Evaluation of a Rapid Method for Screening Heat Stress Tolerance Using Three Korean Wheat (Triticum aestivum L.) Cultivars

Phenotyping methods to assess heat stress resilience in grapevine

Global warming has become an issue in recent years in viticulture, as increasing temperatures have a negative impact on grapevine (Vitis vinifera) production and on wine quality. Phenotyping for grapevine response to heat stress is, therefore, important to understand thermotolerance mechanisms, with the aim of improving field management strategies or developing more resilient varieties. Nonetheless, the choice of the phenotypic traits to be investigated is not trivial and depends mainly on the objectives of the study, but also on the number of samples and on the availability of instrumentation. Moreover, the grapevine literature reports few studies related to thermotolerance, generally assessing physiological responses, which highlights the need for more holistic approaches. In this context, the present review offers an overview of target traits that are commonly investigated in plant thermotolerance studies, with a special focus on grapevine, and of methods that can be employed to evaluate those traits. With the final goal of providing useful tools and references for future studies on grapevine heat stress resilience, advantages and limitations of each method are highlighted, and the available or possible implementations are described. In this way, the reader is guided in the choice of the best approaches in terms of speed, complexity, range of application, sensitivity, and specificity.

Optimization of a wheat small red bean double cropping system in South Korea

Wheat (Triticum aestivum L.) and small red bean [Vigna angularis (Willd. Ohwi & Ohashi)] are the main ingredients of walnut-shaped “Hodugwaja”. An innovative wheat small red bean double cropping system was evaluated in a rice field in the Cheonan region (Korea) to determine its effect on land use. The effects of different nitrogen levels, sowing dates, and density on growth, yield, and quality of wheat and small red bean were also investigated using selected wheat (‘Keumgang’, ‘Sooan’, and ‘Goso’) and small red bean (‘Hongeon’, ‘Chungju’, and ‘Arari’) varieties. The effect of different fertilizer treatments [N1 (50%, 6.6 kg/10a), N2 (100%, 8.8 kg/10a), and N3 (200%, 13.2 kg/10a)] were investigated for wheat, while the effect of sowing date and density were investigated for the small red beans. Our findings revealed that the best variety, sowing date, and nitrogen level combination for wheat small red bean double cropping system in Cheonan area is ‘Goso’ sown on October 26, N3 nitrogen application, and ‘Chungju’ sown on July 10 with high ridge cultivation, at a density of 60 × 15 cm. This system was the most ideal yielding 521.6 kg/10a (1000 m²) and 275 kg/10a of ‘Goso’ and ‘Chungju’, respectively. This pioneering research provides a reliable cultivation plan and theoretical basis for implementing the double cropping system of wheat small red beans in central Korea. Undeniably, this study also provides a basis for future field experiments on wheat planting patterns and small red bean fertilization.

Development and Validation of Diagnostic KASP Markers for Brown Planthopper Resistance in Rice

Rice (Oryza sativa L.) is an important source of nutrition for the world’s burgeoning population that often faces yield loss due to infestation by the brown planthopper (BPH, Nilaparvata lugens (Stål)). The development of rice cultivars with BPH resistance is one of the crucial precedences in rice breeding programs. Recent progress in high-throughput SNP-based genotyping technology has made it possible to develop markers linked to the BPH more quickly than ever before. With this view, a genome-wide association study was undertaken for deriving marker-trait associations with BPH damage scores and SNPs from genotyping-by-sequencing data of 391 multi-parent advanced generation inter-cross (MAGIC) lines. A total of 23 significant SNPs involved in stress resistance pathways were selected from a general linear model along with 31 SNPs reported from a FarmCPU model in previous studies. Of these 54 SNPs, 20 were selected in such a way to cover 13 stress-related genes. Kompetitive allele-specific PCR (KASP) assays were designed for the 20 selected SNPs and were subsequently used in validating the genotypes that were identified, six SNPs, viz, snpOS00912, snpOS00915, snpOS00922, snpOS00923, snpOS00927, and snpOS00929 as efficient in distinguishing the genotypes into BPH-resistant and susceptible clusters. Bph17 and Bph32 genes that are highly effective against the biotype 4 of the BPH have been validated by gene specific SNPs with favorable alleles in M201, M272, M344, RathuHeenati, and RathuHeenati accession. These identified genotypes could be useful as donors for transferring BPH resistance into popular varieties with marker-assisted selection using these diagnostic SNPs. The resistant lines and the significant SNPs unearthed from our study can be useful in developing BPH-resistant varieties after validating them in biparental populations with the potential usefulness of SNPs as causal markers.

