Impairment in a member of AP2/ERF and F-box family protein enhances complete panicle exsertion, an economically important trait in rice.

Complete panicle exsertion (CPE) is an economically important quantitative trait that contributes to grain yield in rice. We deployed an integrated approach for understanding the molecular mechanism of CPE using a stable EMS mutant line, CPE-109 of Samba Mahsuri (SM) exhibiting CPE. Two consistent genomic regions have been identified for CPE through QTL mapping [qCPE-4 (28.24-31.22 Mb) and qCPE-12 (2.30-3.18 Mb)] and QTL-sequencing [Chr-4 (31.21-33.69 Mb) and Chr-12 (0.12-3.15 Mb)]. Two non-synonymous SNPs, viz; KASP 12-12 (T→C; Chr12:1269983) in Os12g0126300; AP2/ERF transcription factor and KASP 12-16 (G→A; Chr12:1515198) in Os12g0131400; F-box domain-containing protein explained 81.05 and 59.61% phenotypic variance respectively and exhibited strong co-segregation with CPE in F2 mapping populations, advanced generation lines and CPE exhibiting SM mutants through KASP assays. The downregulation of these genes in CPE-109 compared to SM was observed in transcriptome sequencing of flag leaves which was validated through qRT-PCR. We propose that the abrogation of Os12g0126300 and Os12g0131400 in CPE-109 combinatorially influences the downregulation of ethylene biosynthetic genes viz. ACC synthase, ethylene-responsive factor-2, and up-regulation of gibberellic acid synthetic genes viz. ent-kaurene synthase and two cytokinin biosynthesis genes viz. cytokinin-O-glucosyltransferase 2, carboxy-lyase which result in complete panicle exsertion.

Strong culm: a crucial trait for developing next-generation climate-resilient rice lines.

Lodging, a phenomenon characterized by the bending or breaking of rice plants, poses substantial constraints on productivity, particularly during the harvesting phase in regions susceptible to strong winds. The rice strong culm trait is influenced by the intricate interplay of genetic, physiological, epigenetic, and environmental factors. Stem architecture, encompassing morphological and anatomical attributes, alongside the composition of both structural and non-structural carbohydrates, emerges as a critical determinant of lodging resistance. The adaptive response of the rice culm to various biotic and abiotic environmental factors further modulates the propensity for lodging. Advancements in next-generation sequencing technologies have expedited the genetic dissection of lodging resistance, enabling the identification of pertinent genes, quantitative trait loci, and novel alleles. Concurrently, contemporary breeding strategies, ranging from biparental approaches to more sophisticated methods such as multi-parent-based breeding, gene pyramiding, genomic selection, genome-wide association studies, and haplotype-based breeding, offer perspectives on the genetic underpinnings of culm strength. This review comprehensively delves into physiological attributes, culm histology, epigenetic determinants, and gene expression profiles associated with lodging resistance, with a specialized focus on leveraging next-generation sequencing for candidate gene discovery.

Characterization of OglDREB2A gene from African rice (Oryza glaberrima), comparative analysis and its transcriptional regulation under salinity stress.

In this study, AP2 DNA-binding domain-containing transcription factor, OglDREB2A, was cloned from the African rice (Oryza glaberrima) and compared with 3000 rice genotypes. Further, the phylogenetic and various structural analysis was performed using in silico approaches. Further, to understand its allelic variation in rice, SNPs and indels were detected among the 3000 rice genotypes which indicated that while coding region is highly conserved, yet noncoding regions such as UTR and intron contained most of the variation. Phylogenetic analysis of the OglDREB2A sequence in different Oryza as well as in diverse eudicot species revealed that DREB from various Oryza species were diversed much earlier than other genes. Further, structural features and in silico analyses provided insights into different properties of OglDREB2A protein. The neutrality test on the coding region of OglDREB2A from different genotypes of O. glaberrima showed the lack of selection in this gene. Among the different developmental stages, it was upregulated at tillering and flag leaf under salinity treatment indicating its positive role in seedling and reproductive stage tolerance. Real-time PCR analysis also indicated the conserve expression pattern of this gene under salinity stress across the three different Oryza species having different degree of salinity tolerance.