The challenge of meeting the increasing demand for worldwide rice production has driven a sustained quest for advances in rice breeding for yield. Two breakthroughs that led to quantum leaps in ...productivity last century were the introduction of semidwarf varieties and of hybrid rice. Subsequent gains in yield have been incremental. The next major leap in rice breeding is now upon us through the application of rational design to create defined ideotypes. The exploitation of wide-cross compatibility and intersubspecific heterosis,combined with rapid genome sequencing and the molecular identification of genes for major yield and quality traits have now unlocked the potential for rational design.
Soil salinity is a serious menace in rice production threatening global food security. Rice responses to salt stress involve a series of biological processes, including antioxidation, osmoregulation ...or osmoprotection, and ion homeostasis, which are regulated by different genes. Understanding these adaptive mechanisms and the key genes involved are crucial in developing highly salt-tolerant cultivars. In this review, we discuss the molecular mechanisms of salt tolerance in rice-from sensing to transcriptional regulation of key genes-based on the current knowledge. Furthermore, we highlight the functionally validated salt-responsive genes in rice.
The indica and japonica rice (Oryza sativa) subspecies differ in nitrate (NO
) assimilation capacity and nitrogen (N) use efficiency (NUE). Here, we show that a major component of this difference is ...conferred by allelic variation at OsNR2, a gene encoding a NADH/NADPH-dependent NO
reductase (NR). Selection-driven allelic divergence has resulted in variant indica and japonica OsNR2 alleles encoding structurally distinct OsNR2 proteins, with indica OsNR2 exhibiting greater NR activity. Indica OsNR2 also promotes NO
uptake via feed-forward interaction with OsNRT1.1B, a gene encoding a NO
uptake transporter. These properties enable indica OsNR2 to confer increased effective tiller number, grain yield and NUE on japonica rice, effects enhanced by interaction with an additionally introgressed indica OsNRT1.1B allele. In consequence, indica OsNR2 provides an important breeding resource for the sustainable increases in japonica rice yields necessary for future global food security.
Grain size determines grain weight and affects grain quality. Several major quantitative trait loci (QTLs) regulating grain size have been cloned; however, our understanding of the underlying ...mechanism that regulates the size of rice grains remains fragmentary. Here, we report the cloning and characterization of a dominant QTL, GRAIN SIZE ON CHROMOSOME 2 (GS2), which encodes Growth-Regulating Factor 4 (OsGRF4), a transcriptional regulator. GS2 localizes to the nucleus and may act as a transcription activator. A rare mutation of GS2 affecting the binding site of a microRNA, OsmiR396c, causes elevated expression of GS2/OsGRF4. The increase in GS2 expression leads to larger cells and increased numbers of cells, which thus enhances grain weight and yield. The introduction of this rare allele of GS2/OsGRF4 into rice cultivars could significantly enhance grain weight and increase grain yield, with possible applications in breeding high-yield rice varieties.
Grain size determines grain weight and affects grain quality. GS2, a dominant QTL, encodes Growth-Regulating Factor 4 (OsGRF4), which acts as a transcriptional regulator. A mutation in this gene at the OsmiR396c target site results in elevated transcript levels of GS2 and accumulation of GS2 leads to enlarged cell size and increased cell number, which in turn results in enhanced grain weight and yield.
The drive toward more sustainable agriculture has raised the profile of crop plant nutrient-use efficiency. Here we show that a major rice nitrogen-use efficiency quantitative trait locus (qNGR9) is ...synonymous with the previously identified gene DEP1 (DENSE AND ERECT PANICLES 1). The different DEP1 alleles confer different nitrogen responses, and genetic diversity analysis suggests that DEP1 has been subjected to artificial selection during Oryza sativa spp. japonica rice domestication. The plants carrying the dominant dep1-1 allele exhibit nitrogen-insensitive vegetative growth coupled with increased nitrogen uptake and assimilation, resulting in improved harvest index and grain yield at moderate levels of nitrogen fertilization. The DEP1 protein interacts in vivo with both the Gα (RGA1) and Gβ (RGB1) subunits, and reduced RGA1 or enhanced RGB1 activity inhibits nitrogen responses. We conclude that the plant G protein complex regulates nitrogen signaling and modulation of heterotrimeric G protein activity provides a strategy for environmentally sustainable increases in rice grain yield.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Plants need to cope with complex environments throughout their life cycle. Abiotic stresses, including drought, cold, salt and heat, can cause a reduction in plant growth and loss of crop yield. ...Plants sensing stress signals and adapting to adverse environments are fundamental biological problems. We review the stress sensors in stress sensing and the responses, and then discuss ionic stress signaling and the responses. During ionic stress, the calcineurin B-like proteins (CBL) and CBL-interacting protein kinases (CBL-CIPK) complex is identified as a primary element of the calcium sensor for perceiving environmental signals. The CBL-CIPK system shows specificity and variety in its response to different stresses. Obtaining a deeper understanding of stress signaling and the responses will mitigate or solve crop yield crises in extreme environments with fast-growing populations.
