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18 páginas, 6 tablas, 1 figura, Delayed senescence could contribute to maintain yield under water stress and low nitrogen stress. Landraces from arid areas can provide favorable alleles for stay green under stress. The objectives of this study were to estimate varietal and heterosis effects of Algerian Saharan populations and their crosses for stay-green under water stress and no-nitrogen fertilization and to identify the most promising populations as sources of stay-green under stress. Six Algerian maize populations were evaluated in a diallel under water stress (300 mm irrigation) versus control (600 mm) and no-nitrogen fertilization versus 120 kg/ha N fertilization. Both varietal and specific heterosis were involved in delayed senescence under stress. Breeding programs could capitalize additive components by using the populations IZM or IGS with favorable varietal effects for delayed senescence under nitrogen stress, or dominance effects by using the population AOR with favorable heterotic effects for plant color under water and nitrogen stresses. Based on specific heterosis, under water stress conditions with no-nitrogen supply, the most promising cross was AOR × IZM for delayed senescence, while IZM × BAH (with no-nitrogen supply), and SHH × BAH (with nitrogen fertilizer), will allow a longer maintenance of the plant coloration. We suggest reciprocal recurrent selection with these populations for developing drought-tolerant and low nitrogen hybrids to improve stay-green., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This research was funded by the École Nationale Supérieure Agronomique; Spanish Ministerio de Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI) and the European Fund for Regional Development (FEDER), UE (project code PID2019-108127RB-I00) and by PRIMA, a program supported by the European Union under H2020 framework programme (Proj. 1586, Ref PCI2021-121912).

Interspecific hybridization resulted in the creation of B. juncea introgression lines (ILs) generated from B. carinata with increased productivity and adaptability. Forty ILs were crossed with their respective B. juncea recipient parents to generate introgression line hybrids (ILHs) and the common tester (SEJ 8) was used to generate test hybrids (THs). Mid-parent heterosis in ILHs and standard heterosis in THs were calculated for eight yield and yield-related traits. Heterotic genomic regions were dissected using ten ILs with significant mid-parent heterosis in ILHs and standard heterosis in THs for seed yield. A high level of heterosis for seed yield was contributed by 1000 seed weight (13.48%) in D31_ILHs and by total siliquae/plant (14.01%) and siliqua length (10.56%) in PM30_ILHs. The heterotic ILs of DRMRIJ 31 and Pusa Mustard 30 were examined using polymorphic SNPs between the parents, and a total of 254 and 335 introgressed heterotic segments were identified, respectively. This investigation discovered potential genes, viz., PUB10, glutathione S transferase, TT4, SGT, FLA3, AP2/ERF, SANT4, MYB, and UDP-glucosyl transferase 73B3 that were previously reported to regulate yield-related traits. The heterozygosity of the FLA3 gene significantly improved siliqua length and seeds per siliqua in ILHs of Pusa Mustard 30. This research proved that interspecific hybridization is an effective means of increasing the diversity of cultivated species by introducing new genetic variants and improving the level of heterosis.

Heterosis is the phenomenon in which some hybrid traits are superior to those of their parents. Most studies have analyzed the heterosis of agronomic traits of crops; however, heterosis of the panicles can improve yield and is important for crop breeding. Therefore, a systematic study of panicle heterosis is needed, especially during the reproductive stage. RNA sequencing (RNA Seq) and transcriptome analysis are suitable for further study of heterosis. Using the Illumina Nova Seq platform, the transcriptome of ZhongZheYou 10 (ZZY10), an elite rice hybrid, the maintainer line ZhongZhe B (ZZB), and the restorer line Z7-10 were analyzed at the heading date in Hangzhou, 2022. 581 million high-quality short reads were obtained by sequencing and were aligned against the Nipponbare reference genome. A total of 9000 differential expression genes were found between the hybrids and their parents (DGHP). Of the DGHP, 60.71% were up-regulated and 39.29% were down-regulated in the hybrid. Comparative transcriptome analysis revealed that 5235 and 3765 DGHP were between ZZY10 and ZhongZhe B and between ZZY10 and Z7-10, respectively. This result is consistent with the transcriptome profile of ZZY10 and was similar to Z7-10. The expression patterns of DGHP mainly exhibited over-dominance, under-dominance, and additivity. Among the DGHP-involved GO terms, pathways such as photosynthesis, DNA integration, cell wall modification, thylakoid, and photosystem were significant. 21 DGHP, which were involved in photosynthesis, and 17 random DGHP were selected for qRT-PCR validation. The up-regulated PsbQ and down-regulated subunits of PSI and PSII and photosynthetic electron transport in the photosynthesis pathway were observed in our study. Extensive transcriptome data were obtained by RNA-Seq, providing a comprehensive overview of panicle transcriptomes at the heading stage in a heterotic hybrid.

Heterosis contributes greatly to crop production, but the genetic basis of heterosis is not fully understood. To identify heterotic loci (HLs) for grain yield, 12 yield traits were evaluated in four rice (Oryza sativa L.) mapping populations: one parental population of chromosome segment substitution lines derived from a cross between the japonica cultivar Nipponbare and indica cultivar 9311 and three connected test populations in either a homozygous 9311 genetic background or a heterozygous background. A total of 390 HLs were detected for the measured traits in two environments. The genetic bases of heterosis differed between the backcross and testcross populations. At least 10 HLs were confirmed in F1 hybrids between 9311 and near-isogenic lines, each of which carried a heterotic locus of interest in the same 9311 background. All 10 showed overdominant or dominant effects on grain yield and yield components. Among them, three were verified as being associated with yield heterosis and colocalized in the same regions as those containing previously reported heterosis-associated genes. Five HLs were identified to be promising candidate loci that could be used to achieve more than 15% yield heterosis in several commercial rice hybrids. These findings suggest the potential of indica or japonica introgression for increasing yield in hybrid rice breeding programs.

