Screening Methods for Downy Mildew Resistance in Maize: A Systematic Review.

Abstract

Background/Objectives: Downy mildew, caused by Peronosclerospora and Sclerophthora species, is a major constraint to maize production in tropical and subtropical regions, with yield losses of 30-100%. This systematic review synthesised evidence on methods used to screen maize for downy mildew resistance and assessed their effectiveness, reliability, and associated markers. Methods: PubMed, Google Scholar, ScienceDirect, and CAB Abstracts were searched (last searched 22 October 2025) for English-language studies (1990-2025) evaluating phenotypic or molecular screening methods. Risk of bias was assessed using the RoB 2 framework. Narrative synthesis was conducted following a protocol registered on the Open Science Framework. Results: Twelve studies met the inclusion criteria, predominantly from India and Cambodia. Spreader row systems (seven studies) and conidial spray inoculation (six studies) were the most common field methods, while the glasshouse sandwich technique generated the highest disease pressure. Cross-method correlations were strong (r = 0.92-0.99), and heritability estimates ranged from 0.50 to 0.97. QTL mapping identified resistance loci on chromosomes 2, 3, and 6, with chromosome 6 stable across multiple pathogen species. Evidence certainty was moderate for method effectiveness and low for molecular markers. Conclusions: Established phenotypic screening methods reliably discriminate resistant germplasm; however, standardised protocols, broader geographic validation, and independent molecular marker confirmation are needed.

Plant phenotyping relevance

トウモロコシのべと病抵抗性という植物状態を評価する表現型スクリーニング法を体系的にレビューし、方法の有効性・信頼性を比較しているため、手法レビューとして収載する。

Code and data availability

This is a systematic review of downy mildew screening methods in maize. The authors state no new data were created or analysed, and no public phenotype datasets, images, analysis code, or trained models specific to this paper are described. The supplementary materials link is generic and not explicitly stated tocontain

No evidence-backed public reproduction asset is currently recorded.