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10 pages, 2976 KiB

Open AccessArticle

Development and Characterization of Two Wheat–Rye Introgression Lines with Resistance to Stripe Rust and Powdery Mildew

by Yuzhou Ji, Guotang Yang, Xingfeng Li, Honggang Wang and Yinguang Bao

Int. J. Mol. Sci. 2024, 25(21), 11677; https://doi.org/10.3390/ijms252111677 - 30 Oct 2024

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Abstract

Rye (Secale cereale L.) genes, which contribute to the tertiary gene pool of wheat, include multiple disease resistance genes useful for the genetic improvement of wheat. Introgression lines are the most valuable materials for wheat breeding because of their small alien segments [...] Read more.

Rye (Secale cereale L.) genes, which contribute to the tertiary gene pool of wheat, include multiple disease resistance genes useful for the genetic improvement of wheat. Introgression lines are the most valuable materials for wheat breeding because of their small alien segments and limited or lack of linkage drag. In the present study, wheat–rye derivative lines SN21627-2 and SN21627-6 were produced via distant hybridization. A genomic in situ hybridization analysis revealed that SN21627-2 and SN21627-6 lack alien segments, while a multi-color fluorescence in situ hybridization analysis detected structural changes in both introgression lines. At the seedling and adult plant stages, SN21627-2 and SN21627-6 were highly resistant to stripe rust and powdery mildew. Primers for 86 PCR-based landmark unique gene markers and 345 rye-specific SLAF markers were used to amplify SN21627-2 and SN21627-6 genomic DNA. Eight markers specific to rye chromosome 2R were detected in both introgression lines, implying these lines carry chromosome 2R segments with genes conferring stripe rust and powdery mildew resistance. Therefore, SN21627-2 and SN21627-6 are resistant to more than one major wheat disease, making them promising bridging parents for breeding disease-resistant wheat lines. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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17 pages, 8723 KiB

Open AccessArticle

Breeding Maize Hybrids with Improved Drought Tolerance Using Genetic Transformation

by Zhaoxia Li, Juren Zhang and Xiyun Song

Int. J. Mol. Sci. 2024, 25(19), 10630; https://doi.org/10.3390/ijms251910630 - 2 Oct 2024

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Abstract

Drought is considered the main agricultural menace, limiting the successful realization of land potential, and thereby reducing crop productivity worldwide. Therefore, breeding maize hybrids with improved drought tolerance via genetic manipulation is necessary. Herein, the multiple bud clumps of elite inbred maize lines, [...] Read more.

Drought is considered the main agricultural menace, limiting the successful realization of land potential, and thereby reducing crop productivity worldwide. Therefore, breeding maize hybrids with improved drought tolerance via genetic manipulation is necessary. Herein, the multiple bud clumps of elite inbred maize lines, DH4866, Qi319, Y478 and DH9938, widely used in China, were transformed with the Escherichia coli betA gene encoding choline dehydrogenase (EC 1.1.99.1), a key enzyme in the biosynthesis of glycine betaine from choline, using Agrobacterium to generate betA transgenic lines. After 3–4 consecutive generations of self-pollination in these transgenic plants, progenies with a uniform appearance, excellent drought tolerance, and useful agricultural traits were obtained. We evaluated the drought tolerance of T4 progenies derived from these transgenic plants in the field under reduced irrigation. We found that a few lines exhibited much higher drought tolerance than the non-transformed control plants. Transgenic plants accumulated higher levels of glycine betaine and were relatively more tolerant to drought stress than the controls at both the germination and early seedling stages. The grain yield of the transgenic plants was significantly higher than that of the control plants after drought treatment. Drought-tolerant inbred lines were mated and crossed to create hybrids, and the drought tolerance of these transgenic hybrids was found to be enhanced under field conditions compared with those of the non-transgenic (control) plants and two other commercial hybrids in China. High yield and drought tolerance were achieved concurrently. These transgenic inbred lines and hybrids were useful in marginal and submarginal lands in semiarid and arid regions. The betA transgene can improve the viability of crops grown in soils with sufficient or insufficient water. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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20 pages, 4226 KiB

Open AccessArticle

Chromosome-Level Assembly Reveals a Fifteen-Chromosome Aneuploid Genome and Environmental Adaptation Strategy of Chinese Traditional Medical Fungus Wolfiporia hoelen

by Shoujian Li, Bing Li and Shunxing Guo

Int. J. Mol. Sci. 2024, 25(16), 8786; https://doi.org/10.3390/ijms25168786 - 13 Aug 2024

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Abstract

The sclerotia of Wolfiporia hoelen are one of the most important traditional Chinese medicines and foods commonly used in China, Japan, Korea, and other Asian countries. To provide a high-quality reference genome and deepen our understanding of the genome of W. hoelen to [...] Read more.

