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Low temperature is one of the most severe abiotic stress factors that limit chrysanthemum growth and development. Natural temperature changes are more complex, and cold stress from a laboratory incubator cannot accurately represent the natural temperature stress. Here, nine separate high-throughput mRNA sequencing technology (RNA-Seq) libraries were generated from the RNA sample of roots from different temperatures, including chilling (Ch), freezing (Fr), and control (CK). The 7 069 and 3 952 differentially transcribed genes were identified as CK vs. Ch and CK vs. Fr, respectively. The Kyoto encyclopedia of genes and genomes pathway (KEGG) enrichment analysis showed that significantly different flavonoid biosynthesis and linolenic acid pathways commonly appeared in CK vs. Ch and CK vs. Fr. Arginine and proline metabolism, lipid metabolism, fatty acid degradation, and fructose and mannose metabolism pathways were found in CK vs. Ch, and only in the CK vs. Fr enrichment metabolic pathway included steroid biosynthesis and monoterpenoid biosynthesis. The transcription of genes on differential metabolic pathways and MYBs were successfully validated using quantitative real-time PCR. At the same time, the antioxidant activity, malondialdehyde, and proline content were analyzed under low temperature. These datasets may aid in understanding and carrying out future studies on the molecular basis of cold stress and contribute to chrysanthemum breeding. [ABSTRACT FROM AUTHOR]

The occurrence of shade and drought stress either individually or simultaneously causes altered morphophysiological and molecular responses in crops. Nevertheless, responses of crop plants to combined shade and drought stress are unique as compared to those of individually occurring stress which urges need to study and identify distinctions, commonalities, and the interaction between responses of plants to these concurrent stress factors. In the present review, we outlined currently available knowledge on responses of plants to shade and drought stress on a shared as well as the unique basis and tried to find a common thread potentially underlying these responses. Then, we briefly described some plausible mitigation strategies to cope with these stresses along with future perspectives. A deeper insight into plant responses to co-occurring shade and drought stress will help us to generate crops with broad-spectrum stress tolerance and increased resilience to such stresses in high planting densities or intercropping systems, thus, ensuring food security. [ABSTRACT FROM AUTHOR]

An interactive effect of simultaneous shade and drought stress on drought-tolerant and drought-sensitive cultivars of soybean was studied. As drought stress intensified, the net photosynthetic rate decreased in both cultivars due to reduced leaf area, relative water content, transpiration rate, stomatal conductance, chlorophyll content, and Rubisco activity which ultimately led to yield reduction. Moreover, the chlorophyll fluorescence parameters also decreased. Interestingly, a moderate shade was found helpful in alleviating the adverse effects of drought stress, specifically in resistant cultivar N12 where seed yield improved significantly under moderate drought conditions in contrast to the cultivar C103. In summary, the effect of drought stress on soybean depended on the irradiance conditions and shade could enhance soybean drought resistance, although this resistance was cultivar dependent. With appropriate cultivar selection, a moderate shade can help optimize yield and improve the performance of drought-exposed soybean. [ABSTRACT FROM AUTHOR]

In order to explore whether leaf area of developing leaves was regulated by systemic irradiance signal from mature leaves, we investigated the leaf area, leaf anatomy, photosynthesis, auxin, gibberellin, and cytokinin contents of new developing leaves in soybean growing under conditions of shaded mature leaves (MS), shaded whole plants (WS), and under full sunlight (NS). The results showed that developing leaves under MS exhibited the higher leaf area and leaf mass than that of WS. Blade thickness, palisade tissue thickness, sponge tissue thickness, cell size, cell numbers, net photosynthetic rate, stomatal conductance, transpiration rate, and cytokinin content of developing leaves under MS were lower, while auxin and gibberellin contents were higher than that of NS. These results indicate that the leaf area, leaf anatomy, and photosynthesis of developing leaves were regulated by the shading environment of mature leaves. Growth hormones may possibly act as candidate signal substances to systemic regulation of leaf area development. [ABSTRACT FROM AUTHOR]