Research On The Physiological Mechanism Of Cassava Resistance To Bacterial Blight

The development of cassava industry is severely limited by the bacterial wilt of cassava,and the most economical and effective measures to prevent and cure the disease are breeding and cultivation of resistant varieties.This experiment selects 6 different cassava varieties with obvious difference in resistance to bacterial wilt disease,were observed in the structure of their leaves at seedling stage of cassava,change and enzyme related antioxidant leaves after inoculation,and physiological and biochemical indexes were analyzed,the results are as follows:1?the difference of stomatal density and wax content in leaves of different varieties was significant,and positively correlated with the resistance of varieties,which showed that waxy layer of cassava leaves is one of the structural factors of defensing against infection of pathogens,there is no correlation between stomatal size and resistance.2?the leaves of resistant and susceptible varieties were observed though the paraffin section,the leaf thickness,the palisade tissue thickness and the spongy tissue thickness were compared.The results show that the high resistant varieties of leaf tissue structure is compact,the palisade tissue and spongy tissue arranged more tightly,and has certain effect on resistance to pathogen infection,more gaps appear in resistant and susceptible cultivars of sponge tissue,it has loose structure.So between the loose leaf structure of SR and the resistance of cassava there is the correlation.3?After the pathogen infection of cassava leaves,the result of antioxidant related indexes in leaves showed that:after inoculating,all varieties of cassava leaves in these three kinds of enzyme activity were increased,which was higher than that ck;The content of MDA in leaves of resistant varieties before inoculation was significantly lower than that of susceptible varieties,and the content of MDA increased in all varieties after inoculation.So that POD,PPO,PAL activity and MDA content are positively correlated to the disease resistance of cassava.4?Soluble protein content of high resistant varieties decreased slightly,while the content of soluble protein in resistant varieties and susceptible varieties increased after inoculation,protein content of resistant varieties was higher than susceptible cultivar,the relationship between the soluble protein and the disease resistance needs further study.5?The change of soluble sugar in different varieties had no obvious regularity before and after inoculation.It could not be used as an index to identify the resistance of cassava at seedling stage.6?The content of free proline before inoculation of susceptible varieties was higher than that of resistant varieties,pre inoculation significantly increased proline content of the sensitive cultivar.During the period,proline content was higher than that of resistant varieties,while it only slightly increased,up to the peak and the nit began to decline after the proline content can be used as a measure of the resistance index of cassava.