The sclerotia of Wolfiporia hoelen are one of the most important traditional Chinese medicines and foods commonly used in China, Japan, Korea, and other Asian countries. To provide a high-quality reference genome and deepen our understanding of the genome of W. hoelen to elucidate various biological phenomena. In this study, we assembled three genomes of W. hoelen using a combination of Nanopore and Illumina sequencing strategies. The fifteen-chromosome genome L7 of W. hoelen was assembled with two-sided telomere and rDNA sequences for the first time. The chromosome count was subsequently confirmed through collinearity analysis, correcting the previous belief that W. hoelen had only fourteen chromosomes. Moreover, the aneuploid genome was discovered in W. hoelen for the first time through sequencing depth analysis of different chromosomes, and only some strains of W. hoelen exhibit aneuploid genomes. According to the genome analysis of homokaryotic offspring and protoplast-isolated strains, a potential variation in chromosome allocation patterns was revealed. Moreover, the gene function enrichment analysis of genes on reduplicated chromosomes demonstrated that aneuploidy in the genome may be the result of environmental adaptation for W. hoelen. The discovery of an aneuploid genome also provides new ideas for genetic improvement of W. hoelen. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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20 pages, 3783 KiB

Open AccessArticle

Functional Characterization of the Effects of CsDGAT1 and CsDGAT2 on Fatty Acid Composition in Camelina sativa

by Kyeong-Ryeol Lee, Yumi Yeo, Jihyea Lee, Semi Kim, Chorong Im, Inyoung Kim, Juho Lee, Seon-Kyeong Lee, Mi Chung Suh and Hyun Uk Kim

Int. J. Mol. Sci. 2024, 25(13), 6944; https://doi.org/10.3390/ijms25136944 - 25 Jun 2024

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Abstract

Triacylglycerols (TAGs) are the storage oils of plant seeds, and these lipids provide energy for seed germination and valuable oils for human consumption. Three diacylglycerol acyltransferases (DGAT1, DGAT2, and DGAT3) and phospholipid:diacylglycerol acyltransferases participate in the biosynthesis of TAGs. DGAT1 and DGAT2 participate [...] Read more.

Triacylglycerols (TAGs) are the storage oils of plant seeds, and these lipids provide energy for seed germination and valuable oils for human consumption. Three diacylglycerol acyltransferases (DGAT1, DGAT2, and DGAT3) and phospholipid:diacylglycerol acyltransferases participate in the biosynthesis of TAGs. DGAT1 and DGAT2 participate in the biosynthesis of TAGs through the endoplasmic reticulum (ER) pathway. In this study, we functionally characterized CsDGAT1 and CsDGAT2 from camelina (Camelina sativa). Green fluorescent protein-fused CsDGAT1 and CsDGAT2 localized to the ER when transiently expressed in Nicotiana benthamiana leaves. To generate Csdgat1 and Csdgat2 mutants using the CRISPR/Cas9 system, camelina was transformed with a binary vector carrying Cas9 and the respective guide RNAs targeting CsDGAT1s and CsDGAT2s via the Agrobacterium-mediated floral dip method. The EDD1 lines had missense and nonsense mutations in the CsDGAT1 homoeologs, suggesting that they retained some CsDGAT1 function, and their seeds showed decreased eicosaenoic acid (C20:1) contents and increased C18:3 contents compared to the wild type (WT). The EDD2 lines had a complete knockout of all CsDGAT2 homoeologs and a slightly decreased C18:3 content compared to the WT. In conclusion, CsDGAT1 and CsDGAT2 have a small influence on the seed oil content and have an acyl preference for C20:1 and C18:3, respectively. This finding can be applied to develop oilseed plants containing high omega-3 fatty acids or high oleic acid. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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14 pages, 2392 KiB

