Comparison of antioxidant activity assays in fresh purple waxy corn (Zea mays L.) during grain filling

Purple waxy corn is a good source of antioxidant compounds such as anthocyanins and polyphenols. Promotion of its use requires an appropriate assay to determine antioxidant activity. The aim of this study is to verify compatibility of the antioxidant activity assays by comparing five different assays in daily kernel samples of the fresh purple waxy corn during grain filling. The levels of antioxidants measured by 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and chemiluminescence showed significant positive correlations with the levels measured by the other assays (r = 0.761–0.893; p < 0.01) and with anthocyanin content (r = 0.798–0.924; p < 0.01). Reducing capacity of 2,2ʹ-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) and total phenolic content also showed significant correlations (r = 0.764; p < 0.01). However, during late grain filling, the levels of antioxidants measured by all methods showed strong correlations with each other (r > 0.699; p < 0.05). The inconsistencies among the measurements are largely dependent on the developmental stage of the corn kernel. The combination of at least two assays is required to ensure reliable antioxidant activity estimates, especially for early grain-filling stages. These results will inform efforts to promote fresh purple corn as a source of antioxidants.

Simultaneous Selection of Sweet-Waxy Corn Ideotypes Appealing to Hybrid Seed Producers, Growers, and Consumers in Thailand

Multi-trait selection helps breeders identify genotypes that appeal to divergent groups of preferences. In this study, we performed simultaneous selection of sweet-waxy corn hybrids on several traits covering the perspectives of consumers (taller kernel depth, better eating quality), growers (early maturity, shorter plant stature, and high ear yield), and seed producers (high flowering synchrony, acceptable seed yield, and good plant architecture). Three supersweet corn lines and 8 waxy corn lines were intercrossed to generate 48 F1 hybrids according to North Carolina Design II, and these genotypes were laid out in a randomized complete block design with 3 replications across 2 seasons between 2017 and 2018. A sensory blind test on sweetness, stickiness, tenderness, and overall liking was conducted to assess the eating quality of steamed corn samples. Two methods of simultaneous selection, namely unweighted selection index and overall rank-sum index (ORSI), were applied to rank crosses, following all targeted groups of preferences. Genetic parameters and genetic gain were estimated to evaluate the effectiveness of those selection methods. Both approaches had similar patterns of preferable realized gain on each given trait and could identify similar top five crosses with only slight order changes, implying that these methods were effective to rank genotypes according to given selection criteria. One of the tested crosses, 101L/TSC-10 × KV/mon, consistently had the highest unweighted selection index in the dry (7.84) and the rainy (7.15) seasons and the lowest ORSI (310), becoming a promising candidate as synergistic sweet-waxy corn hybrid appealing to consumers, growers, and seed producers. The expected ideotypes of sweet-waxy corn hybrid are discussed.

Selenium-Functionalized Corn Starch as a Biodegradable GPx Mimic with High Catalytic Performance

Selenium-functionalized starch (Se-starch80) is one of the main functional foods used for selenium supplementation. In traditional agriculture, Se-starch has some deficiencies such as long growth cycle and unstable selenium content that prevent its antioxidant performance. In this study, Se-starch was prepared by the nucleophilic addition between NaSeH and carbon-carbon double bond of octenyl succinic anhydride waxy corn starch ester (OSA starch). Some techniques such as 1HNMR, XPS, SEM-EDS, XRD and FT-IR were used to characterize the relevant samples and the results showed that the modification did not destroy the starch framework significantly and the catalytic center (negative divalent selenium) was anchored on the starch framework. The intensive distribution of catalytic center on the starch surface and the hydrophobic microenvironments derived from the OSA chains furnished the Se-starch80 with a high GPx-like catalytic activity (initial reaction rate = 3.64 μM/min). This value was about 1.5 × 105 times higher than that of a typical small-molecule GPx mimic (PhSeSePh). In addition, the Se-starch80, without any cytotoxicity, showed a saturated kinetic catalytic behavior that is similar to a typical enzyme. This work exemplifies a biodegradable selenium-functionalized polymer platform for the high-performing GPx mimic.

