The Dsup coordinates grain development and abiotic stress in rice.

DNA damage is a serious threat to all living organisms and may be induced by environmental stressors. Previous studies have revealed that the tardigrade (Ramazzotius varieornatus) DNA damage suppressor protein Dsup has protective effects in human cells and tobacco. However, whether Dsup provides radiation damage protection more widely in crops is unclear. To explore the effects of Dsup in other crops, stable Dsup overexpression lines through Agrobacterium-mediated transformation were generated and their agronomic traits were deeply investigated. In this study, the overexpression of Dsup not only enhanced the DNA damage resistance at the seeds and seedlings stages, they also exhibited grain size enlargement and starch granule structure and cell size alteration by the scanning electron microscopy observation. Notably, the RNA-seq revealed that the Dsup plants increased radiation-related and abiotic stress-related gene expression in comparison to wild types, suggesting that Dsup is capable to coordinate normal growth and abiotic stress resistance in rice. Immunoprecipitation enrichment with liquid chromatography-tandem mass spectrometry (IP-LC-MS) assays uncovered 21 proteins preferably interacting with Dsup in plants, suggesting that Dsup binds to transcription and translation related proteins to regulate the homeostasis between DNA protection and plant development. In conclusion, our data provide a detailed agronomic analysis of Dsup plants and potential mechanisms of Dsup function in crops. Our findings provide novel insights for the breeding of crop radiation resistance.

Pyramiding Breeding of Low-Glutelin-Content Indica Rice with Good Quality and Resistance.

Low-glutelin-content rice, a type of functional rice with glutelin levels below 4%, is an essential dietary supplement for chronic kidney disease (CKD) patients. Developing low-glutelin-content rice varieties is crucial to catering to the growing CKD population. In this study, we aimed to create a new low-glutelin indica rice variety with excellent agronomic traits. To achieve this, we employed a combination of molecular-marker-assisted selection and traditional breeding techniques. The cultivars W3660, Wushansimiao (WSSM), and Nantaixiangzhan (NTXZ) were crossbred, incorporating the Lgc-1, Pi-2, Xa23, and fgr alleles into a single line. The result of this breeding effort was "Yishenxiangsimiao", a new indica rice variety that inherits the desirable characteristics of its parent lines. Yishenxiangsimiao (YSXSM) possesses not only a low glutelin content but also dual resistance to blast and bacterial blight (BB). It exhibits high-quality grains with a fragrant aroma. This new low-glutelin indica cultivar not only ensures a stable food supply for CKD patients but also serves as a healthy dietary option for the general public. We also performed RNA-seq of these rice varieties to investigate their internal gene expression differences. The YSXSM exhibited a higher biotic-resistance gene expression in comparison to NTXZ. In summary, we successfully developed a novel low-glutelin indica rice variety, "Yishenxiangsimiao", with superior agronomic traits. This rice variety addresses the dietary needs of CKD patients and offers a nutritious choice for all consumers.

Fine-mapping and candidate gene analysis of a major locus controlling leaf thickness in rice (Oryza sativa L.).

Leaf thickness is an important trait in rice (Oryza sativa L.). It affects both photosynthesis and sink-resource efficiency. However, compared to leaf length and length width, reports seldom focused on leaf thickness due to the complicated measurement and minor difference. To identify the quantitative trait loci (QTL) and explore the genetic mechanism regulating the natural variation of leaf thickness, we crossed a high leaf thickness variety Aixiuzhan (AXZ) to a thin leaf thickness variety Yangdao No.6 (YD 6) and evaluated 585 F2 individuals. We further use bulked sergeant analysis with whole-genome resequencing (BSA-seq) to identify five genomic regions, including chromosomes 1, 6, 9, 10, and 12. These regions represented significant allele frequency differentiation between thick and thin leaf thickness among the mixed pool offspring. Moreover, we conducted a linkage mapping using 276 individuals derived from the F2 population. We fine-mapped and confirmed that chromosome 9 contributed the primary explanation of phenotypic variance. We fine-mapped the candidate regions and confirmed that the chromosome 9 region contributed to flag leaf thickness in rice. We observed the virtual cellular slices and found that the bundle sheath cells in YD 6 flag leaf veins are fewer than AXZ. We analyzed the potential regions on chromosome 9 and narrowed the QTL candidate intervals in the 928-kb region. Candidate genes of this major QTL were listed as potentially controlled leaf thickness. These results provide promising evidence that cloning leaf thickness is associated with yield production in rice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11032-022-01275-y.

[Single nucleotide polymorphism (SNP) and its application in rice].

Single nucleotide polymorphisms (SNPs) distribute numerously and high-density throughout rice (Oryza sativa L.) genome. A total of 80,127 SNP sites were identified in rice genome, and one SNP every 154 bp was found between two rice subspecies indica and japonica. The SNP rate is 0.65%. SNPs also are very considerable among within-subspecies cultivars, even it can be found between closely related cultivars, in which it has been difficult to find polymorphic sites by conventional methods. The frequency of SNPs in rice genome varied between chromosomes, moreover it showed uneven distribution of polymorphism-rich and -poor regions along each chromosome. Several routes have been used for identification of SNP in rice, such as sequencing PCR products of DNA samples, screening SNPs in SSR fragments, and searching for SNPs through the rice genome sequences and EST database. A number of genotyping systems have been developed to identify SNPs in rice genome. High automation in SNPs identification has become a very convenient operation by the automatized systems. SNPs can be converted to CAPS (cleaved amplified polymorphic sequence) or dCAPS (derived-CAPS), and allele-specific PCR markers. SNP has shown huge potential in establishing rice genetic maps, genes cloning and functional genomics, MAS (marker assisted selection) in rice breeding, and studying on classification and evolution of germplasm.