Elucidating Mitochondrial DNA Markers of Ogura-Based CMS Lines in Indian Cauliflowers (Brassica oleracea var. botrytis L.) and Their Floral Abnormalities Due to Diversity in Cytonuclear Interactions

Mitochondrial markers can be used to differentiate diverse mitotypes as well as cytoplasms in angiosperms. In cauliflower, cultivation of hybrids is pivotal in remunerative agriculture and cytoplasmic male sterile lines constitute an important component of the hybrid breeding. In diversifying the source of male sterility, it is essential to appropriately differentiate among the available male sterile cytoplasms in cauliflower. PCR polymorphism at the key mitochondrial genes associated with male sterility will be instrumental in analyzing, molecular characterization, and development of mitotype-specific markers for differentiation of different cytoplasmic sources. Presence of auto- and alloplasmic cytonuclear combinations result in complex floral abnormalities. In this context, the present investigation highlighted the utility of organelle genome-based markers in distinguishing cytoplasm types in Indian cauliflowers and unveils the epistatic effects of the cytonuclear interactions influencing floral phenotypes. In PCR-based analysis using a set of primers targeted to orf-138, 76 Indian cauliflower lines depicted the presence of Ogura cytoplasm albeit the amplicons generated exhibited polymorphism within the ofr-138 sequence. The polymorphic fragments were found to be spanning over 200–280 bp and 410–470 bp genomic regions of BnTR4 and orf125, respectively. Sequence analysis revealed that such cytoplasmic genetic variations could be attributed to single nucleotide polymorphisms and insertion or deletions of 31/51 nucleotides. The cytoplasmic effects on varying nuclear-genetic backgrounds rendered an array of floral abnormalities like reduction in flower size, fused flowers, splitted style with the exposed ovule, absence of nonfunctional stamens, and petaloid stamens. These floral malformations caused dysplasia of flower structure affecting female fertility with inefficient nectar production. The finding provides an important reference to ameliorate understanding of mechanism of cytonuclear interactions in floral organ development in Brassicas. The study paves the way for unraveling developmental biology of CMS phenotypes in eukaryotic organisms and intergenomic conflict in plant speciation.

Diallel analysis of “dedo-de-moça” pepper seeds in relation to physiological potential

ABSTRACT “Dedo-de-moça” (Capsicum baccatum var. pendulum) is one of the main chili peppers grown worldwide. However, studies on genetics and breeding of this species are rare, when compared to other Capsicum species, manly in relation to physiological seed quality traits. In this sense, this study aimed to evaluate the combining ability of “dedo-de-moça” chili pepper in relation to physiological seed quality traits, determine the gene effects involved in the expression of these traits, and identify promising hybrid combinations. Crosses among five parents (Hortivale, Horticeres, Brs Mari, UEL 110 and UEL 111) in a full diallel mating design, resulted in 20 F1 hybrids. Griffing’s diallel model was used to estimate general and specific combining ability (GCA and SCA, respectively) as well as the reciprocal effect (RE). Wide genetic variability was observed for all evaluated traits. Significant effects of GCA, SCA and RE were also verified for all traits, showing that additive, non-additive and cytoplasmic effects are involved in the genetic control of physiological seed quality. Non-additive effects were predominant for all traits, being UEL 111 (♂) × Hortivale (♀) and Hortivale (♂) × UEL 110 (♀) considered promising hybrids for obtaining more vigorous seeds with higher germination and greater longevity.

Elucidating mitochondrial DNA-markers of Ogura-based CMS linesin Indian cauliflowers (Brassica oleracea var. botrytis L.) and their floral abnormalities due to diversity in cyto-nuclear interaction

