Chromosome doubling methods in doubled haploid and haploid inducer-mediated genome-editing systems in major crops

Author(s):  
Isidre Hooghvorst ◽  
Salvador Nogués
2021 ◽  
pp. 1-10
Author(s):  
Sourbh Kumar ◽  
Uttam Chandel ◽  
Satish Kumar Guleria

Abstract An investigation to optimize the protocol for application of colchicine for enhancing the doubled haploid production in maize was done. 106 maize genotypes were used as maternal parents, whereas, pollen source involved tropically adopted haploid inducer (TAIL P1 and TAIL hybrid). After the elimination of chromosomes of inducer lines, haploid seeds were obtained from the crosses. Haploid seedlings were treated with three different doses, such as 0.04, 0.06 and 0.08 per cent of colchicines for different durations (8, 12 and 15 hours). The response of various colchicine concentrations applied for different time durations revealed significant differences at P ≤ 0.05 for various parameters viz., per cent plants survivability, stalk colour, the fertility of tassel, silk present/absent, pollen viability, seed set and per cent doubled haploid formation. In maize, colchicine doses of 0.04 per cent for 12 hours and 0.06 per cent for 8 hours, respectively were established as optimum for enhanced doubled haploid production. But among these two, 0.04 per cent for 12 hours was observed to be best dose for doubled haploid production in maize.


2020 ◽  
Vol 80 (03) ◽  
Author(s):  
R. K Khulbe ◽  
A. Pattanayak ◽  
Lakshmi Kant ◽  
G. S. Bisht ◽  
M. C. Pant ◽  
...  

The use of in vivo haploid induction system makes the doubled haploid (DH) technology easier to adopt for the conventional maize breeders. However, despite having played an important role in the initial developmental phases of DH technology, Indian maize research has yet to harvest its benefits. Haploid Inducer Lines (HILs) developed by CIMMYT are being widely used in maize breeding programmes in many countries including India. There, however, is no published information on the efficiency of DH line production using CIMMYT HILs in Indian maize breeding programmes. In the present study, the efficiency of DH production using CIMMYT’s tropically adapted inducer line TAILP1 was investigated with eight source populations including two of sweet corn. The average haploid induction rate (HIR) of TAILP1 was 5.48% with a range of 2.01 to 10.03%. Efficiency of DH production ranged from 0.14 to 1.87% for different source populations with an average of 1.07%. The information generated will be useful for maize breeders intending to use DH technology for accelerated development of completely homozygous lines.


2020 ◽  
Vol 79 (04) ◽  
Author(s):  
R. K. Khulbe ◽  
A. Pattanayak ◽  
Vivek Panday

The current method of doubled haploid (DH) development in maize involves in vivo production of haploids using R1-njbased haploid inducer lines that upon use as male render a small fraction of seed in the pollinated female ears haploid. Identification of haploid seed relies on R1-nj marker expression in the endosperm and embryo, and the degree of its expression determines efficiency of DH development process. In the present study, R1-nj expression in the endosperm was characterized in crosses of CIMMYT’s R1-nj-based haploid inducer TAILP1 with a set comprising 18 early maturity hybrids and their 23 parental inbreds. Kernel colour inhibition was observed only in a small proportion of the hybrids and inbreds. Comparison of R1-nj expression in the hybrids and their parental inbreds revealed a distinct pattern, which may be useful in identifying source populations and/or determining parental constituents for synthesizing source populations with predicted amenability to doubled haploid development using R1-nj-based haploid inducers. However, deviation from the pattern was noted in hybrids involving inbreds with higher degree of colour inhibition, which suggests complex nature of R1-nj phenotype expression and necessitates further investigation involving larger sets of germplasm for dissecting the role of maternal and paternal genetic factors in determining R1-nj phenotype expression. The hybrids found exhibiting complete kernel anthocyanin expression in present study can be used directly as source populations for DH development using R1-nj based haploid inducers. Besides, since the inbreds used in the study have originated from and/or are accessible to CGIAR/NARS maize breeding programmes, the information on their kernel anthocyanin expression can be helpful in selection of source populations or generating new source populations amenable for DH development using R1-nj based haploid inducers.


