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Root architecture development, an agronomic trait that influences crop yield, is regulated by multiple plant hormones. Abscisic acid (ABA) is a stress hormone that responds to multiple stresses, including salt, drought, and cold stress, and modulates various aspects of plant growth and development. In recent years, it has been found that ABA synthesized under mild stress or well-watered conditions can support plant growth and stress resistance by positively regulating root architecture development. In this review, we summarize the molecular, cellular, and organismal basis of ABA homeostasis in the root and how ABA signaling affects root architecture development both as an inhibitor and as an activator. We discuss the implications of these studies and the potential for exploiting the components of ABA signaling in designing crop plants with improved root system development and stress resistance.

Climate change is a major concern to people all over the world. Most studies have considered singular or dual effects of climate change implications on plant growth and development; however, the combination of multiple factors has received little attention. We therefore studied the single and combined effects of two environmental stress factors (high temperature and water stresses) and abscisic acid on tomato seedlings (Solanum lycoperscum L.). Plants were grown in controlled environment growth chambers under two temperatures (22/18 °C or 28/24 °C; 16 h light/8 h dark), two watering regimes (well-watered or water-stressed), and two abscisic acid treatments (0 and 100 µL of 1mM abscisic acid solution, every other day). Plants were placed under experimental conditions for a total of 33 days, including a 13-day period of initial growth and hardening. Morphological, biochemical, and physiological parameters were measured to assess the growth and development of plants in response to the three factors. ANOVA and Scheffé's multiple-comparison procedures were used to establish significant differences among treatments and among the three factors being manipulated. All three factors decreased plant height and growth rate. Dry mass accumulation was negatively affected by high temperatures. Transpiration, stomatal conductance, and gas exchange parameters were negatively affected by all three factors; additionally, net carbon dioxide assimilation was reduced by water stress and abscisic acid application. Non-photochemical quenching was decreased in plants grown under higher temperature and in abscisic acid-treated plants. Though it was not significant, abscisic acid appears to mitigate the negative effect of higher temperature and water stress on the nitrogen balance index and total chlorophyll content. [ABSTRACT FROM AUTHOR]

Sanghuangporus baumii is a traditional medicinal fungus that produces pharmacological terpenoids, but natural resources are insufficient for applications, and its growth and development mechanisms are poorly understood. Combining metabolomic and transcriptomic analyses, we found four terpenoid hormones and a central gene, isopentenyl diphosphate isomerase (IDI), involved in growth and development. Additionally, an exogenous hormone test was used to further confirm the importance of the four terpenoid hormones. Finally, hormone content determination and qRT−PCR were performed to explore the growth and development mechanism; we found thatcis-zeatin (CZ) plays a major role in the mycelia stage, trans-zeatin (TZ) and gibberellin A4 (GA4) are important in the primordia stage, GA4 is crucial for the fruiting bodies stage, and abscisic acid (ABA) may be a marker of maturity. The IDI gene was also found to affectterpenoid hormone content by regulating the relative gene transcript levels, thereby controlling morphological changes in S. baumii. Our results revealthe growth and development mechanisms of S. baumii and may promote the breeding and utilisation of high-quality varieties. [ABSTRACT FROM AUTHOR]

Climate change is a major concern to people all over the world. Most studies have considered singular or dual effects of climate change implications on plant growth and development; however, the combination of multiple factors has received little attention. We therefore studied the single and combined effects of two environmental stress factors (high temperature and water stresses) and abscisic acid on tomato seedlings (Solanum lycoperscum L.). Plants were grown in controlled environment growth chambers under two temperatures (22/18 °C or 28/24 °C; 16 h light/8 h dark), two watering regimes (well-watered or water-stressed), and two abscisic acid treatments (0 and 100 µL of 1mM abscisic acid solution, every other day). Plants were placed under experimental conditions for a total of 33 days, including a 13-day period of initial growth and hardening. Morphological, biochemical, and physiological parameters were measured to assess the growth and development of plants in response to the three factors. ANOVA and Scheffé’s multiple-comparison procedures were used to establish significant differences among treatments and among the three factors being manipulated. All three factors decreased plant height and growth rate. Dry mass accumulation was negatively affected by high temperatures. Transpiration, stomatal conductance, and gas exchange parameters were negatively affected by all three factors; additionally, net carbon dioxide assimilation was reduced by water stress and abscisic acid application. Non-photochemical quenching was decreased in plants grown under higher temperature and in abscisic acid-treated plants. Though it was not significant, abscisic acid appears to mitigate the negative effect of higher temperature and water stress on the nitrogen balance index and total chlorophyll content.