Background: Mitochondrial markers can be used to differentiate diverse mitotypes as well as cytoplasms in angiosperms. In cauliflower, cultivation of hybrids is pivotal in remunerative agriculture and cytoplasmic male sterile lines constitute an important component of the hybrid breeding. Thus, the breeders look for utilizing diverse male sterile cytoplasms in hybrid progamme. In diversifying source of male sterility,it is essential to appropriately differentiate among the available male sterile cytoplasms in cauliflower.PCR polymorphism atthe key mitochondrial genes associated with male sterility will be useful in developing mitochondria specific markers for the different male sterile cytoplasms. Also, the auto and alloplasmic cytonuclear combinations result in complex floral abnormalities.Thus, the study aimed at developing mitotype specific markers of the sterile cytoplasms and to unravel thegenetic effects of the cytonuclear interactions on flower morphology in Indian cauliflowers.Results: In PCR based analysis using a set of primers targeted to orf-138, 76 Indian cauliflower lines showed presence of Ogura cytoplasm though amplicons showed polymorphism within the ofr-138 sequence. The polymorphic loci were found to be spanning over 200-280 bp and 410-470bp genomic regions of BnTR4 and orf125, respectively. Sequence analysis revealed that such cytoplasmic genetic variations could be due to single nucleotide polymorphisms and insertion or deletions of31/51 nucleotides.The cytoplasmic effects on varying nuclear-genetic backgrounds led to varying degree of floral malformations ranging from reduction in flower size, stamens and style length, modification in position of styleand anthers, absence of non-functional stamens to other floral abnormalities. These floral malformations caused dysplasia of flower structure affecting female fertility and inefficient nectar production.Conclusions: The mitochondria specific markers can distinguish ogurabased male sterile cytoplasm. Large number of Indian cauliflower lines showed mitotype variations even within the ogura based cytoplasm. Variable nucleo-cytoplasmic interactions resulted into diverse type of floral malformationsin addition to pollen sterility even within the group of ogura based CMS lines. The finding provide important reference ameliorate understanding of mechanism of cytonuclear interactions in floral organ development in Brassicas. The study will help the breeders in selecting CMS lines without any floral abnormalities in B. oleracea.

Characterization for Drought Tolerance and Physiological Efficiency in Novel Cytoplasmic Male Sterile Sources of Sunflower (Helianthus annuus L.)

Sunflower is sensitive to drought, and furthermore, sunflower hybrids display limited cytoplasmic diversity. In addition, the wild cytoplasmic sources of sunflower are not well explored for their potential to introduce drought tolerance into newly developed hybrids. Therefore here, we carried out a Line × Tester-based genetic study using 19 sunflower genotypes representing, 13 cytoplasmic male sterile (CMS) lines from wild and conventional sources, 2 maintainer lines, and 4 restorer lines. The CMS and maintainer lines were crossed with restorer lines to develop sixty F1 hybrids. The parents and their hybrids were evaluated under two water regimes, normal irrigation and drought stress (i.e., withholding water). A total of twelve important plant descriptors were studied over a period of two years and the significant differences between parents and hybrids are reported here. More specifically, hybrid lines were higher in average values for all the descriptors. The contribution of female parent was more prominent in the expression of traits in hybrids as compared to male parents. The CMS sources varied significantly regarding seed yield per plant and other physiological traits. Proline content in the leaves of all the genotypes was three times higher in the water stress regime. Accession CMS-PKU-2A was identified as the best general combiner for leaf area and specific leaf weight., whereas CMS-234A was the best general combiner for biological yield and photosynthetic efficiency under both conditions. The cross combinations CMS-ARG-2A × RCR-8297, CMS-234A × P124R, and CMS-38A × P124R were found significant for biological yield, seed yield and oil content under both environments. Overall, this study provides useful information about the cytoplasmic effects on important sunflower traits and drought stress tolerance.

The Cytoplasm Affects the Epigenome in Drosophila melanogaster

Cytoplasmic components and their interactions with the nuclear genome may mediate patterns of phenotypic expression to form a joint inheritance system. However, proximate mechanisms underpinning these interactions remain elusive. To independently assess nuclear genetic and epigenetic cytoplasmic effects, we created a full-factorial design in which representative cytoplasms and nuclear backgrounds from each of two geographically disjunct populations of Drosophila melanogaster were matched together in all four possible combinations. To capture slowly-accumulating epimutations in addition to immediately occurring ones, these constructed populations were examined one year later. We found the K4 methylation of histone H3, H3K4me3, an epigenetic marker associated with transcription start-sites had diverged across different cytoplasms. The loci concerned mainly related to metabolism, mitochondrial function, and reproduction. We found little overlap (<8%) in sites that varied genetically and epigenetically, suggesting that epigenetic changes have diverged independently from any cis-regulatory sequence changes. These results are the first to show cytoplasm-specific effects on patterns of nuclear histone methylation. Our results highlight that experimental nuclear-cytoplasm mismatch may be used to provide a platform to identify epigenetic candidate loci to study the molecular mechanisms of cyto-nuclear interactions.

