Genetic characteristics and ploidy trigger the high inducibility of double haploid (DH) inducer in Brassica napus

Background Our recently reported doubled haploid (DH) induction lines e.g., Y3380 and Y3560 are allo-octoploid (AAAACCCC, 2n = 8× ≈ 76), which can induce the maternal parent to produce DH individuals. Whether this induction process is related to the production of aneuploid gametes form male parent and genetic characteristics of the male parent has not been reported yet. Results Somatic chromosome counts of DH inducer parents, female wax-less parent (W1A) and their F1 hybrid individuals revealed the reliability of flow cytometry analysis. Y3560 has normal chromosome behavior in metaphase I and anaphase I, but chromosome division was not synchronized in the tetrad period. Individual phenotypic identification and flow cytometric fluorescence measurement of F1 individual and parents revealed that DH individuals can be distinguished on the basis of waxiness trait. The results of phenotypic identification and flow cytometry can identify the homozygotes or heterozygotes of F1 generation individuals. The data of SNP genotyping coupled with phenotypic waxiness trait revealed that the genetic distance between W1A and F1 homozygotes were smaller as compared to their heterozygotes. It was found that compared with allo-octoploids, aneuploidy from allo-octoploid segregation did not significantly increase the DH induction rate, but reduced male infiltration rate and heterozygous site rate of induced F1 generation. The ploidy, SNP genotyping and flow cytometry results cumulatively shows that DH induction is attributed to the key genes regulation from the parents of Y3560 and Y3380, which significantly increase the induction efficiency as compared to ploidy. Conclusion Based on our findings, we hypothesize that genetic characteristics and aneuploidy play an important role in the induction of DH individuals in Brassca napus, and the induction process has been explored. It provides an important insight for us to locate and clone the genes that regulate the inducibility in the later stage.

Improvement ability of male parent by gibberellic acid application to enhancing the outcrossing of cytoplasmic male sterility rice lines

<p class="042abstractstekst">The study quantified the effect of gibberellic acid (GA₃) as a pre-flowering treatment for male parent Giza 178 R and the influence of male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) for two Cytoplasmic Male Sterility (CMS) lines (‘IR69625’ and ‘G46’) on hybrid rice seed production. The main plots were occupied by CMS lines while; GA3 application for male parent Giza 178R were arranged in the sub plots and male to female ratio was arranged in the sub-sub plots. The results indicated that, the, duration of floret opening, angle of floret opening, filaments exsertion, filaments length<strong>, </strong>anther length, plant height and number of tiller hill^-1of male parent Giza 178R were significantly at 300 g GA₃ ha^-1 concentration. Plant height, panicle exsertion, panicle length, flag leaf angle and 1000-grain mass of CMS were not significantly affected by the GA₃ application for male parent and male to female ratio, while, number of fertile panicles hill^-1, panicle mass, seed set, seed yield and harvest index of CMS lines were highly significantly affected. The highest seed yield (2.880 and 2.950 t ha^-1) was obtained by CMS line IR69625A using 300 g GA₃ ha^-1 of male parent Giza 178R with male to female ratio of 2R:14A during both seasons.</p>

Improvement ability of male parent by gibberellic acid application to enhancing the outcrossing of cytoplasmic male sterility rice lines

<p class="042abstractstekst">The study quantified the effect of gibberellic acid (GA₃) as a pre-flowering treatment for male parent Giza 178 R and the influence of male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) for two Cytoplasmic Male Sterility (CMS) lines (‘IR69625’ and ‘G46’) on hybrid rice seed production. The main plots were occupied by CMS lines while; GA3 application for male parent Giza 178R were arranged in the sub plots and male to female ratio was arranged in the sub-sub plots. The results indicated that, the, duration of floret opening, angle of floret opening, filaments exsertion, filaments length<strong>, </strong>anther length, plant height and number of tiller hill^-1of male parent Giza 178R were significantly at 300 g GA₃ ha^-1 concentration. Plant height, panicle exsertion, panicle length, flag leaf angle and 1000-grain mass of CMS were not significantly affected by the GA₃ application for male parent and male to female ratio, while, number of fertile panicles hill^-1, panicle mass, seed set, seed yield and harvest index of CMS lines were highly significantly affected. The highest seed yield (2.880 and 2.950 t ha^-1) was obtained by CMS line IR69625A using 300 g GA₃ ha^-1 of male parent Giza 178R with male to female ratio of 2R:14A during both seasons.</p>

