scholarly journals Concurrent Disruption of Genetic Interference and Increase of Genetic Recombination Frequency in Hybrid Rice Using CRISPR/Cas9

2021 ◽  
Vol 12 ◽  
Author(s):  
Chaolei Liu ◽  
Yiwei Cao ◽  
Yufeng Hua ◽  
Guijie Du ◽  
Qing Liu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Hybrid Rice ◽  
Genetic Recombination ◽  
Recombination Frequency ◽  
Rice Variety ◽  
Female Fertility ◽  
Central Component ◽  
Linkage Drag ◽  
Genetic Interference ◽  
Null Mutants

Manipulation of the distribution and frequency of meiotic recombination events to increase genetic diversity and disrupting genetic interference are long-standing goals in crop breeding. However, attenuation of genetic interference is usually accompanied by a reduction in recombination frequency and subsequent loss of plant fertility. In the present study, we generated null mutants of the ZEP1 gene, which encodes the central component of the meiotic synaptonemal complex (SC), in a hybrid rice using CRISPR/Cas9. The null mutants exhibited absolute male sterility but maintained nearly unaffected female fertility. By pollinating the zep1 null mutants with pollen from indica rice variety 93-11, we successfully conducted genetic analysis and found that genetic recombination frequency was greatly increased and genetic interference was completely eliminated in the absence of ZEP1. The findings provided direct evidence to support the controversial hypothesis that SC is involved in mediating interference. Additionally, the remained female fertility of the null mutants makes it possible to break linkage drag. Our study provides a potential approach to increase genetic diversity and fully eliminate genetic interference in rice breeding.

scholarly journals Evolving Patterns of Cryptosporidiosis: Issues and Implications in the Context of Public Health in India

2021 ◽  
Author(s):  
Bijay Ranjan Mirdha
Keyword(s):  
Public Health ◽  
Genetic Diversity ◽  
Genetic Recombination ◽  
Acute Infection ◽  
Transmission Intensity ◽  
Future Research ◽  
Cryptosporidium Hominis ◽  
Host Preferences ◽  
Childhood Growth ◽  
Life Years

AbstractCryptosporidiosis is one of the major causes of diarrhea in immune-compromised individuals and children besides causing sporadic water-borne, food-borne, and zoonotic outbreaks. In 2016, Cryptosporidium species infection was the fifth leading cause of diarrhea and acute infection causing more than 4.2 million disability-adjusted life years lost besides a decrease in childhood growth. Human cryptosporidiosis is primarily caused by two species/genotype: Cryptosporidium hominis (anthroponotic) and Cryptosporidium parvum (zoonotic) besides other six rare species/genotypes. Transmission intensity, genetic diversity, and occurrence of genetic recombination have shaped the genus Cryptosporidium population structures into palmitic, clonal, and epidemic. Genetic recombination is more in C. parvum compared with C. hominis. Furthermore, parasite–host co-evolution, host adaptation, and geographic segregation have led to the formation of “subtype- families.” Host-adapted subtype-families have distinct geographical distribution and host preferences. Genetic exchanges between subtypes played an important role throughout the evolution of the genus leading to “adaptation introgression” that led to emergence of virulent and hyper-transmissible subtypes. The population structure of C. hominis in India appears to be more complex where both transmission intensity and genetic diversity are much higher. Further, study based on “molecular strain surveillance” has resulted newer insights into the epidemiology and transmission of cryptosporidiosis in India. The identification at the species and genotype levels is essential for the assessment of infection sources in humans and the public health potential of the parasite at large. The results of the study over three decades on cryptosporidiosis in India, in the absence of a national surveillance data, were analyzed highlighting current situation on epidemiology, genetic diversity, and distribution particularly among vulnerable population. Despite creditable efforts, there are still many areas need to be explored; therefore, the intent of this article is to facilitate future research approaches for mitigating the burden associated with this disease.

scholarly journals Performance of hybrid rice grown from separated tillers

2019 ◽  
Vol 17 (4) ◽  
pp. 507-513
Author(s):  
FN Kamarum Munira ◽  
Md. Parvez Anwar ◽  
Sabina Yeasmin ◽  
Md. Harun Or Rashid ◽  
Mst Farzana Rahman ◽  
...  
Keyword(s):  
Grain Yield ◽  
Plant Height ◽  
Hybrid Rice ◽  
Rice Variety ◽  
Field Laboratory ◽  
Split Plot ◽  
Rice Seeds ◽  
Four Levels ◽  
Plot Design

