| Plant Cytoplasmic male sterility（CMS）is the basis of heterosis utilization and a good material for studying the theory of nucleocytoplasmic interaction.Kenaf（Hibiscus cannabinus L.）is an annual herbaceous cash crop,which has important uses in the textile,paper and construction industries.Its heterosis is very significant.Since Professor Zhou Ruiyang discovered kenaf CMS germplasm UG93S in 2001,the male sterility and heterosis utilization of kenaf in our research group have been studied in many aspects,but its sterility mechanism is still not clear.The kenaf CMS line UG93A and its maintainer line UG93B and hybrid F1generation（UG93A/UG93R）had been used as materials,Reactive oxygen species（ROS）metabolism and related physiological indexes of anthers at different developmental stages were determined.The influence of Methyl jasmonate（Me JA）induction on anther dehiscence was verified,and the differently expressed genes in the transcriptome during anther abortion were analyzed.The main results are as follows:（1）ROS metabolism-related indicators showed that ROS（H2O2and O2.-）and MDA contents showed a trend of gradual increase in the five development stages of the three materials.The ROS（H2O2and O2.-）and MDA contents of UG93A were significantly higher than those of UG93B and hybrid F1generation from the tetrad stage,mononuclear stage and dinuclear stage,respectively.The activities of SOD,POD and CAT of UG93A were significantly lower than those of UG93B and hybrid F1 generation from binuclear stage to mature stage,but SOD was significantly lower than that of fertile material in the tetrad period.The reduced ROS enzyme activity failed to remove excessive ROS in time,leading to a large accumulation of ROS in UG93A.ATP content determination results showed that the ATP content of UG93A decreased sharply from binuclear stage to mature stage,while the ATP content of UG93B and hybrid F1 generation increased sharply,and the content of UG93A at mature stage was significantly lower than that of UG93B and hybrid F1 generation.The Programmed Cell Death（PCD）signal in the anther tapetum of UG93A and UG93B is the most obvious in the tetrad stage,and the PCD process of UG93A is later than that of UG93B.These results suggested that the large accumulation of ROS in the anther of UG93A,the delayed degradation of tapetum and the lack of ATP energy might be the main reasons for its abortion.（2）Exogenous Me JA induction showed that:no obvious signs of anther dehiscent were found after spraying different concentrations of Me JA at the full flowering stage of kenaf UG93A.Furthermore,Hc AOC1,a key gene in the jasmonic acid synthesis pathway,was cloned by homologous method,and differential expression analysis was conducted by RT-q PCR.The results showed that the expression of Hc AOC1 gene was significantly higher under low concentration T1（0.5mmol/L）Me JA than that in the control group,and reached1.6,5.3 and 1.2 times of that in the control group at 5,10 and 15 days,respectively.（3）The transcriptome analysis showed that Unigenes were mainly distributed in the carbohydrate metabolism pathway,energy metabolism pathway,amino acid metabolism and plant signal transduction pathway.There were 4866 Differential genes（DEGs）in UG93A,UG93B and hybrid F1generation.Clustering and KEGG pathway analysis showed that UG93A had 40DEGs in the oxidative phosphorylation metabolic pathway,including 5up-regulated genes and 35 down-regulated genes.There were 16 DEGs in the peroxidase metabolism pathway,10 up-regulated genes and 6 down-regulated genes.There were 13 DEGs,3 up-regulated genes and 10 down-regulated genes in the metabolic pathway of the TCA cycle.There were 19 DEGs,10up-regulated genes and 9 down-regulated genes in the linolenic acid metabolism pathway.There were 3 DEGs in the jasmonic acid metabolic pathway,including1 up-regulated gene and 2 down-regulated genes.The abnormal expression of these DEGs in the pathway affects the removal of UG93A reactive oxygen species and the production of ATP as well as the normal operation of the signal transduction mechanism,which may be the internal cause of the abortion of UG93A anthers. |
