Improvement of resistance to rice blast and bacterial leaf streak by CRISPR/Cas9-mediated mutagenesis of Pi21 and OsSULTR3;6 in rice (Oryza sativa L.)

Rice (Oryza sativa L.) is a staple food in many countries around the world, particularly in China. The production of rice is seriously affected by the bacterial leaf streak and rice blast, which can reduce rice yield or even cause it to fail to be harvested. In this study, susceptible material 58B was edited by CRISPR/Cas9, targeting a target of the Pi21 gene and a target of the effector-binding element (EBE) of the OsSULTR3;6 gene, and the mutants 58b were obtained by Agrobacterium-mediated method. The editing efficiency of the two targets in the T0 generation was higher than 90.09%, the homozygous mutants were successfully selected in the T0 generation, and the homozygous mutation rate of each target was higher than 26.67%. The expression of the edited pi21 and EBE of Ossultr3;6 was significantly reduced, and the expression of defense responsive genes was significantly upregulated after infected with rice blast. The lesion areas of rice blast and bacterial leaf streak were significantly reduced in 58b, and the resistance of both was effectively improved. Furthermore, the gene editing events did not affect the agronomic traits of rice. In this study, the resistance of 58b to rice blast and bacterial leaf streak was improved simultaneously. This study provides a reference for using Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (CRISPR/Cas9) to accelerate the improvement of rice varieties and the development of new materials for rice breeding

Impacts of Protein from High-Protein Rice on Gelatinization and Retrogradation Properties in High- and Low-Amylose Reconstituted Rice Flour

High-protein rice is nutritional, but its taste attributes are inferior to low-protein rice. Many documents correlate its taste attributes with its gelatinization and retrogradation properties. This study investigated the changes in gelatinization and retrogradation properties of low- and high-amylose reconstituted rice flour (RRF) added with different fractions of proteins extracted from high-protein rice. The addition of protein decreased the RVA (rapid viscosity analyzer) viscosity parameters of the RRF but increased the peak time. The high amylose fractions in the RRF mainly increased the parameters PV, FV, SB, and peak times, and scarcely affected the parameters BD and PaT. The interaction between amylose and protein determined the pasting temperature. Protein addition in RRF significantly decreased gelatinization enthalpies but increased the onset temperature (To) and peak temperature (Tp), while the amylose in RRF increased the gelatinization enthalpies, To and Tp. Protein additions decreased the gel hardness and the pore size, while the amylose increased the gel hardness but decreased pore size. Our findings may be potentially useful in breeding and cultivating high-protein rice

Development of the PARMS Markers of the Waxy Gene and Utilization in Discriminating Wild Accessions, and Cultivated Rice (Oryza sativa L.) with Different Eating and Cooking Quality

Amylose content (AC) is the major indicator of rice eating and cooking quality (ECQ). Its synthesis in rice endosperm is mainly regulated by the protein, granule-bound starch synthase 1, which is encoded by the waxy gene (Os06g0133000, LOC_Os06g04200). The diversity of AC is largely attributable to the allelic variation at the Wx locus and the development of effective and accurate functional molecular markers to target rice variant alleles is crucial in the breeding strategy. In the present study, we developed six pairs of penta-primer amplification refractory mutation system (PARMS) markers to distinguish between Wxlv, Wxa, Wxin, Wxb, Wxmp, and Wxop,hp. These markers were successfully used to screen the genotype of large assets of genetic resources including 98 wild accessions, 55 cultivars, and 22 parental lines. Our results showed that Wxb in a low AC type was predominant in Guangxi cultivated rice as a result of cultural preference, while Wxlv in the wild accessions. Moreover, our findings surprisingly revealed the presence of Wxb in wild accession, which is a new outcome that may contribute to understanding the origin, selection and domestication processes of rice. These functional markers could be effectively used in marker-assisted breeding to improve selection efficiency of cultivars with desired AC in the early generation

Development of the PARMS Markers of the Waxy Gene and Utilization in Discriminating Wild Accessions, and Cultivated Rice (<i>Oryza sativa</i> L.) with Different Eating and Cooking Quality

