Abstract
Maize chlorotic mottle virus (MCMV) causes maize lethal necrosis disease in combination with a cereal-infecting potyvirus, leading to high yield losses. There is limited information on seed infection or contamination rate by MCMV and its comparison with transmission rate to maize seedlings. This study was conducted to determine the extent of seed contamination in seed lots from MCMV-infected maize fields in Kenya and the transmission of MCMV from seeds to seedlings. To determine the contamination levels, whole seeds were ground and the extract tested for the presence of MCMV using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Seedling grow-outs were tested for seed transmission of MCMV using DAS-ELISA and real-time reverse transcription polymerase chain reaction (real-time RT-PCR) methods. The seed contamination rates of the four seed lots tested ranged from 4.9 to 15.9%. MCMV transmission frequency for 37,617 seedlings, tested in 820 pools of varying seed amounts by DAS-ELISA, was 0.17%, whereas a transmission frequency of 0.025% was obtained from 8,322 seedlings tested in 242 pools by real-time RT-PCR. Seeds from plants mechanically inoculated with MCMV had an overall seed transmission rate of 0.04% in 7,846 seedlings tested in 197 pools. The study showed that even with substantial contamination of maize seed with MCMV, the transmission of the virus from the seed to seedlings was low. Nevertheless, even low rates of transmission can be significant under field conditions where insect vectors can further spread the disease from infected seedlings, unless diseased plants are detected in time and properly managed. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .
Highlights
Maize has the highest production among the cereal crops globally and is the important cereal in Latin America and sub-Saharan Africa (Ranum et al 2014)
Results from the present study showed that seeds sampled from commercial hybrid maize seed lots in Kenya were contaminated with Maize chlorotic mottle virus (MCMV) at varying levels ranging from 4.9 to 15.93%
The level of seed contamination may not be correlated to the rate of seed transmission (Dombrovsky and Smith 2017), as in the present study, in which we found lower seed transmission in seed lots with higher seed contamination of MCMV and vice versa
Summary
2015 2017 Blended, rainfed fields the substrate step, which was incubated at room temperature for. The optical density absorbance values of the reaction were measured using a microplate reader (Elx808 BioTek Instruments) at a wavelength of 405 nm, 1 h after incubation at ambient temperature Similar controls as those described above were used in all the microplates. The MCMV-free maize seed was obtained from a seed company and tested for confirmation Samples from both experiments with an average optical absorbance value from the two replicates that was higher than twice that of the negative maize seed control and extraction buffer were considered positive for MCMV. Seed to seedling transmission of MCMV was tested by germinating seeds from the four seed lots (Table 1) by planting the sampled seeds and from the healthy certified seed (DK777) in trays filled with vermiculite mixed with sterile soil at a ratio of 1:2, at KALRO-Kabete, in a seed laboratory, at average day room temperature of 21C, with an average of 12 h light and 12 h night. A total of 37,617 seedlings from the four seed lots (Table 2) were tested using DAS-ELISA in 820 pools with a varying number of seedlings from each tray, ranging from seven to 50
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