Understanding the molecular mechanisms regulating stone cell formation in pear fruit

Stone cells are highly-lignified cells present in Chinese pear fruit flesh. They cause a gritty flesh texture which reduces the eating quality of the fruit and its export value. Consequently, the cells are targets for reduction in pear breeding programmes.

Plant & Food Research scientists, Drs Jia-Long Yao and Andrew Allan, in collaboration with Professor Jun Wu’s group in Nanjing Agricultural University, recently published two papers on understanding the molecular mechanisms regulating stone cell formation in pear fruit flesh.  

Using molecular biology and genomics tools, the scientists identified a microRNA (miR397a) as a negative regulator and a transcription factor (MYB169) as a positive regulator for lignin deposition in the walls of the stone cells.  

They also identified a mutation in the miR397a gene in pear germplasm, which is associated with a reduced number of stone cells. This finding provides a genetic marker that could be used in the early selection of low-stone-cell seedlings (at the seedling stage). 

These discoveries could inform strategies to reduce, or even eliminate, the stone cells in pear fruit for future breeding programmes. 

Journal references:

Xue C, Yao JL, Qin MF, Zhang MY, Allan AC, Wang DF, Wu J 2019.  PbrmiR397a regulates lignification during stone cell development in pear fruit. Plant Biotechnology Journal. Vol 17 (1) DOI: DOI: 10.1111/pbi.12950

Xue C, Yao JL, Xue YS, Su GQ, Wang L, Lin LK, Allan AC, Zhang SL, Wu J 2019.  PbrMYB169 positively regulates lignification in fruit stone cells of pear (Pyrus bretschneideri), Journal of Experimental Botany. Vol 70 (6) DOI: 10.1093/jxb/erz039