Heterosis, the phenomenon in which hybrids outperform their parents, has been utilized in maize (Zea mays L.) for over 100 years. To provide a more complete understanding of heterosis, we collected a comprehensive transcriptome and translatome dataset on seedling leaves for B73, Mo17, and their F1 hybrid, which provided a dynamic landscape of transcriptomic and translatomic variation in maize. Although additivity accounted for a large proportion of variation at two omics-levels, an elevated nonadditive effect was observed in the translatome, especially in the translated subgenome maize1 genes, and the genes that switched from additivity in the transcriptome to nonadditivity in the translatome were significantly enriched in the subgenome maize1. Many genes with allele-specific expression and translation show dramatic regulatory switches between the transcriptome and translatome, and partial genes with allele-specific translation underlying regulatory mechanism also exhibited subgenome bias. Interestingly, we found the translated isoforms show different expression patterns compared with transcriptome and more genes changed their dominant isoforms during the genetic flow from parents to the hybrid at the translatome level. The translated genes with switched dominant isoforms significantly biased to the subgenome maize2 while genes with conserved dominant isoforms significantly enriched in subgenome maize1. Together, the dynamic changed patterns in translatome across hybrid and parental lines show translational fractionation of the maize subgenomes, which may be associated with heterosis in maize and provides a potential theoretical basis for breeding.

With the application of hybrid wheat, lodging is becoming one of the major factors limiting high yield in its production. However, few studies have focused on combining ability and heterosis analysis of stem-related traits. In this study, 24 crosses were made according to NCII genetic design, using the three (photo-sensitive male sterile lines)×eight (restorer lines) incomplete diallel crosses. The length of basal second internode (LBSI) and breaking strength of basal second internode (BSBSI) as well as other stem-related traits were used to perform the principal component analysis (PCA), combining ability and heterosis analysis. The PCA results showed that the variables could be classified into two main factors, which were named as the positive factor (factor 1) and the negative factor (factor 2), and accounted for 52.3 and 33.2%, respectively, of the total variance in different variables, combined with the analysis for index weight indicated that the factor 1-related traits play positive roles in lodging resistance formation of hybrids. Combining ability variance analysis indicated that its genetic performance was mainly dominated by additive gene effects, and the hybrid combinations with higher lodging resistance can be selected by using of 14GF6085 (R1), 14GF6343-2 (R4), 14GF6937 (R6), 14GF7433-1 (R7), and BS1086 (M3), which are with the features with lower general combining ability (GCA) effects of factor 2-related traits whereas higher GCA effects of factor 1-related traits. The heterosis analysis showed that the wide range of heterosis varied with the traits and combinations, and GCA or specific combining ability (SCA) effects of factor 1-related traits except wall thickness of basal second internode (WTBSI) were positively and closely related to the heterosis of lodging resistance. Generally, the correlation coefficients of heterosis to GCA effects of sterile lines (GCAm) of factor 1-related traits are significantly higher than that to GCA of restorer lines (GCAr) and SCA, combined with the higher GCAm variance values of factor 1-related traits compared to GCAr, the GCAm of factor 1-related traits should be particularly considered when breeding hybrid combinations. The heritability analysis showed that the narrow-sense heritability of the diameter of basal second internode (DBSI) and the center of gravity height (TCGH) were obviously lower (

3 páginas, Maize has been an organism of historical importance to all biologists as eminent researchers such as Beadle, Emerson, McClintock, Stadler and Rhoades made ground-breaking genetic discoveries in maize that hold true for all living organisms (Andorf et al., 2016). Nowadays, plant lignocellulose represents the world’s greatest repository of renewable energy amenable to conversion into liquid, and maize has become one of the preferred choices due to their high biomass yields, broad geographic adaptation, carbon sequestration potential and nutrient utilization (Courtial et al., 2013; van der Weijde et al.). Therefore, this Research Topic aimed (1) to put forward the importance of research focuses in maize as a model organism, presenting recent developments and important accomplishments in moving forward the study of plants, and (2) to shed light on the progress made in the past decade working with maize as an important crop used worldwide., AB and RS work was financed by Spanish National Research Council (CSIC), MG was supported by the Bill and Melinda Gates Foundation (B&MGF), and the United States Agency for International Development (USAID) through the AGGMW (Accelerating Genetic Gains in Maize and Wheat for Improved Livelihoods, B&MGF Investment ID INV-003439) project.

Flag leaf heterosis of inter-subspecific hybrid rice is suggested to be related to leaf area, gene expression pattern and allele-specific expression, putatively related to DNA methylation differences between the hybrid and its parents. Inter-subspecific hybrid rice combinations of indica × japonica have great potential to broaden genetic diversity and enhance the heterosis. The genetic and epigenetic molecular mechanism of its heterosis is not completely understood. Here, the dissection of gene expression and epigenetic regulation of an elite inter-subspecific hybrid rice were reported. In the hybrid, plant height, flag leaf area and Pn showed significant heterosis at the heading stage. Chloroplast-related differentially expressed genes (DEGs) and 530 allele-specific expression genes in hybrid were identified. Analysis of the genome-wide distribution of DNA methylation (5-methylcytosine, 5mC) and its association with transcription showed that there were variant DNA methylation maps and that the regulation of gene expression levels was negatively regulated by DNA methylation in the inter-subspecific hybrid rice. Differentially methylated DEGs were significantly enriched in photosynthetic functions. Moreover, distinct 5mC sequence contexts and distinct functional elements (promoter/gene body) may have different influences on heterosis related genes. The data identified heterosis related molecular mechanisms in inter-subspecific hybrid rice and suggested that epigenetic changes could extensively influence the flag leaf gene expression and heterosis.

Normal microsporogenesis is determined by both nuclear and mitochondrial genes. In maize C-type cytoplasmic male sterility, it is unclear how the development of meiocytes and microspores is affected by the mitochondrial sterility gene and the nuclear restorer gene. In this study, we sequenced the transcriptomes of single meiocytes (tetrad stage) and early mononucleate microspores from sterile and restorer lines. The numbers of expressed genes varied in individual cells and fewer than half of the expressed genes were common to the same cell types. Four comparisons revealed 3379 differentially expressed genes (DEGs), with 277 putatively associated with mitochondria, 226 encoding transcription factors, and 467 possibly targeted by RF4. KEGG analysis indicated that the DEGs in the two lines at the tetrad stage were involved predominantly in carbon metabolism and in amino acid biosynthesis and metabolism, whereas the DEGs during the transition from the tetrad stage to the early mononucleate stage were associated mostly with regulation of protein metabolism, fatty acid metabolism, and anatomical structure morphogenesis. Thus, meiocyte and microspore development was affected by the surrounding cells and the restorer gene, and the restorer gene helped restore the redox homeostasis of microspores and the normal cellular reconstruction during the transition.