The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during July to November 2016 to investigate the performance of separated tillers of hybrid rice variety Dhani Gold. The experiment comprised three times of tiller transplantation viz. 3, 4 and 5 week aged tiller seedlings and four levels of number of tiller seedlings transplanted hill-1 viz. 2, 3, 4 and 5 tiller seedlings hill-1 laid out in a split plot design with 3 replications. The highest plant height was obtained when 3-week aged tiller seedlings were transplanted at the rate of 3 tiller seedlings hill-1. The highest number of total tillers hill-1 and number of effective tillers hill-1 were found when 3-week aged tiller seedlings were transplanted with 5 tiller seedlings hill-1. The highest grains panicle-1 was obtained when 4-week aged tiller seedlings were transplanted with 5 tiller seedlings hill-1. The highest grain yield was found when 3-week aged tiller seedlings were transplanted with 5 tiller seedlings hill-1. The lowest grain yield was found when 5-week aged tiller seedlings were transplanted with 2 tiller seedlings hill-1 in hybrid rice variety Dhani Gold. Based on the findings of the present study it may be concluded that 3-week old tiller seedlings of Dhani Gold should be transplanted at the rate of 4 or 5 tiller seedlings hill-1 for higher yield. Thus present study confirms the potentiality of growing hybrid rice from separated tillers in case of unavailability of seedlings or to minimize the seed cost of high value hybrid rice seeds. J Bangladesh Agril Univ 17(4): 507–513, 2019

GENETIC RECOMBINATION IN SEXUAL CROSSES OF PHYCOMYCES

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 445-462
Author(s):  
A P Eslava ◽  
M I Alvarez ◽  
Patricia V Burke ◽  
M Delbrück
Keyword(s):  
Mating Type ◽  
Genetic Recombination ◽  
Recombination Frequency ◽  
Intragenic Recombination ◽  
Phycomyces Blakesleeanus ◽  
Sexual Crosses ◽  
Color Marker ◽  
Three Factor

ABSTRACT Sexual crosses between strains of Phycomyces blakesleeanus, involving three auxotrophic and one color marker and yielding a high proportion of zygospore germination, are described. Samples of 20-40 germ spores from 311 individual fertile germ sporangia originating from five two-factor and three three-factor crosses were characterized. The results show: (1) absence of any contribution of apogamic nuclei to the progeny, (2) confirmation of Burgeff's conjecture that the germ spores of any germ sporangium in most cases derive from one meiosis. In a cross involving two allelic markers the analysis of 175 pooled germ sporangia suggests an intragenic recombination frequency of 0.6%. All other factor combinations tested are unlinked. The bulk of the germ spores are homokaryotic. However, a small portion (4%) are heterokaryotic with respect to mating type.

Genetic Recombination in Coprinus

1970 ◽  
Vol 6 (3) ◽  
pp. 669-678
Author(s):  
B. C. LU
Keyword(s):  
Fruiting Body ◽  
Temperature Effects ◽  
Cold Shock ◽  
Genetic Recombination ◽  
Recombination Frequency ◽  
Temperature Treatment ◽  
Sensitive Period ◽  
Crossing Over ◽  
Synaptinemal Complex ◽  
Before And After

The frequency of genetic recombination in Coprinus lagopus may be modified by heat and cold shock. By removal of samples from a fruiting body before and after temperature treatment, it is possible to study the ultrastructure of chromosomes at the time recombination frequency (between den+ x +me-1) can be modified. The sensitive period for temperature effects and, therefore, probably the time of crossing over, commences with the formation of the synaptinemal complex (S.C.) and ends with its disappearance, i.e. during the entire existence of the S.C. It is concluded that recombination is an event subsequent to the formation of the S.C. and is independent of the process of its formation. It is suggested that the event takes place at the synaptic centre.

scholarly journals Genetic Diversity Studies in MAGIC Population of Soybean (Glycine max (L.) Merrill) Based on Mahalanobis D2 Distance

2021 ◽  
pp. 18-25
Author(s):  
Bidush Ranjan Swar ◽  
V. Swarnalatha ◽  
M. Rajendar Reddy ◽  
S. Vanisree
Keyword(s):  
Genetic Diversity ◽  
Seed Weight ◽  
Quantitative Traits ◽  
Genetic Recombination ◽  
Breeding Programs ◽  
Total Genetic Diversity ◽  
Glycine Max L ◽  
Diversity Studies ◽  
100 Seed Weight ◽  
Number Of Branches