Open AccessArticle

Meta-QTL and Candidate Gene Analyses of Agronomic Salt Tolerance and Related Traits in an RIL Population Derived from Solanum pimpinellifolium

by Maria J. Asins and Emilio A. Carbonell

Int. J. Mol. Sci. 2024, 25(11), 6055; https://doi.org/10.3390/ijms25116055 - 31 May 2024

Viewed by 721

Abstract

Breeding salt-tolerant crops is necessary to reduce food insecurity. Prebreeding populations are fundamental for uncovering tolerance alleles from wild germplasm. To obtain a physiological interpretation of the agronomic salt tolerance and better criteria to identify candidate genes, quantitative trait loci (QTLs) governing productivity-related [...] Read more.

Breeding salt-tolerant crops is necessary to reduce food insecurity. Prebreeding populations are fundamental for uncovering tolerance alleles from wild germplasm. To obtain a physiological interpretation of the agronomic salt tolerance and better criteria to identify candidate genes, quantitative trait loci (QTLs) governing productivity-related traits in a population of recombinant inbred lines (RIL) derived from S. pimpinellifolium were reanalyzed using an SNP-saturated linkage map and clustered using QTL meta-analysis to synthesize QTL information. A total of 60 out of 85 QTLs were grouped into 12 productivity MQTLs. Ten of them were found to overlap with other tomato yield QTLs that were found using various mapping populations and cultivation conditions. The MQTL compositions showed that fruit yield was genetically associated with leaf water content. Additionally, leaf Cl⁻ and K⁺ contents were related to tomato productivity under control and salinity conditions, respectively. More than one functional candidate was frequently found, explaining most productivity MQTLs, indicating that the co-regulation of more than one gene within those MQTLs might explain the clustering of agronomic and physiological QTLs. Moreover, MQTL1.2, MQTL3 and MQTL6 point to the root as the main organ involved in increasing productivity under salinity through the wild allele, suggesting that adequate rootstock/scion combinations could have a clear agronomic advantage under salinity. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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18 pages, 5501 KiB

Open AccessArticle

Identification of Quantitative Trait Loci Controlling Root Morphological Traits in an Interspecific Soybean Population Using 2D Imagery Data

by Mohammad Shafiqul Islam, Amit Ghimire, Liny Lay, Waleed Khan, Jeong-Dong Lee, Qijian Song, Hyun Jo and Yoonha Kim

Int. J. Mol. Sci. 2024, 25(9), 4687; https://doi.org/10.3390/ijms25094687 - 25 Apr 2024

Cited by 1 | Viewed by 1271

Abstract

Roots are the hidden and most important part of plants. They serve as stabilizers and channels for uptaking water and nutrients and play a crucial role in the growth and development of plants. Here, two-dimensional image data were used to identify quantitative trait [...] Read more.

Roots are the hidden and most important part of plants. They serve as stabilizers and channels for uptaking water and nutrients and play a crucial role in the growth and development of plants. Here, two-dimensional image data were used to identify quantitative trait loci (QTL) controlling root traits in an interspecific mapping population derived from a cross between wild soybean ‘PI366121’ and cultivar ‘Williams 82’. A total of 2830 single-nucleotide polymorphisms were used for genotyping, constructing genetic linkage maps, and analyzing QTLs. Forty-two QTLs were identified on twelve chromosomes, twelve of which were identified as major QTLs, with a phenotypic variation range of 36.12% to 39.11% and a logarithm of odds value range of 12.01 to 17.35. Two significant QTL regions for the average diameter, root volume, and link average diameter root traits were detected on chromosomes 3 and 13, and both wild and cultivated soybeans contributed positive alleles. Six candidate genes, Glyma.03G027500 (transketolase/glycoaldehyde transferase), Glyma.03G014500 (dehydrogenases), Glyma.13G341500 (leucine-rich repeat receptor-like protein kinase), Glyma.13G341400 (AGC kinase family protein), Glyma.13G331900 (60S ribosomal protein), and Glyma.13G333100 (aquaporin transporter) showed higher expression in root tissues based on publicly available transcriptome data. These results will help breeders improve soybean genetic components and enhance soybean root morphological traits using desirable alleles from wild soybeans. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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14 pages, 5554 KiB