Soybean [Glycine max (L.) Merr.] provides a rich source of plant protein and oil worldwide. The commercial use of transgenic technology in soybean has become a classical example of the application of biotechnology to crop improvement. Although genetically modified soybeans have achieved commercial success, hybrid soybean breeding is also a potential way to increase soybean yield. Soybean cytoplasmic male-sterile (CMS) lines have been used in three-line hybrid breeding systems, but their application to exploiting soybean heterosis has been limited by rare germplasm resource of sterile lines. The generation of various genetic diversity male-sterile soybean lines will help to overcome the shortcoming. In this study, we used targeted editing of AMS homologs in soybean by CRISPR/Cas9 technology for the first time to generate stable male-sterile lines. Targeted editing of GmAMS1 resulted in a male-sterile phenotype, while editing of GmAMS2 failed to produce male-sterile lines. GmAMS1 functions not only in the formation of the pollen wall but also in the controlling the degradation of the soybean tapetum. CRISPR/Cas9 technology could be used to rapidly produce stable male-sterile lines, providing new sterile-line materials for soybean hybrid breeding systems.

As an important genetic improvement technique in current production practice, heterosis is widely used to enhance the productive traits of hybrid progeny from their parents. Alternative splicing (AS) analysis can be used as a method for exploring the molecular manifestations of heterosis. In our research, 16 hybrids and their parents were utilized to analyze the heterosis performance and AS events. Statistics of plant gross weight (PGW) showed that these hybrids had prominent heterosis, with the mid-parent heterosis values (MPV) ranging from 15.69% to 233.98%. Through pairwise comparison among the female parent, male parent, and hybrid, there were 2980–3205 AS events in each combination, with intron retention being the most common type followed by alternate 3’ splice site, alternative 5’ splice site, skipped exon, and mutually exclusive exon.There were 263–409 differential AS genes (DASGs) between the female parent and the hybrid, and 234–425 DASGs between the male parent and the hybrid in cross combinations. The DASGs were significantly enriched in 33 metabolic pathways in 16 cross combinations, and DASGs of different cross combinations were enriched in different metabolic pathways. Moreover, 76 DASGs in the strong heterosis combinations were identified and significantly enriched in the metabolic pathways related to amino acid metabolism. Further analysis revealed that most of these DASGs in amino acid metabolism were expressed differently in strong heterosis combinations. In addition, the expression levels of BraA06g014310.3C and BraA03g041700.3C in amino acid metabolism significantly correlated with PGW. These results could provide an index for future studies of the genetic and molecular mechanism of heterosis in hybrids.

Extensive exotic introgression could significantly enlarge the genetic distance of hybrid parental populations to promote strong heterosis. The goal of this study was to investigate whether genome-wide prediction can support pre-breeding in populations with exotic introgressions. We evaluated seed yield, seed yield related traits and seed quality traits of 363 hybrids of Brassica napus (AACC) derived from two parental populations divergent on massive exotic introgression of related species in three environments. The hybrids presented strong heterosis on seed yield, which was much higher than other investigated traits. Five genomic best linear unbiased prediction models considering the exotic introgression and different marker effects (additive, dominance, and epistatic effects) were constructed to test the prediction ability for different traits of the hybrids. The analysis showed that the trait complexity, exotic introgression, genetic relationship between the training set and testing set, training set size, and environments affected the prediction ability. The models with best prediction ability for different traits varied. However, relatively high prediction ability (e.g., 0.728 for seed yield) was also observed when the simplest models were used, excluding the effects of the special exotic introgression and epistasis effect by 5-fold cross validation, which would simplify the prediction for the trait with complex architecture for hybrids with exotic introgression. The results provide novel insights and strategies for genome-wide prediction of hybrids between genetically distinct parent groups with exotic introgressions.

Increasing sorghum production per unit area in the farmer’s field by developing high yielding tannin-free and grain mold tolerant varieties in Senegal is the goal of the present study. Line × tester mating design was used to cross eleven tannin-free non-photoperiodic male fertile sorghum varieties with two male-sterile A-lines to produce 22 F1 hybrids. These hybrids along with the thirteen parents and one grain mold resistant hybrid check were evaluated under natural grain mold infestation in two contrasted sites using a 6 × 6 lattice design with three replications. Results on combining ability suggested that additive gene actions were important in the control of grain mold resistance while non-additive gene actions were preponderant in the inheritance of grain yield. The parental lines F2-20, Macia, Faourou, and Dorado were the best general combiner for grain mold resistance. Of these, Dorado was identified as the best combiner for yield and yield components. Additionally, the hybrid CE310-31A × Sureno was identified as the best hybrids combination for yield, yield components and grain mold resistance. Furthermore, the hybrid crosses CE310-31A × F2-20, CE310-31A × Sureno and AVG-1 × Dorado showed the best mid-parent heterosis for grain yield and resistance to grain mold. Moreover, based on their combining ability and heterosis, seven hybrids were identified for their resistance to grain mold and high yielding. These hybrids could be tested in multi-location trials for a subsequent release.

Heterosis is an important biological phenomenon and widely applied in agriculture. Although many studies have been performed by using vegetative organs of F1 hybrid plants, how heterosis (or hybrid vigor) is initiated and formed, particularly the underlying molecular mechanism, remain elusive. Hybrid contemporary seeds of rice indica varieties 9311 and PA64 were innovatively used and analysis of DNA methylome of embryo and endosperm at early developing stages revealed the globally decreased DNA methylation. Genes, especially those relate to hormones function and transcriptional regulation present non-additive methylation. Previously identified heterosis-related superior genes are non-additively methylated in early developing hybrid contemporary seeds, suggesting that key genes/loci responsible for heterosis are epigenetically modified even in early developing hybrid seeds and hypomethylation of hybrid seeds after cross-pollination finally result in the long-term transcriptional change of F1 hybrid vegetative tissues after germination, demonstrating that altered DNA methylation in hybrid seeds is essential for initiation regulation and maintenance of heterosis exhibiting in F1 hybrid plants. Notably, a large number of genes show non-additive methylation in the endosperm of reciprocal hybrids, suggesting that endosperm might also contribute to heterosis.

