Abstract: Plant biotechnology has become an essential tool in the effort to enhance global food security. Faced with challenges such as a growing population, climate change, and land degradation, plant biotechnology plays a crucial role in improving food production, quality, and agricultural sustainability.

Plant biotechnology enables the development of crop varieties that are more resistant to biotic and abiotic environmental stresses. In this presentation, I will share our research group’s findings on the development of pigmented rice plants. We began by screening pigmented rice plants for resistance to various environmental stress conditions, including drought and salinity, as well as pest and pathogen stresses.

Through genetic engineering techniques, pigmented rice plants can be precisely modified to enhance productivity and nutritional content. Our research focuses on the transcription factors, RWP-RK DOMAIN PROTEIN (RKD), a key regulator of gamete cell differentiation and embryo development in land plants. Ectopic overexpression of RKD is associated with increased cell proliferation and the formation of somatic embryo-like structures, bypassing the need for exogenous growth regulators.

In silico analysis has identified the rice RWP-RK transcription factor Oryza sativa RKD3 (OsRKD3), closely related to Arabidopsis thaliana RKD4 (AtRKD4) and Marchantia polymorpha RKD (MpRKD). Our research shows that the ectopic overexpression of OsRKD3, which is preferentially expressed in reproductive tissues, can trigger the formation of somatic embryos in the Indonesian black rice variety Cempo Ireng, which is usually resistant to somatic embryogenesis. By analyzing the transcriptome of the induced tissue, we identified 5,991 genes with differential expression in response to OsRKD3 induction. Of these genes, 50% were up-regulated while the other half were down-regulated. About 37.5% of the up-regulated genes contained a sequence motif in their promoter regions, which was also observed in RKD targets from Arabidopsis. Furthermore, OsRKD3 was shown to mediate the transcriptional activation of discrete gene networks, including several transcription factors such as APETALA 2-like (AP2-like)/ETHYLENE RESPONSE FACTOR (ERF), MYB, and CONSTANS-like (COL), as well as chromatin remodelling factors associated with hormone signal transduction, stress responses, and post-embryogenic pathways.

Our data indicate that OsRKD3 regulates a broad gene network, and its activation is associated with the initiation of a somatic embryo program that facilitates genetic transformation in black rice. These findings are very promising for increasing crop productivity and developing agricultural practices in black rice.

Biography: Dr. Purwestri is an associate professor at the Faculty of Biology and currently as Head of Research Center for Biotechnology Universitas Gadjah Mada (UGM). Her research group specialise in studying the biochemistry, molecular biology and physiology of local pigmented rice varieties. The group performs extensive phenotyping to analyse various aspects of the rice traits, such as their anthocyanin content, flowering time, as well as their response to biotic and abiotic stress.

Three recent and relevant publications from the group are listed below:

Sebastian et al. 2022. Identification and characterization of drought-tolerant local pigmented rice from Indonesia. Physiology and Molecular Biology of Plants.

Susanto et al. 2020. Establishment of a plant tissue culture system and genetic transformation for agronomic improvement of Indonesian black rice ( Oryza sativa L .). Plant Cell, Tissue and Organ Culture (PCTOC). 141(3): 1 – 13.

Purwestri YA, Lee YS, Meehan C, Mose W, Susanto FA, Wijayanti P, Fauzia AN, Nuringtyas TR, Hussain N, Putra HL, Gutierrez-Marcos J. RWP-RK Domain 3 (OsRKD3) induces somatic embryogenesis in black rice. BMC Plant Biol. 2023 Apr 19;23(1):202.