Evaluation of the biological effectiveness of inducers of resistance to viral diseases and their impact on potato yield in the field

Оценена биологическая эффективность Фармайода (йод) и Имуноцитофита (эфир арахидоновой кислоты) как индукторов устойчивости картофеля к вирусам в мелкоделяночных (г. Москва) и производственных опытах в Астраханской, Липецкой и Московской областях в 2015–2016 и 2018 годах. В Липецкой области картофель сорта Рамос заражен Y-вирусом картофеля (PVY) и комплексом вирусов M и S (PVM + PVS); в Астраханской области на сорте Импала отмечали комплексы PVM+PVS и PVM+PVS+PVY, в Московской области на сорте ВР-808 был отмечен Y-вирус. Биологическая эффективность Фармайода против Y-вируса в мелкоделяночных опытах на сорте Ред Скарлетт в 2015–2016 годах составила 76,4%, в 2018 году – 73,4%, а Иммуноцитофита – 47,4% и 48,4%. Прибавка урожайности от Фармайода была 21,6–34,4%, а от Иммуноцитофита – 17,0–21,3%. Против М-вируса на сорте Адретта биологическая эффективность Фармайода и Иммуноцитофита в 2015–2016 годах была 70,8% и 51,1%, в 2018 году – 56,5% и 41,3%. Урожайность в 2015–2016 годах увеличилась на 35,2% от применения Фармайода, от Иммуноцитофита – на 16,7%; в 2018 году прибавка – 24,0% и 15,3%, соответственно. В хозяйстве Московской области эффективность Фармайода составила 74,9%, предпосадочная обработка им клубней эффекта не дала. В Липецкой области биологическая эффективность Фармайода была в среднем 73%, Иммуноцитофита – 52%. Прибавка валовой урожайности от Фармайода – 9,1 т/га, Иммуноцитофита – 3,8 т/га, при урожайности в контроле 24,0 т/га; в 2016 году – 6,8 т/га и 3,3 т/га, в контроле – 19,5 т/га. В Астраханской области в 2016 году биологическая эффективность Фармайода – 73,2%, прибавка – 8,6 т/га, у Иммуноцитофита эти показатели – 53,2% и 5,2 т/га, в контроле 18,9 т/га. The biological effectiveness of Pharmaiod (100 g/l iodine) and Immunocitophyt (20 g/kg of ethylic ester of arachidonic acid) as inducers of potato resistance to viruses was evaluated in small plot trials (Moscow) and field experiments in the Astrakhan, Lipetsk and Moscow oblast in 2015–2016 and 2018. In the Lipetsk oblast, the potato variety Ramos was infected with the potato virus Y (PVY) and the complex infection of the potato viruses M and S (PVM + PVS); in Astrakhan oblast on Impala variety, the PVM + PVS and PVM + PVS + PVY virus complexes were noted; in Moscow oblast the potato variety VR-808 was infected with PVY. In 2015–2016 in small plot trials the biological effectiveness of Pharmaiod against PVY on Red Scarlet variety averaged 76.4%, in 2018–73.4% and Immunocitophyt – 47.4% and 48.4%. The yield increase from the use Pharmaiod was 21.6–34.4%, and from Immunocitophyt – 17.0–21.3%. The biological effectiveness of Pharmaiod and Immunocitophyt against the M-virus on Adretta variety in 2015–2016 was 70.8% and 51.1%, in 2018–56.5% and 41.3%. The total yield in 2015–2016 increased by 35.2% from the use of Pharmaiod, from Immunocytofit by 16.7%, in 2018, the increase was by 24.0% and 15.3%, respectively. In the farm of Moscow Oblast, the effectiveness of Pharmaiod was 74.9%, the pre-planting treatment of tubers did not have a significant effect. In Lipetsk oblast, the biological effectiveness of Pharmaiod averaged 73%, Immunocitophyt – 52%. The total yield increase from the use Pharmaiod is 9.1 t/ha, from Immunocitophyt – 3.8 t/ha, when the yield in the control variant was 24.0 t/ha; in 2016–6.8 t/ha and 3.3 t/ha, in control – 19.5 t/ha. In 2016 in Astrakhan oblast the biological effectiveness of Pharmaiod was 73.2%, the increase was 8.6 t/ha, in Immunocitophyt these rates were 53.2% and 5.2 t/ha, in the control 18.9 t/ha.