Rice (Oryza sativa), a major staple throughout the world and a model system for plant genomics and breeding, was the first crop genome sequenced almost two decades ago. However, reference genomes for all higher organisms to date contain gaps and missing sequences. Here, we report the assembly and analysis of gap-free reference genome sequences for two elite O. sativa xian/indica rice varieties, Zhenshan 97 and Minghui 63, which are being used as a model system for studying heterosis and yield. Gap-free reference genomes provide the opportunity for a global view of the structure and function of centromeres. We show that all rice centromeric regions share conserved centromere-specific satellite motifs with different copy numbers and structures. In addition, the similarity of CentO repeats in the same chromosome is higher than across chromosomes, supporting a model of local expansion and homogenization. Both genomes have over 395 non-TE genes located in centromere regions, of which ∼41% are actively transcribed. Two large structural variants at the end of chromosome 11 affect the copy number of resistance genes between the two genomes. The availability of the two gap-free genomes lays a solid foundation for further understanding genome structure and function in plants and breeding climate-resilient varieties.

Estimation the magnitude of heterosis for yield and yield contributing parameters of Okra was conducted. Fifty-four F1 hybrids were generated by line x tester mating design. These F1s along with 21 parents and commercial check (Mhyco-10) were evaluated in a randomized block design with two replications. Analysis of variance with respect to yield and quality characters in parents and hybrids were highly significant. This indicates the existence of high variation in parents and hybrids for different characters studied. Out of 54 cross combinations, seven crosses revealed the significant and positive heterosis over better parent. While 11 crosses showed positive and significant heterosis over economic parent. It is pertinent to mention that the crop has potential to produce the heterotic cross combinations and such crosses can be used for further improvement of this crop. Five crosses, namely L43 × T44, L22 × T36, L22 × T44, L53 × T36 and L31 × T23 were found to be potential for the production of fruit yield per plant and other desired characters. The high heterosis and per se performance was found in hybrid L43 × T44 over both better parents and standard check for fruit yield per plant. This indicates that the cross can be exploited commercially. Bangladesh J. Bot. 50(3): 531-540, 2021 (September)

In soybean, heterosis achieved through the three-line system has been gradually applied in breeding to increase yield, but the underlying molecular mechanism remains unknown. We conducted a genetic analysis using the pollen fertility of offspring of the cross NJCMS1A×NJCMS1C. All the pollen of F1 plants was semi-sterile; in F2, the ratio of pollen-fertile plants to pollen-semi-sterile plants was 208:189. This result indicates that NJCMS1A is gametophyte sterile, and the fertility restoration of NJCMS1C to NJCMS1A is a quality trait controlled by a single gene locus. Using bulked segregant analysis, the fertility restorer gene Rf in NJCMS1C was located on chromosome 16 between the markers BARCSOYSSR_16_1067 and BARCSOYSSR_16_1078. Sequence analysis of genes in that region showed that GmPPR576 was non-functional in rf cultivars. GmPPR576 has one functional allele in Rf cultivars but three non-functional alleles in rf cultivars. Phylogenetic analysis showed that the GmPPR576 locus evolved rapidly with the presence of male-sterile cytoplasm. GmPPR576 belongs to the RFL fertility restorer gene family and is targeted to the mitochondria. GmPPR576 was knocked out in soybean N8855 using CRISPR/Cas9. The T1 plants showed sterile pollen, and T2 plants produced few pods at maturity. The results indicate that GmPPR576 is the fertility restorer gene of NJCMS1A.

Apomixis is considered to be a natural mode of clonal propogation from seed to seed, in which progeny serves as a replica of maternal genotype. The process evades creation of variation by circumventing sexual fusion and recombination, offering great advantage to fix heterosis or hybrid vigour in plants. As this would permit the conservation of complex favourable genotypes that are of agricultural value, it has immense potential in crop seed production. In order to accomplish this, a comprehensive knowledge on the genetic basis and the molecular mechanisms regulating different components of apomixis stands as a key prerequisite. So far, despite of the persistent interest and extensive research on apomixis, the underlying gene regulatory networks and their evolutionary origins are not well deciphered and still remain unclear. From the developmental perspective, apomixis is widely accepted to be controlled or deviated form of sexual reproduction and studies based on comparative analysis of genes or mutants regulating sexual and apomictic pathways revealed their resemblance across various plant species. Since apomixis is a complex, yet well regulated phenomenon that constantly requires action of specific genes during all developmental stages, the present review summarises recent advances in apomixis and compiles information on vital genes and mutants involved in regulating apomixis during various stages of development. Graphical abstract: Brief illustration on mechanisms of apomictic and sexual life cycle in angiosperms. Apomixis avoids the process of meiosis and recombination offering advantage over sexuals by conservation of heterosis or vigor for several generations, easy maintenance of superior genotypes and rapid production of homozygous lines. In sexuals owing to nuclear division and fertilization, fixation of heterosis cannot be achieved and maintenance/development of homozygous lines becomes intricate.*Based on the fertilization the ploidy of endosperm may vary.

Provitamin A-enriched maize (Zea mays L.) is an important complementary food staple for combating vitamin A deficiency (VAD) in high maize-producing and maize-consuming countries of sub-Saharan Afr...

Hybrid necrosis, caused by complementary genes Ne1 and Ne2, is a serious barrier for combining desirable traits from different genotypes of wheat, affecting the full utilisation of heterosis. To date, both Ne1 and Ne2 are still not isolated although they were documented decades ago. We report here the map-based cloning and functional characterisation of Ne2, encoding a coiled coil-nucleotide-binding site-leucine-rich repeat (CC-NBS-LRR) protein. Homozygous frameshift mutations generated using the CRISPR/Cas9 approach confirmed the Ne2-inducing hybrid necrosis in wheat. Upregulated expression of Ne2 induced by Ne1 and excess hydrogen peroxide accumulation are associated with the necrosis formation. Genetic analyses of a Ne2 allele (Ne2m ) and leaf rust resistance gene LrLC10/Lr13 revealed that they might be the same gene. Furthermore, we demonstrated that the frequency of the Ne2 allele was much lower in landraces (2.00%) compared with that in modern cultivars (13.62%), suggesting that Ne2 allele has been partially applied in wheat genetic improvement. Our findings open opportunities of thoroughly investigating the molecular mechanism of hybrid necrosis, selecting Lr13 and simultaneously avoiding hybrid necrosis in wheat breeding through marker-assisted selection.

