natural variation in an abc transporter gene associated with seed size evolution in tomato speciesabc转运蛋白基因的自然变化与种子大小茄物种进化.pdfVIP

Natural Variation in an ABC Transporter Gene Associated with Seed Size Evolution in Tomato Species 1 1,2 Cintia Hotta Orsi , Steven D. Tanksley * 1 Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York, United States of America, 2 Department of Plant Biology, Cornell University, Ithaca, New York, United States of America Abstract Seed size is a key determinant of evolutionary fitness in plants and is a trait that often undergoes tremendous changes during crop domestication. Seed size is most often quantitatively inherited, and it has been shown that Sw4.1 is one of the most significant quantitative trait loci (QTLs) underlying the evolution of seed size in the genus Solanum—especially in species related to the cultivated tomato. Using a combination of genetic, developmental, molecular, and transgenic techniques, we have pinpointed the cause of the Sw4.1 QTL to a gene encoding an ABC transporter gene. This gene exerts its control on seed size, not through the maternal plant, but rather via gene expression in the developing zygote. Phenotypic effects of allelic variation at Sw4.1 are manifested early in seed development at stages corresponding to the rapid deposition of starch and lipids into the endospermic cells. Through synteny, we have identified the Arabidopsis Sw4.1 ortholog. Mutagenesis has revealed that this ortholog is associated with seed length variation and fatty acid deposition in seeds, raising the possibility that the ABC transporter may modulate seed size variation in other species. Transcription studies show that the ABC transporter gene is expressed not only in seeds, but also in other tissues (leaves and roots) and, thus, may perform functions in parts of the plants othe