Quantitative Trait Loci for Resistance to Potato Dry Rot Caused by Fusarium sambucinum

Tuber dry rot is an important disease of potato caused by soil and seed-borne pathogens of the Fusarium genus leading to losses that may reach 60% of the yield. The goal of this work was to study the inheritance of the dry rot resistance in two diploid potato hybrid populations (11-36 and 12-3) with complex pedigrees, including several wild Solanum spp. We used an aggressive isolate of F. sambucinum for phenotyping both progenies, parents, and standard potato cultivars in laboratory tuber tests, in three subsequent years. The QTL for dry rot resistance were mapped by interval mapping on existing genetic maps of both mapping populations. The most important and reproducible QTL for this trait was mapped on chromosome I and additional year- and population-specific QTL were mapped on chromosomes II, VII, IX, XI, and XII, confirming polygenic control of this resistance. This is the first study mapping the loci affecting tuber dry rot resistance in potato genome that can contribute to better understanding of potato-F. sambucinum interaction and to more efficient breeding of resistant potato cultivars.

Response of potato (Solanum tuberosum L.) cultivars to drought stress under in vitro and field conditions

Background Potato (Solanum tuberosum L.), the world’s third most important crop, is frequently thought to be sensitive to moderately sensitive to drought, and yield has fallen considerably over consecutive stress periods. Drought produces a wide range of responses in potato, from physiological alterations to variations in growth rates and yield. Knowledge about these responses is essential for getting a full understanding of drought-tolerance mechanism in potato plants which will help in the identification of drought-tolerant cultivars. Results A set of 21 commercial potato cultivars representing the genetic diversity in the Middle East countries market were screened for drought tolerance by measuring morpho-physiological traits and tuber production under in vitro and field trials. Cultivars were exposed to drought stress ranging from no drought to 0.1, 0.2 and 0.3 mol L−1 sorbitol in in vitro-based screening and 60, 40 and 20% soil moisture content in field-based screening. Drought stress adversely affected plant growth, yield and cultivars differed for their responses. Shoots and roots fresh weights, root length, surface area of root, no. of roots, no. of leaves, leaf area, plant water content %, K+ content, under in vitro drought treatments and shoots fresh and dry weights, no. of tubers and tuber yield under field drought treatments were examined and all decreased due to drought. The stress tolerance index decreased with increasing drought in examined cultivars; nevertheless, it revealed a degree of tolerance in some of them. Grouping cultivars by cluster analysis for response to drought resulted in: (i) a tolerant group of five cultivars, (ii) a moderately tolerant group of 11 cultivars, and (iii) a sensitive group of five cultivars. Furthermore, stress-related genes, i.e., DRO, ERECTA, ERF, DREB and StMYB were up-regulated in the five cultivars of the tolerant group. Likewise, the stomatal conductance and transpiration explained high correlation with the tuber yield in this group of cultivars. Conclusion The diversity in germplasm indicated that potato cultivars can be developed for production under certain degrees of drought. Some cultivars are good candidates to be included in drought-tolerant breeding programs and recommended for cultivation in drought-stricken regions. Graphical Abstract

Traditional Selection Potato Varieties and Their Resistance to the 28-punctata Potato Ladybug Henosepilachna vigintioctomaculata (Coleoptera: Coccinellidae) in the Southern Russian Far East

Background: Henosepilachna vigintioctomaculata is a polytrophic pest, causing the greatest damage to plants from the nightshade family. The study aimed to research the resistance of potato cultivars that are promising for breeding to damage by a potato ladybug in laboratory and field experiments. Methods: In laboratory experiments, the indicators of fertility, mortality and duration of development, morphological anomalies and the effect of potato varieties on the composition of Epilakhna’s hemolymph were studied. The sample consisted of 50 individuals with a slight predominance of females. The experiment used 13 varieties of potatoes. Result: A specific dependence of the frequency of phytophage anomalies on the variety was revealed. The influence of nutrition on survival and the timing of ontogenesis has been established. The results obtained indicate the high breeding value of the material when recommending it for cultivation in regions with a high number of pests, as well as when creating new varieties.

Plant Growth and Stomatal Responses of Potato Cultivars under High Temperature Stress

Background: The higher temperatures resulted due to global warming might bring about changed geographical distribution of crops and even in the season. In other words, heat stress is likely to be an eventual challenge for crop production in general and for potatoes in particular. Thus, imparting heat tolerance in potato cultivars is of utmost importance. Methods: The experiment was conducted in pots and the ambient temperature was approximately 33±0.5oC which constitutes heat stress for potato crop. Potato cultivars namely Kufri Ashoka (relatively heat susceptible) and Kufri Surya (relatively heat tolerant), cultivars, were used in this experiment. The observations were made on the fourth leaf from the top of the mother shoot in potted plants which was fully expanded; data collected were subjected to statistical analysis by using analysis of variance under completely randomized design. Result: Data recorded on different morphological and stomatal attributes indicate that there was significant difference between susceptible and tolerant cultivars of potato wherein Kufri Surya showed better shoot/root ratio, stomatal density as well as stomata index as compared to Kufri Ashoka.

Potassium-Induced Drought Tolerance of Potato by Improving Morpho-Physiological and Biochemical Attributes

Potato (Solanum tuberosum) is the third and fourth most important tuberous crop in terms of human consumption and production, respectively. However, its growth and development are affected by drought, which is an emerging threat to agriculture especially in arid and semiarid areas. Potassium (K) is a well-known macronutrient that improves the performance of crops under drought. Therefore, the present study was enacted with the aim of evaluating the impact of K fertilizer on potato crop growth, productivity, and drought tolerance under full root irrigation (FRI) and partial root irrigation (PRI) conditions. Two potato cultivars (Lady Rosetta and Hermes) were grown under normal field conditions followed by FRI and PRI applications. Potassium sulfate was applied in three doses (T0 = 50 kg·ha−1, T1 = 75 kg·ha−1, and T2 = 100 kg·ha−1). The experiment was laid out under randomized complete block design (RCBD) with split plot arrangement. The main plot was allocated to irrigation, along with a subplot to potassium and a sub-subplot to potato cultivars. The results indicated that K application significantly improved the plant growth and yield by exhibiting better performance in morpho-physiological and biochemical attributes under FRI and PRI conditions; however, a more remarkable change was noticed under PRI compared with FRI. K application alleviated drought stress regardless of cultivars. This study suggests that K application at the rate of 100 kg·ha−1 is an effective approach for inducing drought tolerance in potato crops.