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Fine-tuned interactions between melatonin (MT) and hormones affected by environmental inputs are crucial for plant growth. Under high light (HL) conditions, melatonin reduced photodamage in

Background. The reproductive incompatibility of cultivated ( Pisum sativum ) and wild ( P. fulvum ) pea species determines the difficulties of obtaining hybrids as well as the transfer of valuable wild parent alleles into interspecific hybrids and their use in the breeding process. The aim of the research was a comparative study of protein spectra of pea interspecific hybrids BC 2 F 5 P. sativum × P. fulvum obtained by the authors and their parents. Materials and methods. The band composition of seed proteins in the interspecific hybrids of peas BC 2 F 5 , variety Stabil ( P. sativum ) × accession from VIR collection I-609881 ( P. fulvum ) has been studied. Effectiveness of parent gene transfer determining each polymorphic position of electrophoretic spectrum were evaluated. Results. The ratio of the actual frequencies of the bands of the cultivated and wild parents in the introgression lines corresponded to the expected level in 73% positions of the electrophoretic spectrum. The introgression rate of individual seed protein bands from wild parent into interspecific pea hybrids in the absence of selection significantly exceeded the expected level, which may indicate the adaptive value of alleles encoding unique seed protein isoforms. Conclusion. The possibility of introgressive transfer of wild-type alleles to the cultivated genotypes of pea, as well as the presence of identified cultivated isoforms of storage proteins in all studied lines of BC 2 F 5 interspecific hybrids in 88.2% of the polymorphic positions of the electrophoretic spectrum, indicates the possibility of using the wild species P. fulvum in pea breeding.

Chloroplasts' mechanisms of adaptation to elevated temperatures are largely determined by the gene expression of the plastid transcription apparatus. Gene disruption of iron-containing superoxide dismutase PAP4/FSD3 and PAP9/FSD2, which are parts of the DNA-RNA polymerase complex of plastids, contributed to a decrease in resistance to oxidative stress caused by the prolonged action of elevated temperatures (5 days, 30 °C). Under heat stress conditions, pap4/fsd3 and pap9/fsd2 mutants showed a decline in chlorophyll content and photosynthesis level, as measured by photosynthetic parameters, and a different amplitude of HSP gene response to heat stress. The expression of nuclear- and plastid-encoded photosynthesis genes and corresponding proteins was strongly inhibited in the mutants as compared with wild-type plants and was further suppressed or displayed no additional changes at 30 °C. NEP-dependent plastid genes, as well as NEP genes RPOTp and RPOTmp, were also downregulated in the mutants by high temperature or remained stable, unlike in wild-type seedlings where these genes were strongly upregulated. The results obtained correspond to the concept of the complex effect of various forms of reactive oxygen species under all types of stresses, including heat stress, and confirm the hypothesis of a new regulatory function in plastid transcription acquired by enzymatic proteins during evolution.

Fine-tuned interactions between melatonin (MT) and hormones affected by environmental inputs are crucial for plant growth. Under high light (HL) conditions, melatonin reduced photodamage in Arabidopsis thaliana and contributed to the restoration of the expression of the cytokinin (CK) synthesis genes IPT3, IPT5 and LOG7 and genes for CK signal transduction AHK2,3 and ARR 1, 4, 5 and 12 which were downregulated by stress. However, CK signaling mutants displayed no significant changes in the expression of CK genes following HL + MT treatment, implying that a fully functional cytokinin signaling pathway is a prerequisite for MT–CK interactions. In turn, cytokinin treatment increased the expression of the key melatonin synthesis gene ASMT under both moderate and HL in wild-type plants. This upregulation was further accentuated in the ipt3,5,7 mutant which is highly sensitive to CK. In this mutant, in addition to ASMT, the melatonin synthesis genes SNAT and COMT, as well as the putative signaling genes CAND2 and GPA1, displayed elevated transcript levels. The results of the study suggest that melatonin acts synergistically with CK to cope with HL stress through melatonin-associated activation or repression of the respective hormonal genes.