Insight into the transcriptional regulation of the abnormal development of avocado somatic embryos

Avocado is one of the most important staple fruit crops worldwide, but diverse factors make its mass propagation difficult. Somatic embryogenesis (SE) has the potential to solve this issue. However, despite four decades of research, several drawbacks have prevented the implementation of SE in this species. In this work, we conducted a de novo transcriptomic analysis to decipher the molecular mechanisms underlying the poor embryo maturation observed during avocado SE progression. Doing so, we obtained a collection of 80,013 unigenes. 7,950 (9.93%) of these unigenes were identified as differentially expressed among the four stages we surveyed: cell suspension, early globular, late globular, and white-opaque embryos. Among these, genes involved in auxin biosynthetic signaling were downregulated throughout the avocado SE progression. Comparative analysis of differential avocado transcripts confirms an alteration of genes associated with plant growth regulators, including auxin and cytokinin. These results provide new insight into the pathways of avocado signaling somatic embryogenesis. Our study is also a valuable resource for further scrutiny of somatic embryogenesis in this species.