Producing a superior genotype from agria potato cultivar using somaclonal variation

This study was performed to produce a superior genotype from Agria potato cultivar using somaclonal variation. Two leaf and meristem explants in combination with four doses of 2,4-D (0, 2, 3 and 4 mg / l) were used for callus induction in a factorial model based on a completely randomized design with 3 replications. Results showed that the meristem explant, along with 3 mg 2,4-D produced the most suitable calluses. In the mentioned regeneration media, the best calluses were regenerated and one of the regenerated genotypes, which was very different from the parent cultivar was selected. The regenerated genotype, was compared with the maternal genotype (Agria) and a control cultivar (Sante), in a field experiment based on a randomized complete block design with 3 replications. The results showed that in terms of most of the studied traits such as tuber weight per plant, stolon length, percentage of dry matter and percentage of starch, the new genotype was superior, compared to the parent cultivar and in terms of peel percentage and maturity date, the parental cultivar was superior. The results of the molecular comparison also showed that based on CBDP marker, both in terms of band number and band size, there were differences between the new genotype and the parental cultivar. In general, results showed that somaclonal variation can be an effective method to generate new genotypes with superior characteristics.

INFLUENCE OF FLURIDONE ON THE CONTENT OF HORMONES IN CALL OF BARLEY CV. STEPTOE AND TS ABA‑DEFICIENT MUTANT AZ34

The effect of the inhibitor of endogenous ABA synthesis fluridone on the content and distribution of endogenous ABA and IAA in the calli of ABA-deficient mutant AZ34 barley and its parental cultivar Steptoe was studied using the methods of immuno-enzymatic solid-phase assay and immunolocalization of phytohormones. It was found that by the 4th week of in vitro culture, fluridone causes a significant decrease in the ABA level in calli of both genotypes compared to the control, and the inhibitory effect of fluridone in AZ34 is more pronounced than in Steptoe. In the calli of both genotypes, a significant increase in the IAA content was revealed against the background of a decrease in the ABA content upon treatment with fluridone as compared to the control. It was concluded that ABA plays an important role in the process of embryoido-genesis in vitro.

Artificially Edited Alleles of the Eukaryotic Translation Initiation Factor 4E1 Gene Differentially Reduce Susceptibility to Cucumber Mosaic Virus and Potato Virus Y in Tomato

Eukaryotic translation initiation factors, including eIF4E, are susceptibility factors for viral infection in host plants. Mutation and double-stranded RNA-mediated silencing of tomato eIF4E genes can confer resistance to viruses, particularly members of the Potyvirus genus. Here, we artificially mutated the eIF4E1 gene on chromosome 3 of a commercial cultivar of tomato (Solanum lycopersicum L.) by using CRISPR/Cas9. We obtained three alleles, comprising two deletions of three and nine nucleotides (3DEL and 9DEL) and a single nucleotide insertion (1INS), near regions that encode amino acid residues important for binding to the mRNA 5' cap structure and to eIF4G. Plants homozygous for these alleles were termed 3DEL, 9DEL, and 1INS plants, respectively. In accordance with previous studies, inoculation tests with potato virus Y (PVY; type member of the genus Potyvirus) yielded a significant reduction in susceptibility to the N strain (PVYN), but not to the ordinary strain (PVYO), in 1INS plants. 9DEL among three artificial alleles had a deleterious effect on infection by cucumber mosaic virus (CMV, type member of the genus Cucumovirus). When CMV was mechanically inoculated into tomato plants and viral coat accumulation was measured in the non-inoculated upper leaves, the level of viral coat protein was significantly lower in the 9DEL plants than in the parental cultivar. Tissue blotting of microperforated inoculated leaves of the 9DEL plants revealed significantly fewer infection foci compared with those of the parental cultivar, suggesting that 9DEL negatively affects the initial steps of infection with CMV in a mechanically inoculated leaf. In laboratory tests, viral aphid transmission from an infected susceptible plant to 9DEL plants was reduced compared with the parental control. Although many pathogen resistance genes have been discovered in tomato and its wild relatives, no CMV resistance genes have been used in practice. RNA silencing of eIF4E expression has previously been reported to not affect susceptibility to CMV in tomato. Our findings suggest that artificial gene editing can introduce additional resistance to that achieved with mutagenesis breeding, and that edited eIF4E alleles confer an alternative way to manage CMV in tomato fields.

Development of superior somaclones of aromatic local cultivar of rice (Oryza sativa L.)

The traditional local aromatic rice cultivars are poor combiners. Here we report development of superior somaclones plants through tissue culture. The somaclones, TC 4/8 had the maximum yield followed by TC 5-1, TC 4/4, TC 4/5, and TC 4/7. Yield increase of TC 4/8, TC-5-1 was 54.75% and 50.33% more over the yield of parental cultivar, respectively. The plant tissue culture thus may be recommended to create genetic variability in rice as a trustworthy biotechnological tool.

