Genetic variant linked to cucumber fruit length

 

In an effort to identify the genetic basis of fruit length variation in cucumber, a team of researchers led by Xiaolan Zhang at China Agricultural University analyzed 150 cucumber lines with different fruit lengths. They identified two variants of a gene named CsFUL1 that differed by a single base pair in the DNA code. The CsFUL1^A variant appeared in long-fruited East Asian cucumbers, whereas the CsFUL1^C variant was randomly distributed in wild and semi-wild cucumber populations.

 

The researchers demonstrated that decreased expression of CsFUL1^A was responsible for longer fruit, whereas shorter fruit was caused by increased expression of the A variant, or by the C variant at this locus, which they showed is not fully functional. Therefore, the authors concluded that CsFUL1^A functions as a repressor of fruit length that emerged during selection of Asian long cucumber. They further showed that CsFUL1^A directly represses the expression of CsSUP, a known regulator of cell expansion and division. In addition, the expression of two auxin transporter genes, CsPIN1 and CsPIN7, was found to be directly inhibited by CsFUL1^A, leading to reduced accumulation of the growth hormone auxin.

 

This research has singled out a key modulator of fruit length and sets the stage for developing strategies to manipulate fruit length in cucumber breeding.

 

As next steps, first author Jianyu Zhao said: “We aim to identify the upstream regulators of CsFUL1^A in fruit length variation in cucumber and to dissect the relationship between CsFUL1^A and other fruit length genes.”

 

Full citation: Zhao, J., Jiang, L., Che, G., et al. (2019). A functional allele of CsFUL1 regulates fruit length through repressing CsSUP and inhibiting auxin transport in cucumber. Plant Cell doi: https://10.1105/tpc.18.00905.