中国主要禾本科植物花的基本类型与系统分类

本文研究、分析了禾本科33个族、174个属(632种)的花的性状;讨论了重要性状演化的趋势。根据花、尤其花中鳞被的比较形态,把禾本科植物的花概括为三大类型七个亚型：竹型(包括真竹亚型,稻亚型、芦竹亚型、针茅亚型)、早熟禾型(含早熟禾亚型)和黍型(包括画眉草亚型,真黍亚型)。其结果与花的基本类型相对应的大类群,以及与幼苗基本类型、颖果基本类型相对应的大类群是一致的,即竹亚科、稻亚科、芦竹亚科、针茅亚科、早熟禾亚科、画眉草亚科,黍亚科。     

竹亚科系统学和生物地理学研究进展及存在的问题

对近年来在竹亚科作为一个单系类群的界定、其系统位置的确定、内部系统演化趋势以及地理分布和起源方面研究所取得的进展进行了评述。竹亚科作为一个单系类群仅包括了木本的竹族（Bambuseae)和一个草本的莪利竹族（Olyreae),其中莪利竹族分布在新几内亚的伊里安竹（Buergersiochloa)处于Olyreae最基部。禾本科12个亚科中除了3个亚科为基部类群以外,其余9个亚科分成PACCAD（包括黍亚科,狭义的芦竹亚科,广义的虎尾草亚科,假淡竹叶亚科,三芒草亚科和扁芒草亚科）和BOP单系分支（包括竹亚科,稻亚科和早熟禾亚科）。在BOP支中,竹亚科与早熟禾亚科相近缘,共同组成稻亚科的姐妹群。竹亚科分成草本和木本两个单系类群,木本竹子又分成热带和温带支系,热带支系进一步分成新世界热带和旧世界热带两个单系类群。从现有的化石证据和基部类群的地理分布推断,竹亚科很可能起源于晚白垩纪的冈瓦纳古陆。最后,本文就竹亚科研究尚存在的问题做了初步探讨。     

内蒙古典型草原禾本科植硅体形态

运用地层中植硅体组合解释过去草原植被及气候变化的关键之一,是要了解研究区现代植硅体形态及表土植硅体组合与现代植被的关系。文中研究内蒙古典型草原禾本科植物根、茎、叶、芒以及种子等不同部位的植硅体,对其中的12种主要禾本科植物叶表皮短细胞硅酸体进行分类及统计。研究表明：内蒙古典型草原禾本科叶表皮短细胞硅酸体可分为8种特殊形态类型。C3植物早熟禾亚科的叶表皮短细胞硅酸体形态多样。几乎所有早熟禾亚科都能产生圆型硅酸体,以贝加尔针茅(85．5％)、大针茅(89．7％)、克氏针茅(90％)以及芨芨草(96．6％)中的圆型硅酸体含量最丰富。针茅哑铃型主要见于针茅植物叶表皮短细胞中,克氏针茅的针茅哑铃型含量相对较高。羊草中未见针茅哑铃型硅酸体。浴草、披缄草叶表皮短细胞硅酸体以齿型为主,分别含87．3％和57．2％,齿型在硬质早熟禾中也占一定比例。沙生冰草中的脊圆型占优势,含74．4％。C3植物早熟禾亚科的叶表皮短细胞产生的截锥型硅酸体含量较少。C4植物虎尾草亚科中的糙隐子草叶表皮短细胞硅酸体以黍哑铃型、简单哑铃型、鞍型为主;黍亚科狗尾草则以黍哑铃型占优势(82．9％)。     

禾本科植物叶片表皮结构细胞主要类型的演化与系统分类和发育途径的探讨

通过对禾本科２０３属３２８种植物的叶表皮解剖观察,对表皮各类结构细胞分别进行了演化探讨。根据结构细胞在类群间呈现的各种差异以及与外部形态、地理分布的相互印证,将禾本科分划为５亚科３超族,原来的芦竹亚科被归并到黍亚科中。同时以结构细胞在类群中显示的类型数、类型演化总体水平和类型变异趋势,对禾本科各大类群进行了系统位置的评认和亲缘关系、演化途径的推导。     

