Endophytic Effects Of Aspergillus Oryzae On Radish(Raphanus Sativus)and Its Herbivore,Plutella Xylostella

Endophytic fungi and herbivorous insects share food,energy and habitats provided by host plants.The complex and dynamic interactions among them are crucial for biological control,biological evolution,and plant productivity.To explore,evaluate and validate the interactions among Raphanus sativus L.,Aspergillus oryzae,and Plutella xylostella,endophytic colonization by the fungus A.oryzae was induced in radish seedlings by soaking their seeds in spore suspension.We evaluated the promotion of growth in R.sativus colonized by A.oryzae and measured the fitness of P.xylostella on plants with fungal symbionts.The main results are shown below.1.The colonization of R.sativus by A.oryzaeA.oryzae was introduced into radish seeds through a soaking process,and radish seedlings were tested every other week until A.oryzae could no longer be found.The results showed that A.oryzae colonization rates in leaves were significantly higher than in roots and stems.Colonization rates gradually decreased in the different plant tissues,reaching in roots,stems,and leaves in 2,5 and 7 weeks,respectively.This study showed that after seed inoculation,A.oryzae gradually lost its colonization ability.2.Effects of A.oryzae colonization on R.sativus growthR.sativus seeds were soaked in the spore suspension for 12 hours,planted in sterile soil and checked for germination.The leaf length,leaf width,stem height,root length,plant height,and dry weight of the radish seedlings were measured every other week for a total of 7 weeks.The results showed that the treatment of seeds with A.oryzae had no influence on the germination rate,leaf length,leaf width,stem height,and root length.However,the plant height and dry weight were significantly promoted by the treatment.The leaf length,leaf width,stem height,root length,plant height and stem weight all had different degrees of promotion caused by the treatment.3.Effect of A.oryzae colonization on P.xylostella fitnessP.xylostella was reared with leaves colonized by A.oryzae to assess the effect of the plant endophyte on the fitness of the herbivore pest.The main conclusions were as follows:the rearing consumption,larval weight,pupation rate,pupal weight,emergence rate,and larval mortality of P.xylostella all showed a different decreasing trend.However,there were no influences on the development,fecundity and hatching rate of P.xylostella.These results indicate that A.oryzae has a certain harmful effect on the growth and development of P.xylostella.4.Effect of A.oryzae colonization on the 4^thinstar larval transcriptomeP.xylostella were reared in two groups:one on radish plants containing the endophyte A.oryzae and the other on endophyte-free plants.Significant weight loss was found in larvae in the treatment group.In the transcriptome sequencing analysis,significant decreases in expression of many digestive pathway-related genes,including those associated with trypsin production,proteolysis,and ryanodine receptors were found;similar phenomena were also found in the carbohydrate metabolism pathway,namely,the expression levels of catalytic enzymes involved inglycolysis and the TCA cycle had significantly declined.These results show thatfeeding on plants with A.oryzae is not conducive to the growth and development of P.xylostella because A.oryzae can causes protein degradation and a decrease in carbohydrate synthesis.This study found that A.oryzae could be effectively inoculated into radish by the seed-soaking method and that it promoted the growth of radish.Meanwhile,it could also inhibit the food intake,growth and development of P.xylostella.This study showed that the radish plants with A.oryzae symbionts have further potential applications in the biological control of P.xylostella.