Modern Cultivars Research Articles

Wild grapevines as rootstock regulate the oxidative defense system of in vitro grafted scion varieties under drought stress.

The narrow genetic base of modern cultivars is becoming a key bottleneck for crop improvement and the use of wild relatives is an appropriate approach to improve the genetic diversity of crops to manage the sustainable production under different abiotic and biotic constraints. In Pakistan, wild germplasm of grapevine viz Dakh, Toran, and Zarishk belong to Vitis vinifera subsp. sylvestris and Fatati belong to Vitis vinifera subsp. sativa is naturally present in humid and sub-humid areas of mountainous and sub-mountainous regions and showed varying level of tolerance against drought stress but have not been evaluated as rootstock. In this study, different tolerant behavior of wild grapevines as rootstock in grafted scion varieties were explored under different levels of PEG-6000 mediated drought stress i.e., -4.00, -6.00, and -8.00 bars. In response to drought stress, wild grapevines evoked several non-enzymatic and enzymatic activities. Among non-enzymatic activities, total chlorophyll contents of commercial varieties were sustained at higher level when grafted on wild grapevines Dakh and Fatati which subsequently reduced the damage of cell membrane via MDA. Whereas, to cope the membranous damage due to excessive cellular generation of ROS, wild grapevines triggered the enhanced activities of SOD to dismutase the free oxygen radicals into H2O2, then CAT enzyme convert the H2O2 into water molecules. Higher accumulation of ROS in commercial scion varieties were also coped by wild grapevines Dakh and Fatati through the upregulation of POD and APX enzymes activities. Based on these enzymatic and non-enzymatic indices, biplot and cluster analysis classified the wild grapevines as rootstock into three distinct categories comprises on relatively tolerant i.e., Dakh (Vitis vinifera subsp. sylvestris) and Fatati (Vitis vinifera subsp. sativa), moderate tolerant i.e., Toran (Vitis vinifera subsp. sylvestris) and relatively susceptible category i.e., Zarishk (Vitis vinifera subsp. sylvestris).

Genetic Gains in Grain Yield and Agronomic Traits of Argentinian Durum Wheat from 1934 to 2015

Understanding the basis of genetic gains in grain yield and yield-related traits is essential for designing future breeding strategies that lead to the development of higher-yielding wheat cultivars. The objectives of this study were to assess the changes in grain yield achieved by durum wheat breeding in Argentina and to identify the agronomic traits associated with these changes. To this end, a wide set of Argentinian cultivars was analyzed in three field trials. A significant linear trend (R2 = 0.55) was observed between the grain yield and the cultivar’s release year, with an increase of 26.94 kg ha−1 yr−1 from 1934 to 2015. The harvest index and grain number were key traits that explained the increases in grain yield. The number of grains per plant increased with the cultivar’s release year, while the thousand kernel weight remained unchanged. The grain yield showed an increase of 51% when comparing old cultivars (<1980) with intermediate ones (1980–1999), whereas the increase between intermediate and modern cultivars (2000+) was only 16%. Thus, the genetic gains were mostly associated with the incorporation of semi-dwarfism into the germplasm in the 1980s, with low genetic gains after that.

Progress in Marker-Assisted Selection to Genomics-Assisted Breeding in Tomato

Tomato is an important vegetable crop for fresh and processed products. In the past decades, conventional breeding cum marker-assisted selection (MAS) has been deployed widely to develop modern tomato cultivars with desirable agronomic traits, market classes, and consumer preferences. The rapid developments in sequencing technologies with the reduced costs per sample, high-throughput single nucleotide polymorphism (SNP) genotyping platforms, and bioinformatics tools have revolutionized crop improvement programs, and deciphered the tomato genome sequence in 2012. Since then thousands of cultivated, its close relatives, and wild species have been genome resequenced to analyze structural variants population structure, genetic diversity, high-density map construction so on. Further, tomato pan-genomes have been constructed to search genomics regions associated with agronomic traits to expedite the breeding process. Importantly, genomics-assisted research has begun in tomatoes with the identification of genes, and SNP markers associated with phenotypic variation by applying genome resequencing, genome-wide association studies (GWAS) using SNP array, and genotyping-by-sequencing techniques. Further, the genomic selection (GS) method is expected to increase breeding efficiency and genetic gain rapidly. This review provides the latest information on progress in MAS to genome resequencing, pan-genomes, SNP genotyping, GWAS, and GS for genomics-assisted breeding in tomatoes.