Amylose content (AC) is the major indicator of rice eating and cooking quality (ECQ). Its synthesis in rice endosperm is mainly regulated by the protein, granule-bound starch synthase 1, which is encoded by the waxy gene (Os06g0133000, LOC_Os06g04200). The diversity of AC is largely attributable to the allelic variation at the Wx locus and the development of effective and accurate functional molecular markers to target rice variant alleles is crucial in the breeding strategy. In the present study, we developed six pairs of penta-primer amplification refractory mutation system (PARMS) markers to distinguish between Wxlv, Wxa, Wxin, Wxb, Wxmp, and Wxop,hp. These markers were successfully used to screen the genotype of large assets of genetic resources including 98 wild accessions, 55 cultivars, and 22 parental lines. Our results showed that Wxb in a low AC type was predominant in Guangxi cultivated rice as a result of cultural preference, while Wxlv in the wild accessions. Moreover, our findings surprisingly revealed the presence of Wxb in wild accession, which is a new outcome that may contribute to understanding the origin, selection and domestication processes of rice. These functional markers could be effectively used in marker-assisted breeding to improve selection efficiency of cultivars with desired AC in the early generation

Computational and Transcriptomic Analysis Unraveled OsMATE34 as a Putative Anthocyanin Transporter in Black Rice (Oryza sativa L.) Caryopsis

Anthocyanin is a flavonoid compound with potential antioxidant properties beneficial to human health and sustains plant growth and development under different environmental stresses. In black rice, anthocyanin can be found in the stems, leaves, stigmas, and caryopsis. Although the anthocyanin biosynthesis in rice has been extensively studied, limited knowledge underlying the storage mechanism and transporters is available. This study undertook the complementation of computational and transcriptome analysis to decipher a potential multidrug and toxic compound extrusion (MATE) gene candidate for anthocyanin transportation in black rice caryopsis. The phylogenetic analysis showed that OsMATE34 has the same evolutionary history and high similarities with VvAM1, VvAM3, MtMATE2, SlMATE/MTP77, RsMATE8, AtFFT, and AtTT12 involved in anthocyanin transportation. RNA sequencing analysis in black caryopsis (Bc; Bc11, Bc18, Bc25) and white caryopsis (Wc; Wc11, Wc18, Wc25), respectively, at 11 days after flowering (DAF), 18 DAF, and 25 DAF revealed a total of 36,079 expressed genes, including 33,157 known genes and 2922 new genes. The differentially expressed genes (DEGs) showed 15,573 genes commonly expressed, with 1804 and 1412 genes uniquely expressed in Bc and Wc, respectively. Pairwise comparisons showed 821 uniquely expressed genes out of 15,272 DEGs for Wc11 vs. Bc11, 201 uniquely expressed genes out of 16,240 DEGs for Wc18 vs. Bc18, and 2263 uniquely expressed genes out of 16,240 DEGs for Wc25 vs. Bc25. Along with anthocyanin biosynthesis genes (OsPAL, OsCHS, OsCHI, OsF3H, OsDFR, OsANS, and OsUFGT/Os3GT), OsMATE34 expression was significantly upregulated in all Bc but not in Wc. OsMATE34 expression was similar to OsGSTU34, a transporter of anthocyanin in rice leaves. Taken together, our results highlighted OsMATE34 (Os08g0562800) as a candidate anthocyanin transporter in rice caryopsis. This study provides a new finding and a clue to enhance the accumulation of anthocyanin in rice caryopsis

Recent Insights into Anthocyanin Pigmentation, Synthesis, Trafficking, and Regulatory Mechanisms in Rice (Oryza sativa L.) Caryopsis

