The Role Of Secondary Symbiont Hamiltonella In The Transmission Of Tomato Yellow Leaf Curl Virus By Bemisia Tabaci Biotype Q

Our paper detect the composition of symbionts in B. tabaci populations with PCR, clarified theremoval efficiency of different treatment to the symbionts, and antibiotics treatment and geneintrogression were used to establish the same nuclear background of both Hamiltonella-infected andHamiltonella-uninfected strains. Further functional analysis revealed the role of this symbiont in thetransmission of TYLCV, and the biological roles for the growth, development and reproductive of B.tabaci Q. The specific results are as follows:1) The detection of symbionts in B. tabaci biotypes B and Q100.0%of all individuals of the two B. tabaci biotype populations had Portiera. Hamiltonella wasfound in B and Q biotypes, with the infection frequency of91.7%and100.0%, respectively.Rickettsia was detected in the B biotype, and the infection frequency was87.5%, whereas it wasnot found in the Q biotype.2) The study of removal of endosymbionts in B. tabaci biotypes B and Q using antibioticThe three antibiotics failed to eliminate Portiera from any individual of the B and Q biotypes.Rickettsia of the B biotype was selectively eliminated by kanamycin sulfate in a dose-dependentmanner. The ability of Hamiltonella removal depended on the species and dose of antibiotic eventhe interaction between these two factors. Rifampicin can eliminate Hamiltonella better thanampicillin and kanamycin sulfate in each dose, and the elimination effects of high dose was betterthan low dose of the same antibiotic.3) The establishment of a Q strain of free-Hamiltonella and introgressionAntibiotic treatments were administered for direct feeding by adults with50μg/ml rifampicin. Afterthe antibiotic treatment and introgression, the relative concentration of Hamiltonella was3600-foldhigher in the control (H~+) strain than in treatment strain, here, we name the treatment H~–Q strain.We also carried out an introgression series to homogenize the nuclear background of both H~+andH~_strains for at least six generations.4) The roles of Hamiltonella in the acquisition, retention, and transmission of TYLCV by B. tabaci QH~+Q acquired more viral DNA and achieved a peak viral load in a shorter time than H~_Q.Viruliferous adults of both H~+and H~_Q could retain TYLCV DNA for their entire life, but viraltiter decreased at a slower rate in H~+Q than in H~_Q when feeding on cotton (a non-host ofTYLCV). With respect to transmission, the percentage of symptomatic tomato plants after a24-hexposure to1,5, and10viruliferous females per plant was60,100, and100, respectively, for H~+Qbut0,10, and30, respectively, for H~_Q. Moreover, relative viral accumulation in plants exposed toviruliferous whiteflies was greater with H~+Q females than with H~+Q males, and was much greaterwith H~+Q than with H~_Q regardless of sex. 5) The biological role of Hamiltonella in B. tabaci QCompared with Hamiltonella uninfected whiteflies, Hamiltonella-infected whiteflies producedmore eggs, had longer longevity and higher survival rate from egg to adulthood, developed faster,and larger adult body size.