Screening coffee genotypes for brown eye spot resistance in Brazil

Several researchers have attempted to develop coffee plants that are
resistant to brown eye spot (BES); however, no coffee cultivars are
resistant to the disease. In the present study, a blend of strains from
Cercospora coffeicola was inoculated into 19 Brazilian commercial
cultivars and 41 accessions from the Germplasm Collection of Minas Gerais
to evaluate the genetic resistance ability within the population and
select superior genotypes for the breeding program. After predicting the
genotypic values of the studied material, the evaluations number necessary
for selecting genotypes with accuracy and efficiency was determined based
on the data of severity to BES. The action of defense mechanisms plant was
also investigated by assessing the levels of total soluble phenolic
compounds and soluble lignin in contrasting genotypes for disease
susceptibility. Based on the results, the accession MG 1207 Sumatra, had
an intrinsic genetic capacity to maintain low levels of severity to BES.
 The genotype MG 1207 Sumatra can substantially contribute to the
development of new cultivars, which may lead to the reduced use of
pesticides. According to the accuracy and efficiency results obtained,
four evaluations BES severity are sufficient to achieve accuracy,
providing expressive genetic gains. Finally, the levels of lignin and
phenolic compounds were not found to be associated with the resistance of
coffee genotypes to BES.

诸多研究者已尝试培育抗咖啡棕眼斑病（brown eye spot, BES）的咖啡植株，但目前尚无对该病害具备抗性的咖啡栽培品种。本研究将混合的咖啡尾孢菌（Cercospora coffeicola）菌株接种至19个巴西商业栽培品种与41份来自米纳斯吉拉斯州种质资源库（Germplasm Collection of Minas Gerais）的种质材料中，以评估群体内的遗传抗性能力，并为育种项目筛选优良基因型。在预测供试材料的基因型值后，本研究基于咖啡棕眼斑病病情严重度数据，确定了精准高效筛选基因型所需的调查次数。本研究还通过分析不同抗病/感病对照基因型的总可溶性酚类物质与可溶性木质素含量，探究了植物防御机制的作用效果。研究结果显示，种质系MG 1207 Sumatra具备维持低咖啡棕眼斑病病情严重度的内在遗传能力，该种质系可显著助力新型抗病咖啡品种的培育，进而减少农药的使用量。基于所得精准性与效率结果，对咖啡棕眼斑病病情开展4次调查即可达到理想精准度，可获得可观的遗传增益。最后，本研究未发现木质素与酚类物质含量与咖啡基因型对咖啡棕眼斑病的抗性存在关联。