Pollen Competition and Paternal Contribution during Artificially Controlled Pollination of Black Locust (Robinia pseudoacacia L.) without Castration

(1) Background: Considering the serious damage caused by castration and the extremely high outcrossing rate in nature, we hypothesized that artificial controlled pollination of black locust without castration could be conducted for hybridization breeding. (2) Methods: The study conducted controlled pollination on 20 mating combinations of black locust without castration using a single or mixed male parent. Offspring of different developmental stages and the leaves of parents were collected to extract DNA and perform paternity analysis using SSR molecular markers. (3) Results: The contribution rate of each male parent differed according to developmental stage after pollination using different pollens mixed in equal proportions. There were significant correlations between the genetic similarity between each male parent and female parent and contribution rate of each male parent at three different developmental stages after pollination. (4) Conclusions: The composition of offspring pollen donors showed no bias toward selfing or outcrossing when artificially pollinated without castration. Hybrid breeding of black locust by artificially controlled pollination without castration may not be feasible, given that our manual method resulted in a large number of abortive and abnormal offspring. Introduction of honeybees in a limited space to conduct controlled pollination of black locust for hybrid breeding may be feasible.

Comparative analysis morphology, anatomical structure and transcriptional regulatory network of chlorophyll biosynthesis in Oryza longistaminata, O. sativa and their F1 generation

Oryza longistaminata, a perennial wild species, is widely distributed in the African continent. It has strong tolerance to biotic and abiotic stresses, and high biomass production on poor soils. Chlorophyll biosynthesis is important for photosynthesis in rice. However, the chlorophyll biosynthesis and related gene profiles of O. longistaminata and its descendants remained unclear. Here, the F1 generation of O. sativa and O. longistaminata were obtained. Then, the comparative analysis morphology, anatomical structure, and transcriptional regulatory networks of chlorophyll biosynthesis were detected and analyzed. Results showed that the F1 generation has obvious long awn, similar with that of the male parent. The purple color of the long awn is different from that of the male parent. Microstructural results showed that the flag leaves of F1 have large mesophyll cell gaps in the upper- and lower-positions, small mesophyll cell gaps in the middle position, and more chloroplasts. Increased chlorophyll content was also observed in the F1 generation. In the lower-position flag leaves, the total chlorophyll contents of F1 were 1.55 and 1.5 times those of O. sativa and O. longistaminata, respectively. POR, MgCH and HEMA1 showed higher expression levels than the other related genes selected in the chlorophyll biosynthesis pathway. The HEMA1 expression level in the middle-position flag leaves of O. longistaminata was the highest, and it was 2.83 and 2.51 times that of O. sativa and F1, respectively. The expression level of DVR gene in lower-position flag leaves of F1 were 93.16% and 95.06% lower than those of O. sativa and O. longistaminata, respectively. This study provided a potential reference for studying the photosynthesis and heterosis utilization of O. longistaminata.

Male parent birds exert more effort to reproduce in two desert passerines

Background Parental investment by birds is limited by the habitat environment, and a male parent increases its effort to reproduce in birds that live in high-altitude areas. Methods A study of the reproductive behaviour of the Saxaul Sparrow (Passer ammodendri) and the Isabelline Shrike (Lanius isabellinus) was carried out at the Gansu An’xi Extremely Arid Desert National Nature Reserve in northwest China to determine the reproductive input of passerine species in desert habitats. Results In Saxaul Sparrows, compared to the female parent, the male parent exhibited a significantly higher frequency of nest-defense behaviour (chirping and warning) during nesting, hatching and feeding periods. In addition, in comparison to the female parent, the male parent exhibited almost equal frequencies of nesting and incubation but fed nestlings significantly more times. Similar to the male sparrows, the feeding rates of the male Isabelline Shrikes were significantly higher than those of the females. The hatching rate and fledging rate of the Saxaul Sparrow on average in this study were 81.99 and 91.92%, respectively, while those of the shrike were 69.00 and 96.53%, respectively. Conclusions These two different passerine species living in the same desert environment exhibited the same trend in their reproductive investments. Adapting to desert environments is a strategy that may have evolved in passerines where male parent birds put more effort than females into reproduction to ensure high reproductive output.

