Hybrid proline-rich proteins (HyPRPs) belong to the family of 8-cysteine motif (8CM) containing proteins that play important roles in plant development processes, and tolerance to biotic and abiotic stresses.

To gain insight into the rice HyPRPs, we performed a systematic genome-wide analysis and identified 45 OsHyPRP genes encoding 46 OsHyPRP proteins. The phylogenetic relationships of OsHyPRP proteins with monocots (maize, sorghum, and Brachypodium) and a dicot (Arabidopsis) showed clustering of the majority of OsHyPRPs along with those from other monocots, which suggests lineage-specific evolution of monocots HyPRPs. Based on our previous RNA-Seq study, we selected differentially expressed OsHyPRPs genes and used quantitative real-time-PCR (qRT-PCR) to measure their transcriptional responses to biotic (Magnaporthe oryzae) and abiotic (heat, cold, and salt) stresses and hormone treatment (Abscisic acid; ABA, Methyl-Jasmonate; MeJA, and Salicylic acid; SA) in rice blast susceptible Pusa Basmati-1 (PB1) and blast-resistant near-isogenic line PB1+Pi9. The induction of OsHyPRP16 expression in response to the majority of stresses and hormonal treatments was highly correlated with the number of cis-regulatory elements present in its promoter region. In silico docking analysis of OsHyPRP16 showed its interaction with sterols of fungal/protozoan origin. The characterization of the OsHyPRP gene family enables us to recognize the plausible role of OsHyPRP16 in stress tolerance.


See https://www.mdpi.com/2223-7747/8/9/343



Figure 3:

Phylogenetic relationship of rice HyPRPs with that of Arabidopsis, maize, sorghum and B. distachyon. The 8CM region of all the HyPRPs was used to construct the phylogenetic tree. The multiple sequence alignment and phylogenetic tree construction were performed with MEGA6.06 using maximum likelihood method with 500 bootstrap replicates. The different shapes with color code represent the HyPRPs of different plant species; red sphere for Arabidopsis, magenta square for rice, cyan triangle for sorghum, lawn-green diamond for maize, and blue diamond for Brachypodium. The one protein each from sorghum and Arabidopsis does not group with other HyPRPs and thus considered as highly divergent outliers.