我国主要禾本科植物幼苗发育基本类型与系统分类

本文在观察了代表22个族76个属的203种禾本科植物幼苗的发育过程和 各种性状的基础上,探讨了重要性状的形成与分布区、生境条件的关系及重要性 状之间的相关性。 根据胚轴和根系发育的不同形式,将禾本科幼苗划分为三大 型：竹型、狐茅型和黍型。根据苗叶和不定根的特点,又把这些大型分为七个 亚型：真竹亚型、稻亚型、芦竹亚型、针茅亚型、狐茅亚型、画眉草亚型和真黍亚 型。 经过与胚体和植株各方面数据的互相印证,证明与幼苗形态的七个亚型相 对应,在系统分类上是七个亚科：竹亚科、稻亚科、芦竹亚科、针茅亚科、狐茅亚科、画眉草亚科和黍亚科。     

小麦与玉米杂交产生小麦单倍体的研究进展

在作物改良中,常利用植物属间的远缘杂交,将异种植物的有用性状向栽培种转移。植物远缘杂交的难易程度一般由两亲本亲缘关系的远近所决定。近年来的研究表明,禾本科中的两个亚科即早熟禾亚科（Ｐｏｏｉｄｅａ）和黍亚科（Ｐａｎｉｃｏｉｄｅａ）之间的杂交并不完全受这一规律的限制,特别是六倍体的普通小麦（早熟禾亚科）和玉米（黍亚科）之间的杂交,可以发生高频率的受精作用和胚胎形成。为了扩大小麦的基因资源,近年来育种学家突破了小麦族内各物种间的杂交限制,观察到小麦×玉米和小麦×高粱的受精率（单、双受精）分别可达到５９…     

一些水稻的重复DNA顺序在稻属和其它禾本科植物中的多态性

重复DNA顺序是真核生物基因组的特征,很多重复DNA顺序已从小麦、拟南芥菜、燕麦、水稻、玉米等植物的基因组中克隆出来,还发现有一些重复DNA顺序具有基因组特异性,用它们作探针可以分析同属或同科物种的起源和亲缘关系,并建立系统进化树。小卫星DNA或微小卫星DNA所产生的指纹图谱可作为一种遗传学标志来研究系统进化、染色体的精细结构和物种的鉴定。一些中度重复DNA序列还可以作为组织培养株系和细胞杂交筛选的分子标志。稻属已发现并定名的有22个种,根据杂交亲和性、细胞遗传学和生理生化等将它分为6个二倍体组型(AA、BB、CC、DD、EE和FF)和2个四倍体组型(BBCC和CCDD)。现多把禾本科分作5个亚科:竹亚科、稻亚科、早熟禾亚科、画眉草亚科和     

虎尾草亚科(Chloridoideae)的分类系统述评

简要介绍了禾本科虎尾草亚科的分类历史。考察虎尾草亚科属上阶元的变化过程,概括不同时期该亚科分类学研究的进展及分类原则,对3种研究方法的不足进行评价。自1990年《中国植物志》第10卷第1分册出版以来,对中国虎尾草亚科植物属种水平的系统变化进行了说明。为了更好地理解虎尾草亚科的系统发育关系,指出了虎尾草亚科没有解决的问题及今后的研究方向。     

禾本科虎尾草亚科细胞学研究分析

总结了虎尾草亚科72属601个分类单位的细胞学资料。虎尾草亚科的染色体基数是10和9,来源于原始染色体基数6经非整倍性减少为5,再经多倍化及非整倍性减少而来。细胞学性状对虎尾草亚科属上类群的分类具有相当重要的价值。推测染色体基数演化的趋势为:x=6→x=5→x=10→x=9。据认为,虎尾草亚科的原始染色体基数为5的二倍体类群在演化早期就灭绝了。     

禾本科植物叶片表皮结构细胞主要类型的演化与系统分类和发育途径的探讨（续）

禾本科植物叶片表皮结构细胞主要类型的演化与系统分类和发育途径的探讨（续）蔡联炳,郭延平（中国科学院西北高原生物研究所,西宁８１０００１）（河南大学生物系,开封４７５００１）３类群的系统位置及演化途径３．１竹亚科Ｓｕｂｆａｍ．ＢａｍｂｕｓｏｉｄｅａｅＮ...     

