Knots in the family tree: evolutionary relationships and functions of knox homeobox genes

Knotted-like homeobox (knox) genes constitute a gene family in plants. Class I knox genes are expressed in shoot apical meristems, and (with notable exceptions) not in lateral organ primordia. Class II genes have more diverse expression patterns. Loss and gain of function mutations indicate that knox genes are important regulators of meristem function. Gene duplication has contributed to the evolution of families of homeodomain proteins in metazoans. We believe that similar mechanisms have contributed to the diversity of knox gene function in plants. Knox genes may have contributed to the evolution of compound leaves in tomato and could be involved in the evolution of morphological traits in other species. Alterations in cis-regulatory regions in some knox genes correlate with novel patterns of gene expression and distinctive morphologies. Preliminary data from the analysis of class I knox gene expression illustrates the evolution of complex patterns of knox expression is likely to have occurred through loss and gain of domains of gene expression.     

Out of step: The function of TALE homeodomain transcription factors that regulate shoot meristem maintenance and meristem identity

The indeterminate growth pattern displayed by shoots is mediated by the proper maintenance of the shoot meristem.Meristem maintenance is dependent upon the balance of stem cell perpetuation in the cent...     

CENTRORADIALIS maintains shoot meristem indeterminacy by antagonizing THORN IDENTITY1 in Citrus

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高等植物成花基因的研究

高等植物的成花可分为两个阶段：由茎顶端分生组织转变成花分生组织和花器官的形成。前者主要受成花计时基因的控制,而后一阶段主要由植物的同源（异型）框基因调控。本文综述了近年来对植物成花调控基因的研究,并着重对第一阶段成花基因的功能、它们间的相互作用和特点进行了总结。Abstract:Plant flower can be divided into two phases——from stem apex meristem tissue into flower meristem tissue and floral apparatus.The flower time genes control the flower development and the homologous genes control flower apparatus identify.This paper summarizes recent studies on plant flower and emphasizes on the first phase flower control genes,theirs interaction and function,characteristic of the homologous genes.     

Overexpression of the JAZ factors with mutated jas domains causes pleiotropic defects in rice spikelet development

In a determinate meristem, such as a floral meristem, a genetically determined number of organs are produced before the meristem is terminated. In rice, iterative formation of organs during flower development with defects in meristem determinacy, classically called ‘proliferation’, is caused by several mutations and observed in dependence on environmental conditions. Here we report that overexpression of several JAZ proteins, key factors in jasmonate signaling, with mutations in the Jas domains causes an increase in the numbers of organs in florets, aberrant patterns of organ formation and repetitious organ production in spikelets. Our results imply that JAZ factors modulate mechanisms that regulate meristem functions during spikelet development.     

Morphology and biomass production of prairie cordgrass on marginal lands

Prairie cordgrass (Spartina pectinata Link.) is indigenous throughout most of the continental United States and Canada to 60°N latitude and is well suited to marginal land too wet for maize (Zea mays L.) and switchgrass (Panicum virgatum L.). Evaluations of prairie cordgrass in Europe and North America indicated it has high potential for biomass production, relative to switchgrass, in short‐season areas. Our objective was to describe morphology and biomass production and partitioning in mature stands of ‘Red River’ prairie cordgrass and determine biomass production of natural populations on marginal land. This study was conducted from 2000 to 2008 in eastern South Dakota. Mean biomass production of mature stands of Red River was 12.7 Mg ha^?1. Leaves composed >88% of the biomass, and 60% of the tillers had no internodes. Belowground biomass to a depth of approximately 25 cm, not including roots, was 21 Mg ha^?1. Tiller density ranged from 683 tillers m^?2 for a 10‐year‐old stand to 1140 tillers m^?2 for a 4‐year‐old stand. The proaxis was composed of about eight phytomers, with rhizomes originating at proximal nodes and erect tillers at distal nodes. Vegetative propagation was achieved by both phalanx and guerilla growth. Differences among natural populations for biomass were expressed on gravelly marginal land. However, production, averaged across populations, was low (1.37 Mg ha^?1) and comparable to ‘Cave‐In‐Rock’ switchgrass (1.67 Mg ha^?1) over a 4‐year period. The large carbon storage capacity of prairie cordgrass in proaxes and rhizomes makes it useful for carbon sequestration purposes. Prairie cordgrass should be compared with switchgrass and other C₄ perennial grasses along environmental gradients to determine optimum landscape positions for each and to maximize bioenergy production and minimize inputs.