Heterosis of grain yield is closely associated with heading date in crops. Gene combinations of the major heading date genes Ghd7, Ghd8, and Hd1 play important roles in enhancing grain yield and adaptation to ecological regions in rice. However, the predominant three-gene combinations for a specific ecological region remain unclear in both three-line and two-line hybrids. In this study, we sequenced these three genes of 50 cytoplasmic male sterile/maintainer lines, 31 photo-thermo-sensitive genic male sterile lines, and 109 restorer lines. Sequence analysis showed that hybrids carrying strong functional alleles of Ghd7 and Hd1 and non-functional Ghd8 are predominant in three-line hybrids and are recommended for rice production in the subtropics around 30°N/S. Hybrids carrying strong functional Ghd7 and Ghd8 and non-functional Hd1 are predominant in two-line hybrids and are recommended for low latitude areas around 23.5°N/S rich in photothermal resources. Hybrids carrying strong functional Ghd7 and Ghd8 and functional Hd1 were not identified in commercial hybrids in the middle and lower reaches of the Yangtze River, but they have high yield potential in tropical regions because they have the strongest photoperiod sensitivity. Based on these findings, two genic sterile lines, Xiangling 628S and C815S, whose hybrids often head very late, were diagnosed with these three genes, and Hd1 was targeted to be knocked out in Xiangling 628S and replaced with hd1 in C815S. The hybrids developed from both modified sterile lines in turn had appropriate heading dates and significantly improved grain yield. This study provides new insights for breeding design to develop hybrids for various regions.

Twelve F1 hybrids developed through line × tester design along with seven parents were evaluated for fruit yield, quality, incidence of bacterial wilt disease and anatomical features of root and stem to study the manifestation of heterobeltiosis, and to understand the implication of anatomical characters towards tolerance against bacterial wilt disease. Two hybrids (Utkal Deepti × CLN-2764A and Utkal Kumari × CLN-2777G) registering substantial tolerance against bacterial wilt exhibited marked heterobeltiosis for fruit yield per plant and other component traits. Hypocotyls of the highly tolerant hybrid did not show any bacterial colonization in xylem tissues under light microscope even at 8 days of inoculation with native bacterial isolate. The potted seedlings of tolerant hybrid showed mean disease index of 1.16 even at 20 days of inoculation with bacterial isolate which indicated promise for its utilization in bacterial wilt prone areas. Establishment of significant negative correlations between the incidence of bacterial wilt disease and the ratio of large vessels/small vessels in stem, diameter of large vessels in stem, and diameter of large vessels in roots suggested that these anatomical characters might be considered as important indices for selection of hybrid tolerant to bacterial wilt disease. Significant heterobeltiosis was also manifested for three anatomical traits. This study justified the scope of utilizing the anatomical features of stem and root in breeding tomato cultivars tolerant to bacterial wilt disease. Overwhelming response of non-additive genetic control for these anatomical traits also exposed the evidence of heterosis breeding for their improvement.

Understanding the molecular mechanisms underlying complex phenotypes requires systematic analyses of complicated metabolic networks and contributes to improvements in the breeding efficiency of staple cereal crops and diagnostic accuracy for human diseases. Here, we selected rice (Oryza sativa) heterosis as a complex phenotype and investigated the mechanisms of both vegetative and reproductive traits using an untargeted metabolomics strategy. Heterosis-associated analytes were identified, and the overlapping analytes were shown to underlie the association patterns for six agronomic traits. The heterosis-associated analytes of four yield components and plant height collectively contributed to yield heterosis, and the degree of contribution differed among the five traits. We performed dysregulated network analyses of the high- and low-better parent heterosis hybrids and found multiple types of metabolic pathways involved in heterosis. The metabolite levels of the significantly enriched pathways (especially those from amino acid and carbohydrate metabolism) were predictive of yield heterosis (area under the curve = 0.907 with 10 features), and the predictability of these pathway biomarkers was validated with hybrids across environments and populations. Our findings elucidate the metabolomic landscape of rice heterosis and highlight the potential application of pathway biomarkers in achieving accurate predictions of complex phenotypes., Specific metabolic pathways (especially those from amino acid and carbohydrate metabolism) underlie heterosis of six agronomic traits in rice.

Heterosis, which describes the superior vigor and yield of F1 hybrids with respect to their parents, is observed in many rice hybrid crosses. The exploitation of heterosis is a great leap in the history of rice breeding. With advances in genomics and genetics, high-resolution mapping and functional identification of heterosis-associated loci have been performed in rice. Here we summarize advances in understanding the genetic basis of grain yield heterosis in hybrid rice and provide a vision for the genetic study and breeding application of rice heterosis in the future.

With the ever-increasing human population and deteriorating environmental conditions, there is an urgent need to breed environmentally friendly and resource-conserving rice cultivars to achieve sustainable agricultural development and food security. However, conventional rice improvement strategies, such as hybrid breeding, are time-consuming and laborious processes and may not be able to keep pace with increasing food demand in the future. Targeted genome-editing technologies, especially clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (CRISPR/Cas), permit efficient targeted genome modification and offer great promise for the creation of desired plants with higher yield, improved grain quality, and resistance to herbicides, diseases, and insect pests. There is also great potential for tapping heterosis using the CRISPR/Cas technology. In this review, we focus on the most essential applications of CRISPR/Cas genome editing to rice genetic improvement, considering traits such as yield, quality, and herbicide, disease and insect-pest resistance. We discuss applications of CRISPR/Cas to the exploitation of heterosis. Finally, we outline perspectives for future rice breeding using genome-editing technologies.

Heterosis is an effective way to increase yield and improve quality in alfalfa breeding. The key issue for efficiently use of heterosis is to identify parents having potential for producing hybrid combinations with higher performance. This study aimed to analyze genetic distance between the 48 alfalfa accessions, and combine different hybrid combinations. The results showed that the mating ability of the hybrid combination in which both parents are tetraploid is greater than that in which both parents are diploid or the hybrid combination with different parental ploidy. When the different ploidy levels of parents, the mating ability of alfalfa hybrid combination with diploid as female parent is better than that of alfalfa hybrid combination with tetraploid as female parent. he hybrid combination of diploid alfalfa as a female parent with tetraploid as a male parent is more heterosis than the hybrid combination of diploid as a male parent. Moreover, CYK2ｘHH10 with high heterosis and CYK4xHH10 with high the relative seed setting rate should be possible to breed high yielding hybrid, which could be used as candidate materials for further research.

