Figure 4.

Pol IV Is Required for 21- to 24-nucleotide siRNA Production in Capsella Microspores.

(A) Profile of TE-derived siRNAs in wild-type (wt) and nrpd1 Capsella microspores. RPM, reads per million mapped reads.

(B) Abundance of TE-derived Capsella Pol IV-dependent 21/22-nucleotide siRNAs and 24-nucleotide siRNAs in Capsella microspores. Values are indicated as the log₁₀ of the average RPM of both libraries. Each dot represents one TE for a total of 5455 TEs. A pseudocount of 0.0001 was added to all zero values. The correlation has been tested by a Spearman test (correlation coefficient of 0.6872).

(C) Loss of 21/22-nucleotide and 24-nucleotide siRNAs at TEs is associated with increased transcript levels of TEs in Cr nrpd1 microspores. Increasing accumulation of siRNAs over TEs is plotted from low to high levels of accumulation. The bars from low to high represent quartiles. Only TEs with more siRNAs in the wild type than in Cr nrpd1 are represented. Differences between the first and last categories are significant (P = 3.4e-13 and 1.4e-9, respectively, Wilcoxon test). Boxes show medians and the interquartile range, and error bars show the full range excluding outliers.

(D) sRNA profile of TE-derived siRNAs from Arabidopsis wild-type and nrpd1 microspores.