Genetic Analysis of Mitochondrial Sorting from the MSC3 Mosaic Mutant of Cucumber

Cucumber (Cucumis sativus) plants regenerated from cell cultures occasionally possess mosaic (MSC) phenotypes on cotyledons and leaves. Lines MSC3 and MSC16 have distinct MSC phenotypes and originated from plants regenerated from different cell-culture experiments established using a highly inbred wild-type cucumber. Both the mitochondrial (mt) DNA and MSC phenotype of cucumber show paternal transmission, and MSC3 and MSC16 have different mt coding regions at significantly lower copy numbers relative to wild-type plants. A nuclear locus, Paternal sorting of mitochondria (Psm), conditions a high proportion of wild-type progenies, specifically when MSC16 is crossed as the male with wild-type female plants. During this research, we identified plants that produced a high proportion of wild-type progenies in crosses with MSC3 as the male parent. Plants from an F2 family were crossed with MSC3 as the male, progenies were scored for numbers of MSC vs. wild-type plants, and single-nucleotide polymorphisms (SNP) were identified for genetic mapping. A major quantitative trait locus on chromosome 3 was associated with a higher frequency of wild-type progenies from MSC3 as the male parent, and the 1.5-logarithm-of-odds interval for the most significant SNP was located 627 kb from Psm. These results reveal that separate genetic factors control sorting to the wild-type phenotype in progenies from crosses with different MSC parents. The identification of causal genes controlling mitochondrial sorting in cucumber should provide insight regarding nuclear-mitochondrial interactions affecting the prevalence of specific mitochondrial DNA in plants.

Hybridization of Castor Bean (Ricinus communis L.) in Morelos, México

Objective: To determine the stigma receptivity and the pollen viability in order to make manual crosses and obtain viable progeny in castor bean (Ricinus communis L.).Design/Methodology/Approach: Pollen viability tests were made on breeding materials by staining with acetocarmine solution. In elite materials, the receptivity of the stigma was evaluated with hydrogen peroxide. From the inflorescences, the male ones were removed and the female ones were preserved, which were covered with a glassine bag. After six days, they were checked and when they were considered receptive, manual pollinations were carried out between viable pollen materials and receptive stigma. The pollen of the male parent was impregnated in the stigmas and the inflorescence was covered again.Results: The breeding materials exhibited viable pollen since they were stained red. Whereas, the application of hydrogen peroxide to the stigmas of the elite materials showed bubbling, indicative that they were receptive. In 2014, 400 inflorescences were pollinated with 8 flowers on average and a fruit pollinated percentage of 61.21. In 2015, 245 inflorescences with 12 flowers on average and 61.24% of fruit were pollinated.Study Limitations/Implications: Temperature and relative humidity were fundamental factors for the success of castor bean fertilization.Findings/Conclusions: The elite castor bean materials presented receptive stigmas and the improved viable pollen materials. Manual crosses produced fruits and seeds. The fruits pollinated were 61%.

Studies on sexual compatibility and or incompatibility among Psidium species and their hybridity confirmation through ssr markers

The present investigation was carried out with an aim to determine the cross compatibility between Psidium species (P. chinensis, P. guineense, P. cattleianum and P. molle) and commercial guava cultivars (Arka Kiran, Arka Rashmi, Arka Mridula and Allahabad Safed). The results revealed that, P. chinensis and P. guineense were found to be good cross compatible male parents whereas, Allahabad Safeda and Arka Kiran were found to be good cross compatible female parents. However, no fruit set and seed set were obtained when P. cattleianum and P. molle were used as male parent indicating the cross incompatibility of these species with commercial guava cultivars which is reconfirmed using florescence microscopy technique to understand the pollen-pistil interaction between incompatible P. cattleianum and P. molle species with P. guajava cv. Allahabad Safeda. Result indicated that low fluorescence intensity along with poor pollen germination and improper pollen-tube growth could be the reason for incompatibility. In order to break this incompatibility, a modified pollination technique called stigma maceration technique was followed wherein stigma of the male parent macerated with different chemicals viz., carbohydrate source (2% sucrose), growth regulators (50 ppm GA3 and iaa) and micronutrients (50 ppm of each Boric acid, MgSO4, CaNO3 and KNO3) and pollinated twice i.e., on the day of flower opening and the same time of next day resulted in cross compatibility of P. cattleianum and P. molle with commercial guava cultivars. Further hybridity confirmation of interspecific hybrids using ssr markers revealed that, 8 markers were found to be co-dominant and confirmed the hybridity of interspecific hybrid combinations.