| A number of arthropod pests attack tomato throughout its production cycle. Bemisia tabaci(Gennadius) biotype B is a worldwide pest and since2007has become a severe pest in China causingextreme damage to field tomato production in southern China and to greenhouse tomato production innorthern China. There are no tomato varieties resistant to whitefly in the international and domesticmarkets. Compared with disease and abiotic stress resistance mechanisms, tomato insect resistancemechanisms are more complex and in only a few instances have the genetic basis for resistance beeninvestigated. These problems prevent use of insect-resistant germplasm resources, transformation ofinsect resistance genes and development of breeding for insect resistance.S.lycopersicum ‘9706’,‘LA3556’,‘maofen802’, S.habrochaites ‘LA2329’,‘LA1777’,‘PI134417’,S. pennellii ‘LA0716’and S. Pimpinellifolium ‘TO937’,‘PI126933’ were used in this study. In order toillustrate the mechanism of different tomato accessions resistance to Bemisia tabaci. This reasearchinvolved correlational analysis for trichomes, secondary metabolites on leaf surface and resistance towhitefly among the tomato accessions; secondary metabolite profiles on the leaf surfaces, geneexpression resulting from several whitefly treatments and identification of QTL‘s associated withresistance to Bemisia tabaci in S. habrochaites LA2329. Main results for this study are as follows:1. The resistance of S.habrochaites ‘LA2329’，‘LA1777’，‘PI134417’and S. pennellii ‘LA0176’towhitefly was the strongest. The resistance of S. pimpinellifolium ‘TO937’ to whitefly was significantdifference in different developmental stages. S.lycopersicum ‘9706’,‘LA3556’,‘maofen802’ and S.Pimpinellifoliu ‘PI126933’ were sensitive to whitefly.2. Trichome type and density on abaxial leaf surfaces of the different tomato accessions showedsignificant inter-and intra-specific differences. Type Ⅳ and Ⅵ trichome densities were superior onabaxial leaf surfaces of S. habrochaites, the densities of them were more than5·mm-2. Type Ⅳ trichomedensities were superior on abaxial leaf surfaces of S. pennellii and S. pimpinellifolium ‘TO937’, thedensities were6.7and15.4·mm-2, respectively. Other tomato accessions trichomes on abaxial leafsurfaces were mainly non-glandular trichomes, densities were3.4~10.6·mm-2. Type Ⅳ and Ⅵ trichomedensities were less than4·mm-2on abaxial leaf surface of these tomato accessions. Density of type Ⅳtrichomes, wax content on leaf surfaces, and terpenoid content were significantly negative correlatedwith number of whitefly eggs laid on abaxial leaf surfaces. Conversely, density of type Ⅲ trichomeswas positive correlated with the number of whitefly eggs laid on abaxial leaf surfaces. Density of typeⅥ trichome was positive correlated with terpenoid content, but not correlated with number of whiteflyeggs laid on abaxial leaf surfaces.3. Terpenoids of S. habrochaites ‘LA2329’,‘LA1777’ and ‘PI134417’ were mainly sesquiterpenes,which showed significant inter-and intra-specific differences. Terpenoids of ‘LA1777’ were25compositions including3monoterpenes and22sesquiterpenes that comprised of type CⅠand CⅡsesquiterpenes. Terpenoids of ‘LA2329’ were24compositions including5monoterpenes and16 sesquiterpenes that comprised of type CⅡ sesquiterpenes and sesquiterpenes with the same chemicalstructure of type CⅡ sesquiterpenes. Terpenoids of ‘PI134417’ were14compositions including1monoterpenes and13sesquiterpenes that comprised of type CⅠ sesquiterpenes and sesquiterpenes withthe same chemical structure as type CⅠ sesquiterpenes. Conversely，terpenoids of S. lycopersicum, S.pennellii and S. pimpinellifolium were mainly monoterpenes, which were10compositions andcomprised of6monoterpenes and4type CⅠ sesquiterpenes, which showed little diversity among thethree tomato species. Terpenoid composition was relatively small different among developmental stages,but terpenoid concentration differed significantly among developmental stages.4. Secondary metabolites were significantly different among3tomato accessions of S.habrochaitesafter whitefly treatment,compared to uninfested controls. A total of21kinds of sesquiterpenes of‘LA1777’ were significant difference after whitefly treatment. After8h by whitefly adults infestion,48h exposure to whitely eggs and21d by whitefly nymphs infestion,3sesquiterpenes,8sesquiterpenesand10sesquiterpenes significantly increased. A total of12kinds of sesquiterpenes of ‘LA2329’ weresignificant difference after whitefly treatment. After8h by whitefly adults infestion and48h exposureto whitely eggs7sesquiterpenes significantly decreased and4sesquiterpenes significantly increased.After21d by whitefly nymphs infestion,11sesquiterpenes significantly increased. A total of2kinds ofsesquiterpenes of ‘PI134417’ were significant difference after whitefly treatment. After8h by whiteflyadults infestion and48h exposure to whitely eggs these sesquiterpenes significantly decreased, andafter21d by whitefly nymphs infestion, significantly increased.5. Expression of genes associated with tomato terpenoid biosynthesis of S. habrochaites‘LA2329’,‘LA1777’and ‘PI134417’were highter than others tomato accessions. The result illustrategenes control sesquiterpenes biosynthesis in the transcriptional level. The terpenoid gene expression oftomato accessions was not significant affected by treatment of adult whiteflies. Expressions of FPS,TPS9, TPS12and SSTLH3of tomato accessions were significantly difference after whitefly treatment,compared to uninfested controls. This suggest FPS，TPS9，TPS12and SSTLH3were the key geneswhich regulate sesquiterpenes biosynthesis.6.33QTL associated with insect-resistance were mapped in the BC1population generated fromtomato cultivar‘9706’crossed with S. habrochaites‘LA2329’.8QTL associated with adult whiteflynumbers and oviposition numbers were located in the same locus. Of the8QTL,2major QTL werelocated in the interval defined by the markers InDel_FT45~SSR57and SSR57~InDel_FT49onchromosome2and explained33.2%and39.8%of phenotypic variation，respectively. |
PDF Full Text Request