Characterization of the ‘Oat-Like Rice’ Caused by a Novel Allele OsMADS1Olr Reveals Vital Importance of OsMADS1 in Regulating Grain Shape in Oryza sativa L.

Abstract

Background Grain shape is a critical agronomic trait affecting grain yield and quality. Exploration and functional characterization of grain shape-related genes will facilitate rice breeding for higher quality and yield. Results Here, we characterized a recessive mutant named Oat-like rice for its unique grain shape which highly resembles oat grains. The Oat-like rice displayed abnormal floral organs, an open hull formed by remarkably elongated leafy lemmas and paleae, occasionally formed conjugated twin brown rice, an aberrant grain shape and a low seed setting rate. By map-based cloning, we discovered that Oat-like rice harbors a novel allele of OsMADS1 gene (OsMADS1Olr), which has a spontaneous point mutation that causes the substitution of an amino acid that is highly conserved in the MADS-box domain of the MADS-box family. Further linkage analysis indicated that the point mutation in the OsMADS1Olr is associated with Oat-like rice phenotype, and expression analysis of the OsMADS1 by qRT-PCR and GUS staining also indicated that it is highly expressed in flower organs as well as in the early stages of grain development. Furthermore, OsMADS1Olr-overexpressing plants showed similar phenotypes of Oat-like rice in grain shape, possibly due to the dominant negative effect. And OsMADS1-RNAi plants also displayed grain phenotypes like Oat-like rice. These results suggested that OsMADS1Olr is responsible for the Oat-like rice phenotype including aberrant grain shape. Moreover, the expression levels of representative genes related to grain shape regulation were apparently altered in Oat-like rice, OsMADS1Olr-overexpressing and OsMADS1-RNAi transgenic plants. Finally, compared with Oat-like rice, OsMADS1Olr-overexpressing and OsMADS1-RNAi plants, mild phenotype of seed-specific OsMADS1-RNAi transgenic plants indicated that OsMADS1 may has has a direct regulation role in grain development and the grain phenotypes of Oat-like rice, OsMADS1Olr-overexpressing and OsMADS1-RNAi plants are majorly caused by the abnormal lemma and palea development. Conclusions Altogether, our results showed that grain shape and a low seed setting rate of the notable ‘Oat-like rice’ are caused by a spontaneous point mutation in the novel allele OsMADS1Olr. Furthermore, our findings suggested that OsMADS1 mediates grain shape possibly by affecting the expression of representative genes related to grain shape regulation. Thus, this study not only revealed that OsMADS1 plays a vital role in regulating grain shape of rice but also highlighted the importance and value of OsMADS1 to improve the quality and yield of rice by molecular breeding.

Cell Wall Matrix Polysaccharides Contribute to Salt–Alkali Tolerance in Rice

“…Eight independent plants of Kitaake and mq2 mutant in controlled growth conditions or treated with NaHCO 3 were harvested and analyzed for the major agronomic traits at maturation stage according to the methods reported by Li et al (2020) [ 69 ]. Eight independent biological replicates were performed for the measurement of the indexes of plant height, total aboveground dry weight per plant, grain yield per plant, panicle number per plant, filled grain number per panicle, panicle length, primary branch number per panicle, second branch number per panicle, total grain number per panicle, seed setting rate, and each sample contained a plant.…”

Regulatory mechanism and molecular genetic dissection of rice (Oryza sativa L.) grain size

“…The MAD-box gene is a widely existing transcription factor in plants, which has essential functions in controlling spike development. OsMADS1 , a MADS-box transcriptional regulator gene family member, directly regulates seed development and grain size in rice, mainly caused by abnormal lemma and palea development [ 98 ].…”

Seeds Priming with Melatonin Improves Root Hydraulic Conductivity of Wheat Varieties under Drought, Salinity, and Combined Stress

“…We collected roots from wheat seedlings by using liquid nitrogen and stored them subsequently at −80 • C. Their total RNA was extracted from roots utilizing a Hipure Plant RNA Mini Kit (Magen, Guangzhou, China). Then, first-strand cDNA synthesis and qPCR analysis were performed following Li et al [95]. TaActin gene in wheat was applied as an endogenous control.…”