Strong photosensitivity level doesn’t limit selection for high yield in winter bread wheat

Aim. The aim is to test the validity of home breeders assumption that strong photosensitivity in winter bread wheat limits the possibility of breeding improvement for productivity. Methods. Estimation of photosensitivity levels in modern high-yielding foreign cultivars (mainly from Western Europe) and in the set of F5 hybrids with photosensitivity diversity, which were selected only for relatively high yields. Results. Among the modern high-yielding foreign cultivars recommended for cultivation in Ukraine, carriers of strong photosensitivity have been identified with a significantly high frequency (up to 33.3 ± 0.75 %). In contrast, almost all modern Ukrainian cultivars are weakly photosensitive. When selecting in Odessa environment only the best-yielding families and lines from hybrid combinations, in which parents clearly differed in photosensitivity levels, F5 did not show a shift towards reducing the frequency of highly photosensitive phenotypes. It was statistically consistent with random variation without selection. Conclusions. High photosensitivity does not limit the efforts of breeders to improve the productivity potential of winter bread wheat. And for certain growing regions of this crop, it can be a factor in better environmental adaptability to get a real yield.

Simple Sequence Repeat Markers Reveal Genetic Diversity and Population Structure of Bolivian Wild and Cultivated Tomatoes (Solanum lycopersicum L.).

The western part of South America is a centre of diversity for tomatoes, but genetic diversity studies are lacking for parts of that region, including Bolivia. We used 11 simple sequence repeat (SSR) markers (including seven novel markers) to evaluate genetic diversity and population structure of 28 accessions (four modern cultivars, four advanced lines, nine landraces, 11 wild populations), and to compare their genetic variation against phenotypic traits, geographical origin and altitude. In total, 33 alleles were detected across all loci, with 2–5 alleles per locus. The top three informative SSRs were SLM6-11, LE20592 and TomSatX11-1, with polymorphism information content (PIC) of 0.65, 0.55 and 0.49, respectively. The genetic diversity of Bolivian tomatoes was low, as shown by mean expected heterozygosity (He) of 0.07. Analysis of molecular variance (AMOVA) revealed that 77.3% of the total variation was due to variation between accessions. Significant genetic differentiation was found for geographical origin, cultivation status, fruit shape, fruit size and growth type, each explaining 16–23% of the total variation. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) tree and principal coordinate analysis (PCoA) scatter plot both revealed differentiation between accessions with determinate flowers and accessions with indeterminate flowers, regardless of cultivation status. The genetic profiles of the accessions suggest that the Bolivian tomato gene pool comprises both strictly self-pollinating and open-pollinating genotypes.

Ability of cereal species for nitrogen uptake from cover crop rhizodeposits is not related to domestication level

AbstractBackgroundCereal cultivars vary in root traits, and it can be proposed that wild forms and old cultivars are more adapted to using organic nitrogen (N) sources.AimsInvestigating N uptake from cover crop (CC) rhizodeposits by wheat and barley of different domestication level and their wild relatives, we expected a more efficient N uptake by wild forms and old cultivars, indicated by higher N uptake from rhizodeposits per root biomass.MethodsEleven wheat and seven barley cultivars categorized into three domestication levels (wild, old, and modern) were grown under controlled conditions in pots with soil containing 15N‐labelled CC rhizodeposits. Shoot and root biomass, their 15N‐uptake, and a range of root traits were analyzed.ResultsDomestication level was a weak predictor of root architecture. N taken up from rhizodeposits was similar in all plants at 14% of plant N. Cultivars with largest values for most root traits (e.g., root length or volume) and root to shoot ratio also showed largest total N uptake and N uptake from rhizodeposits. However, N uptake efficiency (N uptake from rhizodeposits per root biomass) was smallest for these cultivars. Two modern wheat cultivars showed the largest N uptake efficiency from CC rhizodeposits, whereas in barley a wild and an old cultivar showed the largest efficiency.ConclusionsIn our study with a limited number of cultivars, domestication level is not related to the ability of cereals to take up N from CC rhizodeposits. The same proportion of N derived from rhizodeposits irrespective of cultivar or root traits indicates that the N provision from rhizodeposits was driven by other factors like mineralization. However, some cultivars had a larger N uptake efficiency.

