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Background: Growth-regulating factors (GRFs) are crucial in rice for controlling plant growth and development. Among the rice cultivation practices, aerobic methods are water efficient but result in significant yield reduction relative to non-aerobic cultivation. Therefore, mechanistic insights into aerobic rice cultivation are important for improving the aerobic performance of rice. Objectives: This study aimed to examine the evolution of GRFs in different rice species, analyse the phenotypic differences between aerobic and non-aerobic conditions in three rice varieties, and assess the expression of GRFs in these varieties under both aerobic and non-aerobic conditions. Materials and Methods: This study comprehensively examined the GRFs gene family in 11 rice species (Oryza barthii, Oryza brachyantha, Oryza glaberrima, Oryza glumipatula, Oryza sativa subsp. indica, Oryza longistaminata, Oryza meridionalis, Oryza nivara, Oryza punctata, Oryza rufipogon, Oryza sativa subsp. japonica) focusing on phylogenetic analysis. Additionally, the expression patterns of 12 GRFs were investigated in three distinct genotypes of O. sativa subsp. indica rice, under both non-aerobic and aerobic conditions. Results: Three major phylogenetic clades were formed based on conserved motifs in the 123 GRFs proteins in eleven rice species. Further, novel motifs were identified especially in O. longistaminata indicative of the species level evolutionary differences in rice. Among the trait performance, the number of tillers was reduced by ~ 36% under aerobic conditions, but the reduction was found to be less in CR Dhan 201, an aerobic variety. Besides, three GRFs namely GRF3, GRF4, and GRF7 were found to be distinct in expression between aerobic and non-aerobic conditions. Conclusion: Three GRF genes namely GRF3, GRF4, and GRF7 could be associated with the aerobic adaptation in rice.
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The cytochrome P450 (CYP450) gene family plays a critical role in plant growth and developmental processes, nutrition, and detoxification of xenobiotics in plants. In the present research, a comprehensive set of 105 OsCYP71 family genes was pinpointed within the genome of indica rice. These genes were categorized into twelve distinct subfamilies, where members within the same subgroup exhibited comparable gene structures and conserved motifs. In addition, 105 OsCYP71 genes were distributed across 11 chromosomes, and 36 pairs of OsCYP71 involved in gene duplication events. Within the promoter region of OsCYP71, there exists an extensive array of cis-elements that are associated with light responsiveness, hormonal regulation, and stress-related signaling. Further, transcriptome profiling revealed that a majority of the genes exhibited responsiveness to hormones and were activated across diverse tissues and developmental stages in rice. The OsCYP71P6 gene is involved in insect resistance, senescence, and yield-related traits in rice. Hence, understanding the association between OsCYP71P6 genetic variants and yield-related traits in rice varieties could provide novel insights for rice improvement. Through the utilization of linear regression models, a total of eight promoters were identified, and a specific gene variant (Ser33Leu) within OsCYP71P6 was found to be linked to spikelet fertility. Additionally, different alleles of the OsCYP71P6 gene identified through in/dels polymorphism in 131 rice varieties were validated for their allelic effects on yield-related traits. Furthermore, the single-plant yield, spikelet number, panicle length, panicle weight, and unfilled grain per panicle for the OsCYP71P6-1 promoter insertion variant were found to contribute 20.19%, 13.65%, 5.637%, 8.79%, and 36.86% more than the deletion variant, respectively. These findings establish a robust groundwork for delving deeper into the functions of OsCYP71-family genes across a range of biological processes. Moreover, these findings provide evidence that allelic variation in the promoter and amino acid substitution of Ser33Leu in the OsCYP71P6 gene could potentially impact traits related to rice yield. Therefore, the identified promoter variants in the OsCYP71P6 gene could be harnessed to amplify rice yields.
RESUMO
To better understand the early response of genotypes to limited-phosphorus (P) conditions and the role of the phosphate transporter OsPHT1 gene family in the presence of PSTOL1, it is essential to characterize the level of tolerance in rice under limited-P conditions. In the present experiment, six rice genotypes were studied in three-way interactions [genotype (G) × phosphorus (P) × duration (D)] by comparing them at two instances (14 d and 28 d) under seven different concentrations of P (0.5â10.0 ppm) in a hydroponic system. Trait differences and interactions of these traits were clearly distinguished among the various P rates. However, aboveground trait expression registered increased growth from 6.0 to 10.0 ppm of P. The major root-attributed traits in 0.5 ppm of P are significantly increased vis-à-vis 10 ppm of P. Analysis of variance displayed a significant difference between the genotypes for PSTOL1 and PHT1 expression. In low P, maximum root length with a shoot and root dry weight was observed in a new indigenous accession, IC459373, with higher expression of PSTOL1 than in Dular and IR64-Pup1 in 0.5 ppm of P at 14 d. Among the 13 PHT1 genes, OsPT1, OsPT2, OsPT6, and OsPT13 showed significant upregulation in IC459373, Dular, and IR64-Pup1. These results indicated that studying the expression levels of the PSTOL1 and PHT1 gene family at the early growth stages would be helpful in identifying superior donors to improve low-P tolerance and P-use efficiency in rice breeding programs.