The clovers that comprise Trifolium genus are naturalized in the subtropical and tropical zones in China. They are valuable bioresources as important green manures and pasture grass, which contribute biologically fixe...The clovers that comprise Trifolium genus are naturalized in the subtropical and tropical zones in China. They are valuable bioresources as important green manures and pasture grass, which contribute biologically fixed dinitrogen （N2） and provide nutrition to farming systems. However, there are very few effective strains available for inoculant production and there is little information available about symbiotic rhizobia in Chinese legume clover root nodules. In this study, 139 root nodule bacteria were isolated from two clover species （Trifolium repens and Trifolium pretense） growing in the subtropical and temperate regions of China, 16S rRNA gene sequence analysis, BOX-PCR, whole cell protein SDS-PAGE, and nodulation tests were performed to characterize these strains. The results showed that phenotypic and genetic diversities among 139 isolates were large, with 83 protein patterns and 66 BOX- AIR profiles, respectively. The rhizobial strains were first divided into two large phenotypic protein groups. The sequencing strains representing the two groups were related to Rhizobium leguminosarum USDA2370T and R. sophorae CCBAU03386T and had 99.6%-100% similarities. The phylogeny specificity of the rhizobia from clover was elucidated, while showed a large variation in the fingerprints of the phenotypes and genotypes and genetic diversity was high （revealed by Shannon diversity index, H＇）. The rhizobial isolates from subtropical regions, such as Anhui Province, Yunnan Province and Hubei Province, had higher diversities than those from temperate areas, such as Hebei Province and Shanxi Province, which could be used to identify rhizobial strains from clover and screen efficient inoculum strains. A number of diverse rhizobial strains had been identified and a pool of currently available clover rhizobial strains were increased. This would ultimately increase the likelihood of identifying more efficient strains suited for developing a successful inoculation strategy for the production of white clover.展开更多
The thrips quantity ratio（TQR） model is an important tool for evaluating crop resistance to thrips based on the correlation between thrips quantities and cultivars. Unfortunately, it is inaccurate, and the results a...The thrips quantity ratio（TQR） model is an important tool for evaluating crop resistance to thrips based on the correlation between thrips quantities and cultivars. Unfortunately, it is inaccurate, and the results appear significantly inconsistent when analysing the same cultivars in the same field study. To improve this model, we first studied the resistance of 28 alfalfa cultivars to thrips in Cangzhou, Hebei Province, north China. The results showed that the most suitable evaluation period was from May to June, as the thrips population was stable during this period. Second, we found that the natural enemy population was significantly positively correlated with the thrips population density（R=0.7275, P〈0.0001）, which might influence resistance estimation. Hence, we introduced a parameter ‘α＇, corresponding to the natural enemy quantity ratio, to eliminate the effect of the natural enemy using ＂αTQR＂. Using the improved method, 28 cultivars were clustered into three classes： the resistant class, sensitive class, and median class. All numerical values were calculated for αTQR displayed as a Gaussian distribution. This information showed that all data should be divided into nine groups using a median value of 1±0.1 with an equal difference of 0.1. Based on the new standard cultivars, Gongnong 1, Alfaking, Cangzhou and Algonquin were classified as highly resistant cultivars; Zhongmu 3, Gongnong 2, Zhongmu 1 and Zhongmu 2 were classified in the resistant group; Queen was classified in the moderately resistant group; Derby, WL354HQ, KRIMA, Apex, 53 HR, SARDI 5 and Farmers Treasure were classified in the median class; WL319HQ, WL343HQ and Sitel were classified as the low sensitive group; WL440 HQ and SARDI7 as the moderately sensitive group; WL168HQ and Sanditi as the sensitive group; and SARDI 10, WL363HQ, FD4, WL323 and SOCA as the highly sensitive group.展开更多
基金Supported by the National Natural Science Foundation of China(30970005,30370051,and 31360003)the Key Bioengineering Discipline of Hebei Province(1050-5030023)+2 种基金the Public Service Sectors(Agriculture)Research and Special Funds(201303061)the Key Discipline Project for Biotechnology of Hebei ProvinceHebei University Construction Project for Comprehensive Strength Promotion of Midwest Colleges and Universities
文摘The clovers that comprise Trifolium genus are naturalized in the subtropical and tropical zones in China. They are valuable bioresources as important green manures and pasture grass, which contribute biologically fixed dinitrogen （N2） and provide nutrition to farming systems. However, there are very few effective strains available for inoculant production and there is little information available about symbiotic rhizobia in Chinese legume clover root nodules. In this study, 139 root nodule bacteria were isolated from two clover species （Trifolium repens and Trifolium pretense） growing in the subtropical and temperate regions of China, 16S rRNA gene sequence analysis, BOX-PCR, whole cell protein SDS-PAGE, and nodulation tests were performed to characterize these strains. The results showed that phenotypic and genetic diversities among 139 isolates were large, with 83 protein patterns and 66 BOX- AIR profiles, respectively. The rhizobial strains were first divided into two large phenotypic protein groups. The sequencing strains representing the two groups were related to Rhizobium leguminosarum USDA2370T and R. sophorae CCBAU03386T and had 99.6%-100% similarities. The phylogeny specificity of the rhizobia from clover was elucidated, while showed a large variation in the fingerprints of the phenotypes and genotypes and genetic diversity was high （revealed by Shannon diversity index, H＇）. The rhizobial isolates from subtropical regions, such as Anhui Province, Yunnan Province and Hubei Province, had higher diversities than those from temperate areas, such as Hebei Province and Shanxi Province, which could be used to identify rhizobial strains from clover and screen efficient inoculum strains. A number of diverse rhizobial strains had been identified and a pool of currently available clover rhizobial strains were increased. This would ultimately increase the likelihood of identifying more efficient strains suited for developing a successful inoculation strategy for the production of white clover.
基金financial support by the earmarked fund for China Agriculture Research System (CARS-35-07)
文摘The thrips quantity ratio（TQR） model is an important tool for evaluating crop resistance to thrips based on the correlation between thrips quantities and cultivars. Unfortunately, it is inaccurate, and the results appear significantly inconsistent when analysing the same cultivars in the same field study. To improve this model, we first studied the resistance of 28 alfalfa cultivars to thrips in Cangzhou, Hebei Province, north China. The results showed that the most suitable evaluation period was from May to June, as the thrips population was stable during this period. Second, we found that the natural enemy population was significantly positively correlated with the thrips population density（R=0.7275, P〈0.0001）, which might influence resistance estimation. Hence, we introduced a parameter ‘α＇, corresponding to the natural enemy quantity ratio, to eliminate the effect of the natural enemy using ＂αTQR＂. Using the improved method, 28 cultivars were clustered into three classes： the resistant class, sensitive class, and median class. All numerical values were calculated for αTQR displayed as a Gaussian distribution. This information showed that all data should be divided into nine groups using a median value of 1±0.1 with an equal difference of 0.1. Based on the new standard cultivars, Gongnong 1, Alfaking, Cangzhou and Algonquin were classified as highly resistant cultivars; Zhongmu 3, Gongnong 2, Zhongmu 1 and Zhongmu 2 were classified in the resistant group; Queen was classified in the moderately resistant group; Derby, WL354HQ, KRIMA, Apex, 53 HR, SARDI 5 and Farmers Treasure were classified in the median class; WL319HQ, WL343HQ and Sitel were classified as the low sensitive group; WL440 HQ and SARDI7 as the moderately sensitive group; WL168HQ and Sanditi as the sensitive group; and SARDI 10, WL363HQ, FD4, WL323 and SOCA as the highly sensitive group.