Native versus Modern Almond Cultivars of Mallorca Island: From Biodiversity to Industrial Aptitude and Fruit Quality

Almond, one of the most characteristic crops in the agricultural landscape of Mallorca Island, cultivated mainly under rainfed conditions and from native cultivars, represents an important source of income for the Island. Nowadays, modern cultivars were introduced to meet the almond demand, agronomical needs, and climate change issues. Consumption has considerably increased in the last years and the SARS-CoV-2 virus contributed to consumer behavior changes. The present work aimed to characterize 14 cultivars of which 9 were modern and 5 natives. In general, the natives cultivars presented a lower weight (1.3 g), size (21 mm), darker skin (L = 38), softer texture (107 N), with more benzaldehyde flavor (2-fold change) and “twins” (16%), but with a greater thickness, fiber, and linoleic acid (0.1-fold change, respectively). Modern cultivars offered greater weight (1.5 g), size (24 mm), lighter skin (L = 39), and harder texture (121 N), with no or low benzaldehyde flavor and no “twins”. Finally, ‘Belona’, ‘Ferragnès’, ‘Marta’, ‘Masbovera’, ‘Penta’, ‘Soleta’, ‘Vairo’, ‘Duareta’, ‘Jordi’ and ‘Vivot’ met all the requirements to be certified under the quality guarantee Protected Indication of Origin “Almendra de Mallorca”. However, each cultivar presented its own profile which makes them suitable for different purposes in the food industry.

TaABI19 positively regulates grain development in wheat

Starch is the most important component in the endosperm, and its synthesis is regulated by multiple transcription factors (TFs) in cereals. However, whether the functions of these TFs are conserved among cereals remains unclear. In this study, we cloned a B3 family TF in wheat, named TaABI19, based on its orthologous sequence in maize (Zea mays L.). Alignment of the DNA and protein sequences showed that ABI19 is conserved in maize and wheat (Triticum aestivum L.). We found that TaABI19 is highly expressed in young spikes and developing grains, and encodes a nucleus-localized transcriptional activator in wheat. The taabi19-b1 null mutants obtained by EMS exhibited a down-regulation of starch synthesis, shorter grain length and lower thousand-grain weight (TGW). Furthermore, we proved that TaABI19 could bind to the promoters of TaPBF homologous genes and enhance their expression. Haplotype association showed that TaABI19-B1 is significantly associated with TGW. We found that Hap2 and Hap3 were favored and had undergone positive selection in China’s wheat breeding programs. Less than 50% of the modern cultivars convey the favored haplotypes, indicating that TaABI19 still can be considered as a target locus for marker-assisted selection breeding to increase TGW in China.

Differences in bread protein digestibility traced to wheat cultivar traits

Wheat grain storage proteins, i.e. the gluten proteins, and alpha-amylase trypsin inhibitors are partially resistant to gastrointestinal digestion. They figure among the wheat components that are potential triggers of non-celiac wheat sensitivity. To explore the digestibility of bread wheat proteins in relation to heritable plant traits, old and modern wheat varieties grown in two environments were genotyped, phenotyped, and processed into breads, which were partially digested in vitro in a system resembling human digestion. The extent of proteolysis measured after 2 h of digestion was variable. Digestion of proteins present in bread made from old wheat cultivars registered before 1960 and modern cultivars registered after 1960 was similar. No major plant trait was correlated to partial protein digestibility of bread from cultivars with high grain protein content. The protein digestibility of bread from high yield cultivars was influenced by protein composition, as well as the genetic distance per chromosome from a reference variety. Improving high yield cultivars by breeding for highly digestible proteins might help to mitigate adverse reactions to a range of wheat proteins in susceptible individuals.

Morphological and physiological variation in drought tolerance of wheat landraces originated from southeast Türkiye

Drought stress, which is the most important abiotic stress factor affecting arable land in the world, causes serious crop losses. These crop losses reach up to 70% in some agricultural plants. Understanding the complex drought stress response is very important to develop a strategy against this form of stress. Although some progress has been achieved with the previous studies, the desired targets have not been reached up to now. Therefore, using resistant varieties in environmental conditions has become a widely used strategy in combating drought stress today. In this study, a total of 23 cultivars (16-landraces and 7 modern wheat cultivars) were used. The aim of this study was to reveal the drought tolerance degrees of 16 landraces by comparing them to 7 modern wheat cultivars. For this purpose, 23 cultivars were exposed to drought stress for seven days by withholding watering. After that, stem length, MDA and proline content of cultivars were determined and compared. According to our results, MDA and proline contents of sensitive modern cultivars were found to be high, while tolerant cultivars were found to be low. It has also been determined that some of the landraces exhibit a similar profile to the cultivars known to be tolerant. Among these cultivars, especially 88, 90 and 108 cultivars have low MDA and proline content under stress, which may indicate that these cultivars are potentially drought tolerant.