It is generally accepted that plants use the complex signaling system regulated by light and abscisic acid (ABA) signaling components to optimize growth and development in different situations. The role of ABA–light interactions is evident in the coupling of stress defense reactions with seed germination and root development, maintaining of stem cell identity and stem cell specification, stem elongation and leaf development, flowering and fruit formation, senescence, and shade avoidance. All these processes are regulated jointly by the ABA–light signaling system. Although a lot of work has been devoted to ABA–light signal interactions, there is still no systematic description of central signaling components and protein modules, which jointly regulate plant development. New data have emerged to promote understanding of how ABA and light signals are integrated at the molecular level, representing an extensively growing area of research. This work is intended to fill existing gaps by using literature data combined with bioinformatics analysis. [ABSTRACT FROM AUTHOR]

NAC (NAM, ATAF1-2, and CUC2) transcription factors (TFs) play a vital role in plant growth and development, as well as in plant response to biotic and abiotic stressors (Duan et al., 2019; Guerin et al., 2019). Chrysanthemum is a plant with strong stress resistance and adaptability; therefore, a systematic study of NAC TFs in chrysanthemum is of great significance for plant breeding. In this study, 153 putative NAC TFs were identified based on the Chrysanthemum nankingense genome. According to the NAC family in Arabidopsis and rice, a rootless phylogenetic tree was constructed, in which the 153 CnNAC TFs were divided into two groups and 19 subfamilies. Moreover, the expression levels of 12 CnNAC TFs belonging to the OsNAC7 subfamily were analyzed in C. nankingense under osmotic and salt stresses, and different tissues were tested during different growth periods. The results showed that these 12 OsNAC7 subfamily members were involved in the regulation of root and stem growth, as well as in the regulation of drought and salt stresses. Finally, we investigated the function of the CHR00069684 gene, and the results showed that CHR00069684 could confer improved salt and low temperature resistance, enhance ABA sensitivity, and lead to early flowering in tobacco. It was proved that members of the OsNAC7 subfamily have dual functions including the regulation of resistance and the mediation of plant growth and development. This study provides comprehensive information on analyzing the function of CnNAC TFs, and also reveals the important role of OsNAC7 subfamily genes in response to abiotic stress and the regulation of plant growth. These results provide new ideas for plant breeding to control stress resistance and growth simultaneously. [ABSTRACT FROM AUTHOR]

Chinese cabbage is an important vegetable in Asia, and high-yielding hybrids are needed to cope with the growing demand. A comparative transcriptome profiling was conducted to reveal the differentially expressed genes (DEGs) associated with heterosis in two hybrids relative to their parents. Our data suggests that heterosis is underlined by a significant upregulation of gene expression. High expression of DEGs in glycolysis and photosynthesis pathways in hybrids depicted their relation with growth and hybrid vigor. Besides, DEGs related to auxin, abscisic acid, ethylene and gibberellin were identified, implying that these hormones may boost the mechanisms of growth and developmental processes in the hybrids. Furthermore, transcription factors, including bHLH, ERF, MYB and WRKY were predicted to regulate downstream genes linked to hybrid vigor. Collectively, the present study will be helpful for a better understanding of the regulation mechanisms of heterosis to aid cabbage yield improvement. • Transcriptional mechanisms of heterosis in Chinese cabbage was studied. • Heterosis is underlined by a significant upregulation of gene expression. • Heterosis is mainly associated with non-additive expression. • Glycolysis and photosynthesis pathways were altered in hybrids. • Phytohormones related genes play crucial role in heterosis. [ABSTRACT FROM AUTHOR]

The NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF) genes, initially characterized as nitrate or peptide transporters in plants, are involved in the transport of a large variety of substrates, including amino acids, nitrate, auxin (IAA), jasmonates (JAs), abscisic acid (ABA) and gibberellins (GAs) and glucosinolates. A total of 169 potential functional NPF genes were excavated in Brassica napus, and they showed diversified expression patterns in 90 different organs or tissues based on transcriptome profile data. The complex time-serial expression changes were found for most functional NPF genes in the development process of leaves, silique walls and seeds, which indicated that the expression of Brassica napus NPF (BnaNPF) genes may respond to altered phytohormone and secondary metabolite content through combining with promoter element enrichment analysis. Furthermore, many BnaNPF genes were detected to respond to vernalization with two different patterns, and 20 BnaNPF genes responded to nitrate deficiency. These results will provide useful information for further investigation of the biological function of BnaNPF genes for growth and development in rapeseed. [ABSTRACT FROM AUTHOR]