Evaluation And Mechanism Preliminary Research Of Cold Tolerance Stylosanthes

In order to obtain cold-tolerant Stylosanthes germplasm, low-temperature pot experiment method and electrolyte leakage rate method were used for evaluation of cold tolerance among 24 Stylosanthes varieties in this study. The results show that malonyldialdehyde (MDA) content, relative conductivity of Stylosanthes leaves, superoxide dismutase (SOD) activity and leaf rolling index increased under cold stress. After return to normal conditions, the survival rates of different Stylosanthes germplasm were different as well. Physiological indexes of low-temperature pot experiment have been quantified with subordinate function in order to evaluate cold tolerance among 24 Stylosanthes varieties. Thereafter electrolyte leakage rate method was used in the lethal temperature (LT50) measurement to verify the low-temperature pot experiment results. The results of electrolyte leakage rate method were consistent with that of low-temperature pot experiment. Based on the results of both methods, we get 6 cold-tolerant Stylosanthes varieties (S. guianensis cv. Reyin No.18; S. guianensis Pin109; S. guianensis stylo1979; S. hippocampoides; S. guianensis cv. Yueyan No.l; S. guianensis TPRC90075) and 5 cold-sensitive Stylosanthes varieties (S. guianensis CIAT46; S. guianensis Tardio;S. guianensis CIAT104; S. guianensis CIAT1262; S. angustifolia CIAT1278). This study can provide theoretical and material basis for future Stylosanthes cold-tolerance breeding. Using the Illumina Hi-Seq TM2000 sequencing technologies for the transcriptome sequencing on the CK group and low-temperature group of S. guianensis cv. Reyan No.5. We received 24,5585 Contigs,200,744 Transcripts and 36,558 Unigenes. Conducted bioinformatics annotation on Unigenes with NR, Swissprot, GO, eggNOG, KEGG database, we accepted 27468 Unigenes in GO,8986 Unigenes in KEGG,26764 Unigenes in eggNOG,22258 Unigenes in Swissprot. We selected 1475 cold tolerance related Unigenes,86 of them were AP2 family gene. Among them we selected 20 cold tolerant related AP2 family genes and 20 randomly selected genes to verify their functions by means of Realtime PCR. The results show that AP2 family genes are related to cold response.