The role of the MAP kinase−kinase protein StMKK1 in potato immunity to different pathogens

Mitogen-activated protein kinase (MAPK) cascades play important roles in plant immunity. Previously, we reported that the potato StMKK1 protein negatively regulates Nicotiana benthamiana resistance to Phytophthora infestans. However, the functions of StMKK1 in potato immunity are unknown. To investigate the roles of StMKK1 in potato resistance to different pathogens, such as the potato late-blight pathogen P. infestans, the bacterial wilt pathogen Ralstonia solanacearum, and the gray-mold fungal pathogen Botrytis cinerea, we generated StMKK1 transgenic lines and investigated the response of potato transformants to destructive oomycete, bacterial, and fungal pathogens. The results showed that overexpression and silencing of StMKK1 do not alter plant growth and development. Interestingly, we found that StMKK1 negatively regulated potato resistance to the hemibiotrophic/biotrophic pathogens P. infestans and R. solanacearum, while it positively regulated potato resistance to the necrotrophic pathogen B. cinerea. Further investigation showed that overexpression of StMKK1 suppressed potato pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and salicylic acid (SA)-related responses, while silencing of StMKK1 enhanced PTI and SA-related immune responses. Taken together, our results showed that StMKK1 plays dual roles in potato defense against different plant pathogens via negative regulation of PTI and SA-related signaling pathways.

Natural genetic diversity in the potato resistance gene RB confers suppression avoidance from Phytophthora effector IPI-O4

RB is a potato gene that provides resistance to a broad spectrum of genotypes of the late blight pathogen Phytophthora infestans. RB belongs to the CC-NB-LRR (coiled-coil, nucleotide-binding, leucine-rich repeat) class of resistance (R) genes, a major component of the plant immune system. The RB protein detects the presence of Class I and II IPI-O effectors from P. infestans to initiate a hypersensitive resistance response, but this activity is suppressed in the presence of the Class III effector IPI-O4. Using natural genetic variation of RB within potato wild relatives, we identified two amino acids in the CC domain that alter interactions needed for suppression of resistance by IPI-O4. We have found that separate modification of these amino acids in RB can diminish or expand the resistance capability of this protein against P. infestans in both Nicotiana benthamiana and potato. Our results demonstrate that increased knowledge of the molecular mechanisms that determine resistance activation and R protein suppression by effectors can be utilized to tailor-engineer genes with the potential to provide increased durability.

Genetic aspects of potato resistance to phytophthorosis

Phytophthora infestans Mont. de Bary is the main oomycete pathogen of cultivated crops in the family Solanaceae, especially potato (Solanum tuberosum). Because potato is the fourth most cultivated crop worldwide, its annual losses from late blight are tremendous. Studies of the basic mechanisms of interaction between potato and the late blight pathogen not only expand the fundamental knowledge in this area, but also open up new possibilities for regulating these interactions in order to increase resistance to the pathogen. The interaction of potato and the late blight pathogen can be considered from a genetic point of view, and it is interesting to consider both the response of the potato to the colonization process by P. infestans and the change in gene activity in late blight during plant infection. We can also investigate this process by changing the profile of secondary metabolites of the host and the pathogen. In addition to fundamental work in this area, applied work in the form of the development of new preparations for protecting potatoes is of no less importance. This review briefly describes the main stages of studies of potato resistance to late blight, starting almost from the first works. Much attention is paid to key works on changing the profile of secondary metabolites phytoalexins. A separate section is devoted to the description of both qualitative and quantitative characteristics of potato resistance to the late blight pathogen: their contribution to overall resistance, gene mapping, and regulation capabilities. Both types of traits are important for potato breeding: quantitative resistance due to R-genes is quickly overcome by the pathogen, while quantitative trait loci make it possible to create varieties with almost absolute resistance due to the pyramid of effective genes. The latest approaches in molecular biology make it possible to study translatomic profiles, which makes it possible to look at the interaction of potatoes and the late blight pathogen at a different angle. It has been shown that the process of potato colonization affects not only the activity of various genes and the profile of secondary metabolites: proteins­markers of the response to infection from potatoes have also been identified: they are pathogen-bound proteins and plastid carbonic anhydrase. On the part of P. infestans, fungal cellulose synthase proteins and haustorium-specific membrane protein were markers of infection. Thus, the review contains information on the most relevant complex studies of the genetic mechanisms of potato resistance to late blight.