Inheritance of germination vigour in sugar beet sterility maintainers and their diallel hybrids

Aim. To determine the degree of dominance of the “seed germination” sign and combination ability of sterility maintainers using diallel analysis. Methods. Hybridization of sterility maintainers was arranged as diallel crosses. Genetic determination of the sign was determined in accordance with Heyman’s method. Results. Used in crossing sterility maintainer lines have been studied in terms of their productivity in previous variety tests. D. The dominant inheritance of “seed germination” sign in diallel hybrids was determined as following: in the structure of the sign variability 43 % of cross combinations inherited this sign as positive dominance. Genetic determination of the “synergy of germination” sign was determined by the effects of combination ability. The additive effect of the female parent was assessed at 18.4 %, in male parent at 18.1 %, while the nonadditive effect of interaction between the components was at 40.7 % The influence of cytoplasmic effects amounted to 22,7 %. Selected were the best lines in specific pairs; their genetic value was studied as the average value of heterosis in many crossings involving specific lines. Conclusions. When forming sources of improved signs it is advisable to consider the cytoplasmic gene effects, which share is estimated at 22.7 %. The best lines in terms of general combination ability for seed germination found to be sterility maintainers Ot 1 and Ot 2. Keywords: sterility maintainers, combination ability, seed germination, additive, non-additive, and reciprocal effects.

Characterization for Drought Tolerance and Physiological Efficiency in Novel Cytoplasmic Male Sterile Sources of Sunflower (Helianthus annuus L.)

Sunflower is sensitive to drought and its hybrids have a limited cytoplasmic diversity. The wild cytoplasmic sources of sunflower are not well exploited to their potential for drought tolerance and hybrid development. In this respect, we carried out a Line × Tester based genetic study using 19 sunflower genotypes representing, 13 cytoplasmic male sterile (CMS) lines from wild and conventional sources, 2 maintainer lines, and 4 restorer lines. The CMS and maintainer lines were crossed with restorer lines to develop sixty one-way F1 hybrids. The parents and their hybrids were evaluated under two water regimes viz., normal irrigated and water stress. A total of twelve important plant descriptors were studied over a period of two years. The significant differences were observed between parents and hybrids in both water regimes. Hybrids were higher in average values for all the descriptors than parents. The role of female parent was more prominent in the expression of traits in hybrids as compared to male parents. The CMS sources varied significantly regarding seed yield per plant and other physiological traits. Proline content was three times higher in parents and their hybrids under water stress, and it was not correlated with any other descriptor. Accession CMS-PKU-2A was identified as the best general combiner for leaf area and specific leaf weight. Whereas, CMS-234A was the best general combiner for biological yield and photosynthetic efficiency under both the conditions. The cross combinations CMS-ARG-2A × RCR-8297, CMS-234A × P124R, and CMS-38A × P124R were found significant for biological yield, seed yield and oil content under both environments. Overall, this study provides useful information about the cytoplasmic effects on important sunflower traits and drought stress tolerance when used in the different combinations.

Combining ability and heterosis analysis for mineral elements by using cytoplasmic male-sterile systems in non-heading Chinese cabbage (Brassica rapa)

Brassica vegetables are an important source of dietary nutrition. The nutritional quality of mineral elements is becoming one of the most important studied traits because of the year-round supply of vegetables in China. However, there are few reports about breeding and utilisation of mineral elements in non-heading Chinese cabbage (Brassica napus L.). Using two newly reported CMS (cytoplasmic male-sterile) lines of non-heading Chinese cabbage, we conducted incomplete diallel experiments to analyse heterosis, combining ability and cytoplasmic effects for mineral elements such as calcium (Ca), iron (Fe), magnesium (Mg) and zinc (Zn). Heterosis analysis of mineral elements indicated that the crossing combinations A1 (hau CMS) × C03, A2 (eru CMS) × C03 and A2 × C11 exhibited desirable positive effects of mid-parent heterosis and high-parent heterosis in terms of mineral element content that could be exploited for commercial purposes. Analysis of general combining ability (GCA) effects of the parental lines indicated that the tester C11 was superior for the improvement of the four mineral elements; CMS line A1 had greater GCA effects than CMS line A2 for Ca and Fe. The hybrid combinations A2 × C11, B × C05 and B × C12 showed positive specific combining ability (SCA) effects for the four mineral elements on overall performance. The analysis revealed that cytoplasmic effects of hau CMS and eru CMS were both positive for Ca and Fe, and that A1 had more obvious cytoplasmic effects than did A2. These results indicated that the two isonuclear, alloplasmic CMS lines of non-heading Chinese cabbage might be useful for improving the nutritional quality traits of cruciferous vegetables and for heterosis utilisation.