Inheritance of seed size by hybrid populations of pea (F1, F2)

Pea (Pisum sativum L.) is one of the ancient and valuable high-protein leguminous cultures in the world. Breeding of new high-yielding cultivars is the main reserve to increase production of pea seeds. At the present time, intraspecific hybridization has a great importance in selection of new cultivars of pea. However, consistent patterns of inheritance of a number of economically valuable traits by hybrids are still insufficiently investigated. The objective of this research work was to study inheritance of seed size (1000-kernel weight) by pea hybrids of the first and second filial generations (F1, F2). The crossing and back-crossing (reciprocal crossing) were conducted. In our experiments, the first filial generation hybrids (F1) had a lower 1000-kernel weight than the large-seeded parental cultivars. Herewith the large-seeded genotype of the female parental cultivar had more influence on displaying of this trait in hybrids than of the male parental cultivar. In the second filial generation hybrids (F2) showed intermediate inheritance of seed size. The results of our experiments attest high efficiency of seed size selection in segregating generations of hybrids, obtained from crosses between cultivars carrying genes of seed size.

Dynamics of the contents and distribution of ABA, auxins and aquaporins in developing caryopses of an ABA-deficient barley mutant and its parental cultivar

Dynamics of abscisic acid (ABA) and indole-3-acetic acid (IAA) contents were followed in developing barley caryopses of the ABA-deficient mutant AZ34 and its parental cultivar Steptoe. Distribution of these hormones and HvPIP2 aquaporins (AQPs) was studied with the help of immunohistochemical methods in the roots and coleorhiza of developing embryos. In Steptoe, maturation of the caryopsis was accompanied by vast accumulation of ABA, while this hormone accumulated more slowly in the caryopsis of AZ34 and its content was lower than in Steptoe. Accumulation of ABA was accompanied by a decline in IAA level in the developing caryopsis, the process being delayed in AZ34 in accordance with the slower accumulation of ABA. ABA accumulated to high levels in the coleorhiza cells of Steptoe, while the effect was absent in AZ34. The high level of ABA was likely to be important for maintaining the barrier function of the coleorhiza, preventing germination of seminal roots and enabling seed dormancy, while the absence of ABA accumulation in coleorhiza of AZ34 may be responsible for the initiation of root germination inside the caryopsis. The abundance of HvPIP2 AQPs in the seminal roots was higher at the beginning of maturation of Steptoe caryopsis and declined afterwards, while the levels of APQs increased later in AZ34 in accordance with the delay in ABA accumulation. These results suggest the importance of ABA accumulation in coleorhiza for preventing precocious growth of seminal roots, and suggest regulation of IAA and aquaporin levels by this hormone during maturation of embryos.

Transgenic Winter Wheat Expressing the Sucrose Transporter HvSUT1 from Barley does not Affect Aphid Performance

Winter wheat expressing the sucrose transporter HvSUT1 from barley (HOSUT) has an increased yield potential. Genetic engineering should improve cultivars without increasing susceptibility to biotic stresses or causing negative impacts on ecosystem services. We studied the effects of HOSUT wheat on cereal aphids that feed on the sugar-rich phloem sap. Three HOSUT winter wheat lines, their conventional parental cultivar Certo, and three conventional cultivars were used. Clip cage experiments in the greenhouse showed no differences in life-table parameters of Rhopalosiphum padi and Sitobion avenae (Hemiptera: Aphididae) on transgenic lines compared to Certo, except higher fecundity of S. avenae on one HOSUT line. Population development of both aphid species over three weeks on caged flowering tillers did not reveal differences between the HOSUT lines and Certo. When aphids were monitored in a Swiss field study over two years, no differences between HOSUT lines and Certo were observed. We conclude that HOSUT wheat did not have consistent effects on aphids compared to the parental cultivar and measured parameters were generally in the range observed for the conventional winter wheat cultivars. Thus, HOSUT wheat is unlikely to suffer from increased aphid damage.

MUTATION BREEDING OF A RICE DWARF LINE WITH SLIGHT YIELD LOSS UNDER DROUGHT STRESS

Lack of adequate water leading to drought stress is a common constraint in upland cultivation system ofrice. a rice mutant line (MT58) was developed in previous research after mutagenesis of cv. Neda by ethylmethane sulfonate (EMS) and selected for dwarfism (18 cm shorter than Neda). The extent of its molecularchanges relative to parental cultivar was assessed by SSR and ISSR markers, and the response of the linealong with parental cultivar and another mutant line (MTA) to mild and severe water deficit, was evaluated ina field experiment. a molecular assessment by using 41 SSR markers showed that stunt line MT58 had significantmolecular difference with two other lines as confirmed by cluster analysis. ISSR assay also proved theconsiderable mutational effect of EMS on two mutant lines compared to original wild line. Field experimentsrevealed that limited irrigation caused mild to severe decrease in all the studied traits including chlorophyllcontents. In both mild and sever water stress (S1 and S2) dwarf mutant MT58 had not significant differencesin plant yield from parental cultivar Neda. In mild water stress cultivar Neda and mutant line MT58, respectively,showed highest (14%) and lowest (3%) yield loss, while in sever water stress mutant lines MTA andMT58, respectively, showed highest (33%) and lowest (19%) yield loss. In severe stress, cultivar Neda hadhighest plant height, tiller number and plant yield, and mutant MT58 had highest panicle length, total kernelsper panicle, fertile kernels and chlorophyll contents. Reduction in chlorophyll content at drought stress conditionwas correlated with yield loss (0.64 and 0.697 for chl.a and chl.b, respectively). The results of this researchobviously confirm that mutant line MT58 despite of its stunt figure did not show yield difference fromits parental cultivar in drought stress.