Messenger RNA （mRNA） turnover in eukaryotic cells begins with shortening of the poly （A） tail at the 3＇ end, a process called deadenylation. In yeast, the deadenylation reaction is predominantly mediated by CCR4 ...Messenger RNA （mRNA） turnover in eukaryotic cells begins with shortening of the poly （A） tail at the 3＇ end, a process called deadenylation. In yeast, the deadenylation reaction is predominantly mediated by CCR4 and CCR4- associated factor 1 （CAF1）, two components of the well-characterised protein complex named CCR4-NOT. We report here that AtCAF1a and AtCAF1b, putative Arabidopsis homologs of the yeast CAF1 gene, partially complement the growth defect of the yeast call mutant in the presence of caffeine or at high temperatures. The expression of At-CAF1a and AtCAFlb is induced by multiple stress-related hormones and stimuli. Both AtCAF1a and AtCAFlb show deadenylation activity in vitro and point mutations in the predicted active sites disrupt this activity. T-DNA insertion mutants disrupting the expression of AtCAF1a and/or AtCAF1b are defective in deadenylation of stress-related mRNAs, indicating that the two AtCAF1 proteins are involved in regulated mRNA deadenylation in vivo. Interestingly, the single and double mutants of AtCAF1a and AtCAFlb show reduced expression of pathogenesis-related （PR） genes PR1 and PR2 and are more susceptible to Pseudomonas syringae pv tomato DC3000 （Pst DC3000） infection, whereas transgenic plants over-expressing AtCAFla show elevated expression of PR1 and PR2 and increased resis-tance to the same pathogen. Our results suggest roles of the AtCAF1 proteins in regulated mRNA deadenylation and defence responses to pathogen infections.展开更多
Plants in their natural environment are constantly subjected to various abiotic and biotic stressors and,therefore,have developed several defense mechanisms to maintain fitness.Stress responses are intricate and requi...Plants in their natural environment are constantly subjected to various abiotic and biotic stressors and,therefore,have developed several defense mechanisms to maintain fitness.Stress responses are intricate and require various physiological,biochemical,and cellular changes in plants.The reaction mechanisms in plants subjected to drought,salinity,or heat stress alone have been explained in numerous studies.However,the field conditions are significantly different from the controlled laboratory conditions.In the field,crops or plants are simultaneously exposed to two or more abiotic and/or biotic stress conditions,such as a combination of salinity and heat,drought and cold,or any of the abiotic stresses combined with pathogen infection.Studies have shown that plants’reactions to combinations of more than two stress factors are distinct and cannot be explicitly deduced from their responses to different stresses when applied separately.Therefore,additional research is needed to understand the complete mechanism of plant responses to stress by analyzing data between single stress and multiple stress responses.This review aims to provide an overview of current research on plant responses to a combination of various stress conditions and their influence on the metabolic,transcriptional,and physiological characteristics of plants.展开更多
文摘Messenger RNA （mRNA） turnover in eukaryotic cells begins with shortening of the poly （A） tail at the 3＇ end, a process called deadenylation. In yeast, the deadenylation reaction is predominantly mediated by CCR4 and CCR4- associated factor 1 （CAF1）, two components of the well-characterised protein complex named CCR4-NOT. We report here that AtCAF1a and AtCAF1b, putative Arabidopsis homologs of the yeast CAF1 gene, partially complement the growth defect of the yeast call mutant in the presence of caffeine or at high temperatures. The expression of At-CAF1a and AtCAFlb is induced by multiple stress-related hormones and stimuli. Both AtCAF1a and AtCAFlb show deadenylation activity in vitro and point mutations in the predicted active sites disrupt this activity. T-DNA insertion mutants disrupting the expression of AtCAF1a and/or AtCAF1b are defective in deadenylation of stress-related mRNAs, indicating that the two AtCAF1 proteins are involved in regulated mRNA deadenylation in vivo. Interestingly, the single and double mutants of AtCAF1a and AtCAFlb show reduced expression of pathogenesis-related （PR） genes PR1 and PR2 and are more susceptible to Pseudomonas syringae pv tomato DC3000 （Pst DC3000） infection, whereas transgenic plants over-expressing AtCAFla show elevated expression of PR1 and PR2 and increased resis-tance to the same pathogen. Our results suggest roles of the AtCAF1 proteins in regulated mRNA deadenylation and defence responses to pathogen infections.
基金the University Grants Commission(UGC-BSR Research Start-up-Grant No.F30-409/2018)the Deanship of Scientific Research,King Khalid University,Saudi Arabia(No.R.G.P.2/11/42)for their financial assistance。
文摘Plants in their natural environment are constantly subjected to various abiotic and biotic stressors and,therefore,have developed several defense mechanisms to maintain fitness.Stress responses are intricate and require various physiological,biochemical,and cellular changes in plants.The reaction mechanisms in plants subjected to drought,salinity,or heat stress alone have been explained in numerous studies.However,the field conditions are significantly different from the controlled laboratory conditions.In the field,crops or plants are simultaneously exposed to two or more abiotic and/or biotic stress conditions,such as a combination of salinity and heat,drought and cold,or any of the abiotic stresses combined with pathogen infection.Studies have shown that plants’reactions to combinations of more than two stress factors are distinct and cannot be explicitly deduced from their responses to different stresses when applied separately.Therefore,additional research is needed to understand the complete mechanism of plant responses to stress by analyzing data between single stress and multiple stress responses.This review aims to provide an overview of current research on plant responses to a combination of various stress conditions and their influence on the metabolic,transcriptional,and physiological characteristics of plants.
