[ Objective] This study aimed to analyze the genetic potymorphism of 39 cassava varieties （lines） preserved in Guangxi Zhuang Autonomous Region Research Institute for Subtropical Crops. [ Method ] ISSR primers with ...[ Objective] This study aimed to analyze the genetic potymorphism of 39 cassava varieties （lines） preserved in Guangxi Zhuang Autonomous Region Research Institute for Subtropical Crops. [ Method ] ISSR primers with good polymorphisms and amplification effects in cassava were selected for PCR amplification of 39 cassava germplasms, statistics and analysis of the amplified bands were conducted. In addition, cluster analysis was conducted by using UPGMA method based on the genetic similarity among cassava varieties （lines）. [ Result] Ten pairs of ISSR primers were selected. A total of 70 clear electrophoretic bands were amplified, each pair of primers had amplified 3 -9 electrophoretic bands, with an average of 7, and the length of amplified bands ranged from 150 to 2,000 bp; cluster analysis showed that 39 cassava varieties （lines） were clustered into two categories by the similarity coefficient of 0.67 ; in addition, the genetic distance among cassava was very narrow, with genetic similarity coefficients ranging between 0.80 and 1.00. [ Conclusion] This study laid foundation for breeding of high- cmalitv cassava in China.展开更多
Let B（G） denote the bipartite double cover of a non-bipartite graph G with v ≥ 2 vertices and s edges. We prove that G is a perfect 2-matching covered graph if and only if B（G） is a 1-extendable graph. Furthermor...Let B（G） denote the bipartite double cover of a non-bipartite graph G with v ≥ 2 vertices and s edges. We prove that G is a perfect 2-matching covered graph if and only if B（G） is a 1-extendable graph. Furthermore, we prove that B（G） is a minimally l-extendable graph if and only if G is a minimally perfect 2-matching covered graph and for each e = xy ∈ E（G）, there is an independent set S in G such that ｜ГG（S）｜ = ｜S｜ ＋ 1, x ∈ S and ｜ГG-xy（S）｜ = ｜S｜ Then, we construct a digraph D from B（G） or G and show that D is a strongly connected digraph if and only if G is a perfect 2-matching covered graph. So we design an algorithm in O（x√vε） time that determines whether G is a perfect 2-matching covered graph or not.展开更多
基金Supported by Special Fund for Basic Scientific Research Operation Expenses of Nonprofit Research Institutes Directly Under Guangxi Zhuang Autonomous Region (200803)Guangxi Scientific Research and Technological Development Project (Chairman Fund 09203-03)
文摘[ Objective] This study aimed to analyze the genetic potymorphism of 39 cassava varieties （lines） preserved in Guangxi Zhuang Autonomous Region Research Institute for Subtropical Crops. [ Method ] ISSR primers with good polymorphisms and amplification effects in cassava were selected for PCR amplification of 39 cassava germplasms, statistics and analysis of the amplified bands were conducted. In addition, cluster analysis was conducted by using UPGMA method based on the genetic similarity among cassava varieties （lines）. [ Result] Ten pairs of ISSR primers were selected. A total of 70 clear electrophoretic bands were amplified, each pair of primers had amplified 3 -9 electrophoretic bands, with an average of 7, and the length of amplified bands ranged from 150 to 2,000 bp; cluster analysis showed that 39 cassava varieties （lines） were clustered into two categories by the similarity coefficient of 0.67 ; in addition, the genetic distance among cassava was very narrow, with genetic similarity coefficients ranging between 0.80 and 1.00. [ Conclusion] This study laid foundation for breeding of high- cmalitv cassava in China.
基金Acknowledgements The authors would like to thank the referees very much for their careful reading and their very instructive suggestions which improve this paper greatly. This work was supported in part by the National Natural Science Foundation of China （Grant No. 11201158）.
文摘Let B（G） denote the bipartite double cover of a non-bipartite graph G with v ≥ 2 vertices and s edges. We prove that G is a perfect 2-matching covered graph if and only if B（G） is a 1-extendable graph. Furthermore, we prove that B（G） is a minimally l-extendable graph if and only if G is a minimally perfect 2-matching covered graph and for each e = xy ∈ E（G）, there is an independent set S in G such that ｜ГG（S）｜ = ｜S｜ ＋ 1, x ∈ S and ｜ГG-xy（S）｜ = ｜S｜ Then, we construct a digraph D from B（G） or G and show that D is a strongly connected digraph if and only if G is a perfect 2-matching covered graph. So we design an algorithm in O（x√vε） time that determines whether G is a perfect 2-matching covered graph or not.
