The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl...The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl： 0, 100, 200 and 500 mmol·L^-1. Growth of MAJ and NAU was enhanced by 100 mmol·L^-1 NaCl but severely inhibited at the concentration of 500 mmol·L^-1. NAU exhibited a greater capacity to exclude Na^＋ and Cl^- under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na^＋/K^＋, Na^＋/Ca^2＋ and Na^＋/Mg^2＋ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L^-1 NaCl but markedly increased at 500 mmol·L^-1. This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na^＋ influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L^-1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.展开更多
Metallothionein (MT) gene has an important role in the detoxification of toxic metals especially some heavy metals. Based on the published sequences of MT genes from Agaricus bisporus, Garnoderma lucidum, Taiwanofungu...Metallothionein (MT) gene has an important role in the detoxification of toxic metals especially some heavy metals. Based on the published sequences of MT genes from Agaricus bisporus, Garnoderma lucidum, Taiwanofungus camphoratus and Paxillus involutus as a type of the edible or medical mushroom in NCBI database, their molecular structures, physiological functions and evolutionary relationship were analyzed using the bioinformatics methods. Results showed that AbMT, GlMT, TcMT and PiMT genes contained complete open reading frame (ORF) and their theoretical points of the last three encoding proteins were higher than 7.0. AbMT, GlMT, TcMT and PiMT were relatively rich in random coil and extended strand, but transmembrane helices and signal peptides were not found. 4 MTs were mainly localized in cell nucleus (over 60%) and their cellular functions might have some relation to central intermediary metabolism. Multiple sequence alignment indicated relatively high identity (more than 52%) and short genetic distances (lower than 0.900) among 4 MT nucleotide sequences. Abundant genetic diversity and strong codon bias were found based on the halotype diversity, average number of nucleotide differences, nucleotide diversity, effective number of codons, codon bias index and scaled chisquare. Simultaneously, we deduced that 4 MT genes during molecular evolution were under positive selection. The present study might provide basis for further investigation of MTs molecular mechanisms and genetic laws.展开更多
基金supported jointly by the Alexander von Humboldt-Stiftung/Foundation(Germany),German Science Foundation through Poplar Research Group Germany(PRG),the key project of National Natural Science Foundation of China(Grant No.30430430)the Hi-Tech Research and Development Program of China("863"Program,2006AA 10Z 131)+1 种基金a Foundation for the Author of National Excellent Doctoral Dissertation of P.R.China(200152)the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institu-tion of MOE,PRC(2002-323).
文摘The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl： 0, 100, 200 and 500 mmol·L^-1. Growth of MAJ and NAU was enhanced by 100 mmol·L^-1 NaCl but severely inhibited at the concentration of 500 mmol·L^-1. NAU exhibited a greater capacity to exclude Na^＋ and Cl^- under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na^＋/K^＋, Na^＋/Ca^2＋ and Na^＋/Mg^2＋ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L^-1 NaCl but markedly increased at 500 mmol·L^-1. This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na^＋ influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L^-1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.
文摘Metallothionein (MT) gene has an important role in the detoxification of toxic metals especially some heavy metals. Based on the published sequences of MT genes from Agaricus bisporus, Garnoderma lucidum, Taiwanofungus camphoratus and Paxillus involutus as a type of the edible or medical mushroom in NCBI database, their molecular structures, physiological functions and evolutionary relationship were analyzed using the bioinformatics methods. Results showed that AbMT, GlMT, TcMT and PiMT genes contained complete open reading frame (ORF) and their theoretical points of the last three encoding proteins were higher than 7.0. AbMT, GlMT, TcMT and PiMT were relatively rich in random coil and extended strand, but transmembrane helices and signal peptides were not found. 4 MTs were mainly localized in cell nucleus (over 60%) and their cellular functions might have some relation to central intermediary metabolism. Multiple sequence alignment indicated relatively high identity (more than 52%) and short genetic distances (lower than 0.900) among 4 MT nucleotide sequences. Abundant genetic diversity and strong codon bias were found based on the halotype diversity, average number of nucleotide differences, nucleotide diversity, effective number of codons, codon bias index and scaled chisquare. Simultaneously, we deduced that 4 MT genes during molecular evolution were under positive selection. The present study might provide basis for further investigation of MTs molecular mechanisms and genetic laws.