Current Achievements of the Latvian Apple Breeding Programme

Abstract The commercial apple growing industry in Latvia has a lack of climate adapted modern cultivars. The Latvian apple breeding programme is targeted at cultivars adapted to the cool climate of Baltic countries and Scandinavia, with fruit quality and storage suitable for commercial production. Since 1989, scab resistance (Rvi6, Rvi5) donors are included in crosses. Several cultivars already show commercial promise — ‘Dace’, ‘Gita’, ’Monta’ (Rvi6) and the polygenic resistant ‘Laila’ and ‘Pure Ametist’. However, in 2020, the Rvi6 resistance was overcome in Latvia. Donors of polygenic scab tolerance may prove a better alternative. The most successful donors have been ‘Iedzēnu’, ‘Eksotika’, ‘Alesya’, and ‘Bohemia’. Marker assisted gene pyramiding was started, including markers linked to the resistance genes Rvi5 and Rvi6. Scab resistant cultivars ‘Edite’, ‘Felicita’, ‘Ligita’, and ‘Paulis’ show low susceptibility to Neonectria ditissima canker. To achieve high fruit quality and good storage, worldwide commercial cultivars are crossed with local adapted cultivars. Such crosses that have been registered include ‘Inta’, ‘Lora’, and ‘Saulesmeita’. Recent crosses for quality include ‘Honeycrisp’, where H-1-07-36 and H-1-07-42 show most promise. Improved biochemical content and flesh structure is one of the main targets. An additional line of breeding is aimed at ornamental and cider apples. The scab resistant Nr.19-97-154 (Cidross) was selected for cider. The red leaf columnar apple ‘Karlens’ and the compact red-leaf crab ‘Auce’ have been registered.

Nutrient Homeostasis of Aegilops Accessions Differing in B Tolerance Level under Boron Toxic Growth Conditions.

Simple SummaryBoron toxicity stress is known to obstruct the uptake of nutrients in plants inhibiting their proper growth. Thus, the root-shoot nutrient homeostasis of plants under B toxicity stress is an important criterion that should be focused on understanding nutrients’ role in providing tolerance to tolerant genotypes under excess B. Thus, in this study, the effect of toxic and highly toxic B on the nutrient uptake of Aegilops genotypes differing in B tolerance was studied for the first time. The results suggested that the readjustment of nutrient element levels in root-shoot tissues under high B stress are attributable to improved B toxicity tolerance. The information could be used to alleviate high B stress symptoms in modern wheat cultivars via breeding programs.Boron (B) is a crucial microelement for several biological processes in plants; however, it becomes hazardous when present in excess in the soil. B toxicity adversely affects the wheat yield all around the world, particularly in the arid and semiarid regions. Aegilops, the nearest wild wheat relatives, could be an efficient source to develop B toxicity tolerance in modern cultivars. However, to potentially utilize these species, it is necessary to understand the underlying mechanisms that are involved in providing them tolerance. Other than hampering cellular and physiological activities, high B inhibits the uptake of nutrients in wheat plants that lead to nutrients deficiency causing a hindered growth. Thus, it is crucial to determine the effect of B toxicity on nutrient uptake and finally, to understand the role of nutrient homeostasis in developing the adaptive mechanism in tolerant species. Unfortunately, none of the studies to date has explored the effect of high B supply on the nutrient uptake in B toxicity tolerant wild wheat species. In this study, we explored the effect of 1 mM B (toxic B), and 10 mM B (very toxic B) B on the nutrient uptake in 19 Aegilops genotypes differing in B tolerance in contrast to Bolal 2973, the familiar B tolerant genotype. The obtained outcomes suggested a significant association between the B toxicity tolerance and the level of nutrient uptake in different genotypes. The B toxicity tolerant genotypes, Ab2 (TGB 026219, A. biuncialis genotype) and Ac4 (TGB 000107, A. columnaris genotype) were clustered together in the nutrient homeostasis-based heat map. Though B toxicity mostly had an inhibitory effect on the uptake of nutrients in root-shoot tissues, the tolerant genotypes revealed an increase in nutrient uptake under B toxicity in contrast with Control. The study directs towards future research where the role of external supply of few nutrients in enhancing the B toxicity tolerance of susceptible genotypes can be studied. Moreover, the genotype-dependent variation in the nutrient profile of the studied Aegilops genotypes under high B suggested that increasing number of Aegilops germplasm should be screened for B toxicity tolerance for their successful inclusion in the pre-breeding programs focusing on this issue.