Correlation of elongation factor 1A accumulation with photosynthetic pigment content and yield in winter wheat varieties under heat stress conditions

Heat stress is one of the most important environmental factors that influences wheat growth and development, leading to significant losses in grain yield and has become a significant detrimental factor for worldwide wheat production. In recent years, several studies suggested that eukaryotic elongation factor 1A (eEF1A), may contribute to heat tolerance in plants, therefore the aim of this study was: to investigate the accumulation of eEF1A in wheat under conditions of moderate and high air temperatures; to determine the amount of photosynthetic pigments and to determine the yield traits; and to examine whether there is a correlation between eEF1A accumulation, photosynthetic pigments, and yield in different wheat varieties. The results showed that heat stress induced accumulation of eEF1A significantly different among wheat varieties and showed that varieties with a higher accumulation of eEF1A under heat stress are characterized by a smaller decrease in the photosynthetic pigments. A correlation between higher accumulation of eEF1A under heat stress and yield traits was found. Analyzed parameters from two growing seasons, indicated that the higher accumulation of eEF1A and a smaller decrease in photosynthetic pigments distinguishes the varieties more resistant to heat stress. The analysis of the molecular mechanisms by immunoblot, under conditions of high and moderate air temperatures in two growing seasons, aims to develop agricultural strategy and develop wheat varieties tolerant to heat stress.

Overexpression of the HDA15 Gene Confers Resistance to Salt Stress by the Induction of NCED3, an ABA Biosynthesis Enzyme

Salt stress constitutes a major form of abiotic stress in plants. Histone modification plays an important role in stress tolerance, with particular reference to salt stress resistance. In the current study, we found that HDA15 overexpression confers salt stress resistance to young seedling stages of transgenic plants. Furthermore, salt stress induces HDA15 overexpression. Transcription levels of stress-responsive genes were increased in transgenic plants overexpressing HDA15 (HDA15 OE). NCED3, an abscisic acid (ABA) biosynthetic gene, which is highly upregulated in HDA15 transgenic plants, enhanced the accumulation of ABA, which promotes adaptation to salt stress. ABA homeostasis in HDA15 OE plants is maintained by the induction of CYP707As, which optimize endogenous ABA levels. Lastly, we found that the double-mutant HDA15 OE/hy5 ko plants are sensitive to salt stress, indicating that interaction between HDA15 and ELONGATED HYPOCOTYL 5 (HY5) is crucial to salt stress tolerance shown by HDA15 OE plants. Thus, our findings indicate that HDA15 is crucial to salt stress tolerance in Arabidopsis.

Enhanced anthocyanin accumulation confers increased growth performance in plants under low nitrate and high salt stress conditions owing to active modulation of nitrate metabolism

Plants require nitrogen (N) for growth and development. However, they are frequently exposed to conditions of nitrogen deficiency. In addition, anthocyanin accumulation is induced under salt stress and nitrate deficiency. To date, most studies have revealed that nitrate deficiency under high sucrose levels induce high levels of anthocyanin accumulation in plants. However, the underlying mechanisms remain unclear. Under nitrate-starved conditions, plant growth rapidly worsens and cells eventually die. In addition, plants are severely affected by salt exposure. Therefore, in this study, we determined whether increased levels of anthocyanin could improve plant growth under salt stress and nitrate-starved conditions. We used PAP1-D/fls1ko and ttg1 plants which have a perturbed anthocyanin biosynthesis pathway to explore the role of anthocyanin in plant adaptation to nitrate-deficient conditions and salt stress. Our results demonstrate that high anthocyanin accumulation in PAP1-D/fls1ko plants confers enhanced tolerance to nitrate-deficient conditions combined with high salinity. PAP1-D/fls1ko plants appeared to use absorbed nitrate efficiently during the nitrate reduction process. In addition, nitrate-related genes such as NRT1.1, NiA1 and NiA2 were upregulated in the PAP1-D/fls1ko plants. On the basis of these findings, it can be concluded that high anthocyanin accumulation helps plants to cope with salt stress under nitrate-deficient conditions via the effective utilization of nitrate metabolism.

Paenibacillus pabuli strain P7S promotes plant growth and induces anthocyanin accumulation in Arabidopsis thaliana

In this study, a novel plant growth-promoting rhizobacteria (PGPR), the bacterial strain Paenibacillus pabuli P7S (PP7S), showed promising plant growth-promoting effects. Furthermore, it induced anthocyanin accumulation in Arabidopsis. When co-cultivated with PP7S, there was a significant increase in anthocyanin content and biomass of Arabidopsis seedlings compared with those of the control. The quantitative reverse transcription-polymerase chain reaction analysis revealed higher expression of many key genes regulating anthocyanin and flavonoid biosynthesis pathways in PP7S-treated seedlings when compared with that of the control. Furthermore, higher expression of pathogen-related genes and microbe-associated molecular pattern genes was also observed in response to PP7S, indicating that the PGPR triggered the induced systemic response (ISR) in A. thaliana. These results suggest that PP7S promotes plant growth in A. thaliana and increases anthocyanin biosynthesis by triggering specific ISRs in plant.