Discovery of anisiflupurin, an inhibitor of cytokinin dehydrogenase that mitigates heat-induced yield reduction in rice.

BACKGROUND: In a screening of anilinopurine, anisiflupurin was identified as potent inhibitor of cytokinin dehydrogenase/oxidase (CKX). Inhibitors of CKX have been supposed to be potent plant growth regulators to alleviate the detrimental effects of abiotic stress on crop production. The aim of the study was to profile anisiflupurin in a set of physiological assays and to evaluate its potential for heat stress mitigation in rice field trials. RESULTS: Anisiflupurin delayed dark-induced senescence and increased transpiration in detached maize leaves in a dose-dependent manner. Similarly, the transpiration of young rice plants under heat stress was increased for several days after application with anisiflupurin. Application of anisiflupurin during early phases of generative growth not only restored heat-induced pollen alterations it increased grain yield in field grown rice under heat conditions as demonstrated in a large field program conducted in southeast Asia. Thereby, efficacy of anisiflupurin was rate-dependent and most effective when applied during early generative growth phases prior heat stress. CONCLUSIONS: Application of anisiflupurin secures seed setting by protecting pollen development and enhances grain weight under heat stress conditions in rice. The results of this research opens up a promising avenue for mitigating the adverse effects of heat stress in rice cultivation. © 2024 Society of Chemical Industry.

Foliar application of benzovindiflupyr shows non-fungicidal effects in wheat plants.

BACKGROUND: The fungicide benzovindiflupyr belongs to the class of succinate dehydrogenase inhibitors (SDHIs). Certain SDHIs have shown plant physiological effects, so-called secondary effects, that appeared to be related to the plant water status. Therefore, the effect of benzovindiflupyr on transpiration of leaves and whole wheat plants was studied under controlled conditions. Furthermore, wheat yield trials under controlled and natural drought stress in the field were conducted. RESULTS: Transpiration of detached wheat leaves was reduced by benzovindiflupyr in a dose-dependent manner. Similarly, whole-plant transpiration decreased for several days following application of this fungicide. In 16 field trials under drought stress conditions that were classified as disease-free, treatment of wheat plants at the flag leaf stage or at heading with benzovindiflupyr showed a grain yield increase (+5.2%; P ≤ 0.01) that was partially attributed to an increased thousand-grain weight. CONCLUSIONS: Water saving during pre-anthesis as a result of benzovindiflupyr application may be associated with better seed setting and filling under dry field conditions in wheat. The results of this research provide new insights into secondary effects of SDHIs that lead directly to yield improvements. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genome-wide transcriptomic analysis of response to low temperature reveals candidate genes determining divergent cold-sensitivity of maize inbred lines.

Maize, despite being thermophyllic due to its tropical origin, demonstrates high intraspecific diversity in cold-tolerance. To search for molecular mechanisms of this diversity, transcriptomic response to cold was studied in two inbred lines of contrasting cold-tolerance. Microarray analysis was followed by extensive statistical elaboration of data, literature data mining, and gene ontology-based classification. The lines used had been bred earlier specifically for determination of QTLs for cold-performance of photosynthesis. This allowed direct comparison of present transcriptomic data with the earlier QTL mapping results. Cold-treated (14 h at 8/6 °C) maize seedlings of cold-tolerant ETH-DH7 and cold-sensitive ETH-DL3 lines at V3 stage showed strong, consistent response of the third leaf transcriptome: several thousand probes showed similar, statistically significant change in both lines, while only tens responded differently in the two lines. The most striking difference between the responses of the two lines to cold was the induction of expression of ca. twenty genes encoding membrane/cell wall proteins exclusively in the cold-tolerant ETH-DH7 line. The common response comprised mainly repression of numerous genes related to photosynthesis and induction of genes related to basic biological activity: transcription, regulation of gene expression, protein phosphorylation, cell wall organization. Among the genes showing differential response, several were close to the QTL regions identified in earlier studies with the same inbred lines and associated with biometrical, physiological or biochemical parameters. These transcripts, including two apparently non-protein-coding ones, are particularly attractive candidates for future studies on mechanisms determining divergent cold-tolerance of inbred maize lines.