Beaked corn represents one of the most characteristics and neglected group of Italian maize landraces. These genotypes, classified in the “Rostrata” group, were mostly grown in northern Italy, on the left bank of the Po river, until the end of the Second World War and then subjected to strong genetic erosion because of the subsequent introduction of improved genotypes and hybrids of US origin. These materials are experiencing a revival period for cultivation, commercial exploitation and an increased number of farmers is seeking particular genotypes for the production of niche products. In Valchiavenna (Sondrio, Lombardia, Italy) maize cultivation has historical importance for polenta preparation and is characterized by the presence of at least three accessions of “Mais Rostrato Val Chiavenna”, one conserved since 1982 in germplasm bank ( here named as R17_BG) and two in situ (here named as R17_M; R17_T), with distinctive morphological traits at both ear and plant level. In the present study, these accessions have been characterized at the morphological and genetic level with 10 SSR markers and compared to other landraces of the Rostrata group. SSR analysis revealed from 3 to 11 alleles per locus evidencing a good level of heterosis and absence of allele fixation for landraces. Both phylogenetic and STRUCTURE analysis evidence that the three “Mais Rostrato Val Chiavenna” are different entities with a distinct genetic origin. Historical investigation revealed that the morphology most close to the “original” Mais Rostrato di Val Chiavenna is that of R17_T, dating back to the XIX century. These observations, coupled with morphological and genetic results may corroborate that R17_T corresponds to the original “Mais Rostrato Val Chiavenna”.

Carrot root being used as vegetable and salad due to the nutritional value, hence consumers demanding carrot production. Thus, the production can be achieved by an understanding of the genetics of root traits namely root length, root weight, root diameter, core diameter, flesh thickness and root to top (shoot) ratio. Thus, the results assist in the development of carrot hybrids or varieties. Genetic analysis of economic traits of carrot was estimated through three cross combinations, and the results revealed the existence of additive [d], dominance [h], additive × additive [i], additive × dominance [j] and dominance × dominance [l] gene actions. The nature and magnitude of gene interaction and effects showed the importance of the inheritance modes, and the complimentary type of non-epistatic gene action of traits could be used for the exploitation of heterosis through favourable positive [h] and [l] gene interaction and effects. This information on root genetics aided to the adoption of suitable breeding method, handling and selection of segregates with desirable economic traits.

Heterosis is a well-known phenomenon widely applied in agriculture. Recent studies have suggested that differential gene and protein expression between hybrids and their parents play important roles in heterosis. Alternative splicing (AS) is an essential posttranscriptional mechanism that can greatly affect the transcriptome and proteome diversity in plants. However, genome-wide AS divergence in hybrids compared to their parents and its potential contribution to heterosis have not been comprehensively investigated. We report the direct profiling of the AS landscape using RNA sequencing data from immature ears of the maize hybrid ZD808 and its parents NG5 and CL11. Our results revealed a large number of significant differential AS (DAS) events in ZD808 relative to its parents, which can be further classified into parental-dominant and novel DAS patterns. Parental-dominant, especially NG5-dominant, events were prevalent in the hybrid, accounting for 42% of all analyzed DAS events. Functional enrichment analysis revealed that the NG5-dominant AS events were involved mainly in regulating the expression of genes associated with carbon/nitrogen metabolism and cell division processes and contributed greatly to maize ear heterosis. Among ZD808, CL11, and NG5, 32.5% of DAS contained or lacked binding sites of at least one annotated maize microRNA (miRNA) and may be involved in miRNA-mediated posttranscriptional regulation. Cis regulation was the predominant contributor to AS variation and participates in many important biological processes associated with immature ear development. This study provides a comprehensive view of genome-wide alternative splicing variation in a maize hybrid.

Heterosis refers to the improved agronomic performance of F1 hybrids relative to their parents. Although this phenomenon is widely employed to increase biomass, yield, and stress tolerance of plants, the underlying molecular mechanisms remain unclear. To dissect the metabolic fluctuations derived from genomic and/or environmental differences contributing to the improved biomass of F1 hybrids relative to their parents, we optimized the growth condition for Arabidopsis thaliana F1 hybrids and their parents. Modest but statistically significant increase in the biomass of F1 hybrids was observed. Plant samples grown under the optimized condition were also utilized for integrated omics analysis to capture specific changes in the F1 hybrids. Metabolite profiling of F1 hybrids and parent plants was performed using gas chromatography-mass spectrometry. Among the detected 237 metabolites, 2-oxoglutarate (2-OG) and malate levels were lower and the level of aspartate was higher in the F1 hybrids than in each parent. In addition, microarray analysis revealed that there were 44 up-regulated and 12 down-regulated genes with more than 1.5-fold changes in expression levels in the F1 hybrid compared to each parent. Gene ontology (GO) analyses indicated that genes up-regulated in the F1 hybrids were largely related to organic nitrogen (N) process. Quantitative PCR verified that glutamine synthetase 2 (AtGLN2) was upregulated in the F1 hybrids, while other genes encoding enzymes in the GS-GOGAT cycle showed no significant differences between the hybrid and parent lines. These results suggested the existence of metabolic regulation that coordinates biomass and N metabolism involving AtGLN2 in F1 hybrids.

BackgroundSelf-incompatibility (SI) systems prevent self-fertilization in several species of Poaceae, many of which are economically important forage, bioenergy and turf grasses. Self-incompatibility ensures cross-pollination and genetic diversity but restricts the ability to fix useful genetic variation. In most inbred crops it is possible to develop high-performing homozygous parental lines by self-pollination, which then enables the creation of F1 hybrid varieties with higher performance, a phenomenon known as heterosis. The inability to fully exploit heterosis in outcrossing grasses is partially responsible for lower levels of improvement in breeding programmes compared with inbred crops. However, SI can be overcome in forage grasses to create self-compatible populations. This is generating interest in understanding the genetical basis of self-compatibility (SC), its significance for reproductive strategies and its exploitation for crop improvement, especially in the context of F1 hybrid breeding.ScopeWe review the literature on SI and SC in outcrossing grass species. We review the currently available genomic tools and approaches used to discover and characterize novel SC sources. We discuss opportunities barely explored for outcrossing grasses that SC facilitates. Specifically, we discuss strategies for wide SC introgression in the context of the Lolium–Festuca complex and the use of SC to develop immortalized mapping populations for the dissection of a wide range of agronomically important traits. The germplasm available is a valuable practical resource and will aid understanding the basis of inbreeding depression and hybrid vigour in key temperate forage grass species.ConclusionsA better understanding of the genetic control of additional SC loci offers new insight into SI systems, their evolutionary origins and their reproductive significance. Heterozygous outcrossing grass species that can be readily selfed facilitate studies of heterosis. Moreover, SC introduction into a range of grass species will enable heterosis to be exploited in innovative ways in genetic improvement programmes.

