Evaluation of Maize Downy Mildew using Spreader Row Technique

Abstract

This study was conducted to evaluate maize downy mildew resistance using spreader row technique in Cambodia. A total of forty maize lines were used in this experiment. Seven Korean varieties and seven breeding lines showed high infection rates (80~100%) and highly susceptible (HS) to downy mildew disease in both spring and fall. Also most of nested association mapping (NAM) parent lines were highly susceptible (HS). Meanwhile three inbred lines, Ki3, Ki11, and CML228, showed highly resistant (HR) or resistant (R) in spring and moderately resistant (MR) in fall. These three lines were already known as resistant inbred lines against downy mildew disease. It appears that spreader row technique was suitable for selection of maize downy mildew resistance in Cambodia. The incidence of downy mildew was influenced by weather conditions, especially relative humidity and temperature. Among several inoculation methods to screen for downy mildew resistance, this spreader row technique is effectively and easily used in the field of Southeast Asia.

Identification and Validation of Candidate Genes Conferring Resistance to Downy Mildew in Maize (Zea mays L.)

“…DM disease was scored in the field using a modified spreader-row technique [2]. Susceptible genotypes (B73 and CML270) were used as two 5-m-long spreader rows with 20 plants per row after every 10th row of the test entries on the border rows of the experimental block ( Figure S1) [44,47]. Seeds of the spreader genotypes germinated after 7 days, then a DM-infected maize plant in a pot was placed in each experimental block for 2 weeks to infect the spreader plants.…”

“…The results are categorized as 0% (no symptoms) = highly resistant (HR), 1-10% = resistant (R), 11-25% = moderately resistant (MR), 26-50% = moderately susceptible (MS), 51-75% = susceptible (S), and 76-100% = highly susceptible (HS) [44].…”

“…B73 was the DM-susceptible parent from the temperate stiff-stalk maize line. This inbred line was developed at Iowa State University (Ames, IA) in the United States and is known to be susceptible to DM and drought, as well as being photoperiod-sensitive [43][44][45][46]. The F 1 families were planted in 2013, and then F 7 families of the RILs (n = 192) were obtained by selfing each individual plant in an experimental field at Dongguk University, Korea in 2017.…”

Comparison of the Antioxidant Activity of Maysin (C-Glycosylflavone) and Other Flavonoids

“…Maize is an important food crop, serving as a source of syrup, dextrose, dextrin, lactose and sucrose. Furthermore, maize fermented is used as the production of various staple medical products such as penicillin, bacitracin and neomycin 2 .…”

Identification of downy mildew resistance gene candidates by positional cloning in maize (Zea mays subsp. mays; Poaceae)

“…Rapid evaluation of DM resistance is an outstanding advantage of this protocol because infection was achieved within 3 or 4 wk after inoculation. In a previous study to evaluate 40 maize cultivars, including five NAM parent lines, for DM resistance and incidence, B73 and CML270 were determined as susceptible, while Ki3, Ki11, and CML228 were determined as resistant (Kim et al, 2016). Congruently with our DM phenotyping, B73 and CML270 were found to be susceptible.…”