7. Fruit development

Tomato is one of the most popular ‘vegetable fruit’ around the world and serves as a model plant for research on fruit formation. In collaboration with other groups, we have conducted a series of molecular biology and genomic studies on different genes involved in plant growth and fruit development in tomato. In one of these projects, we were interested in understanding genes that control the formation of a ‘pointed tip’ on the bottom-end of tomato fruit. We performed a genomics analysis, known as GWAS for genome-wide association study, on a collection of 311 tomato germplasm accessions that display natural variations either with or without a ‘pointed tip’ on the fruit. Among several potential genes responsible for the ‘pointed tip’ phenotype, one gene, designated as ‘POINTED TIP’ or PT, was discovered to play a prominent role for the formation the ‘pointed tip’ trait. In wild tomato species, the PT gene encodes a transcription factor that has a histidine (H) in the key motif of the protein, and the fruit has a round bottom-end without a pointed tip. In many domesticated tomato cultivars, the PT gene has a change of a nucleotide, and its encoded protein contains an arginine (R) instead of histidine (H). As a result, an auxin hormone transporter is activated during fruit formation, leading to the development of a ‘pointed tip’ on the fruit (Song et al., 2022). This work elucidated the effect of two allele variants (PT-H and PT-R) of a naturally existing gene locus (PT) on the formation of a ‘pointed tip’ on tomato fruit and provides valuable information for the molecular breeding of fruit shape in tomato. 

References

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Chen C, Wang Y, Wu K, Ding Y, Tang M, Zhang X, Pan Y, Wu L, Su C, Hong Z, Zhang J, Li J (2025) The DnaJ1 heat shock protein interacts with the flavanone 3-hydroxylase-like protein F3HL to synergistically enhance drought tolerance by scavenging reactive oxygen species in tomato. Plant J 121: e70097 (DOI: 10.1111/tpj.70097)

Cui L, Zheng F, Li C, Li G, Ye J, Zhang Y, Wang T, Hong Z, Ye Z, Zhang J (2024) Defective mutations of SlSGR1, SlPSY1 and MYB12 genes lead to formation of green ripe fruit in tomato. J Exp Bot 75: 3322-3336 (DOI: 10.1093/jxb/erae095).

Cui L, Zheng F, Wang J, Zhang C, Zhang D, Gao S, Zhang C, Ye J, Zhang Y, Ouyang B, Wang T, Hong Z, Ye Z, Zhang J (2022a) The tomato CONSTANS-LIKE protein SlCOL1 regulates fruit yield by repressing SFT gene expression. BMC Plant Biol 22: 429 (doi: 10.1186/s12870-022-03813-4)

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Hu G, Zhang D, Luo D, Sun W, Zhou R, Hong Z, Munir S, Ye Z, Yang C, Zhang J, Wang T (2023) SlTCP24 and SlTCP29 synergistically regulate compound leaf development through interacting with SlAS2 and activating transcription of SlCKX2 in tomato. New Phytol 240: 1275-1291

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