Temporal regulation of vegetative phase change in plants.

During their vegetative growth, plants reiteratively produce leaves, buds, and internodes at the apical end of the shoot. The identity of these organs changes as the shoot develops. Some traits change gradually, but others change in a coordinated fashion, allowing shoot development to be divided into discrete juvenile and adult phases.

Short-interval traffic lines: versatile tools for genetic analysis in Arabidopsis thaliana.

Traffic lines are transgenic stocks of Arabidopsis thaliana that contain a pair of linked seed-specific eGFP and DsRed markers. These stocks were originally developed for the purpose of studying recombination, but can also be used to follow the inheritance of unmarked chromosomes placed in trans to the marked chromosome. They are particularly useful for this latter purpose if the distance between markers is short, making double recombination within this interval relatively rare.

How was apical growth regulated in the ancestral land plant? Insights from the development of non-seed plants.

Land plant life cycles are separated into distinct haploid gametophyte and diploid sporophyte stages. Indeterminate apical growth evolved independently in bryophyte (moss, liverwort, and hornwort) and fern gametophytes, and tracheophyte (vascular plant) sporophytes. The extent to which apical growth in tracheophytes co-opted conserved gametophytic gene networks, or exploited ancestral sporophytic networks, is a long-standing question in plant evolution.

VAL genes regulate vegetative phase change via miR156-dependent and independent mechanisms.

How organisms control when to transition between different stages of development is a key question in biology. In plants, epigenetic silencing by Polycomb repressive complex 1 (PRC1) and PRC2 plays a crucial role in promoting developmental transitions, including from juvenile-to-adult phases of vegetative growth. PRC1/2 are known to repress the master regulator of vegetative phase change, miR156, leading to the transition to adult growth, but how this process is regulated temporally is unknown.

Lonely at the top? Regulation of shoot apical meristem activity by intrinsic and extrinsic factors.

All the above-ground organs of a plant are derived from stem cells that reside in shoot apical meristems (SAM). Over the past 25 years, the genetic pathways that control the proliferation of stem cells within the SAM, and the differentiation of their progenitors into lateral organs, have been described in great detail. However, longstanding questions regarding the importance of communication between cells within the SAM and lateral organs have, until recently, remained unanswered.

regulates leaf identity independently of miR156-mediated translational repression.

In , loss of the carboxypeptidase ALTERED MERISTEM PROGRAM1 (AMP1) produces an increase in the rate of leaf initiation, an enlarged shoot apical meristem and an increase in the number of juvenile leaves. This phenotype is also observed in plants with reduced levels of miR156-targeted () transcription factors, suggesting that AMP1 might promote SPL activity. However, we found that the mutant phenotype is only partially corrected by elevated gene expression, and that has no significant effect on transcript levels, or on the level or the activity of miR156.

Role for the shoot apical meristem in the specification of juvenile leaf identity in .

The extent to which the shoot apical meristem (SAM) controls developmental decisions, rather than interpreting them, is a longstanding issue in plant development. Previous work suggests that vegetative phase change is regulated by signals intrinsic and extrinsic to the SAM, but the relative importance of these signals for this process is unknown. We investigated this question by examining the effect of meristem-deficient mutations on vegetative phase change and on the expression of key regulators of this process, miR156 and its targets, SPL transcription factors.

Candidate regulators of Early Leaf Development in Maize Perturb Hormone Signalling and Secondary Cell Wall Formation When Constitutively Expressed in Rice.

All grass leaves are strap-shaped with a series of parallel veins running from base to tip, but the distance between each pair of veins, and the cell-types that develop between them, differs depending on whether the plant performs C or C photosynthesis. As part of a multinational effort to introduce C traits into rice to boost crop yield, candidate regulators of C leaf anatomy were previously identified through an analysis of maize leaf transcriptomes. Here we tested the potential of 60 of those candidate genes to alter leaf anatomy in rice.

The role of small RNAs in vegetative shoot development.

Shoot development consists of the production of lateral organs in predictable spatial and temporal patterns at the shoot apex. To properly integrate such programs of growth across different cell and tissue types, plants require highly complex and robust genetic networks. Over the last twenty years, the roles of small, non-coding RNAs (sRNAs) in these networks have become increasingly apparent, not least in vegetative shoot growth.

Cracking the Kranz enigma with systems biology.

Leaves with Kranz anatomy exhibit a highly characteristic arrangement of closely spaced veins surrounded by concentric wreaths of bundle sheath and mesophyll cells. This anatomical framework is vital for effective C4 photosynthesis in nearly all known land plant lineages and has evolved independently on over 60 occasions. Over the last 3 years, technological advances, particularly in high-throughput DNA sequencing, have allowed the development of Kranz anatomy to be interrogated at unprecedented depth.

Genome-wide transcript analysis of early maize leaf development reveals gene cohorts associated with the differentiation of C4 Kranz anatomy.

Photosynthesis underpins the viability of most ecosystems, with C4 plants that exhibit 'Kranz' anatomy being the most efficient primary producers. Kranz anatomy is characterized by closely spaced veins that are encircled by two morphologically distinct photosynthetic cell types. Although Kranz anatomy evolved multiple times, the underlying genetic mechanisms remain largely elusive, with only the maize scarecrow gene so far implicated in Kranz patterning.

Evolution of GOLDEN2-LIKE gene function in C(3) and C (4) plants.

A pair of GOLDEN2-LIKE transcription factors is required for normal chloroplast development in land plant species that encompass the range from bryophytes to angiosperms. In the C(4) plant maize, compartmentalized function of the two GLK genes in bundle sheath and mesophyll cells regulates dimorphic chloroplast differentiation, whereas in the C(3) plants Physcomitrella patens and Arabidopsis thaliana the genes act redundantly in all photosynthetic cells. To assess whether the cell-specific function of GLK genes is unique to maize, we analyzed gene expression patterns in the C(4) monocot Sorghum bicolor and C(4) eudicot Cleome gynandra.