Genome Size Variation Assessment in Vitis vinifera L. Landraces in Ibiza and Formentera (Balearic Islands).

Plant genome size has many applications in different biological fields including ecology and plant breeding. The 2C value for Vitis vinifera L. has not been widely studied; furthermore, to date, no data from local landraces in the Pityusic Islands (the two smaller inhabited Balearic Islands, Ibiza, and Formentera) have been reported. This research aims to contribute to this knowledge and investigate whether there are variations between different grape landraces cultivated in Ibiza and Formentera and also among the same landraces on each island. To this end, 36 accessions of 15 cultivars and 6 landraces, identified with SSR markers, were assessed using flow cytometry. The results revealed that 2C values ranged from 1.09 pg to 1.28 pg. There were statistically significant differences in ‘AG1’ and ‘AG2’ landraces and ‘Santa Magdalena’, ‘Garnatxa’, ‘Danugue’, and ‘Valencí tinto/Grumier’ cultivars. No statistically significant differences were found in terms of the genome size content between islands. Statistically significant differences were found in accessions within ‘AG2’ landrace group and ‘Beba’ cultivar. The results presented here constitute the first-ever reported information on genome size in the genus Vitis vinifera in Pityusic, Balearic, and, in general, Spanish accessions, and they are one of the largest prospections in this field for this species anywhere. Further research should be conducted to explain the differences in nuclear DNA content found between landraces and cultivars studied here with others cultivated in different islands or countries to understand whether genome size varies in modern cultivars compared with local landraces. Additionally, it would be interesting to investigate whether there is a relationship between genome size and adaptations to diverse climatology conditions, crop management, and ripening characteristics.

Comparative Genetic Analysis of Durum Wheat Landraces and Cultivars Widespread in Tunisia.

The durum wheat (Triticum turgidum L. ssp. durum Desf.) landraces constitute a useful natural germplasm to increase the genetic diversity in the modern durum cultivars. The Tunisian durum germplasm constitutes 28 accessions conserved in Genebank of Tunisia, which are still unexplored. In this study, a comparative genetic analysis was performed to investigate the relationships between the Tunisian durum lines and the modern cultivars and detect divergent loci involved in breeding history. The genetic diversity analyses carried out using nine morphological descriptors and the 25K single-nucleotide polymorphism (SNP) array allowed us to distinguish two groups of Tunisian landraces and one of durum cultivars. The analysis of molecular variance and diversity indices confirmed the genetic variability among the groups. A total of 529 SNP loci were divergent between Tunisian durum landraces and modern cultivars. Candidate genes related to plant and spike architecture, including FLOWERING LOCUS T (FT-B1), zinc finger CONSTANS, and AP2/EREBPs transcription factors, were identified. In addition, divergent genes involved in grain composition and biotic stress nucleotide-binding site and leucine-reach repeats proteins and disease resistance proteins (NBS-LRR and RPM) were found, suggesting that the Tunisian durum germplasm may represent an important source of favorable alleles to be used in future durum breeding programs for developing well-adapted and resilient cultivars.

Pleiotropic Effect of the compactum Gene and Its Combined Effects with Other Loci for Spike and Grain-Related Traits in Wheat.

Club wheat (Triticum aestivum ssp. compactum) with a distinctly compact spike morphology was conditioned by the dominant compactum (C) locus on chromosome 2D and resulted in a redistribution of spike yield components. The disclosure of the genetic basis of club wheat was a prerequisite for the development of widely adapted, agronomically competitive club wheat cultivars. In this study, we used a recombinant inbred line population derived from a cross between club wheat Hiller and modern cultivar Yangmai 158 to construct a genetic linkage map and identify quantitative trait loci associated with 15 morphological traits. The club allele acted in a semi-dominant manner and the C gene was mapped to 370.12–406.29 Mb physical region on the long arm of 2D. Apart from compact spikes, C exhibited a pleiotropic effect on ten other agronomic traits, including plant height, three spike-related traits and six grain-related traits. The compact spike phenotype was correlated with decreased grain size and weight, but with an increase in floret fertility and grain number. These pleiotropic effects make club wheat have compatible spike weight with a normal spike from common wheat. The genetic effects of various gene combinations of C with four yield-related genes, including Ppd-D1, Vrn-D3, Rht-B1b and Rht8, were evaluated. C had no epistatic interaction with any of these genes, indicating that their combinations would have an additive effect on other agronomically important traits. Our research provided a theoretical foundation for the potentially effective deployment of C gene into modern breeding varieties in combination with other favorable alleles.