A super pan-genomic landscape of rice Shang, Lianguang; Li, Xiaoxia; He, Huiying ...
Cell research,
10/2022, Letnik:
32, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Abstract
Pan-genomes from large natural populations can capture genetic diversity and reveal genomic complexity. Using de novo long-read assembly, we generated a graph-based super pan-genome of rice ...consisting of a 251-accession panel comprising both cultivated and wild species of Asian and African rice. Our pan-genome reveals extensive structural variations (SVs) and gene presence/absence variations. Additionally, our pan-genome enables the accurate identification of nucleotide-binding leucine-rich repeat genes and characterization of their inter- and intraspecific diversity. Moreover, we uncovered grain weight-associated SVs which specify traits by affecting the expression of their nearby genes. We characterized genetic variants associated with submergence tolerance, seed shattering and plant architecture and found independent selection for a common set of genes that drove adaptation and domestication in Asian and African rice. This super pan-genome facilitates pinpointing of lineage-specific haplotypes for trait-associated genes and provides insights into the evolutionary events that have shaped the genomic architecture of various rice species.
Salinity is one of the major abiotic stresses limiting rice production worldwide. Understanding the genetic basis of salinity tolerance is key for rice breeding. In this study, a recombinant inbred ...line (RIL) population derived from a super hybrid rice Liang–You–Pei–Jiu (LYP9) parents 93-11 and PA64s, exhibited variation in phenotypes including shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW), and root dry weight (RDW) under 50 and 100 mM NaCl stress. QTL analysis identified a total of 38 QTLs for these 6 traits under two distinct concentrations of salt, distributing on chromosomes 1, 2, 3, 4, 5, 6, 7 and 10. A total of 21 QTLs were found in 6 stable loci. A novel major QTL,
qSL7
for shoot length on chromosome 7 was identified in two distinct concentrations. A chromosome segment substitution line (CSSL) harboring the
qSL7
locus from PA64s with 93-11 background was developed and exhibited higher SL value, higher K
+
concentration, and lower Na
+
concentration compared to 93-11. With BC
5
F
2:3
derived from CSSL-
qSL7
/93-11, the
qSL7
was fine mapped within a 252.9 kb region on chromosome 7 where 40 annotated genes located including,
LOC_Os07g43530
, which encodes a DNA-binding domain containing protein reported previously as a transcription factor playing a positive role in salt stress tolerance. Our study provides new genetic resources for improvement of salinity tolerance in rice breeding.
Chlorophyll (Chl) b is a ubiquitous accessory pigment in land plants, green algae, and prochlorophytes. This pigment is synthesized from Chl a by chlorophyllide a oxygenase and plays a key role in ...adaptation to various environments. This study characterizes a rice mutant, pale green leaf (pgl), and isolates the gene PGL by using a map-based cloning approach. PGL, encoding chlorophyllide a oxygenase 1, is mainly expressed in the chlorenchyma and activated in the light-dependent Chl synthesis process. Compared with wild-type plants, pgl exhibits a lower Chl content with a reduced and disorderly thylakoid ultrastructure, which decreases the photosynthesis rate and results in reduced grain yield and quality. In addition, pgl exhibits premature senescence in both natural and dark-induced conditions and more severe Chl degradation and reactive oxygen species accumulation than does the wild-type. Moreover, pgl is sensitive to heat stress.
As one of the great survivors of the plant kingdom, barnyard grasses (Echinochloa spp.) are the most noxious and common weeds in paddy ecosystems. Meanwhile, at least two Echinochloa species have ...been domesticated and cultivated as millets. In order to better understand the genomic forces driving the evolution of Echinochloa species toward weed and crop characteristics, we assemble genomes of three Echinochloa species (allohexaploid E. crus-galli and E. colona, and allotetraploid E. oryzicola) and re-sequence 737 accessions of barnyard grasses and millets from 16 rice-producing countries. Phylogenomic and comparative genomic analyses reveal the complex and reticulate evolution in the speciation of Echinochloa polyploids and provide evidence of constrained disease-related gene copy numbers in Echinochloa. A population-level investigation uncovers deep population differentiation for local adaptation, multiple target-site herbicide resistance mutations of barnyard grasses, and limited domestication of barnyard millets. Our results provide genomic insights into the dual roles of Echinochloa species as weeds and crops as well as essential resources for studying plant polyploidization, adaptation, precision weed control and millet improvements.