The modulation of light quality on carotenoids in maize (Zea mays L.) sprouts.

The present study aimed to identify the regulatory mechanisms of red, blue, and white light on carotenoid biosynthesis in maize sprouts. Determinations of carotenoid, chlorophyll and phytohormone profiles, as well as relative gene expression, were explored. The results identified enhancement of carotenoid and chlorophyll production as well as gene expression. Most notably, the expression levels of CRY, HY5, and beta-carotene 3-hydroxylase genes peaked under blue light. Photomorphogene-related hormone, auxins and strigolactone production was also altered under different lights and might have a role in carotenoid metabolism. Gibberellins competed with carotenoids for the precursor geranylgeranyl diphosphate and were hindered by certain light characteristics, probably via DELLA-PIF4 signalling. ERF021 and MYB68 were negative regulators of carotenoid biosynthesis in maize sprouts. These findings provide new insights into the light-regulated mechanism and biofortification of carotenoids in maize sprouts.

Drug Inducible CRISPR/Cas Systems.

Clustered, regularly interspaced, short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems have been employed as a powerful versatile technology for programmable gene editing, transcriptional modulation, epigenetic modulation, and genome labeling, etc. Yet better control of their activity is important to accomplish greater precision and to reduce undesired outcomes such as off-target events. The use of small molecules to control CRISPR/Cas activity represents a promising direction. Here, we provide an updated review on multiple drug inducible CRISPR/Cas systems and discuss their distinct properties. We arbitrarily divided the emerging drug inducible CRISPR/Cas systems into two categories based on whether at transcription or protein level does chemical control occurs. The first category includes Tet-On/Off system and Cre-dependent system. The second category includes chemically induced proximity systems, intein splicing system, 4-Hydroxytamoxifen-Estrogen Receptor based nuclear localization systems, allosterically regulated Cas9 system, and destabilizing domain mediated protein degradation systems. Finally, the advantages and limitations of each system were summarized.

Synthesis and inhibitory activity of deoxy-d-allose amide derivative against plant growth.

1,2,6-Trideoxy-6-amido-d-allose derivative was synthesized and found to exhibit higher growth-inhibitory activity against plants than the corresponding deoxy-d-allose ester, which indicates that an amide group at C-6 of the deoxy-d-allose amide enhances inhibitory activity. In addition, the mode of action of the deoxy-d-allose amide was significantly different from that of d-allose which inhibits gibberellin signaling. Co-addition of gibberellin GA3 restored the growth of rice seedlings inhibited by the deoxy-d-allose amide, suggesting that it might inhibit biosynthesis of gibberellins in plants to induce growth inhibition.

Hormonal diterpenoids derived from ent-kaurenoic acid are involved in the blue-light avoidance response of Physcomitrella patens.

Gibberellins (GAs) are diterpenoid hormones that regulate growth and development in flowering plants. The moss Physcomitrella patens has part of the GA biosynthetic pathway from geranylgeranyl diphosphate to ent-kaurenoic acid via ent-kaurene, but it does not produce GA. Disruption of the ent-kaurene synthase gene in P. patens suppressed caulonemal differentiation. Application of ent-kaurene or ent-kaurenoic acid restored differentiation, suggesting that derivative(s) of ent-kaurenoic acid, but not GAs, are endogenous regulator(s) of caulonemal cell differentiation. The protonemal growth of P. patens shows an avoidance response under unilateral blue light. Physiological studies using gene mutants involved in ent-kaurene biosynthesis confirmed that diterpenoid(s) regulate the blue-light response. Here, we discuss the implications of these findings, and provide data for the ent-kaurene oxidase gene-disrupted mutant.

Gibberellin driven growth in elf3 mutants requires PIF4 and PIF5.

The regulatory connections between the circadian clock and hormone signaling are essential to understand, as these two regulatory processes work together to time growth processes relative to predictable environmental events. Gibberellins (GAs) are phytohormones that control many growth processes throughout all stages of the plant life cycle, including germination and flowering. An increasing number of examples demonstrate that the circadian clock directly influences GA biosynthesis and signaling. EARLY FLOWERING 3 (ELF3) participates in a tripartite transcriptional complex known as the Evening Complex (EC). In this capacity, ELF3 is fundamental to core circadian clock activity, as well as time-of-day specific regulation of genes directly responsible for growth control, namely the PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5 genes. Here we show that the GA biosynthesis inhibitor paclobutrazol substantially reduces the long hypocotyl and petiole phenotypes of Arabidopsis elf3 mutants. In addition, loss of ELF3 activity causes upregulation of the key GA biosynthesis genes GA20ox1 and GA20ox2. Moreover, GA20ox1 and GA20ox2 expression depends strongly on the redundant activities of PIF4 and PIF5. These findings indicate that the defining growth phenotypes of elf3 mutants arise from altered GA biosynthesis due to misregulation of PIF4 and PIF5. These observations agree with recent work linking increased GA production with the elongated growth phenotypes of the barley elf3 mutant. Thus, the role of the EC in regulation of GA biosynthesis and signaling in eudicots is shared with monocots and, therefore, is a highly conserved mechanism for growth control.

Analysis of ent-kaurenoic acid by ultra-performance liquid chromatography-tandem mass spectrometry.

ent-Kaurenoic acid (KA) is a key intermediate connected to a phytohormone gibberellin. To date, the general procedure for quantifying KA is by using traditional gas chromatography-mass spectrometry (GC-MS). In contrast, gibberellins, which are more hydrophilic than KA, can be easily quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this study, we have established a new method to quantify KA by LC-MS/MS by taking advantage of a key feature of KA, namely the lack of fragmentation that occurs in MS/MS when electrospray ionization (ESI) is in the negative mode. Q1 and Q3 were adopted as identical channels for the multiple reaction monitoring of KA. The method was validated by comparing with the results obtained by selected ion monitoring in GC-MS. This new method could be applicable for the quantification of other hydrophobic compounds.

Phosphorylation-independent binding of 14-3-3 to NtCDPK1 by a new mode.

14-3-3 pproteins play essential roles in diverse cellular processes through the direct binding to target proteins. REPRESSION OF SHOOT GROWTH (RSG) is a tobacco (Nicotiana tabacum) transcription factor that is involved in gibberellin (GA) feedback regulation. The 14-3-3 proteins bind to RSG depending on the RSG phosphorylation of Ser-114 and negatively regulate RSG by sequestering it in the cytoplasm in response to GAs. The Ca(2+)-dependent protein kinase NtCDPK1 was identified as an RSG kinase that promotes 14-3-3 binding of RSG by phosphorylation of RSG. 14-3-3 weakly binds to NtCDPK1 by a new mode. The autophosphorylation of NtCDPK1 was necessary for the formation of the binding between NtCDPK1 and 14-3-3 but not for its maintenance. In this study, we showed that 14-3-3 binding to NtCDPK1 does not require the autophosphorylation when RSG was bound to NtCDPK1. These data suggest that 14-3-3 binds to an unphosphorylated motif in NtCDPK1 exposed by a conformational change in NtCDPK1 but not to a phosphate group generated by autophosphorylation of NtCDPK1.