Aims Within inflorescences of sexually reproducing hermaphrodites,the production of ovules,fruits and seeds commonly declines from basal(early-opening)to distal(late-opening)flowers,while pol-len production remains co...Aims Within inflorescences of sexually reproducing hermaphrodites,the production of ovules,fruits and seeds commonly declines from basal(early-opening)to distal(late-opening)flowers,while pol-len production remains constant or only changes slightly,with the result that distal(late-opening)flowers become functionally male.However,few empirical studies have specifically examined whether or not changes in allocation to pollen production actually lead to changes in the number of seeds sired,a more direct measure of male fitness.in pseudogamous apomicts,fitness depends on the number of seeds produced;thus,a contrasting pattern of variation in the pollen-to-ovule(P/o)ratio within inflorescences might be expected.Methods We investigated floral sex allocation and reproductive success within racemes of Hosta ventricosa,a pseudogamous apomictic hermaphrodite possessing flowers that open acropetally.We quan-tified variations in pollen number,ovule number,the P/o ratio and fruit and seed production,from 2007 to 2011,among flowers within racemes of four populations of H.ventricosa in southwest China.Ecological causes for fruit and seed production were evaluated by observing patterns of pollen deposition,flower removal and sup-plemental pollination.Important Findings Pollen number,ovule number and the P/o ratio declined from basal-to-distal positions in all sampled populations(years).Fruit and seed production decreased distally in most populations(years).low fruit and seed set of distal flowers was not due to pollen limitation because pollen deposition never declined distally and the low fruit and seed set of distal flowers remained even after supplementary pollination was provided.The flower-removal experiment indicated that inter-fruit competition for resources among flowers was common.The low P/o ratio of distal flowers in H.ventricosa might be favored because they were unable to obtain fitness by donat-ing pollen and siring seeds on other plants.our study may help to understand the adaptive significance of sex allocation among flow-ers within inflorescences of sexually reproducing hermaphrodites.展开更多
A total of 13 types of endophytic fungi,classified into six genera,were isolated from Hosta.ventricosa based on 18 S rDNA sequencing of ITS region and microscopic examination.The antioxidant activities of the crude ex...A total of 13 types of endophytic fungi,classified into six genera,were isolated from Hosta.ventricosa based on 18 S rDNA sequencing of ITS region and microscopic examination.The antioxidant activities of the crude extracts were investigated by T-AOC,DPPH and ABTS＋ methods.The results showed that the crude extracts from Fusarium oxysporum（HoV1） and Epicoccum（HoV4）,which presented higher phenol levels（1.90±0.03 mg/g,and 2.41±0.01 mg/g,respectively）,exhibited stronger comprehensive antioxidant activities,with higher T-AOC values（63.46±0.26 U/g,and 66.05±0.71 U/g,respectively）,lower EC_（50） values against ABTS~＋（30.25±0.05 μg/m L,and 24.66±0.65 μg/m L,respectively） and DPPH radicals（83.42±0.24 μg/m L,and 59.136 μg/m L,respectively）.Moreover,Fusarium oxysporum（Ho V8） showed excellent scavenging activity against DPPH radicals（EC_（50） = 16.02 μg/m L）,which was better than BHT.All of them could be useful in the developing of new natural antioxidant agents.展开更多
基金National Natural Science Foundation of China(30870388,31370436).
文摘Aims Within inflorescences of sexually reproducing hermaphrodites,the production of ovules,fruits and seeds commonly declines from basal(early-opening)to distal(late-opening)flowers,while pol-len production remains constant or only changes slightly,with the result that distal(late-opening)flowers become functionally male.However,few empirical studies have specifically examined whether or not changes in allocation to pollen production actually lead to changes in the number of seeds sired,a more direct measure of male fitness.in pseudogamous apomicts,fitness depends on the number of seeds produced;thus,a contrasting pattern of variation in the pollen-to-ovule(P/o)ratio within inflorescences might be expected.Methods We investigated floral sex allocation and reproductive success within racemes of Hosta ventricosa,a pseudogamous apomictic hermaphrodite possessing flowers that open acropetally.We quan-tified variations in pollen number,ovule number,the P/o ratio and fruit and seed production,from 2007 to 2011,among flowers within racemes of four populations of H.ventricosa in southwest China.Ecological causes for fruit and seed production were evaluated by observing patterns of pollen deposition,flower removal and sup-plemental pollination.Important Findings Pollen number,ovule number and the P/o ratio declined from basal-to-distal positions in all sampled populations(years).Fruit and seed production decreased distally in most populations(years).low fruit and seed set of distal flowers was not due to pollen limitation because pollen deposition never declined distally and the low fruit and seed set of distal flowers remained even after supplementary pollination was provided.The flower-removal experiment indicated that inter-fruit competition for resources among flowers was common.The low P/o ratio of distal flowers in H.ventricosa might be favored because they were unable to obtain fitness by donat-ing pollen and siring seeds on other plants.our study may help to understand the adaptive significance of sex allocation among flow-ers within inflorescences of sexually reproducing hermaphrodites.
基金National Natural Science Foundation of China(Grant No.81703387)the Foundation for the demonstration of tea-fruit-medicine organic ecological safety belt in Ya’an
文摘A total of 13 types of endophytic fungi,classified into six genera,were isolated from Hosta.ventricosa based on 18 S rDNA sequencing of ITS region and microscopic examination.The antioxidant activities of the crude extracts were investigated by T-AOC,DPPH and ABTS＋ methods.The results showed that the crude extracts from Fusarium oxysporum（HoV1） and Epicoccum（HoV4）,which presented higher phenol levels（1.90±0.03 mg/g,and 2.41±0.01 mg/g,respectively）,exhibited stronger comprehensive antioxidant activities,with higher T-AOC values（63.46±0.26 U/g,and 66.05±0.71 U/g,respectively）,lower EC_（50） values against ABTS~＋（30.25±0.05 μg/m L,and 24.66±0.65 μg/m L,respectively） and DPPH radicals（83.42±0.24 μg/m L,and 59.136 μg/m L,respectively）.Moreover,Fusarium oxysporum（Ho V8） showed excellent scavenging activity against DPPH radicals（EC_（50） = 16.02 μg/m L）,which was better than BHT.All of them could be useful in the developing of new natural antioxidant agents.
