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[学术文献 ] Transcriptomic analysis identifies novel genes and pathways for salt stress responses in Suaeda salsa leaves 进入全文
Nature
Salinity is a critical abiotic stress, which significantly impacts the agricultural yield worldwide. Identification of the molecular mechanisms underlying the salt tolerance in euhalophyte Suaeda salsa is conducive to the development of salt-resistant crops. In the present study, high-throughput RNA sequencing was performed after S. salsa leaves were exposed to 300 mM NaCl for 7 days, and 7,753 unigenes were identified as differently expressed genes (DEGs) in S. salsa, including 3,638 increased and 4,115 decreased unigenes. Moreover, hundreds of pathways were predicted to participate in salt stress response in S. salsa by Gene Ontology (GO), MapMan and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, including ion transport and sequestration as well as photoprotection of photosystem (PS) II. The GO enrichment analysis indicated that genes related to ion transport, reactive oxygen species (ROS) scavenging and transcriptional factors were highly expressed upon NaCl treatment. The excessive Na+ and Cl− ions were supposed to be absorbed into the vacuole for ion sequestration and balance adjustment by potassium transporters (such as KEA3) with high expressions. Moreover, we predicted that mutiple candidate genes associated with photosynthesis (such as PSB33 and ABA4), ROS (such as TAU9 and PHI8) and transcriptional regulation (HB-7 and MYB78) pathways could mitigate salt stress-caused damage in S. salsa.
[学术文献 ] A putative bHLH transcription factor is a candidate gene for male sterile 32, a locus affecting pollen and tapetum development in tomato 进入全文
nature
The tomato (Solanum lycopersicum) male sterile 32 (ms32) mutant has been used in hybrid seed breeding programs largely because it produces no pollen and has exserted stigmas. In this study, histological examination of anthers revealed dysfunctional pollen and tapetum development in the ms32 mutant. The ms32 locus was fine mapped to a 28.5 kb interval that encoded four putative genes. Solyc01g081100, a homolog of Arabidopsis bHLH10/89/90 and rice EAT1, was proposed to be the candidate gene of MS32 because it contained a single nucleotide polymorphism (SNP) that led to the formation of a premature stop codon. A codominant derived cleaved amplified polymorphic sequence (dCAPS) marker, MS32D, was developed based on the SNP. Real-time quantitative reverse-transcription PCR showed that most of the genes, which were proposed to be involved in pollen and tapetum development in tomato, were down regulated in the ms32 mutant. These findings may aid in marker-assisted selection of ms32 in hybrid breeding programs and facilitate studies on the regulatory mechanisms of pollen and tapetum development in tomato.
[学术文献 ] Creation of aromatic maize by CRISPR/Cas 进入全文
Journal of Integrative Plant Biology
Aroma is an important quality parameter for breeding in rice (Oryza sativa). For example, the aromatic rice varieties basmati and jasmine rice, with a popcorn‐like scent, are popular worldwide and routinely command a price premium. 2‐acetyl‐1‐pyrroline (2AP) is a key flavor compound among over 200 volatiles identified in fragrant rice. A naturally fragrant germplasm exists in multiple plant species besides rice, which all exhibit lower activity of BETAINE ALDEHYDE DEHYDROGENASE 2 (BADH2). However, no equivalent aromatic germplasm has been described in maize (Zea mays). Here, we characterized the two maize BADH2 homologs, ZmBADH2a and ZmBADH2b. We generated zmbadh2a and zmbadh2b single mutants and the zmbadh2a‐zmbadh2b double mutant by CRISPR/Cas in four inbred lines. A popcorn‐like scent was only noticeable in seeds from the double mutant, but not from either single mutant or in wild type. In agreement, we only detected 2AP in fresh kernels and dried mature seeds from the double mutant, which accumulated between 0.028 and 0.723 mg/kg 2AP. These results suggest that ZmBADH2a and ZmBADH2b redundantly participate in 2AP biosynthesis in maize, and represent the creation of the world's first aromatic maize by simultaneous genome editing of the two BADH2 genes.
