Chinese scientists lead in revealing the history of tomato breeding

A few days ago, the international tomato variation group research team led by Huang Sanwen, a researcher at the Institute of vegetables and Flowers of the Chinese Academy of Agricultural Sciences and deputy director of Shenzhen Agricultural Genome Institute, constructed a complete tomato genetic variation group map by re-sequencing 360 tomato germplasm around the world, which laid a foundation for revealing tomato evolution history, gene mining and molecular breeding. The latest findings are published online in the Oct. 13 issue of the journal Nature Genetics.

It is reported that the large fruit cultivated tomatoes that people eat are domesticated from wild tomatoes. In the process of long-term domestication, significant changes have taken place in the weight, color and shape of wild tomato fruits. The fruit of wild tomato is very small, weighing only 1 to 2 grams, while the fruit weight of modern cultivated tomato is more than 100 times that of its ancestors. however, the process of artificial domestication of tomato has not been fully studied. Through population genetic analysis, the research team successfully revealed that tomato fruit enlargement experienced two evolutionary processes from gooseberry tomato to cherry tomato and then to large fruit cultivated tomato. In this process, 5 and 13 fruit weight genes were selected by humans, respectively.

At the same time, by comparing the genomic differences of different tomato populations, the research team found that chromosome 5 is the main genome region that determines the difference between fresh tomato and processing tomato. This region contains a number of genes that control tomato soluble solids and fruit firmness. These genes give processing tomato significant characteristics. Through genome-wide association analysis, the team found a key variation site that determines the pericarp color of powdery fruit, which leads to the deletion of the promoter region of SIMYB12 gene, which affects the expression of the gene, so that flavonoids can not be accumulated in mature pink fruit tomato pericarp. This discovery provides an effective molecular breeding tool for cultivating pink fruit tomato varieties.

In addition, in order to solve the problem that wild germplasm resources are widely used in modern tomato breeding, the team accurately defined the position and length of wild tomato genome fragments in cultivated tomato genome by comparative genomics, which makes it possible to further expand tomato breeding space. In order to solve the problem of tomato quality decline due to the pursuit of high yield and tolerance to storage and transportation in commercial tomato breeding, on the basis of big data, a tomato variant group, Huang Sanwen's team is working closely with the tomato quality breeding team led by Professor HarryKlee, academician of the American Academy of Sciences, to clarify the mechanism of metabolism and accumulation of more than 20 volatile compounds that affect tomato flavor, and provide a new tool for cultivating more delicious tomatoes.