Cacao families and parents selected as resistant to natural infection of Moniliophthora perniciosa

Abstract The known sources of resistance to witches' broom (WB), a severe disease of cacao, are limited. Aiming to identify families and parents resistant to Moniliophthora perniciosa, a population of 22 families was evaluated by assessing the number of brooms formed per tree during 10 years under field conditions. The population was established in randomized blocks with three replications of 12 plants each. Significant differences were observed among families. The most outstanding families were NA33 x RB39 and RB39 x P4B, which presented the lowest WB incidence during 10 years. The increase in natural field infection of Scavina clones families and their descendants were clearly demonstrated after 2006. The existence of additive effects for resistance appears clearly for families, which had other source of resistance associated with Scavina. Clones RB39, RB36, P4B, NA33 and CSUL3 are promising parents for pyramiding resistance genes and increasing the stability and durability of resistance to WB.摘要 已知的可可严重病害女巫帚病（witches' broom, WB）的抗源十分有限。本研究旨在鉴定抗寄生柱隔孢（Moniliophthora perniciosa）的家系与亲本，通过在田间条件下连续10年统计每株果树的帚状枝数量，对由22个家系组成的试验群体开展了抗病性评价。该试验群体采用随机区组设计，每个处理设置3次重复，每次重复含12株植株。分析结果显示，不同家系间的抗病性存在显著差异。其中表现最为突出的家系为NA33 × RB39与RB39 × P4B，其在10年观测期内的WB发病率最低。2006年后，斯卡维纳（Scavina）无性系家系及其后代的自然田间感染率显著升高的现象得到明确证实。对于携带与斯卡维纳相关的其他抗源的家系而言，其抗病性存在显著的加性效应。无性系RB39、RB36、P4B、NA33与CSUL3可作为优良亲本，用于聚合抗病基因，以提升可可对WB的抗病稳定性与持久性。