Open AccessArticle

Genome-Wide Association Study to Identify Marker–Trait Associations for Seed Color in Colored Wheat (Triticum aestivum L.)

by Min Jeong Hong, Chan Seop Ko and Dae Yeon Kim

Int. J. Mol. Sci. 2024, 25(7), 3600; https://doi.org/10.3390/ijms25073600 - 22 Mar 2024

Viewed by 1408

Abstract

This study conducted phenotypic evaluations on a wheat F₃ population derived from 155 F₂ plants. Traits related to seed color, including chlorophyll a, chlorophyll b, carotenoid, anthocyanin, L*, a*, and b*, were assessed, revealing highly significant correlations among [...] Read more.

This study conducted phenotypic evaluations on a wheat F₃ population derived from 155 F₂ plants. Traits related to seed color, including chlorophyll a, chlorophyll b, carotenoid, anthocyanin, L*, a*, and b*, were assessed, revealing highly significant correlations among various traits. Genotyping using 81,587 SNP markers resulted in 3969 high-quality markers, revealing a genome-wide distribution with varying densities across chromosomes. A genome-wide association study using fixed and random model circulating probability unification (FarmCPU) and Bayesian-information and linkage-disequilibrium iteratively nested keyway (BLINK) identified 11 significant marker–trait associations (MTAs) associated with L*, a*, and b*, and chromosomal distribution patterns revealed predominant locations on chromosomes 2A, 2B, and 4B. A comprehensive annotation uncovered 69 genes within the genomic vicinity of each MTA, providing potential functional insights. Gene expression analysis during seed development identified greater than 2-fold increases or decreases in expression in colored wheat for 16 of 69 genes. Among these, eight genes, including transcription factors and genes related to flavonoid and ubiquitination pathways, exhibited distinct expression patterns during seed development, providing further approaches for exploring seed coloration. This comprehensive exploration expands our understanding of the genetic basis of seed color and paves the way for informed discussions on the molecular intricacies contributing to this phenotypic trait. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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22 pages, 4200 KiB

Open AccessArticle

High- or Low-Yielding F₂ Progeny of Wheat Is Result of Specific TaCKX Gene Coexpression Patterns in Association with Grain Yield in Paternal Parent

by Karolina Szala, Marta Dmochowska-Boguta, Joanna Bocian, Wacław Orczyk and Anna Nadolska-Orczyk

Int. J. Mol. Sci. 2024, 25(6), 3553; https://doi.org/10.3390/ijms25063553 - 21 Mar 2024

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Abstract

Members of the TaCKX gene family (GFM) encode oxidase/dehydrogenase cytokinin degrading enzymes (CKX), which play an important role in the homeostasis of phytohormones, affecting wheat development and productivity. Therefore, the objective of this investigation was to test how the expression patterns of the [...] Read more.

Members of the TaCKX gene family (GFM) encode oxidase/dehydrogenase cytokinin degrading enzymes (CKX), which play an important role in the homeostasis of phytohormones, affecting wheat development and productivity. Therefore, the objective of this investigation was to test how the expression patterns of the yield-related TaCKX genes and TaNAC2-5A (NAC2) measured in 7 days after pollination (DAP) spikes and the seedling roots of parents are inherited to apply this knowledge in the breeding process. The expression patterns of these genes were compared between parents and their F₂ progeny in crosses of one mother with different paterns of awnless cultivars and reciprocal crosses of awned and awnless lines. We showed that most of the genes tested in the 7 DAP spikes and seedling roots of the F₂ progeny showed paternal expression patterns in crosses of awnless cultivars as well as reciprocal crosses of awned and awnless lines. Consequently, the values of grain yield in the F₂ progeny were similar to the pater; however, the values of seedling root mass were similar to the mother or both parents. The correlation analysis of TaCKX GFMs and NAC2 in spikes and spikes per seedling roots reveals that the genes correlate with each other specifically with the pater and the F₂ progeny or the mother and the F₂ progeny, which shape phenotypic traits. The numbers of spikes and semi-empty spikes are mainly correlated with the specific coexpression of the TaCKX and NAC2 genes expressed in spikes or spikes per roots of the pater and F₂ progeny. Variable regression analysis of grain yield and root mass with TaCKX GFMs and NAC2 expressed in the tested tissues of five crosses revealed a significant dependency of these parameters on the mother and F₂ and/or the pater and F₂ progeny. We showed that the inheritance of yield-related traits depends on the specific cooperative expression of some TaCKX GFMs, in some crosses coupled with NAC2, and is strongly dependent on the genotypes used for the crosses. Indications for parental selection in the breeding of high-yielding lines are discussed. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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15 pages, 3929 KiB

