Horticulture Research Institute, P.O. Box 810, Marondera, Zimbabwe.
Department of Biotechnology, Chinhoyi University of Technology, P. Bag 7724, Chinhoyi, Zimbabwe.
BMC Ecol. 2019 Mar 12;19(1):13. doi: 10.1186/s12898-019-0229-9.
Local communities in the South Eastern Lowveld of Zimbabwe have adopted the feeding of livestock with Neorautanenia brachypus (Harms) C.A. tuber to mitigate against climate change. Differences within Neorautanenia brachypus (Harms) tuber flesh colour and preferences by cattle have been observed, suggesting possible diversity within the N. brachypus plant community. This study aimed at distinguishing the N. brachypus wild plant species through phenotypic and genetic characterization using morphological descriptors and random amplified polymorphic (RAPD) markers respectively. Leaf samples were selected using judgmental sampling techniques from wards 11-15 in Sengwe (Chiredzi district) for leaf morphology and molecular characterization. RAPD-PCR analysis was done using 18-screened random decamer primers to confirm the diversity in the plant population. The similarity of the biotypes was evaluated using binary coding on the basis of the presence or absence of a morphological indicator as well as distinct DNA amplicon fragments. Primer 7.0.13 was used to estimate morphological and genetic similarities using the unweighted pair group method with arithmetic average (UPGMA). The cluster number was estimated using the Elbow method part of the R package.
Initially, 14 biotype groups were identified from 96 accessions visually characterized basing of leaf characteristics. All the leaf biotypes displayed arcuate venation with differences observed for leaf shape, tip shape and leaf margins. The 14 biotypes clustered into six groups based on the binary data of the morphological characteristics. RAPD primers generated three hundred and sixty eight distinct amplicons with 77.5% being polymorphic from the 14 biotypes. The number of bands produced per primer ranged from four (OPF-02) to 44 (UBC-746). The PIC value ranged from 0.1327 to 0.1873 for the RAPD primers. Use of molecular markers collapsed the biotypes into five clusters. Both the leaf descriptors and RAPD markers showed the existence of genetic diversity within the wild accessions of N. brachypus.
A combination of morphological and RAPD markers effectively refined the resolution of the genetic diversity within the N. brachypus wild accessions to nine biotypes. These findings have indicated to the existence of more than one biotype of N. brachypus with potentially different properties. The favorable biotypes can further be promoted through incorporation in pastures as alternative feed or complementary feed to livestock. As such the output of this study will serve as a guide for N. brachypus germplasm management and improvement.
津巴布韦东南部低地的当地社区采用 Neorautanenia brachypus (Harms) C.A. tuber 喂养牲畜，以减轻气候变化的影响。已经观察到 Neorautanenia brachypus (Harms) tuber 肉质颜色的差异以及牛的偏好，这表明 N. brachypus 植物群内可能存在多样性。本研究旨在通过形态描述符和随机扩增多态性 (RAPD) 标记分别对 Neorautanenia brachypus 野生植物物种进行区分。使用判断抽样技术从 Sengwe（奇雷兹区）第 11-15 病房选择叶片样本，用于叶片形态和分子特征分析。使用 18 个筛选的随机十聚体引物进行 RAPD-PCR 分析，以确认植物种群的多样性。使用基于形态指示物的存在或不存在以及独特 DNA 扩增片段的二元编码来评估生物型的相似性。使用引物 7.0.13 使用不带权对组平均（UPGMA）的算术平均的二进制编码来估计形态和遗传相似性。使用 R 包的肘部法部分估计聚类数。
最初，根据叶片特征，从 96 个访问中确定了 14 个生物型组。所有叶片生物型均显示出弧形脉序，叶片形状、尖端形状和叶片边缘存在差异。基于形态特征的二元数据，14 个生物型聚类为六个组。RAPD 引物从 14 个生物型中产生了 368 个独特的扩增子，其中 77.5%是多态性的。每个引物产生的条带数量范围从 4 个（OPF-02）到 44 个（UBC-746）。RAPD 引物的 PIC 值范围为 0.1327 至 0.1873。分子标记的使用将生物型合并为五个聚类。叶片描述符和 RAPD 标记均显示出 Neorautanenia brachypus 野生访问中的遗传多样性。
形态学和 RAPD 标记的结合有效地将 Neorautanenia brachypus 野生访问的遗传多样性分辨率细化为 9 个生物型。这些发现表明存在具有潜在不同特性的不止一种 Neorautanenia brachypus 生物型。可以通过将有利的生物型纳入牧场作为牲畜的替代饲料或补充饲料来进一步推广。因此，本研究的结果将作为 Neorautanenia brachypus 种质管理和改良的指南。