Low temperature stress in maize (Zea mays L.) induces genes involved in photosynthesis and signal transduction as studied by suppression subtractive hybridization.

Unfavourable environmental conditions such as cold induce the transcription of a range of genes in plants in order to acclimate to these growth conditions. To better understand the cold acclimation of maize (Zea mays L.) it is important to identify components of the cold stress response. For this purpose, cold-induced genes were analysed using the PCR-select cDNA subtraction method. We identified several novel genes isolated from maize seedling exposed for 48h to 6 degrees C. Of 18 Zea mays cold-induced genes (ZmCOI genes) characterized, the majority share similarities with proteins with known function in signal transduction and photosynthesis regulation. RT-PCR was conducted for a selected group of genes, namely ZmCOI6.1, ZmACA1, ZmDREB2A and ZmERF3, confirming the induction by low temperature. In addition, it was found that their expression was strongly induced by other abiotic stresses such as drought and high salt concentration, by stress signalling molecules such as jasmonic acid, salicylic acid and abscisic acid, and by membrane rigidification. These results suggest that this group of genes is involved in a general response to abiotic stresses.

QTL studies reveal little relevance of chilling-related seedling traits for yield in maize.

Prolonged low temperature phases and short-term cold spells often occur in spring during the crucial stages of early maize (Zea mays L.) development. The effect of low temperature-induced growth retardation at the seedling stage on final yield is poorly studied. Therefore, the aim was to identify genomic regions associated with morpho-physiological traits at flowering and harvest stage and their relationship to previously identified quantitative trait loci (QTLs) for photosynthesis and morpho-physiological traits from the same plants at seedling stage. Flowering time, plant height and shoot biomass components at harvest were measured in a dent mapping population for cold tolerance studies, which was sown in the Swiss Midlands in early and late spring in two consecutive years. Early-sown plants exhibited chilling stress during seedling stage, whereas late-sown plants grew under favorable conditions. Significant QTLs, which were stable across environments, were found for plant height and for the time of flowering. The QTLs for flowering were frequently co-localized with QTLs for plant height or ear dry weight. The comparison with QTLs detected at seedling stage revealed only few common QTLs. A pleiotropic effect was found on chromosome 3 which revealed that a good photosynthetic performance of the seedling under warm conditions had a beneficial effect on plant height and partially on biomass at harvest. However, a high chilling tolerance of the seedling seemingly had an insignificant or small negative effect on the yield.

Mapping of quantitative trait loci associated with chilling tolerance in maize (Zea mays L.) seedlings grown under field conditions.

The effect of low growth temperature on morpho-physiological traits of maize was investigated by the means of a QTL analysis in a segregating F(2:3) population grown under field conditions in Switzerland. Chlorophyll fluorescence parameters, leaf greenness, leaf area, shoot dry weight, and shoot nitrogen content were investigated at the seedling stage for two years. Maize was sown on two dates in each year; thus, plants sown early were exposed to low temperature, whereas those sown later developed under more favourable conditions. The main QTLs involved in the functioning of the photosynthetic apparatus at low temperature were stable across the cold environments and were also identified under controlled conditions with suboptimal temperature in a previous study. Based on the QTL analysis, relationships between chlorophyll fluorescence parameters and leaf greenness were moderate. This indicates that the extent and functioning of the photosynthetic machinery may be under different genetic control. The functioning of the photosynthetic apparatus in plants developed at low temperature in the field did not noticeably affect biomass accumulation; since there were no co-locations between QTLs for leaf area and shoot dry weight, biomass accumulation did not seem to be carbon-limited at the seedling stage under cool conditions in the field.