Intra-population variability of oil content and fatty acid composition in modern hemp cultivars

Purpose and objectives. To identify new promising material with high seed productivity, oil content and optimal fatty acid composition
 Results and discussion. It was found that the variability ranges of the oil content and seed weight increased under the influence of selections. Use of distant genotypes in hybridization contributed to the generation of high-oil lines, which later become donors of this trait. High oil content was recorded in hybrids derived from crossing cultivars and self-pollinated lines of the Central European eco-geographical type with cultivars and self-pollinated lines of the southern type. In this case, cultivar-line and line-cultivar hybrids (oil content of 36−39%), rather than inter-line ones, turned out to be the most successful results.
 Family-group selection is a basis for increasing and further stabilizing the oil content in seeds. The oil content was revealed to gradually increase during the breeding for increased oil content. It was found that the population variability of the seed oil content was from 33.99% to 46.98%.
 Continuous breeding selection gradually widens the expression range of the “oil content” trait from medium to maximum. In order to increase the practical value of cultivars via breeding techniques the seed productivity was also increased. The cultivars of different genetic origins, Hlesiia and Mykolaiychyk, as well as the cultivars of hybrid origin, Artemida and Harmoniia, were considered the most promising ones. In Mykolaichyk populations, the oil content gradually increased and stabilized at a level of 33, 35, or 37.8% without changes in the fatty acid composition of oil.
 The selections stabilized the oil content in cultivar populations. This proves the high efficiency of the developed breeding methods to create cultivars with high seed productivity and of targeted selection to increase the oil content in hemp seeds. Thus, the importance of a cultivar combining high seed yield and high oil output rises. The modern cultivars were ranked in order of decreasing oil levels in seeds as follows: Mykolaichyk, Artemida, Harmoniia, Hlesiia.
 Oil of all cultivars had an optimal ratio of omega-3 to omega 6 fatty acids of 1:3.1−1:3.9 (2016−2017). In 2018−2019, the ratio of omega-6 to omega-3 fatty acids was 4.0:1− 4.8:1. The linoleic acid content ranged from 55% to 58% and the linolenic acid content – from 12.58% to 18.23%. Mykolaichyk and Artemida were noticeable for gamma-linolenic acid. These results allow us to assert that the fatty acid composition of hemp seeds is unique and immutable during the breeding for increased oil content.
 Conclusions. We believe that the Central European type is a source and donor of high oil content, while the southern type – of a longer seed formation and, accordingly, of high oil accumulation.
 The heterosis phenomenon resulted from combining distant genotypes in one organism was observed. In this case, cultivar-line and line-cultivar hybrids, but not inter-line hybrids, turned out to be the most successful ones (oil content of 36−39%).
 The new hemp cultivars, Mykolaichyk, Artemida and Harmoniia, which combine high seed productivity with high seed oil content and unique fatty acid composition, have been created.

The Qc5 Allele Increases Wheat Bread-Making Quality by Regulating SPA and SPR.

Common wheat (Triticum aestivum L.) is an important food crop with a unique processing quality. The Q gene positively regulates the processing quality of wheat, but the underlying mechanism remains unclear. Here, a new Q allele (Qc5) responsible for compact spikes and good bread performance was identified. Compared with the Q allele widely distributed in modern common wheat cultivars, Qc5 had a missense mutation outside the miRNA172-binding site. This missense mutation led to a more compact messenger RNA (mRNA) secondary structure around the miRNA172-binding region, resulting in increased Qc5 expression during the spike development stage and a consequent increase in spike density. Furthermore, this missense mutation weakened the physical interaction between Qc5 and storage protein activator (SPA) in seeds and suppressed the expression of storage protein repressor (SPR). These changes increased the grain protein content and improved the bread-making quality of wheat. In conclusion, a missense mutation increases Q expression because of the resulting highly folded mRNA secondary structure around the miRNA172-binding site. Furthermore, this mutation improves the bread-making quality of wheat by repressing the expression of SPR and influencing the physical interaction between Q and SPA. These findings provide new insights into the miRNA172-directed regulation of gene expression, with implications for wheat breeding.

