeds

Kusumawardana A, Pujiasmanto B, Pardono. 2018. Tetrazolium test for evaluating viability of Capsicum annum seeds. Nusantara Bioscience 10: 142-145. Seed quality is important in seeds production. This research was conducted to obtain information of topographical tetrazolium staining pattern of pepper (Capsicum annum) seeds. Tetrazolium test was conducted to determine the seed viability and plant growth vigor. Laboratory test for standard germination and field performances were performed on four lots (A, B, C, D) of pepper seeds. The viability categories pattern were determined by Root Mean Square (RMS), regression, and correlation analyses. Nine topographical patterns were recognized. The laboratory test results and field performances were compared with the topographical pattern. Combination of patterns 1,2 (embryonic axis and cotyledon completely stained) selected as viable category as it gave the least RMS value, the highest determination (R²) and correlation (r) coefficient with standard germination (RMS = 4, 06; R² = 0,761; r = 0,872). Combination of patterns 1,2 also gave the highest determination (R²) and correlation (r) coefficient with field stand (R² = 0,921; r = 0,959). The combination of patterns 1,2 is recommended for estimating plant growth performance in the field.

In vitro pollen viability of maize cultivars at different times of collection

ABSTRACT: In the present study, we aimed to assess the in vitro viability of pollen grains from maize cultivars collected at different times and days in the field. Four cultivars (Sol da Manhã, XB 6012, XB 8010, and BRS 2020) were evaluated from the second to fifth day of anthesis in three times. Pollen samples were evaluated for their in vitro viability through standard germination test in liquid and solid media and tetrazolium staining. The experimental design was completely randomized, in 4x4x3 split-split plots with four replicates. Data were subjected to analysis of variance followed by a means clustering test and linear regression analysis. The average percentage of viable pollen varied according to the day, collection time, and cultivar. In general, XB 8010 and BRS 2020 had the highest frequency of viable pollen. The highest percentages of viable pollen were observed on the second day of anthesis at 10:00h.

Yellow bristle grass seed killed in maize silage

Yellow bristle grass (Setaria pumila) is a serious weed that reduces dairy farm profitability and could potentially infest productive land throughout New Zealand Supplementary feed is used extensively in the dairy industry and farmers are concerned that yellow bristle grass seed may be spread with maize silage Previous studies showed that its seeds did not survive burial in covered silage stacks after 1 week To further investigate the decline in seed viability mesh bags containing 50 seeds were buried at 0 and/or 400 mm depth in two covered Waikato silage stacks and retrieved after 1 2 3 5 and 7 days Germination prior to seed burial was 69 and viability using tetrazolium staining was 88 Germination was reduced after 1 day to 1236 2 days to 030 3 days to 04 and 5 days to 0 Viability was reduced after 1 week from 50 to 40 Temperature and pH conditions during this study were not considered sufficient for rapid seed decay and therefore it appeared that chemicals released after ensiling were responsible Further investigation into mechanisms behind this rapid decay and its potential for effective weed seed control is warranted