Validation of csRNAs in chloroplasts. (A) RT-PCR analysis of ATCG00020 (chloroplast gene encoding chloroplast psbA protein), At4g10760 (nuclear gene encoding chloroplast MTA protein) and At4g15030 (nuclear gene encoding the nuclear TCP4 protein). (B) and (C) Size distribution and Northern blotting of csR-4.5sr-1 in Chinese cabbage. (D) and (E) Size distribution and Northern blotting of csR-23sr-1 in Arabidopsis. Buffer: chloroplast isolation buffer mentioned in ; Br_IC: intact chloroplasts of Chinese cabbage. Br_BC: broken chloroplasts of Chinese cabbage; At_IC: intact chloroplasts of Arabidopsis; At_BC: broken chloroplasts of Arabidopsis; At_total: total RNA samples extracted from Arabidopsis.