Open AccessArticle

Identification and Validation of Key Genes Related to Preferred Flavour Profiles in Australian Commercial Papaya (Carica papaya L.)

by Ziwei Zhou, Chutchamas Kanchana-udomkan, Rebecca Ford and Ido Bar

Int. J. Mol. Sci. 2024, 25(5), 3046; https://doi.org/10.3390/ijms25053046 - 6 Mar 2024

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Abstract

Commercial papaya varieties grown in Australia vary greatly in taste and aroma. Previous profiling has identified undesirable ‘off tastes’ in existing varieties, discouraging a portion of the population from consuming papayas. Our focus on enhancing preferred flavours led to an exploration of the [...] Read more.

Commercial papaya varieties grown in Australia vary greatly in taste and aroma. Previous profiling has identified undesirable ‘off tastes’ in existing varieties, discouraging a portion of the population from consuming papayas. Our focus on enhancing preferred flavours led to an exploration of the genetic mechanisms and biosynthesis pathways that underlie these desired taste profiles. To identify genes associated with consumer-preferred flavours, we conducted whole RNA sequencing and de novo genome assembly on papaya varieties RB1 (known for its sweet flavour and floral aroma) and 1B (less favoured due to its bitter taste and musty aroma) at both ripe and unripe stages. In total, 180,368 transcripts were generated, and 118 transcripts related to flavours were differentially expressed between the two varieties at the ripe stage. Five genes (cpBGH3B, cpPFP, cpSUS, cpGES and cpLIS) were validated through qPCR and significantly differentially expressed. These genes are suggested to play key roles in sucrose metabolism and aromatic compound production pathways, holding promise for future selective breeding strategies. Further exploration will involve assessing their potential across broader germplasm and various growth environments. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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19 pages, 4971 KiB

Open AccessArticle

A Comprehensive Identification and Expression Analysis of the WUSCHEL Homeobox-Containing Protein Family Reveals Their Special Role in Development and Abiotic Stress Response in Zea mays L.

by Xuanxuan Chen, Yunyan Hou, Yongyan Cao, Bo Wei and Lei Gu

Int. J. Mol. Sci. 2024, 25(1), 441; https://doi.org/10.3390/ijms25010441 - 28 Dec 2023

Cited by 2 | Viewed by 1565

Abstract

Maize is an important food and cash crop worldwide. The WUSCHEL (WUS)-related homeobox (WOX) transcription factor (TF) family plays a significant role in the development process and the response to abiotic stress of plants. However, few studies have been reported on the function [...] Read more.

Maize is an important food and cash crop worldwide. The WUSCHEL (WUS)-related homeobox (WOX) transcription factor (TF) family plays a significant role in the development process and the response to abiotic stress of plants. However, few studies have been reported on the function of WOX genes in maize. This work, utilizing the latest maize B73 reference genome, results in the identification of 22 putative ZmWOX gene family members. Except for chromosome 5, the 22 ZmWOX genes were homogeneously distributed on the other nine chromosomes and showed three tandem duplication and 10 segmental duplication events. Based on phylogenetic characteristics, ZmWOXs are divided into three clades (e.g., WUS, intermediate, and ancient groups), and the majority of ZmWOXs in same group display similar gene and protein structures. Cross-species collinearity results indicated that some WOX genes might be evolutionarily conservative. The promoter region of ZmWOX family members is enriched in light, plant growth/hormone, and abiotic stress-responsive elements. Tissue-specific expression evaluation showed that ZmWOX genes might play a significant role in the occurrence of maize reproductive organs. Transcriptome data and RT-qPCR analysis further showed that six ZmWOX genes (e.g., ZmWOX1, 4, 6, 13, 16, and 18) were positively or negatively modulated by temperature, salt, and waterlogging stresses. Moreover, two ZmWOXs, ZmWOX1 and ZmWOX18, both were upregulated by abiotic stress. ZmWOX18 was localized in the nucleus and had transactivation activities, while ZmWOX1 was localized in both the cytoplasm and nucleus, without transactivation activity. Overall, this work offers new perspectives on the evolutionary relationships of ZmWOX genes and might provide a resource for further detecting the biological functions of ZmWOXs. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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Review