Comparative transcriptome analysis reveals a rapid response to phosphorus deficiency in a phosphorus-efficient rice genotype.

Phosphorus (P) is an essential plant nutrient. Most rice growing lands lack adequate P, requiring multiple P fertiliser applications to obtain expected yields. However, P fertiliser is environmentally damaging, and already unaffordable to the marginal farmers. This warrants developing P-efficient rice varieties that require less P to produce the expected yield. However, genetic factors underlying P-use efficiency (PUE) in rice remain elusive. Here, we conducted comparative transcriptome analysis using two rice varieties with contrasting PUE; a P-efficient landrace DJ123 and a P-inefficient modern cultivar IR64. We aimed to understand the transcriptomic responses in DJ123 that allow it to achieve a high PUE under low P conditions. Our results showed that both DJ123 and IR64 had replete tissue P concentrations after 48 h of P deprivation. Yet, DJ123 strongly responded to the external low P availability by inducing P starvation-inducible genes that included SPX2, PHO1, PAPs and SQDs, while these genes were not significantly induced in IR64. We envisage that the ability of DJ123 to rapidly respond to low P conditions might be the key to its high PUE. Our findings lay a valuable foundation in elucidating PUE mechanism in rice, thus will potentially contribute to developing P-efficient modern rice variety.

The Maternal Donor of Chrysanthemum Cultivars Revealed by Comparative Analysis of the Chloroplast Genome.

Chrysanthemum (Chrysanthemum morifolium Ramat) is an important floricultural crop and medicinal herb. Modern chrysanthemum cultivars have complex genetic backgrounds because of multiple cycles of hybridization, polyploidization, and prolonged cultivation. Understanding the genetic background and hybrid origin of modern chrysanthemum cultivars can provide pivotal information for chrysanthemum genetic improvement and breeding. By now, the origin of cultivated chrysanthemums remains unclear. In this study, 36 common chrysanthemum cultivars from across the world and multiple wild relatives were studied to identify the maternal donor of modern chrysanthemum. Chloroplast (cp) genomes of chrysanthemum cultivars were assembled and compared with those of the wild relatives. The structure of cp genomes was highly conserved among cultivars and wild relatives. Phylogenetic analyses based on the assembled cp genomes showed that all chrysanthemum cultivars grouped together and shared 64 substitutions that were distinct from those of their wild relatives. These results indicated that a diverged lineage of the genus Chrysanthemum, which was most likely an extinct or un-sampled species/population, provided a maternal source for modern cultivars. These findings provide important insights into the origin of chrysanthemum cultivars, and a source of valuable genetic markers for chrysanthemum breeding programs.

Performance Evaluation of Ethiopian Bread Wheat (Triticum aestivum L.) Genotypes in Southern Ethiopia

Ethiopia is not self-sufficient to meet its increasing wheat demand from domestic production partly due to a lack of improved seeds. Efforts are undertaken to fill the gap through off-season production of wheat using supplemental irrigation and modern cultivars adapted to arid areas. This study was carried out to evaluate the genetic variability and adaptability of 15 Ethiopian bread wheat genotypes at different agroecologies in Wolaita and Dawuro zones, Ethiopia. The field experiment was conducted at three locations using a randomized complete block design with three replications during the 2019/2020 main cropping season. Analysis of variance based on 11 morphological agronomic traits and two major wheat diseases revealed that there were highly significant differences ( P < 0.01 ) among the genotypes for all the traits studied at each location and combined over locations. The top three cultivars viz. Alidoro, Galema, and Honqolo exhibited higher average grain yield (GY) of 4.54 t/ha, 4.36 t/ha, and 4.0 t/ha, respectively, combined over locations. Eight of the traits (72.73%) exhibited moderate (30–60%) to high broad-sense heritability ( h b 2 > 60%) values. High h b 2 associated with high genetic advance as percent of mean was observed for the severity of both stem and yellow rust diseases combined over locations. GY was significantly related to aboveground biomass at all locations. This study depicted that cultivar Alidoro had wider adaptability for grain yield and resistance to wheat rusts.