MicroRNA regulatory mechanisms on Citrus sinensis leaves to magnesium-deficiency
In China, magnesium (Mg)-deficiency often occurs in citrus orchards, and is responsible for the loss of yield and poor fruit quality. However, very limited data are available on Mg-deficiency-responsive microRNAs (miRNAs) in higher plants. Using Illumina sequencing, we isolated 93 (91 known and 2 novel) up- and 90 (83 known and 7 novel) down-regulated miRNAs from Mg-deficient Citrus sinensis leaves. In addition to the remarkable metabolic flexibility as indicated by the great alteration of miRNA expression, the adaptive responses of leaf miRNAs to Mg-deficiency might also involve the following aspects: (a) accelerating protein turnover and amino acid biosynthesis by repressing the expression of miR2919, miR7812, miR5904 and miR5742; (b) up-regulating stress-related genes by down-regulating miR2919, miR164 and miR7812; (c) enhancing cell transport due to decreased expression of miR2919, miR3946, miR7533, miR1222, miR779, miR6143 and miR2868 and increased expression of miR395, miR1077, miR1160 and miR8019; (d) activating lipid metabolism-related genes by repressing miR158, miR1222, miR7533 and miR3946; (e) inducing cell wall-related genes by decreasing miR7533, miR779 and miR2868 expression; and (f) maintaing primary meristems by down-regulating miR6135. To conclude, we identified some candidate miRNAs that might contribute to Mg-deficiency tolerance. Our results are usefult not only for increasing our understaning of the molecular mechanisms on plant Mg-deficiency tolerance at post-transcriptional level, but also for obtaining the key miRNAs for plant Mg-deficiency tolerance. Overall design: Two libraries were constructed from Citrus sinensis (L.) Osbeck leaves subjected to 0(0 mM MgSO4,Mg-deficient,LD) or 1(Mg-sufficient,control, LS) mM MgSO4 for 16 weeks, and sequenced by Illumina sequencing. Size fractionated small RNAs (16-30 bp) from total RNA extracts was ligated to 5'' and 3'' adapters, and reverse transcribed. After PCR amplification the sample was subjected to Solexa sequencing. The clean tags were used for further analysis.
External Link: /pubmed:26973661