Development And Reproduction Of Bemisia Tabaci Biotype B On Tomato Accessions And QTL Mapping Of Resistance To Bemisicia Tabaci Biotype B

Bemisia tabaci (Gennadius) biotype B has has caused extreme damage in greenhouse tomato production. The damage is the result of not only whitefly feeding also by whitefly transmitted virus. Breeding for insect resistance in tomato breeding is a potentially effective solution to these whitefly problems. But there are no insect-resistant varieties used in current production and the lack of resistance in cultivars sources. Because some wild tomatoes are resistant to white fly, it is useful for breeding to study the resistance gene from wild tomato. Small RNA plays an important role in reaction to biotic stresses. Studying the role of sRNA in the insect-induced responses of tomato could be helpful for identifying transcriptional and post-transcriptional regulation aspects involved in the insect-resistance mechanisms. Development of this information could lead to new paths for breeding insect resistance in tomato.First, I studied the development and reproduction of B.tabaci biotype B on wild and cultivated tomato accessions. B.tabaci (Gennadius), were transferred to eight tomato accessions (3 S. habrochaites, 4 S. lycopersicum and 1 S. pimpinellifolium). Oviposition, body size, rate of development, longevity, and survivorship were investigated. This research showed that the key biological parameter were affected by wild tomatoes. Based on these-results, a simple and effective method for identifying insect-resistant lines was developed. . This method was then used to evaluate a population that segregated for whitefly resistannce. Then the QTLs correlated with resistance with were mapped by QTL analysis. Second, the induced expression, white fly feeding on PI134417 and KR2 in three stage (8h: adult induction; 48h: adult and egg induction; 21d:nymphs induction), were predicted by sRNA sequencing and bioinformatics method. The following are main results:1. The development and reproduction of B tabaci biotype B on wild and cultivated tomato accessions were different and wild tomatoes had effect on some biological parameters.Three parameters of growth and development of B. tabaci differed between susceptible S. lycopiscum and resistant S. habrochaites in all biological parameters including oviposition, body size, rate of development, longevity, and survivorship. B tabaci laid fewer eggs on accession LA1777 (S. habrochaites) than on KR2 (S. lycopersicum) from 10:00 to 14:00 on a sunny day (14 and 164 eggs, respectively). The longevity of female B. tabaci on LA1777 was significantly shorter (5 days) than on Moneymaker S. lycopersicum) (22 days). For second generation: oviposition on LA1777 was significantly lower (7 eggs/female) than on Zaofen No.2 (S. lycopersicum; 95 eggs/female). These three parameters are useful for evaluating resistance/susceptibility to B. tabaci in tomato. These result showed the resistance was complex.2. The detoxification enzymes were affected by feeding on tomato accessions. 12 h after feeding, the activities of CarE (carboxylesterase) and GST (glutathione-S-transferase) were lowest levels. However, 32h after feeding, both enzyme activities were at their highest levels. For AChE (acetylcholinesterase), in the resistant wild tomato PI134417 activity declined faster than that for the cultivar Moneymaker. 3. I found that whitefly prefer laying eggs on the bottom leaflets and on the bottom of leaflets. According to the fecundity, the evaluation method to insect-resistance by in vitro leaf was constructed.4. Eight QTLs related to fecundity were detected. Five QTLs related to fecundity were located on chromosomes 2, 5 and 6 (qBT-2-1, qBT-2-2, qBT-5-1, qBT-5-2, qBT-6-1). Three QTLs related to avoidance were detected, located on chromosome 2 and 6 (qBT-2-2, qBT-6-2, qBT-6-3) respectively. The qBT-2-2 was the common to both phenotypes.5. 10 million-2000million sRNA clean-reads were obtained in each sample by Hiseq deep sequencing. Aligning to the known tomato miRNA, I found that sly-miRNA1916, 1918 and 319 only existed in susceptible group (KR2) not in resistant group (PI134417). All known miRNA expression varied in both groups. There were 426 miRNA unique to in the susceptible group and 416 unique to the resistant group.According to the characteristic hairpin structure of miRNA precursor, novel miRNA and target gene were predicted. 600-889 unique miRNA were predicted in each sample and 73-120 target genes were obtained. And eight miRNAs, induced expression by B.tabaci, were selected. These miRNA target gene was involved to different gene expression.