2019 ◽  
Vol 132 (12) ◽  
pp. 3227-3243 ◽  
Author(s):  
Vijay Chaikam ◽  
Willem Molenaar ◽  
Albrecht E. Melchinger ◽  
Prasanna M. Boddupalli

Key Message Increased efficiencies achieved in different steps of DH line production offer greater benefits to maize breeding programs. Abstract Doubled haploid (DH) technology has become an integral part of many commercial maize breeding programs as DH lines offer several economic, logistic and genetic benefits over conventional inbred lines. Further, new advances in DH technology continue to improve the efficiency of DH line development and fuel its increased adoption in breeding programs worldwide. The established method for maize DH production covered in this review involves in vivo induction of maternal haploids by a male haploid inducer genotype, identification of haploids from diploids at the seed or seedling stage, chromosome doubling of haploid (D0) seedlings and finally, selfing of fertile D0 plants. Development of haploid inducers with high haploid induction rates and adaptation to different target environments have facilitated increased adoption of DH technology in the tropics. New marker systems for haploid identification, such as the red root marker and high oil marker, are being increasingly integrated into new haploid inducers and have the potential to make DH technology accessible in germplasm such as some Flint, landrace, or tropical material, where the standard R1-nj marker is inhibited. Automation holds great promise to further reduce the cost and time in haploid identification. Increasing success rates in chromosome doubling protocols and/or reducing environmental and human toxicity of chromosome doubling protocols, including research on genetic improvement in spontaneous chromosome doubling, have the potential to greatly reduce the production costs per DH line.


2019 ◽  
Vol 12 (4) ◽  
pp. 597-602 ◽  
Author(s):  
Baobao Wang ◽  
Lei Zhu ◽  
Binbin Zhao ◽  
Yongping Zhao ◽  
Yurong Xie ◽  
...  

HortScience ◽  
1994 ◽  
Vol 29 (10) ◽  
pp. 1189-1190 ◽  
Author(s):  
N. Sari ◽  
K. Abak ◽  
M. Pitrat ◽  
J.C. Rode ◽  
R. Dumas de Vaulx

Parthenogenetic haploid embryos of `Crimson Sweet', `Halep Karasi', `Sugar Baby' and `Panonia F1' watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] were obtained after pollination with γ-irradiated (200 or 300 Gy) pollen. Some globular and heart-shaped embryos were observed in fruit harvested 2 to 5 weeks after pollination. The number of embryos per 100 seeds was highest for `Halep Karasi'. After in vitro culture, 17 haploid plants were obtained and doubled haploid lines were generated after chromosome doubling using colchicine.


2005 ◽  
Vol 130 (4) ◽  
pp. 555-560 ◽  
Author(s):  
Elisabet Claveria ◽  
Jordi Garcia-Mas ◽  
Ramon Dolcet-Sanjuan

Homozygous doubled haploid lines (DHLs) from new cucumber (Cucumis sativus L.) accessions could be useful to accelerate breeding for resistant varieties. DHLs have been generated by in vitro rescue of in vivo induced parthenogenic embryos. The protocol developed involves the following: 1) induction of parthenogenic embryos by pollinating with pollen irradiated with a Co60 γ-ray source at 500 Gy; 2) in vitro rescue of putative parthenogenic embryos identified by their morphology and localized using a dissecting scope or X-ray radiography; 3) discrimination of undesirable zygotic individuals from the homozygous plants using cucumber and melon SSR markers; 4) determination of ploidy level from homozygous plants by flow cytometry; 5) in vitro chromosome doubling of haploids; and 6) acclimation and selfing of selected lines. Codominant markers and flow cytometry confirmed the gametophytic origin of plants regenerated by parthenogenesis, since all homozygous lines were haploids. No spontaneous doubled haploid plants were rescued. Chromosome doubling of haploid plants was accomplished by an in vitro treatment with 500 μm colchicine. Rescue of diploid or chimeric plants was shown by flow cytometry, prior to their acclimation and planting in the greenhouse. Selfing of colchicine-treated haploid plants allowed for the perpetuation by seed of homozygous lines. The high rate of seed set, 90% of the lines produced seed, facilitated the recovery of inbred lines. Despite some limiting factors, parthenogenesis is routinely used in a cucumber-breeding program to achieve complete homozygosity in one generation. Breeding for new commercial hybrid cultivars will be accelerated. DHLs are ideal resources for genomic analyses.


Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1441
Author(s):  
Isidre Hooghvorst ◽  
Salvador Nogués

Doubled haploids have played a major role in cucurbit breeding for the past four decades. In situ parthenogenesis via irradiated pollen is the preferred technique to obtain haploid plantlets whose chromosomes are then doubled in Cucurbitaceae, such as melon, cucumber, pumpkin, squash and winter squash. In contrast to doubled haploid procedures in other species, in situ parthenogenesis in cucurbits presents many limiting factors which impede efficient production of haploids. In addition, it is very time-consuming and labor-intensive. However, the haploid inducer-mediated genome-editing system is a breakthrough technology for producing doubled haploids. Several reports have described using the CRISPR/Cas9 system in cucurbit species, and although its application has many bottlenecks, the targeted knock-out of the CENH3 gene will allow breeders to obtain haploid inducer lines that can be used to obtain parthenogenetic embryos. In this review, we discuss the progress made towards the development of doubled haploids and haploid inducer genotypes using CRISPR/Cas9 technologies in cucurbit species. The present review provides insights for the application of haploid inducer-mediated genome-editing system in cucurbit species


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