Anthocyanins are antioxidants used as natural colorants and are beneficial to human health. Anthocyanins contribute to reactive oxygen species detoxification and sustain plant growth and development under different environmental stresses. They are phenolic compounds that are broadly distributed in nature and are responsible for a wide range of attractive coloration in many plant organs. Anthocyanins are found in various parts of plants such as flowers, leaves, stems, shoots, and grains. Considering their nutritional and health attributes, anthocyanin-enriched rice or pigmented rice cultivars are a possible alternative to reduce malnutrition around the globe. Anthocyanin biosynthesis and storage in rice are complex processes in which several structural and regulatory genes are involved. In recent years, significant progress has been achieved in the molecular and genetic mechanism of anthocyanins, and their synthesis is of great interest to researchers and the scientific community. However, limited studies have reported anthocyanin synthesis, transportation, and environmental conditions that can hinder anthocyanin production in rice. Rice is a staple food around the globe, and further research on anthocyanin in rice warrants more attention. In this review, metabolic and pre-biotic activities, the underlying transportation, and storage mechanisms of anthocyanins in rice are discussed in detail. This review provides potential information for the food industry and clues for rice breeding and genetic engineering of rice

Detection of QTLs Regulating Six Agronomic Traits of Rice Based on Chromosome Segment Substitution Lines of Common Wild Rice (Oryza rufipogon Griff.) and Mapping of qPH1.1 and qLMC6.1

Wild rice is a primary source of genes that can be utilized to generate rice cultivars with advantageous traits. Chromosome segment substitution lines (CSSLs) are consisting of a set of consecutive and overlapping donor chromosome segments in a recipient&rsquo;s genetic background. CSSLs are an ideal genetic population for mapping quantitative traits loci (QTLs). In this study, 59 CSSLs from the common wild rice (Oryza rufipogon Griff.) accession DP15 under the indica rice cultivar (O. sativa L. ssp. indica) variety 93-11 background were constructed through multiple backcrosses and marker-assisted selection (MAS). Through high-throughput whole genome re-sequencing (WGRS) of parental lines, 12,565 mapped InDels were identified and designed for polymorphic molecular markers. The 59 CSSLs library covered 91.72% of the genome of common wild rice accession DP15. The DP15-CSSLs displayed variation in six economic traits including grain length (GL), grain width (GW), thousand-grain weight (TGW), grain length-width ratio (GLWR), plant height (PH), and leaf margin color (LMC), which were finally attributed to 22 QTLs. A homozygous CSSL line and a purple leave margin CSSL line were selected to construct two secondary genetic populations for the QTLs mapping. Thus, the PH-controlling QTL qPH1.1 was mapped to a region of 4.31-Mb on chromosome 1, and the LMC-controlling QTL qLMC6.1 was mapped to a region of 370-kb on chromosome 6. Taken together, these identified novel QTLs/genes from common wild rice can potentially promote theoretical knowledge and genetic applications to rice breeders worldwide

DataSheet_1_Improvement of resistance to rice blast and bacterial leaf streak by CRISPR/Cas9-mediated mutagenesis of Pi21 and OsSULTR3;6 in rice (Oryza sativa L.).docx

Rice (Oryza sativa L.) is a staple food in many countries around the world, particularly in China. The production of rice is seriously affected by the bacterial leaf streak and rice blast, which can reduce rice yield or even cause it to fail to be harvested. In this study, susceptible material 58B was edited by CRISPR/Cas9, targeting a target of the Pi21 gene and a target of the effector-binding element (EBE) of the OsSULTR3;6 gene, and the mutants 58b were obtained by Agrobacterium-mediated method. The editing efficiency of the two targets in the T0 generation was higher than 90.09%, the homozygous mutants were successfully selected in the T0 generation, and the homozygous mutation rate of each target was higher than 26.67%. The expression of the edited pi21 and EBE of Ossultr3;6 was significantly reduced, and the expression of defense responsive genes was significantly upregulated after infected with rice blast. The lesion areas of rice blast and bacterial leaf streak were significantly reduced in 58b, and the resistance of both was effectively improved. Furthermore, the gene editing events did not affect the agronomic traits of rice. In this study, the resistance of 58b to rice blast and bacterial leaf streak was improved simultaneously. This study provides a reference for using Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (CRISPR/Cas9) to accelerate the improvement of rice varieties and the development of new materials for rice breeding.</p