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16 pages, 1887 KiB

Open AccessReview

INDETERMINATE DOMAIN Transcription Factors in Crops: Plant Architecture, Disease Resistance, Stress Response, Flowering, and More

by Akiko Kozaki

Int. J. Mol. Sci. 2024, 25(19), 10277; https://doi.org/10.3390/ijms251910277 - 24 Sep 2024

Viewed by 817

Abstract

INDETERMINATE DOMAIN (IDD) genes encode plant-specific transcription factors containing a conserved IDD domain with four zinc finger motifs. Previous studies on Arabidopsis IDDs (AtIDDs) have demonstrated that these genes play roles in diverse physiological and developmental processes, including plant [...] Read more.

INDETERMINATE DOMAIN (IDD) genes encode plant-specific transcription factors containing a conserved IDD domain with four zinc finger motifs. Previous studies on Arabidopsis IDDs (AtIDDs) have demonstrated that these genes play roles in diverse physiological and developmental processes, including plant architecture, seed and root development, flowering, stress responses, and hormone signaling. Recent studies have revealed important functions of IDDs from rice and maize, especially in regulating leaf differentiation, which is related to the evolution of C₄ leaves from C₃ leaves. Moreover, IDDs in crops are involved in the regulation of agriculturally important traits, including disease and stress resistance, seed development, and flowering. Thus, IDDs are valuable targets for breeding manipulation. This review explores the role of IDDs in plant development, environmental responses, and evolution, which provides idea for agricultural application. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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23 pages, 1390 KiB

Open AccessReview

A Systematic Review and Developmental Perspective on Origin of CMS Genes in Crops

by Xuemei Zhang, Zhengpin Ding, Hongbo Lou, Rui Han, Cunqiang Ma and Shengchao Yang

Int. J. Mol. Sci. 2024, 25(15), 8372; https://doi.org/10.3390/ijms25158372 - 31 Jul 2024

Viewed by 1050

Abstract

Cytoplasmic male sterility (CMS) arises from the incompatibility between the nucleus and cytoplasm as typical representatives of the chimeric structures in the mitochondrial genome (mitogenome), which has been extensively applied for hybrid seed production in various crops. The frequent occurrence of chimeric mitochondrial [...] Read more.

Cytoplasmic male sterility (CMS) arises from the incompatibility between the nucleus and cytoplasm as typical representatives of the chimeric structures in the mitochondrial genome (mitogenome), which has been extensively applied for hybrid seed production in various crops. The frequent occurrence of chimeric mitochondrial genes leading to CMS is consistent with the mitochondrial DNA (mtDNA) evolution. The sequence conservation resulting from faithfully maternal inheritance and the chimeric structure caused by frequent sequence recombination have been defined as two major features of the mitogenome. However, when and how these chimeric mitochondrial genes appear in the context of the highly conserved reproduction of mitochondria is an enigma. This review, therefore, presents the critical view of the research on CMS in plants to elucidate the mechanisms of this phenomenon. Generally, distant hybridization is the main mechanism to generate an original CMS source in natural populations and in breeding. Mitochondria and mitogenomes show pleomorphic and dynamic changes at key stages of the life cycle. The promitochondria in dry seeds develop into fully functioning mitochondria during seed imbibition, followed by massive mitochondria or mitogenome fusion and fission in the germination stage along with changes in the mtDNA structure and quantity. The mitogenome stability is controlled by nuclear loci, such as the nuclear gene Msh1. Its suppression leads to the rearrangement of mtDNA and the production of heritable CMS genes. An abundant recombination of mtDNA is also often found in distant hybrids and somatic/cybrid hybrids. Since mtDNA recombination is ubiquitous in distant hybridization, we put forward a hypothesis that the original CMS genes originated from mtDNA recombination during the germination of the hybrid seeds produced from distant hybridizations to solve the nucleo-cytoplasmic incompatibility resulting from the allogenic nuclear genome during seed germination. Full article

(This article belongs to the Special Issue Molecular Breeding and Genetic Regulation of Crops)

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