miRNA present in phloem exudate and lupin tissues. A) Northern blot analysis of miRNA in various lupin tissues and phloem. Small RNA was extracted from phloem exudate, pod walls, seeds, flowers, nodules, roots, stems, cotyledons, mature leaves, young leaves and three-week-old lupin seedlings and four-week-old Arabidopsis seedlings. Small RNA (5 μg) from each sample was separated on a denaturing polyacrylamide gel. After separation, RNA was transferred to Hybond N+ nylon membrane and the membrane was probed with end labelled oligonucleotide probes complementary to microRNAs with conserved sequences in Arabidopsis and rice. The position of RNA oligonucleotide standards are indicated on the right. Ribosomal RNA from each sample was visualised by ethidium bromide staining of the polyacrylamide gels and serve as loading controls. B) Northern blot analysis of miR171 in lupin tissues and phloem exudate. Five μg of small RNA extracted from leaf (L), root (R) and phloem exudates (P) of L. albus plants were separated on a 15% denaturing polyacrylamide gel, transferred to Hybond-N+ nylon membrane and hybridized to specific 32P end-labelled DNA oligonucleotide probes complementary to miR171.