Genetic diversity and relationship of Guinea yam (<Emphasis Type="Italic">Dioscorea cayenensis</Emphasis> Lam.–<Emphasis Type="Italic">D. rotundata</Emphasis> Poir. complex) germplasm in Benin (West Africa) using microsatellite markers

Guinea yam (Dioscorea cayenensis–D. rotundata complex) is an important tuber crop that highly contributes to food security and poverty alleviation in Benin. The knowledge and understanding of the extent of genetic variation of Guinea yam germplasm is important for planning of the genetic conservation, and the utilisation of this resource. The objective of this study was to assess the genetic diversity and relationships of 64 yam landraces whose dried chips are considered as resistant to insect attacks using 41 simple sequence repeat. Among these primers, 13 were found to be polymorphic, giving 113 polymorphic alleles. The number of alleles per locus ranged from 4 (Ym50) to 13 (Ym29), with an average of 8.69. Unique allele was observed with some landraces (Singou and Tchakatchaka) and can be considered as unique gene and use in yam breeding program. The mean polymorphic information content values for all markers used was 0.76 and ranged between 0.58 and 0.91 in loci YM3 and YM32 respectively. The genetic distance of yam landraces ranged from 0.45 (Yasoubagarou) to 0.04 (Assinapeira and Alahina), indicating that the yam germplasm has a high degree of genetic diversity supported by an averagely observed heterozygosity of 0.78. Cluster analysis using unweighted pair group method with arithmetic average grouped the 64 yam landraces into two distinct clusters. This tendency was also observed in the principal coordinate analysis. The analysis of molecular variance revealed that 96 % of the variation was found within the population and only 4 % between the populations. Genetic diversity and relationship assessments among the 64 yam landraces of Benin could provide useful information for efficient use of these materials, especially for genetic improvement.     

In Memoriam:David D.Myrold(1955–2021)

David D.Myrold,65,Professor of Soil Microbiology in the Department of Crop and Soil Science at Oregon State University,passed away in Corvallis,Oregon,USA on July 15,2021.Dave was well known to many soil scientists for his work on soil nitrogen cycling,a career of research work that was summarized in his latest 2021 publication—Transformation of Nitrogen.     

离体条件下评价二倍体马铃薯(Solanum phureja ×S. stenotomum)耐盐性

为评价马铃薯耐盐性,筛选耐盐种质资源,本研究以164份二倍体马铃薯杂种后代及其亲本为试验材料,进行NaCl胁迫处理,测量盐胁迫和对照条件下杂交后代和亲本的芽长、芽鲜重、芽干重、根长、根鲜重和根干重6个形态指标,然后运用隶属函数分析和聚类分析方法进行综合评价及分类。结果表明,以亲本为对照,比较综合评价D值,筛选出26个耐盐无性系和10个盐敏感无性系;利用6个形态指标和D值分别聚类分析,166个无性系均被分为4个耐盐性不同的类群,表明可以分别利用6个形态指标和D值进行聚类,筛选出在同一类群中共同包含的无性系,提高耐盐评价的精确性;后代无性系根长相对值平均值较高(62.5),且聚类分析后,第一类群和第二类群的根长相对值的差异较小,说明根长不是理想的形态筛选指标,可以考虑用主根数替代根长,作为耐盐筛选的形态指标之一。本研究结果为快速评价大量马铃薯种质资源的耐盐性和马铃薯耐盐育种提供了理论依据和材料基础。