Overexpression of a Pak Choi Gene, BcAS2, Causes Leaf Curvature in Arabidopsis thaliana

The LOB domain protein, a novel transcription factor with multiple functions: A review

The LATERAL ORGAN BOUNDARIES DOMAIN (LBD) protein, named for its LATERAL ORGAN BOUNDARIES (LOB) domain, is a member of a class of specific transcription factors commonly found in plants and is absent from all other groups of organisms. LBD TFs have been systematically identified in about 35 plant species and are involved in regulating various aspects of plant growth and development. However, research on the signaling network and regulatory functions of LBD TFs is insufficient, and only a few members have been studied. Moreover, a comprehensive review of these existing studies is lacking. In this review, the structure, regulatory mechanism and function of LBD TFs in recent years were reviewed in order to better understand the role of LBD TFs in plant growth and development, and to provide a new perspective for the follow-up study of LBD TFs.

Physiological Control and Genetic Basis of Leaf Curvature and Heading in Brassica rapa L

BACKGROUND

Heading is an important agronomic feature for Chinese cabbage, cabbage, and lettuce. The heading leaves function as nutrition storage organs, which contribute to the high quality and economic worth of leafy heads. Leaf development is crucial during the heading stage, most genes previously predicted to be involved in the heading process are based on Arabidopsis leaf development studies.

AIM OF REVIEW

Till date, there is no published review article that demonstrated a complete layout of all the identified regulators of leaf curvature and heading. In this review, we have summarized all the identified physiological and genetic regulators that are directly or indirectly involved in leaf curvature and heading in Brassica crops. By integrating all identified regulators that provide a coherent logic of leaf incurvature and heading, we proposed a molecular mechanism in Brassica crops with graphical illustrations. This review adds value to future breeding of distinct heading kinds of cabbage and Chinese cabbage by providing unique insights into leaf development.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Leaf curvature and heading are established by synergistic interactions among genes, transcription factors, microRNAs, phytohormones, and environmental stimuli that regulate primary and secondary morphogenesis. Various genes have been identified using transformation and genome editing that are responsible for the formation of leaf curvature and heading in Brassica crops. A range of leaf morphologies have been observed in Brassica, which are established because of the mutated determinants that are responsible for cell division and leaf polarity.

SlTCP24 and SlTCP29 synergistically regulate compound leaf development through interacting with SlAS2 and activating transcription of SlCKX2 in tomato

The complexity of compound leaves results primarily from the leaflet initiation and arrangement during leaf development. However, the molecular mechanism underlying compound leaf development remains a central research question. SlTCP24 and SlTCP29, two plant-specific transcription factors with the conserved TCP motif, are shown here to synergistically regulate compound leaf development in tomato. When both of them were knocked out simultaneously, the number of leaflets significantly increased, and the shape of the leaves became more complex. SlTCP24 and SlTCP29 could form both homodimers and heterodimers, and such dimerization was impeded by the leaf polarity regulator SlAS2, which interacted with SlTCP24 and SlTCP29. SlTCP24 and SlTCP29 could bind to the TCP-binding cis-element of the SlCKX2 promoter and activate its transcription. Transgenic plants with SlTCP24 and SlTCP29 double-gene knockout had a lowered transcript level of SlCKX2 and an elevated level of cytokinin. This work led to the identification of two key regulators of tomato compound leaf development and their targeted genes involved in cytokinin metabolic pathway. A model of regulation of compound leaf development was proposed based on observations of this study.

Genome-Wide Identification and Expression Analysis of AS2 Genes in Brassica rapa Reveal Their Potential Roles in Abiotic Stress

The ASYMMETRIC LEAVES2/LATERAL ORGAN BOUNDARIES (AS2/LOB) gene family plays a pivotal role in plant growth, induction of phytohormones, and the abiotic stress response. However, the AS2 gene family in Brassica rapa has yet to be investigated. In this study, we identified 62 AS2 genes in the B. rapa genome, which were classified into six subfamilies and distributed across 10 chromosomes. Sequence analysis of BrAS2 promotors showed that there are several typical cis-elements involved in abiotic stress tolerance and stress-related hormone response. Tissue-specific expression analysis showed that BrAS2-47 exhibited ubiquitous expression in all tissues, indicating it may be involved in many biological processes. Gene expression analysis showed that the expressions of BrAS2-47 and BrAS2-10 were significantly downregulated under cold stress, heat stress, drought stress, and salt stress, while BrAS2-58 expression was significantly upregulated under heat stress. RT-qPCR also confirmed that the expression of BrAS2-47 and BrAS2-10 was significantly downregulated under cold stress, drought stress, and salt stress, and in addition BrAS2-56 and BrAS2-4 also changed significantly under the three stresses. In addition, protein-protein interaction (PPI) network analysis revealed that the Arabidopsis thaliana genes AT5G67420 (homologous gene of BrAS2-47 and BrAS2-10) and AT3G49940 (homologous gene of BrAS2-58) can interact with NIN-like protein 7 (NLP7), which has been previously reported to play a role in resistance to adverse environments. In summary, our findings suggest that among the BrAS2 gene family, BrAS2-47 and BrAS2-10 have the most potential for the regulation of abiotic stress tolerance. These results will facilitate future functional investigations of BrAS2 genes in B. rapa.

Genetic Research and Plant Breeding

In the past 20 years, plant genetics and breeding research using molecular biology has been greatly improved via the functional analysis of genes, species identification and transformation techniques [...].

Overexpression of Liriodendron tulipifera JAG Gene (LtuJAG) Changes Leaf Shapes in Transgenic Arabidopsis thaliana

In Arabidopsis thaliana, JAGGED (JAG) is a transcription inhibitor that controls the development of leaf polarity and regulates the expression of genes controlling lateral organ formation. Liriodendron tulipifera is an ornamental tree with extraordinary tulip-shaped flowers and goose web-like leaves, this is one of the suitable plants for morphological development research. To investigate the potential functions of the LtuJAG gene, we isolated the full-length LtuJAG from L. tulipifera, transferred it into A. thaliana via agrobacterium-mediated transformation, and monitored its expression pattern. Subcellular localization showed that LtuJAG was located in the nucleus. RT-qPCR assays indicated that LtuJAG was expressed mainly in leaf buds and flowers, but not in mature leaves and stems. GUS staining results showed that LtuJAG was expressed in the shoot apical meristem (SAM). Overexpressing LtuJAG changed A. thaliana leaf shapes, causing a moderate serration and a slight asymmetric distribution in the medio-lateral and proximal-distal axes. Ectopic expression of LtuJAG induced the expression of lateral organ boundary suppressors JAGGED LATERAL ORGANS (JLO) and ARABIDOPSIS THALIANA HOMEOBOX1 (ATH1). It also repressed the expression of the apical meristem suppressor class-1 KNOX gene (KNOX I) and altered endogenous hormone levels. Our results suggest that LtuJAG plays a role in negatively regulating leaf polarity formation in L. tulipifera.