Kandelia (Rhizophoraceae) has long been regarded as a monotypic mangrove genus. Recent studies in chromosome number, molecular phylogeography, physiological adaptation, and leaf anatomy, however, reveal that there are two well differentiated sets of geographical populations separated by the South China Sea. These are recognized as two distinct species, Kandelia candel (L.) Druce and Kandelia obovata Sheue, Liu & Yong sp. nov.

Variegation in these Begonia is structural, where light areas are created by internal reflection between air spaces and cells in a leaf. Two forms of air space structural variegation occur, distinguished by the location of the air spaces. Both forms may have a common origin in development where dermal tissue becomes loosely connected to mesophyll. Photosynthetic functioning is retained in light areas, and these areas do not include primary veins, potentially limiting the costs of variegation.

Our anatomical analysis revealed that a dry maize seed contains four to five embryonic leaves at different developmental stages. Rudimentary kranz structure (KS) is apparent in the first leaf with a substantial density, but its density decreases toward younger leaves. Upon imbibition, leaf expansion occurs rapidly with new KSs initiated from the palisade-like ground meristem cells in the middle of the leaf. In parallel to the anatomical analysis, we obtained the time course transcriptomes for the embryonic leaves in dry and imbibed seeds every 6 h up to hour 72. Over this time course, the embryonic leaves exhibit transcripts of 30,255 genes at a level that can be regarded as "expressed." In dry seeds, ∼25,500 genes are expressed, showing functional enrichment in transcription, RNA processing, protein synthesis, primary metabolic pathways, and calcium transport. During the 72-h time course, ∼13,900 genes, including 590 transcription factor genes, are differentially expressed. Indeed, by 30 h postimbibition, ∼2,200 genes expressed in dry seeds are already down-regulated, and ∼2,000 are upregulated. Moreover, the top 1% expressed genes at 54 h or later are very different from those before 30 h, reflecting important developmental and physiological transitions. Interestingly, clusters of genes involved in hormone metabolism, signaling, and responses are differentially expressed at various time points and TF gene expression is also modular and stage specific. Our dataset provides an opportunity for hypothesizing the timing of regulatory actions, particularly in the context of KS development.plant leaf development | plant hormones | gene expression profiling M aize, a well-studied crop, has been used as a model plant for C4 photosynthesis study, as its leaves possess the kranz structure (KS) for efficient photosynthesis. However, how its leaves develop from seed following imbibition has not been well studied. In particular, it is unclear how KS forms during leaf development. Using the next generation sequencing technology, Li et al. (1) studied the leaf transcriptomes of four regions of 9-dold third maize leaves: the base, the tip, and two middle regions of the leaf, representing different leaf developmental stages, with the base being the youngest. The data revealed a dynamic transcriptome profile, showing different transcripts enriched in different regions and providing a preliminary view of molecular changes during maize leaf development. However, as the leaf base already exhibits distinct KS, it is not early enough to represent the early leaf development when KS begins to form. Indeed, our anatomical study reveals that KS already exists in a rudimentary form in the first two embryonic leaves of maize dry seeds, and the embryonic leaves develop rapidly after seed imbibition (see below). To correlate the transcriptomic dynamics with the KS development during seed germination, we have obtained the time course transcriptomes of embryonic leaves at every 6 h, starting from dry seeds to hour 72 postimbibition. This set o...

HighlightPhytoplasma effector SAP11 modulates plant volatile organic compound emissions by suppressing the expression of NbOMT1, which encodes an O-methyltransferase required for the biosynthesis of 3-isobutyl-2-methoxypyrazine.

Study of the unique leaf anatomy and chloroplast structure in shade-adapted plants will aid our understanding of how plants use light efficiently in low light environments. Unusual chloroplasts in terms of size and thylakoid membrane stacking have been described previously in several deep-shade plants. In this study, a single giant cup-shaped chloroplast, termed a bizonoplast, was found in the abaxial epidermal cells of the dorsal microphylls and the adaxial epidermal cells of the ventral microphylls in the deep-shade spike moss Selaginella erythropus. Bizonoplasts are dimorphic in ultrastructure: the upper zone is occupied by numerous layers of 2-4 stacked thylakoid membranes while the lower zone contains both unstacked stromal thylakoids and thylakoid lamellae stacked in normal grana structure oriented in different directions. In contrast, other cell types in the microphylls contain chloroplasts with typical structure. This unique chloroplast has not been reported from any other species. The enlargement of epidermal cells into funnel-shaped, photosynthetic cells coupled with specific localization of a large bizonoplast in the lower part of the cells and differential modification in ultrastructure within the chloroplast may allow the plant to better adapt to low light. Further experiments are required to determine whether this shade-adapted organism derives any evolutionary or ecophysiological fitness from these unique chloroplasts.