Soybean MAGIC lines are highly variable breeding material which utilizes both recent and historic genetic recombination events. Present investigation was carried out to assess the genetic diversity present among 95 soybean MAGIC lines along with six checks for 10 different quantitative traits. All the genotypes were grouped into 16 clusters by performing Tocher’s clustering method using Mahalanobis D2 distance. Cluster I was the largest comprising of 30 genotypes followed by cluster II (23 genotypes), cluster X (15 genotypes) and cluster IX (9 genotypes). The maximum genetic distance (D2) was observed between cluster XI and XV (168.37) followed by cluster III and XV (164.3), cluster X and XV (149.64) as well as between cluster XII and cluster XVI (145.99). The cluster mean for most of the traits were high in cluster I and cluster XVI. Oil content contributed maximum (23.86%) towards total genetic diversity followed by number of pods plant-1 (18.97%), seed yield plant-1 (18.63%), 100 seed weight (11.05%) and number of branches plant-1 (10.16%) traits. The soybean MAGIC lines belong to the cluster XI (6-120) and cluster XV (6-30, 6-31, 6-5) were found to be the most divergent hence can be utilised in the recombination breeding programs to exploit maximum heterosis.

Genetic Diversity of Tropical Hybrid Rice Germplasm Measured by Molecular Markers

Rice Science ◽  
2012 ◽  
Vol 19 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Zhi-zhou HE ◽  
Fang-ming XIE ◽  
Li-yun CHEN ◽  
Madonna Angelita DELA PAZ
Keyword(s):  
Genetic Diversity ◽  
Molecular Markers ◽  
Hybrid Rice ◽  
Rice Germplasm

Genetic diversity and population structure of the rice false smut pathogen Ustilaginoidea virens in Sichuan-Chongqing region

Plant Disease ◽  
2021 ◽  
Author(s):  
Anfei Fang ◽  
Zhuangyuan Fu ◽  
Zexiong Wang ◽  
Yuhang Fu ◽  
Yubao Qin ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Genetic Recombination ◽  
Resistance Breeding ◽  
Ustilaginoidea Virens ◽  
Breeding Lines ◽  
Rice False Smut ◽  
Geographical Populations ◽  
False Smut

Rice false smut caused by Ustilaginoidea virens is currently one of the most devastating fungal diseases of rice panicles worldwide. In this study, two novel molecular markers derived from SNP-rich genomic DNA fragments and a previously reported molecular marker were used for analyzing the genetic diversity and population structure of 167 U. virens isolates collected from nine areas in Sichuan-Chongqing region, China. A total of 62 haplotypes were identified, and a few haplotypes with high frequency were found and distributed in two to three areas, suggesting gene flow among different geographical populations. All isolates were divided into six genetic groups. The groups Ⅰ and Ⅵ were the largest including 61 and 48 isolates, respectively. The pairwise FST values showed significant genetic differentiation among all compared geographical populations. AMOVA showed that intergroup genetic variation accounted for 40.17% of the total genetic variation, while 59.83% of genetic variation came from intragroup. The UPGMA dendrogram and population structure revealed that the genetic composition of isolates collected from ST (Santai), NC (Nanchong), YC (Yongchuan), and WS (Wansheng) dominated by the same genetic subgroup was different from those collected from other areas. In addition, genetic recombination was found in a few isolates. These findings will help to improve the strategies for rice false smut management and resistance breeding, such as evaluating breeding lines with different isolates or haplotypes at different elevations and landforms.

scholarly journals Transcriptome and genome sequencing elucidates the molecular basis for the high yield and good quality of the hybrid rice variety Chuanyou6203

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Juansheng Ren ◽  
Fan Zhang ◽  
Fangyuan Gao ◽  
Lihua Zeng ◽  
Xianjun Lu ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Hybrid Rice ◽  
Rice Variety ◽  
Utilization Efficiency ◽  
High Yield ◽  
Mrna Editing ◽  
High Quality ◽  
Flag Leaves ◽  
Yield And Quality

AbstractThe yield heterosis of rice is sought by farmers and strong contributes to food safety, but the quality of hybrid rice may be reduced. Therefore, developing new varieties with both high yield and good quality is a heavily researched topic in hybrid rice breeding. However, the molecular mechanism governing yield heterosis and high rice quality has not been elucidated to date. In this study, a comparative transcriptomics and genomic analysis was performed on a hybrid rice variety, Chuanyou6203 (CY6203), and its parents to investigate the molecular mechanism and gene regulation network governing the formation of yield and quality stages. A total of 66,319 SNPs and InDels between CH3203 and C106B were detected in the 5′-UTR, exon, intronic, and 3′-UTR regions according to the reference genome annotation, which involved 7473 genes. A total of 436, 70, 551, 993, and 1216 common DEGs between CY6203 and both of its parents were identified at the same stage in panicles and flag leaves. Of the common DEGs, the numbers of upregulated DEGs between CY6203 and CH3203 were all greater than those of upregulated DEGs between CY6203 and C106B in panicles and flag leaves at the booting, flowering, and middle filling stages. Approximately 40.61% of mRNA editing ratios were between 0.4 and 0.6, and 1.68% of mRNA editing events (editing ratio ≥ 0.8) in CY6203 favored one of its parents at three stages or a particular stage, suggesting that the hypothetical heterosis mechanism of CY6203 might involve dominance or epistasis. Also 15,934 DEGs were classified into 19 distinct modules that were classified into three groups by the weighted gene coexpression network analysis. Through transcriptome analysis of panicles and flag leaves in the yield and quality stages, the DEGs in the green-yellow module primarily contributed to the increase in the source of CY6203 due to an in increase in photosynthetic efficiency and nitrogen utilization efficiency, and a small number of DEGs related to the grain number added spikelet number per panicle amplified its sink. The balanced expression of the major high-quality alleles of C106B and CH3203 in CY6203 contributed to the outstanding quality of CY6203. Our transcriptome and genome analyses offer a new data set that may help to elucidate the molecular mechanism governing the yield heterosis and high quality of a hybrid rice variety.

