Identification Of Para Rubber Tree (Hevea Brasiliensis) Snornas And Unraveling Their Roles In Latex Regeneration

Rubber trees belong to the Hevea genus plants. The latex generated by the trunk phloem laticifer cells is the main source of natural rubber (NR). However, the yield in China is quite low when compared with the traditional rubber tree planting area,which might be caused by these environmental restrictive factors: typhoon, cold,drought stress and infertility. After tapping, the latex should be regenerated in time to ensure the continuous production for the next tapping. Therefore, the latex regeneration is the fundamental biological research for high-yield mechanism.SnoRNAs are likely to participate in the regulation of latex regeneration, as they are involved in rRNA modification. In this study, the laticifer-specific snoRNAs were identified, and also the relationship between latex regeneration and snoRNAs expression. The main results are as follows:1. The 2x100nt pair-end ncRNA sequencing with latex and leaf library were used to explore snoRNA. Combined with the rubber tree EST and genome data, fifty putative laticifer-specific snoRNAs were identified by the snoScan and snoSeeker program. These snoRNAs which have typical C/D or H/ACA box domain could be classified as 21 C/D guide snoRNAs, 1C/D orphan snoRNA, 1 H/ACA guide snoRNA and 27 H/ACA orphan snoRNAs.2. Thirty-one laticifer-specific snoRNAs were validated by semi-quantitative PCR, which include 12 C/D guide snoRNAs, I H/ACA guide snoRNA and 18 H/ACA orphan snoRNAs.3. The potential modification sites of rRNA on rubber tree were discovered by comparing with the rRNA modification sites in Arabidopsis thaliana and other known model organisms. The putative modification sites of 13 guide snoRNAs were predicted by the snoScan and snoSeeker programs.4. The correlation analysis was carried out between the snoRNA expression and latex yield per plant, TSC/C respectively in the rubber tree F1 cross population.Thirteen high-relevant snoRNAs were identified from 31 laticifer-specific snoRNAs,which include 3 C/D guide snoRNAs, 1 H/ACA guide snoRNA, 9 H/ACA orphan snoRNAs.5. One snoRNA which was high-relevant to latex regeneration was identified by the Spearman correlation analysis between the latex regeneration and high-relevant snoRNAs expression.These results have great significance for unraveling the mechanism of latex metabolism and regeneration, and also provide an alternative studying method for predicting the latex production and early selection of rubber tree clones.