Identification and diversity of tropical maize inbred lines with resistance to common rust (Puccinia sorghi Schwein)
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Crop Science
Abstract
Common rust (CR) caused by Puccinia sorghi Schwein is one of the major foliar
diseases of maize (Zea mays L.) in Eastern and Southern Africa. This study was
conducted to (i) evaluate the response of elite tropical adaptedmaize inbred lines
to Puccinia sorghi and identify resistant lines (ii) examine associations between
CR disease parameters and agronomic traits, and (iii) assess the genetic diversity
of the inbred lines. Fifty inbred lines were evaluated in field trials for three
seasons (2017–2019) in Uganda under artificial inoculation. Disease severity was
rated on a 1–9 scale at 21 (Rust 1), 28 (Rust 2), and 35 (Rust 3) days after inoculation.
Area under disease progress curve (AUDPC) was calculated. The genetic
diversity of the lines was assessed using 44,975 single nucleotide polymorphism
markers. Combined ANOVA across seasons showed significant (P < .001) line
mean squares for the three rust scores andAUDPC.Heritabilitywas high for Rust
2 (0.90), Rust 3 (0.83), and AUDPC (0.93). Of the 50 lines, 12 were highly resistant
to CR. Inbred lines CKL1522, CKL05010, and CKL05017 had significantly
lower Rust 3 scores and AUDPC compared to the resistant check CML444 and
are potential donors of CR resistance alleles. The genetic correlations between
CR disease resistance parameters were positive and strong. A neighbor-joining
(NJ) tree and STRUCTURE suggested the presence of three major groups among
the lines, with lines highly resistant to CR spread across the three groups. The
genetic diversity among the highly resistant lines can be exploited by recycling
genetically distant lines to develop new multiple disease resistant inbred lines
for hybrid development and deployment.
Description
Keywords
Diversity, Tropical maize inbred lines, Common rust (Puccinia sorghi Schwein)
Citation
Sserumaga, J. P., Makumbi, D., Assanga, S. O., Mageto, E. K., Njeri, S. G., Jumbo, B. M., & Bruce, A. Y. (2020). Identification and diversity of tropical maize inbred lines with resistance to common rust (Puccinia sorghi Schwein). Crop Science, 60(6), 2971-2989. DOI: 10.1002/csc2.20345