[学术文献 ] Emerging tools and paradigm shift of gene editing in cereals, fruits, and horticultural crops for enhancing nutritional value and food security 进入全文
Food and Energy Security
Gene editing using sequence‐specific nucleases, particularly CRISPR/Cas ribonucleoprotein, has drawn enormous attention in plant research in recent years. Nearly a decade ago, Cas9 protein was initially discovered for a role in adaptive immunity in bacteria. Owing to vast potential, a large number of reports came out in a short span of time, comprising the identification of Cas protein from different bacterial sources, new Cas9 variants with reduced off‐targets, multiplexing, base editing, prime editing, and RNA manipulation in plants. Studies revealed that CRISPR/Cas‐based gene editing can play a major role in ensuring food security via developing resilient commercial crops with improved yield and nutritional value. Use of the CRISPR/Cas9 system for creating mutation in genes and regulatory regions of promoter generated a number of alleles with variable phenotypes, which can serve as an excellent genetic resource in the breeding program. In this review, we provide a recent overview of state‐of‐art discoveries in the CRISPR/Cas system comprised of new Cas proteins, modifications of existing Cas9, refinements in CRISPR/Cas‐induced gene editing, applications, and outcome emphasizing on major cereals and horticultural crops. We also highlight the current global policy framework for the regulation of gene‐edited crops.
[学术文献 ] Effects of rainfall, temperature and illumination on outcrossing rate of male sterile line in soybean 进入全文
Oil Crop Science
To improve seed yield of male sterile line, the relationship between outcrossing rate and climate factors was explored. Data of blooming period, outcrossing rate of male sterile line and climate during 2006–2016 growing seasons were investigated and analyzed. The shortest blooming period was 18.8 ?d with mean temperature of 24oC–25 ?°C and 18.5 ?d with about 125 ?h natural illumination. More rainfall caused a longer blooming period, and a high outcrossing rate was found with about 100 ?mm rainfall and the mean temperature of 24oC–25 ?°C. Increased natural illumination time by tapetum lucidum mulching improved outcrossing rate by 42.48% compared tocontrol. Overall, the selective combination of climate and environmental factors could be effective for increasing outcrossing rate and hybrid seed yield in the male sterile line of soybean.
[学术文献 ] Fertility restoration of maize CMS‐C altered by a single amino acid substitution within the Rf4 bHLH transcription factor 进入全文
Food and Energy Security
Type C cytoplasmic male sterility (CMS‐C) is the most commonly used form of CMS in maize hybrid seed production. Restorer of fertility 4 (Rf4), the major fertility restorer gene of CMS‐C, is located on chromosome 8S. To positionally clone Rf4, a large F3 population derived from a cross between a non‐restorer and restorer (n = 5104) was screened for recombinants and then phenotyped for tassel fertility, resulting in a final map‐based cloning interval of 12 kb. Within this 12‐kb interval, the only likely candidate for Rf4 was GRMZM2G021276, a basic helix?loop?helix (bHLH) transcription factor with tassel‐specific expression. The Rf4 gene product contains a nuclear localization signal and is likely to not interact directly with the mitochondria. Sequence analysis of Rf4 revealed four encoded amino acid substitutions between restoring and non‐restoring inbreds, however only one substitution, F187Y, was within the highly conserved bHLH domain. The hypothesis that Rf4 restoration is altered by a single amino acid was tested by using clustered regularly interspaced short palindromic repeat (CRISPR)‐CRISPR associated protein 9 (Cas9) homology directed repair (HDR) to create isogenic lines that varied for the F187Y substitution. In a population of these CRISPR‐Cas9 edited plants (n = 780) that was phenotyped for tassel fertility, plants containing F187 were completely fertile, indicating fertility restoration, and plants containing Y187 were sterile, indicating lack of fertility restoration. Structural modeling shows that this amino acid residue 187 is located within the four helix bundle core, a critical region for stabilizing dimer conformation and affecting interaction partner selection.