Ashwagandha is an important, medicinal, less exploited crop and most of its cultivated varieties are local cultivars. Information related to ashwagandha’s genetic diversity is very limited. Hybrid vigor exploitation may be useful in breaking its yield barrier at a commercial scale. A total of 45 F1 crosses were produced during Kharif 2017-18 by using a line x tester matting design, which included three testers along with 15 lines. A total of 65 genotypes were grown in an RBD design, with three replications in three different environments during Kharif 2018-19, and observations were recorded for 11 different yield-attributing traits that were responsible for the estimation of the magnitude of the heterosis. An analysis of variance showed that a valuable amount of diversity existed in the breeding material. Based on the study, three promising crosses viz., UWS-305 × UWS-10, UWS-305 × RVA-100, and UWS-301 × RVA-100 were identified as superior heterotic materials for the root yield at harvest, whereas for the total alkaloid content, three excellent hybrids viz., UWS-309 × RVA-100, UWS-305 × RVA-100, and UWS-314 × RVA-100 were reported. Out of the above crosses, the cross-combination of UWS-305 × RVA-100 showed a significantly positive and useful heterosis on a pooled basis. Hence, the above crosses may be gainfully utilized in breeding programs for ashwagandha.

The effectiveness of haploid induction systems is regarded not only for high haploid induction rate (HIR) but also resource savings. Isolation fields are proposed for hybrid induction. However, efficient haploid production depends on inducer traits such as high HIR, abundant pollen production, and tall plants. Seven hybrid inducers and their respective parents were evaluated over three years for HIR, seeds set in cross-pollinations, plant and ear height, tassel size, and tassel branching. Mid-parent heterosis was estimated to quantify how much inducer traits improve in hybrids in comparison to their parents. Heterosis benefits hybrid inducers for plant height, ear height, and tassel size. Two hybrid inducers, BH201/LH82-Ped126 and BH201/LH82-Ped128, are promising for haploid induction in isolation fields. Hybrid inducers offer convenience and resource-effectiveness for haploid induction by means of improving plant vigor without compromising HIR.

Summary Rice is a facultative short day (SD) plant. In addition to serving as a model plant for molecular genetic studies of monocots, rice is a staple crop for about half of the world’s population. Heading date is a critical agronomic trait, and many genes controlling heading date have been cloned over the last 2 decades. The mechanism of flowering in rice from recognition of day length by leaves to floral activation in the shoot apical meristem has been extensively studied. In this review, we summarise current progress on transcriptional and post‐transcriptional regulation of heading date in rice, with emphasis on post‐translational modifications of key regulators, including Heading date 1 (Hd1), Early heading date 1 (Ehd1), Grain number, plant height, and heading date7 (Ghd7). The contribution of heading date genes to heterosis and the expansion of rice cultivation areas from low‐latitude to high‐latitude regions are also discussed. To overcome the limitations of diverse genetic backgrounds used in heading date studies and to gain a clearer understanding of flowering in rice, we propose a systematic collection of genetic resources in a common genetic background. Strategies in breeding adapted cultivars by rational design are also discussed.

Heterosis is a phenomenon wherein F1 hybrid often displays phenotypic superiority and surpasses its parents in terms of growth and agronomic traits. Investigations on the physiological and biochemical properties of the heterotic F1 hybrid are important to uncover the mechanisms underlying heterosis in plants. In the present study, the photosynthetic capacity of a heterotic F1 hybrid of Zea mays L. (DHM 117) that exhibited a higher growth rate and increased biomass was compared with its parental inbreds at vegetative and reproductive stages in the field during 2017 and 2018. The net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (E) as well as foliar carbohydrates were higher in F1 hybrid than parental inbreds at vegetative and reproductive stages. An increase in total chlorophyll content along with better chlorophyll a fluorescence characteristics including effective quantum yield of photosystem II (ΔF/Fm'), maximum quantum yield of PSII (Fv/Fm), photochemical quenching (qp) and decreased non-photochemical quenching (NPQ) was observed in F1 hybrid than the parental inbreds. Further, the expression of potential genes related to C4 photosynthesis was considerably upregulated in F1 hybrid than the parental inbreds during vegetative and reproductive stages. Moreover, the F1 hybrid exhibited distinct heterosis in yield with 63% and 62% increase relative to parental inbreds during 2017 and 2018. We conclude that improved photosynthetic efficiency associated with increased foliar carbohydrates could have contributed to higher growth rate, biomass and yield in the F1 hybrid.

Heterosis has been extensively utilized to increase productivity in crops, yet the underlying molecular mechanisms remain largely elusive. Here, we generated transcriptome-wide profiles of mRNA abundance, m6A methylation, and translational efficiency from the maize F1 hybrid B73×Mo17 and its two parental lines to ascertain the contribution of each regulatory layer to heterosis at the seedling stage. We documented that although the global abundance and distribution of m6A remained unchanged, a greater number of genes had gained an m6A modification in the hybrid. Superior variations were observed at the m6A modification and translational efficiency levels when compared with mRNA abundance between the hybrid and parents. In the hybrid, the vast majority of genes with m6A modification exhibited a non-additive expression pattern, the percentage of which was much higher than that at levels of mRNA abundance and translational efficiency. Non-additive genes involved in different biological processes were hierarchically coordinated by discrete combinations of three regulatory layers. These findings suggest that transcriptional and post-transcriptional regulation of gene expression make distinct contributions to heterosis in hybrid maize. Overall, this integrated multi-omics analysis provides a valuable portfolio for interpreting transcriptional and post-transcriptional regulation of gene expression in hybrid maize, and paves the way for exploring molecular mechanisms underlying hybrid vigor., A maize F1 hybrid and its parental lines showed dissimilarities of regulatory and heterotic patterns of genes undergoing hierarchical regulation at the mRNA abundance, m6A modification, and translational efficiency.