Growth and production evaluation of corn varieties and genotypes grow from seed with different storage ages

Quality seeds are one of the important elements in maintaining plant potential. One of the factors that can affect the growth potential and production of corn for each variety or genotype is the storage ages of the seeds. The purpose of this study was to obtain varieties or genotypes of corn that have the ability to grow and produce optimally from seeds that have been stored for one and six months. The research was conducted from August to December 2020 at the Cereal Research Institute, Maros, South Sulawesi, Indonesia. The seeds used were Variety of Srikandi Putih, Waxy Corn and Genotype of BC2F1. This study was designed using a randomized block design (RBD) with a two-factor. The first factor is the type of variety/genotype (V) consisting of Srikandi Putih (V1), Waxy Corn (V2) and Genotype of BC2F1 (V3). The second factor is seed storage ages (U) consisting of: 1 month (U1) and 6 months (U2). From these two factors, 6 treatment combinations were obtained which were repeated three times to obtain 18 experimental units. The data were analyzed with the SAS 9 for windows program. The results showed that the seed storage ages of 1 month could maintain the potential for plant height growth, and the weight of 100 seeds in the Variety of Srikandi Putih, Waxy Corn and Genotypes of BC2F1. Seed storage ages of 1 and 6 months did not affect the number of leaves and flowering time, but only 1 month of seed storage ages that could maintain the potential for seed production in Variety of Srikandi Putih, Waxy Corn and Genotypes of BC2F1.

Breeding for Prolificacy, Total Carotenoids and Resistance to Downy Mildew in Small-Ear Waxy Corn by Modified Mass Selection

The study aimed to improve the small-ear waxy corn populations for prolificacy, high total carotenoid content and resistance to downy mildew. Three cycles of modified mass selection were carried out for population improvement. Forty-four genotypes derived from eight C3 populations and six check varieties were evaluated for agronomic traits and yield at Khon Kaen and screened for downy mildew resistance in the rainy season 2020 at two experimental sites in Ban Phang district of Khon Kaen province. Fifty genotypes were clustered into six major groups based on color parameter (h°) and total ear number. Two selected groups (C and E) with two populations of small-ear waxy corn including Nei9008/BK-24-9-B and TY/TF-33-1-B were selected as they were resistant to downy mildew, prolific ears, and intense orange kernel color. Modified mass selection was effective for improvement of multiple traits in waxy corn.

Exogenous 6-Benzyladenine Improves Waterlogging Tolerance in Maize Seedlings by Mitigating Oxidative Stress and Upregulating the Ascorbate-Glutathione Cycle

The synthetic cytokinin 6-benzyladenine (6-BA) regulates plant growth and prevents the negative consequences of various forms of abiotic stress, including waterlogging in crop plants. The present study aimed to investigate the effects of exogenous 6-BA on the growth, oxidative stress, and ascorbate-glutathione (AsA-GSH) cycle system in the inbred SY-MY13 (waterlogging-resistant) and SY-XT1 (waterlogging-sensitive) seedlings of waxy corn in conditions of waterlogging stress. The results demonstrated that waterlogging stress causes chlorosis and necrosis in waxy corn leaves, inhibiting growth and leading to the accumulation of reactive oxygen species (ROS), which induces oxidative stress and, in turn, reduces membrane lipid peroxidation and the disruption of membrane homeostasis. This is specifically manifested in the increased concentrations of superoxide anion radicals (O2-), hydrogen peroxide (H2O2), and malondialdehyde (MDA), in addition to increased relative electrical conductivity (REC%) values. The SY-MY13 strain exhibited growth superior to that of SY-XT1 when waterlogged due to its excellent waterlogging resistance. Thus, exogenous 6-BA was found to be effective in enhancing the growth of plants stressed by waterlogging in terms of the weight of the shoots and roots, shoot height, and leaf area. In addition to this, exogenous 6-BA also reduced the accumulation of O2-, H2O2, and MDA, increased ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR) activity, and enhanced ascorbic acid (AsA), and reduced glutathione (GSH) concentration through the regulation of the efficiency of the AsA-GSH cycle system in maize plants. Hence, the application of exogenous 6-BA can alleviate waterlogging-induced damage and improve waterlogging tolerance in waxy corn via the activation of the AsA-GSH cycle system and the elimination of ROS.