木薯(ManihotesculentaCrantz)是一种食品和工业储存根茎作物,由于其固有的弹性和在制造中提供可生物降解的选择,具有很大的潜力,有助于管理与气候变化相关的风险。在非洲,木薯生产受到两种病毒性疾病的挑战,木薯褐条病(CBSD)和木薯花叶病。在这里,我们在坦桑尼亚地方品种的双亲作图种群中检测到与CBSD相关的数量性状基因座(QTL),Nachinyaya和AR37-80,三年内在两个地点进行了表型分析。目的是使用该信息最终促进标记辅助选择或调整基因组选择中的权重以提高育种效率。这项研究的结果被认为与其他四个双亲群体的结果有关,相似的遗传背景,同时进行表型和基因分型。Further,我们基于全基因组序列信息研究了CBSD抗性QTL在种群间的共定位和亲本的亲缘关系。4号染色体上的两个QTL对CBSD叶面症状具有抗性,而11号和18号染色体上的每个QTL对根坏死具有重要意义。在4号染色体上QTL基础的候选基因中具有重要意义的是苯丙氨酸解氨酶(PAL)和肉桂酰辅酶A还原酶(CCR)基因以及与木质素途径相关的三种PEPR1相关激酶。此外,CCR基因也是11号染色体上抗根坏死QTL的基础。来自早期转录组研究的木薯木质化途径中关键基因的上调,包括PAL和CCR,与易感的地方品种相比,在抗CBSD的地方品种中,表明抗CBSD的地方品种中的基础木质素沉积水平更高。早期的RNAscope®原位杂交成像实验表明,木薯棕色条纹病毒(CBSV)仅限于CBSV抗性品种的韧皮部血管,防止了在叶肉细胞中复制的韧皮部卸载。该结果为木质素途径的参与提供了证据。此外,在优先QTL区域内发现了与植物病毒抗性相关的五个真核起始因子(eIF)基因。
Cassava (Manihot esculenta Crantz) is a food and industrial storage root crop with substantial potential to contribute to managing risk associated with climate change due to its inherent resilience and in providing a biodegradable option in manufacturing. In Africa, cassava production is challenged by two viral diseases, cassava brown streak disease (CBSD) and cassava mosaic disease. Here we detect quantitative trait loci (QTL) associated with CBSD in a biparental mapping population of a Tanzanian landrace, Nachinyaya and AR37-80, phenotyped in two locations over three years. The purpose was to use the information to ultimately facilitate either marker-assisted selection or adjust weightings in genomic selection to increase the efficiency of breeding. Results from this study were considered in relation to those from four other biparental populations, of similar genetic backgrounds, that were phenotyped and genotyped simultaneously. Further, we investigated the co-localization of QTL for CBSD resistance across populations and the genetic relationships of parents based on whole genome sequence information. Two QTL on chromosome 4 for resistance to CBSD foliar symptoms and one on each of chromosomes 11 and 18 for root necrosis were of interest. Of significance within the candidate genes underlying the QTL on chromosome 4 are Phenylalanine ammonia-lyase (PAL) and Cinnamoyl-CoA reductase (CCR) genes and three PEPR1-related kinases associated with the lignin pathway. In addition, a CCR gene was also underlying the root necrosis-resistant QTL on chromosome 11. Upregulation of key genes in the cassava lignification pathway from an earlier transcriptome study, including PAL and CCR, in a CBSD-resistant landrace compared to a susceptible landrace suggests a higher level of basal lignin deposition in the CBSD-resistant landrace. Earlier RNAscope® in situ hybridisation imaging experiments demonstrate that cassava brown streak virus (CBSV) is restricted to phloem vessels in CBSV-resistant varieties, and phloem unloading for replication in mesophyll cells is prevented. The results provide evidence for the involvement of the lignin pathway. In addition, five eukaryotic initiation factor (
eIF) genes associated with plant virus resistance were found within the priority QTL regions.