The molecular mechanisms of Phytophthora infestans in response to reactive oxygen species (ROS) stress

Reactive oxygen species (ROS) are critical for the growth, development, proliferation, and pathogenicity of microbial pathogens; however, excessive levels of ROS are toxic. Little is known regarding the signaling cascades in response to ROS stress in oomycetes such as Phytophthora infestans, the causal agent of potato late blight. Here, P. infestans was used as a model system to investigate the mechanism underlying the response to ROS stress in oomycete pathogens. Results showed severe defects in sporangium germination, mycelial growth, appressorium formation, and virulence of P. infestans in response to H2O2 stress. Importantly, these phenotypes mimic those of P. infestans treated with rapamycin, the inhibitor of target of rapamycin (TOR, 1-phosphatidylinositol-3-kinase). Strong synergism occurred when P. infestans was treated with a combination of H2O2 and rapamycin, suggesting that a crosstalk exists between ROS stress and the TOR signaling pathway. Comprehensive analysis of transcriptome, proteome and phosphorylation omics showed that H2O2 stress significantly induced the operation of the TOR-mediated autophagy pathway. Monodansylcadaverine (MDC) staining showed that in the presence of H2O2 and rapamycin, the autophagosome level increased in a dosage-dependent manner. Furthermore, transgenic potatoes containing double-stranded RNA of PiTOR (TOR in P. infestans) displayed high resistance to P. infestans. Taken together, TOR is involved in the ROS response and is a potential target for control of oomycete diseases, as host-mediated silencing of PiTOR enhances potato resistance to late blight.

EFFECT OF THE COMPLEX OF ENDOPHYTIC BACTERIA BACILLUS WITH SALICYLIC AND JASMONIC ACIDS ON THE STATE OF THE PRO- / ANTIOXIDANT SYSTEM OF PLANTS AND THE RESISTANCE OF POTATOES WHEN INFECTED WITH LATE BLIGHT UNDER STRESS

There was researched the effect of Bacillus subtilis bacteria in combination with salicylic (SA) and jasmonic (JA) acids on the state of the pro / antioxidant system (hydrogen peroxide content, catalase, peroxidase, superoxide dismutase activity) in connection with the development of potato resistance to late blight pathogen - oomycete Phytophthora infestans (Mont.) de Bary under moisture deficit conditions. Plants grown from microtubers of the Rannyaya Rosa cultivar were sprayed with a suspension of B. subtilis (108 cells / ml) and a mixture of bacteria with SA (10-6 M), JA (10-7 M), SA + JA (1:1). 3 days after treatment, the plants were infected with P. infestans (105 spores / ml) and cultivated under artificial soil drought conditions by reducing irrigation. When soil moisture reached 40±5% (7 days after infection), biochemical parameters were assessed in plants. A decrease in the degree of leaves damage by P. infestans was revealed when treated with B. subtilis in combination with SA and JA. The mechanism of increasing the resistance of potato plants to late blight when treated with Bacillus subtilis bacteria in combination with signaling molecules under conditions of drought was associated with the accumulation of H2O2 and modulation of antioxidant enzymes activity.