Germplasm Identification And Hybrids Screening Of Bacterial Wilt Resistance In Cherry Tomato

Cherry tomato is a"fruit type"vegetable with rich nutrition and unique flavor.In recent years,cherry tomato has been favored by consumers and gradually become a necessary fruit for dining tables,which has enlarged the market demand.However,cherry tomatoes are currently suffering from serious soil-borne diseases,especially tomato bacterial wilt,which is restricting the healthy development of the industry.In this study,cherry tomato germplasm was identified for the resistance to bacterial wilt and the resistant inbred combination was made.The study was divided into three parts:The first part was to identify the strong resistance to bacterial wilt of the inbred lines using molecular marker assisted selection,indoor inoculation and field phenotyping.The second part is to backcross’Hawaii7996’with good inbred lines for the creation of new,superior,disease-resistant inbred lines.The third part is to develop hybrid combinations based on the breeding objectives of producing high qualitative varieties and resistance,and to evaluate the crosses based on agronomic and qualitative traits to select superior hybrid combinations with resistance to bacterial wilt,so as to lay the foundation for the selection of new varieties with strong resistance to bacterial wilt,high quality and good overall traits.The main results of this study are as follows:1.Identification and screening of self-breeding lines including the identification and screening of self-breeding lines resistant to bacterial wilt and the screening of self-breeding lines with good traits.On the one hand,five inbred lines like 211LY18-mix-1Q,211ZYY3-Mix-1Q,211TA79-Mix-1Q,211TA82-Mix-1Q and 211TQY29-Mix1-1Q with strong resistance to bacterial wilt were screened by molecular markers,indoor inoculation and field phenotyping to identify resistance to bacterial wilt.On the other hand,the agronomic traits of 123 inbred lines were subjected to variability,principal component analysis,disease resistance analysis and comprehensive evaluation to select 13 excellent inbred lines such as 221TA46,221lu1 and 221ZYY11,of which 221ZYY11 and 221ly13 contain important disease resistance genes such as Frl and Ty-3a/3.These self-breeding lines are important germplasm resources for breeding new varieties with disease resistance and excellent traits.2.Backcrossing to breed high quality and disease-resistant self-cross lines:introduce resistance genes to bacterial wilt into four self-cross lines with better traits,such as211WY62 and 211TA19.Two single plants with a backcross reversion rate higher than 75%in 211WY62BC₁F₂ were screened in spring 2022 using molecular markers,SNP Panel sequencing.And the agronomic traits of 211WY62BC₂ tended to be the same as the recurrent parents in autumn 2022,and the backcrossing and self-crossing could be continued to obtain new disease-resistant inbred lines;the single plants containing both Bwr12 and Bwr6 genes in 211TA57BC₁,211ZYY7BC₁ and 211TA19BC₁ were screened using molecular markers in autumn 2022,and some of their agronomic traits showed segregation,and continued backcrossing was needed.3.The screening of high-quality and disease-resistant hybrid combinations includes hybrid combinations prepared in spring 2021 and spring 2022,correlation and principal component analysis are used to comprehensively evaluate agronomic traits,and variance analysis and fuzzy membership function are used to comprehensively evaluate quality traits such as soluble solid content,VC,and taste.In the autumn of 2021,there were 150 hybrid combinations with rich variations.Combined with disease resistance genes analysis,four disease resistant and high-quality hybrid combinations 212ZJ100,212ZJ116,212ZJ021,and 212ZJ137 were ultimately selected.In the autumn of 2022,six hybrid combinations222ZJ33,222ZJ47,222ZJ60,222ZJ74,222ZJ93,and 222ZJ96 with excellent fruit quality traits and good resistance to bacterial wilt were screened through resistance identification.