Profile of gene expression at the berry enlargement phase of the large berry mutant of ‘Delaware’ grape

The large berry mutant (LBM) is a bud mutant of ‘Delaware’ grape.
The berry flesh weight of the LBM is approximately 1.3 times greater than that of ‘Delaware’ by double gibberellic acid (GA₃) treatment.
Our previous study reported an increment in cell numbers of the mesocarp inner and outer walls in the early developmental stage of LBMs compared with ‘Delaware’. In addition, the GA receptor gene GID1 exhibited higher expression levels in LBM flower buds and berries than those in ‘Delaware’. However, the genetic mutation responsible for larger berry size in LBM has not been identified.
Therefore, this study aimed to identify genes responsible for the large berry size of LBM using transcriptomic analysis by RNA-seq on berries at 10 (DAFB10) and 12 (DAFB12) days after full bloom.
Principal component analysis showed that the difference between LBM and ‘Delaware’ was more notable in DAFB10 than in DAFB12. Differential expression genes (DEGs) were detected; those with a greater than 2-fold change in expression value between LBM and ‘Delaware’ and met a false discovery rate adjusted p-value <0.05 numbered 1,156 at DAFB10 and 308 at DAFB12. Eighty-nine DEGs common to DAFB10 and DAFB12. Our previous study reported differences in several gene expressions related to GA response, therefore the gene causing the bud mutation was suspected to be a transcription factor.
We found nine genes encoding transcription factors among the 89 common DEGs.
A candidate gene encoding ovate family proteins involved in fruit size and shape was found, and mutations in this gene may prove important.
Several other candidate genes identified are known to be involved in cell cycle regulation and may reflect differences in developmental stages between the two lines.

IV Asian Horticultural Congress – AHC2023

H. Ishikawa, Y. Togano, T. Shibuya

berry development, berry size, GA response, the double GA₃ treatment, seedless cultivation

https://doi.org/10.17660/ActaHortic.2024.1404.4