Comparison of Four Systems to Test the Tolerance of 'Fortune' Mandarin Tissue Cultured Plants to Alternaria alternata .

Abstract

Alternaria brown spot is a severe disease that affects leaves and fruits on susceptible mandarin and mandarin-like cultivars, and is produced by Alternaria alternata . Consequently, there is an urge to obtain new cultivars resistant to A. alternata , and mutation breeding together with tissue culture can help shorten the process. However, a protocol for the in vitro selection of resistant citrus genotypes is lacking. In this study, four methods to evaluate the sensitivity to Alternaria of mandarin 'Fortune' explants in in vitro culture were tested. The four tested systems consisted of: (1) the addition of the mycotoxin, produced by A. alternata in 'Fortune', to the propagation culture media, (2) the addition of the A. alternata culture filtrate to the propagation culture media, (3) the application of the mycotoxin to the intact shoot leaves, and (4) the application of the mycotoxin to the previously excised and wounded leaves. After analyzing the results, only the addition of the A. alternata culture filtrate to the culture media and the application of the mycotoxin to the wounded leaves produced symptoms of infection. However, the addition of the fungus culture filtrate to the culture media produced results, which might indicate that, in addition to the mycotoxin, many other unknown elements that can affect the plant growth and behavior could be found in the fungus culture filtrate. Therefore, the application of the toxin to the excised and wounded leaves seems to be the most reliable method to analyze sensitivity to Alternaria of 'Fortune' explants cultured in vitro.

Plant phenotyping relevance

Alternaria感受性（感染症状）を評価する4つの植物表現型取得法を比較し、信頼性の高い評価プロトコルを選定しており、病害表現型の測定法が研究の中心である。

Code and data availability

The paper reports in vitro Alternaria sensitivity assays on 'Fortune' mandarin but provides no public phenotype datasets, images, code, or models. The Data Availability Statement says 'Not applicable', and the only URLs present are the license and two cited references, none of which are paper-specific data or analysis.

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