| Cassava(Manihot esculenta Crantz)is an important root crop in the tropical and subtropical areas where drought and poor soil fertility are the main constraints to crop productivity,owing to its ability of high photo synthetic efficiency,drought resistance,resistance to barren.Stomata is an important structure for regulating the exchange of gases and water between plants and the outside,which is one of the main factors affecting plant drought tolerance.In order to study the relationship between stomatal density and stomatal regulation and cassava drought resistance.The stomatal density of 92 cassava cultivars was analyzed under drought stress condition.Six cultivars with typical stomatal density were selected for further physiological and biochemical indexes,in order to explore the photo synthetic efficiency and drought tolerance of cassava and its stomatal density.At the same time,we found that the stomatal density of MeMYB2-RNAi transgenic cassava was significantly higher than that of non-transgenic plants,and its photosynthetic rate was also higher than that of non-transgenic plants,but the drought tolerance was also improved.The results of several cultivars and MeMYB2-RNAi transgenic cassava showed that there was no correlation between the stomatal density and the drought resistance of cassava.We speculate that cassava,when subjected to drought stress,is likely to reduce the loss of moisture by rapidly closing the pores in order to avoid the drought.This high stomatal density,rapid closing of the stomatal regulation mechanism can not only meet the cassava as a tropical crop high light efficiency needs,but also to ensure its drought tolerance.Plants produce hormonal abscisic acid(ABA)when subjected to drought stress,and thus promote the production of reactive oxygen species(ROS),thus closing the pores to reduce the evaporation of leaf moisture and protect the plants through the dry period.But this process produces a large number of ROS to destroy the intracellular redox balance,causing damage to the plant body.Glutathione/glutaredoxin is a kind of important protein redox system in plants,which is involved in the ROS signaling pathway of plants by regulating the redox state of proteins.CC-type Glutaredoxins(CC-type Glutaredoxins)is a kind of glutenated protein,which is unique to higher plants,and can protect plant cells from oxidative damage when plants are subjected to oxidative stress.In this study,the expression of multiple CC-type GRX genes in cassava was analyzed.It was found that the expression of multiple CC-type GRX genes in cassava was induced by drought stress.In this study,we have made a study on the regulation of stomata in ABA by cassava CC-type GRX.It was found that the ability of ABA to induce stomatal closure was significantly attenuated in transgenic Arabidopsis overexpressing MeGRX232,and the tolerance of transgenic Arabidopsis is reduced.CC-type glutaredoxin can interact with TGA transcription factors to regulate the expression of a series of downstream genes.In order to further explore the interaction protein of CC-type GRX in cassava,we selected the TGA factor which could interact with the cassava CC-type glutathione MeGRX058 and MeGRX785 by yeast two-hybrid experiment.The results showed that MeGRX058 and MeTGA304 could interact with each other.In order to further verify its interaction with TGA transcription factor,we selected the two genes MeGRX058 and MeGRX785 for further in vitro protein expression analysis,in order to lay the foundation for the study of cassava GRX follow-up function.We used different labeling proteins to label MeGRX058 and MeGRX785,respectively,and express the above two recombinant proteins in yeast and transgenic plants,respectively,and try to purify the recombinant protein by labeling the protein.The results of Western blot showed that both recombinant proteins could be expressed in yeast and transgenic plants,but their expression products were degraded.We speculated that MeGRX058 and MeGRX785 proteins were ubiquitinated in vivo. |
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