Mining Of Key Genes For Cold Stress Resistance And Analysis Of Regulatory Network In Tectona Grandis

Teak is a precious tree species in the Verbenaceae family,native to tropical regions,and is one of the main afforestation trees in the world.It has been widely introduced and cultivated in more than 50 countries and regions.Low temperature has been a key issue preventing Teak from being widely planted in sub suitable areas.In temperate regions,plants can adapt to cold stress by regulating gene expression and metabolism under non freezing temperatures,and achieve enhanced cold resistance.However,plants from tropical and subtropical regions are sensitive to low temperature stress because they lack cold acclimation mechanisms.Although ICE-CBF-COR is the main response pathway to cold stress,only 10% to 20% of COR genes are regulated by CBFs,and the triple mutant of CBFs still has the ability to cold acclimatize.Based on genome-wide prediction and transcriptome technology,this study investigated the important response genes to low temperature stress and their regulatory networks in teak,and verified the function of teak inducible CBF genes through the Arabidopsis transformation system.The results are as follows:1、A total of 8 CBF homologous genes have been identified in the genome of Teak.Similar to the CBF gene family in Arabidopsis,they can be further divided into two subgroups.Its encoded proteins range in length from 199 to 246 aa and have a molecular weight of between 20 and 30 k Da,all of which are acidic hydrophilic proteins.Irregular curls and α-The proportion of spirals is large,and the tertiary structure is similar.Subcellular localization analysis showed that all 8 CBF genes were located in the nucleus.2、The key genes of teak under transient low temperature stress were studied using high throughput sequencing technology.A total of 36901 genes were identified,including1055 new genes.Among the genes involved in osmotic regulation,there are significant differences in the expression of glucose metabolism genes.The gene expression of PSI system is more stable than that of PSII system,and the expression of PSI core protein gene changes significantly after 3 hours of low temperature stress,indicating that Teak may be a cold sensitive plant.In addition,all antioxidant enzyme genes can be detected in teak under low temperature stress,indicating that these genes are relatively conservative in evolution.Importantly,ABA,SA,GA,and JA are also involved in the cold stress response of teak to varying degrees,while other hormones also play a role.Surprisingly,CBF1 and CBF3 are almost not induced by low temperature,while CBF2 and CBF4 are induced by low temperature,indicating that the ICE-CBF-COR cold resistance pathway of teak may be different from other plants,and the performance of several important regulatory factors in the ICE-CBF-COR pathway also confirms this.The significant downregulation of HY5 and RVE1 genes after 9 hours of low temperature stress suggests that the CBF independent pathway may play an important role in the low temperature resistance of teak.3 、 Functional verification of TgCBF gene.Using Agrobacterium tumefaciens to transform TgCBF into Arabidopsis plants,the results showed that the cold resistance of Arabidopsis plants overexpressing TgCBF2 and TgCBF4 genes was significantly higher than that of wild type plants.Fluorescence detection showed that the transformants with good cold resistance could detect significant fluorescence signals.Low temperature stress is an inevitable problem in the introduction and cultivation of teak in subtropical or temperate regions.The research results reveal the key genes and complex regulatory networks for low temperature tolerance of teak,which not only provides information for the study of cold resistance mechanism of teak,but also provides reference for the study of cold resistance mechanism of tropical tree species.