scholarly journals Heterosis-associated genes confer high yield in super hybrid rice

2020 ◽  
Vol 133 (12) ◽  
pp. 3287-3297
Author(s):  
Tianzi Lin ◽  
Cong Zhou ◽  
Gaoming Chen ◽  
Jun Yu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Hybrid Rice ◽  
Rice Variety ◽  
Female Parent ◽  
High Yield ◽  
Recurrent Parent ◽  
Sequencing Analysis ◽  
Substitution Lines ◽  
Chromosome Segment Substitution Lines

Abstract Key message Heterosis QTLs, including qSS7 and qHD8, with dominance effects were identified through GBS and large-scale phenotyping of CSSLs and hybrid F1 populations in a paddy field. Abstract Heterosis has contributed immensely to agricultural production, but its genetic basis is unclear. We evaluated dominance effects by creating two hybrid populations: a B-homo set with a homozygous background and heterozygous chromosomal segments and a B-heter set with a heterozygous background and homozygous segments. This was achieved by crossing a set of 156 backcrossed-derived chromosome segment substitution lines (CSSLs) with their recurrent parent (9311), the male parent of the first super-high-yield hybrid Liangyoupei9 (LYP9), and with the female parent (PA64s) of the hybrid. The CSSLs were subjected to a genotyping-by-sequencing analysis to develop a genetic map of segments introduced from the PA64s. We evaluated the heterotic effects on eight yield-related traits in the hybrid variety and F1 populations in large-scale field experiments over 2 years. Using a linkage map consisting of high-density SNPs, we identified heterosis-associated genes in LYP9. Five candidate genes contributed to the high yield of LYP9, with qSS7 and qHD8 repeatedly detected in both B-hybrid populations. The heterozygous segments harboring qSS7 and qHD8 showed dominance effects that contributed to the heterosis of yield components in the hybrid rice variety Liangyoupei9.

Genetic analysis of mango landraces from Mexico based on molecular markers

2009 ◽  
Vol 7 (03) ◽  
pp. 244-251 ◽  
Author(s):  
Didiana Gálvez-López ◽  
Sanjuana Hernández-Delgado ◽  
Maurilio González-Paz ◽  
Enrique Noe Becerra-Leor ◽  
Miguel Salvador-Figueroa ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Molecular Markers ◽  
Fragment Length Polymorphism ◽  
Geographical Origin ◽  
Genetic Recombination ◽  
Genetic Relationships ◽  
Mangifera Indica ◽  
Aflp Analysis ◽  
Significant Genetic Differentiation ◽  
Simple Sequence

Genetic diversity and relationships among 112 mango (Mangifera indica) plants native to 16 states of Mexico and four controls [three mango cultivars (Ataulfo, Manila and Tommy Atkins) and one accession ofMangifera odorata] were evaluated based on amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) molecular markers. Mango germplasm shows broad dispersion through Mexico and genetically similar germplasm from different agroecological regions has previously been found by our group. Both AFLP and SSR analyses indicated high genetic similarity among mango populations that were clustered in two major groups: mangos from Gulf of Mexico coastline and mangos from Pacific Ocean coastline and locations far away from the sea. The highest genetic diversity was found within plants from each state, and significant genetic differentiation (FST = 0.1921, AFLPs and 0.1911, SSRs) was also observed among mango populations based on geographical origin and genetic status (cultivars versus landraces). Heterozygosity values ranged from low (0.38) to moderate (0.68), and no heterozygote deficits were found. The highest genetic variability was found in mango populations from Tabasco, Michoacán and Oaxaca. Data suggested that mangoes are subjected to natural or induced pollination, so segregation as well as genetic recombination plays major roles on genetic diversification of Mexican mangos. AFLP analysis was more robust than SSR for determining the genetic relationships among mango landraces from Mexico.

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