Zakeel Mohamed Cassim Mohamed, Alam Mobashwer, Geering Andrew D W, Topp Bruce, Akinsanmi Olufemi A
Centre for Horticultural Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, Australia.
Centre for Horticultural Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Nambour, QLD, Australia.
Front Plant Sci. 2021 Dec 24;12:756815. doi: 10.3389/fpls.2021.756815. eCollection 2021.
Abnormal vertical growth (AVG) syndrome is a serious threat to the Australian macadamia industry as it decreases the yield of nuts by as much as 70% per annum. A lack of information on the cause of AVG has hindered the development of an effective disease management strategy. Discovery of genetic markers associated with disease resistance can be used as tool for rapid selection of elite cultivars, hence helps in efficient disease management. Differences in field susceptibility of macadamia cultivars provide an opportunity for discovery of genetic markers that are associated with host resistance. REML mixed model analysis was performed to estimate the AVG rating of 51 cultivars from multiple origins using phenotypic data from 359 trees planted in four sites. Most of the Hawaiian cultivars were found as susceptible, while selections from the Australian macadamia industry breeding program were predominantly resistant. All the cultivars were genotyped for 13,221 DArTseq-based single nucleotide polymorphism (SNP) markers. A bulked sample analysis was performed using 20 genotypes each at the extremes of AVG phenotypic ratings. Ten SNP markers were predicted to be associated with AVG resistance and two arbitrarily selected SNP markers were validated using PCR and Sanger sequencing. Our findings suggest that AVG resistance in the commercial cultivars may be derived from the genomic introgression of through interspecific hybridization. The results may support marker-assisted selection for macadamia germplasm with AVG resistance.
异常垂直生长（AVG）综合征对澳大利亚澳洲坚果产业构成严重威胁，因为它每年可使坚果产量降低多达70%。由于缺乏关于AVG病因的信息，阻碍了有效的病害管理策略的制定。发现与抗病性相关的遗传标记可作为快速选择优良品种的工具，从而有助于高效的病害管理。澳洲坚果品种在田间易感性方面的差异为发现与寄主抗性相关的遗传标记提供了机会。利用种植在四个地点的359棵树的表型数据，进行了REML混合模型分析，以估计来自多个产地的51个品种的AVG评级。发现大多数夏威夷品种易感，而澳大利亚澳洲坚果产业育种计划的选种大多具有抗性。对所有品种进行了基于13221个DArTseq单核苷酸多态性（SNP）标记的基因分型。使用AVG表型评级极端的各20个基因型进行了混合样本分析。预测有10个SNP标记与AVG抗性相关，并使用PCR和桑格测序对两个随机选择的SNP标记进行了验证。我们的研究结果表明，商业品种中的AVG抗性可能源自通过种间杂交的基因组渐渗。这些结果可能支持对具有AVG抗性的澳洲坚果种质进行标记辅助选择。