As the end products of cellular regulatory processes, metabolites provide the link between genotypes and phenotypes. Although metabolites have been widely applied for functional gene detection and phenotype prediction in maize, there is little research focusing on the genetic information of metabolites per se. Here, we performed genetic analyses for the kernel metabolites of 11 parental inbred lines of six representative maize varieties, including Zhongdan 2, Danyu 13, Yedan 13, Zhengdan 958, Xianyu 355, and Suyu 16, as well as their 26 reciprocal hybrids. We identified a total of 208 metabolites in maize kernels using untargeted metabolite profiling technology. Both cluster analysis and principal component analysis indicated that kernel metabolites could distinguish hybrids from their parents. Analysis of variance further revealed that 163 metabolites exhibited significant differences between parents and hybrids, and 40 metabolites showed significant differences between reciprocal crosses. We also investigated the genetic effects and heterosis for each metabolite. By taking all hybrids into consideration, about two-thirds of all metabolites displayed overdominant with 36.8% and 31% of them displaying positive overdominant and negative overdominant, respectively. Besides, 27.5% and 20.4% of all hybrid combinations showed significant mid-parent heterosis and over-parent heterosis, respectively. Our findings revealed that kernel metabolites exhibited the diversity of relationship between maize hybrids and their parental lines. Additionally, we identified 25 significant metabolic markers related to 11 agronomic traits using the LASSO method. Seven metabolic markers were associated with more than one trait simultaneously. These results provide a genetic basis for further utilization of metabolites in the genetic improvement of maize.

Traditional maize (Zea mays L.) is deficient in iron (Fe) and zinc (Zn). Metal transporter proteins play pivotal role in uptake, translocation and accumulation of minerals. Here, a set of 70 intergenic SSRs, 20 intragenic SSRs and 20 intragenic InDel markers encompassing 62 metal transporter genes were used for characterization of 24 diverse inbreds varying for Fe (13.95–37.34 µg/g) and Zn (11.83–37.90 µg/g). A total of 356 alleles, with 26 unique (7.03%) and 36 rare (10.11%) alleles were observed. Cluster analysis categorized the inbreds into two main clusters. Five candidate gene-based intragenic SSRs were significantly associated with Fe (r = 0.46–0.52). Two intragenic InDel markers and 11 SSRs were significantly correlated with Zn (r = 0.44–0.76). HUZM-185 and HKI-323 possessed favourable allele of five genes that showed significantly high correlation with Fe. At least six significantly associated genes for Zn were found in BQPML-5207-4-2, CML152, CML169 and HKI193-1. Based on genetic distance, presence of genes and high micronutrients, potential cross combinations were identified for the exploitation of heterosis. This study is the first report on characterizing maize inbreds using markers for metal transporter genes.

Onion (Allium cepa L.) is the most diversified crop of the family Alliaceae; it is in cultivation since from ancient era for its edible bulbs and verdant foliage due to the immense nutritional and medicinal properties. The increased social acceptance of bulb onion in daily diet could lead to an increase in cultivable area with a similar bulb production. However, the output per unit area had limited due to the lack of exploitation of heterosis for bulb yield. The only possibility to increase the onion productivity is to increase the volume of the individual bulb, and it can achieve by exploiting heterosis for earliness, biotic and abiotic stress resistance, bulb weight, and size by the development of hybrid with the use of male sterility mechanisms like cytoplasmic-genic male sterility or cytoplasmic male sterility system in onion. The male sterility trait is precious in heterosis breeding due to its potential advantages in the development of onion hybrids. In these perspectives, the present review reveals the origin, evolution, maintenance, and prevalence of male sterility systems of onion and the technique of identification of the male sterility systems. The polymorphisms between male-sterile and male-fertile phenotypes difference with morphological-molecular markers with the marker-phenotype linkage of onion.

A panel of seven maize inbred lines belonging to Zemun Polje commercial pool were genotypized using SNPs bead chip. 21 hybrids, developed according to the half dialel mating design, were tested in the field together with inbred lines per se. The goal of the study was to determine the genetic distance among seven maize inbred lines and to establish whether there was a significant correlation between the genetic distance among parental inbreds and grain yield, specific combining abilities (SCA) and high-parent (HP) heterosis for the grain yield. The inbred lines ZPL2 and ZPL4 with the genetic distance of 0.487 were the most genetically distant parents, while inbred lines ZPL1 and ZPL2 with the genetic distance of 0.191 were the closest ones. Three subclusters of inbred lines were distinguished in the dendrogram. Inbred lines ZPL5, ZPL6, ZPL3 and ZPL7 were grouped into the first subcluster, while inbred lines ZPL1 and ZPL2, i.e. the inbred line ZPL4 were grouped in the second, i.e. the third subcluster, respectively. The values of the Spearman's rank correlation coefficient between the genetic distance among inbred lines based on the SNP markers, and grain yield, specific combining abilities (SCA) and high- parent (HP) heterosis were positive and statistically significant. The highest correlation coefficient was exhibited between the grain yield and high-parent (HP) heterosis (0.93), and then between the genetic distance and the grain yield (0.92) as well as between the genetic distance and high-parent (HP) heterosis (0.91). Panel od sedam inbred linija kukuruza koje pripadaju komercijalnom pulu Instituta za kukuruz u Zemun Polju je analiziran pomoću SNP čipa. Hibridi dobijeni po metodu nepotpunog dialela su ispitivani u polju zajedno sa inbred linijama per se. Cilj ovog istraživanja je bio da se utvrdi genetička distanca između inbred linija kukuruza i da se ispita da li postoji značajna korelacija između genetičke distance roditeljskih linija, posebnih kombinacionih sposobnosti (PKS) i heterozisa u odnosu na boljeg roditelja (HPH) za osobinu prinos zrna. Genetički najudaljenije linije su bile ZPL2 i ZPL4 sa genetičkom distancom 0.487, dok su najbliže bile inbred linije ZPL1 i ZPL2 sa genetičkom distancom 0.191, kao i inbred linije ZPL5 i ZPL6 sa genetičkom distancom 0.196. Dendrogram je podelio inbred linije u tri različita subklastera. Prvom subklasteru pripadaju inbred linije ZPL5, ZPL6, ZPL3 i ZPL7, drugom inbred linije ZPL1 i ZPL2 i trećem inbred linija ZPL4. Vrednosti Sperman-ovog koeficijenta korelacije ranga između genetičke distance zasnovane na SNP markerima, prinosa zrna, posebnih kombinacionih sposobnosti (PKS) i heterozisa u odnosu na boljeg roditelja (HPH) su bile pozitivne i statistički značajne. Najviši koeficijent korelacije je bio između prinosa zrna i HPH (0,93), zatim između genetičke distance i prinosa (0.92) i između genetičke distance i HPH (0.91).