Plant development includes the initiation of structure patterning, and maturation as plants grow via cell division, elongation, and differentiation. Unlike animals that form all their body parts early in their life, plants constantly generate new structures from meristems in the apex, vascular, and cork cambium tissues throughout their lives. This process is regulated by interactions of endogenous genetic mechanisms and environmental stimuli. When reaching certain developmental stage, plants can sense environmental changes, which stimulate reproductive development from the vegetative phase to generate new individual plants or offspring via sexual or asexual reproduction. There have been extensive investigations to understand genes/alleles and their interaction with environmental signals controlling the formation of plant organs. A recently published Special Topic in Science Bulletin presented 3 invited reviews and 2 research articles regarding Plant Development and Reproduction.
To further understand the biosysnthesis of auxins, which play a fundamental role in coordinating many growth events and organ formation in the plant's life cycle, Dr. Yunde Zhao's group overexpressed a bacterial tryptophan oxidase in the model dicot plant Arabidopsis thaliana and found that it can convert Trp to the imine form of IPA and change IPA levels in transgenic plants. This proves that Arabidopsis uses two approaches to ensure no excess IPA is produced.
Despite accumulated knowledge on the molecular control of stem cells from studies on Arabidopsis, little is known about stem cells in grass species which include many agriculturally important crops. Zeng et al reported stem cell lineage and differentiation during root and leaf development of the monocot model plant, rice (Oryza sativa). They concluded that in leaves and roots there are at least two common steps for vascular development, i.e., formation of a procambium and root pericycle or leaf outer sheath from the preprocambium, and the differentiation of the procambium into xylem, phloem, and circumambient cells. Furthermore, the authors investigated the expression patterns of stem cell identity genes in rice tissues.
The formation of a secondary cell wall is important for plant cell function and plant structure. In this Specific Topic, Li et al presents a summary of the hormonal and transcriptional control of transition from the primary to secondary wall, and addresses the gaps in current knowledge on metabolic mechanisms supporting this transition. The authors also discuss several tools potentially useful in future research on cell wall synthesis.
In this issue, a review by Xu et al illustrates the molecular and genetic control of key events during pollen wall development, such as callose wall synthesis and dissolution, primexine formation, and plasma membrane undulation, synthesis, and deposition of sporopollenin, and patterning of pollen aperture patterns in Arabidopsis.
In higher plants, effective communication between male and female gametophytes determines reproductive success including double fertilization, and the formation of seed and fruit. The molecular control underlying male and female interactions has been a challenging biological question. In the invited review by Chai et al, the authors introduce new advances on the functionality of receptor-like kinases mediating pollen tube growth and fertilization.
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