Phylogenetic structure in the grass family (Poaceae) as inferred from chloroplast DNA restriction site variation

A cladistic analysis of chloroplast DNA restriction site variation among representatives of all subfamilies of the grass family (Poaceae), using Joinvillea (Joinvilleaceae) as the outgroup, placed most genera into two major clades. The first of these groups corresponds to a broadly circumscribed subfamily Pooideae that includes all sampled representatives of Ampelodesmeae, Aveneae, Brachypodieae, Bromeae, Diarrheneae, Meliceae, Poeae, Stipeae, and Triticeae. The second major clade includes all sampled representatives of four subfamilies (Panicoideae [tribes Andropogoneae and Paniceae], Arundinoideae [Arundineae], Chloridoideae [Eragrostideae], and Centothecoideae [Centotheceae]). Within this group (the “PACC” clade), the Panicoideae are resolved as monophyletic and as the sister group of the clade that comprises the other three subfamilies. Within the latter group, Danthonia (Arundinoideae) and Eragroslis (Chloridoideae) are resolved as a stable monophyletic group that excludes Phragmites (Arundinoideae); this structure is inconsistent with the Arundinoideae being monophyletic as currently circumscribed. The PACC clade is placed within a more inclusive though unstable clade that includes the woody Bambusoideae (Bambuseae) plus several disparate tribes of herbaceous grasses of uncertain affinity that are often recognized as herbaceous Bambusoideae (Brachyelytreae, Nardeae, Olyreae, Oryzeae, and Phareae). Among eight most-parsimonious trees resolved by the analysis, four include a monophyletic Bambusoideae sensu lato (comprising Bambuseae and all five of these herbaceous tribes) as the sister group of the PACC clade; in the other four trees these bambusoid elements are not resolved as monophyletic, and the PACC clade is nested among these tribes. These results are consistent with those of previous analyses that resolve a basal or near-basal branch within the family between Pooideae and all other grasses. However, resolution by the present analysis of the PACC clade, which includes Centothecoideae, Chloridoideae, and Panicoideae, but excludes Bambusoideae, is inconsistent with the results of previous analyses that place Bambusoideae and Panicoideae in a monophyletic group that excludes Centothecoideae and Chloridoideae.     

IMMUNOLOGICAL AFFINITIES AMONG SUBFAMILIES OF THE POACEAE

Immunological affinities were investigated among twenty taxa belonging to the grass subfamilies Pooideae, Chloridoideae, Panicoideae, Oryzoideae, and Bambusoideae. Antisera were raised to the prolamin fraction of seed proteins from species of eleven grass genera (Hordeum, Bromus, Festuca, Phleum, Elensine, Panicum, Pennisetum, Tripsacum, Dendrocalamus, and Oryza) and reacted with their homologous antigens and nineteen different heterologous antigens in Enzyme-Linked Immunosorbent Assay (ELISA). The immunological cross-reactivity among the eleven taxa whose prolamin was used for antisera production was analyzed quantitatively by generating matrices of averaged cross-reactivities, Q correlation and distance. The averaged cross-reactivity matrix was calculated from averaging reciprocal immunological reactions while the two other matrices were computed by considering each antiserum as a character and antigens as OTUs. The three matrices were subjected to clustering by the Unweighted Pair Group Method using Arithmetic Averaging (UPGMA). The phenogram based on the averaged similarity matrix showed some distortion, while the other two phenograms were similar in topology and were informative. A phenon line at r = 0.17 divided the phenogram based on Q correlation into four major groups: Pooideae, Oryzoideae, Bambusoideae, and Chloridoideae-Panicoideae. The two subfamilies in the Chloridoideae-Panicoideae group clustered at a correlation coefficient of 0.22. Within the Pooideae, the tribes Aveneae and Agrostideae were closely grouped together (r = 0.85), but they were quite distinct (r = 0.16) from the tightly clustered (r = 0.84–0.85) Bromeae, Poeae, and Triticeae. The Oryzoideae and Bambusoideae showed low immunological similarity (r = –0.07). The two tribes of the Panicoideae, Paniceae and Andropogoneae, displayed extensive immunological similarity clustering tightly at r = 0.84–0.86. The immunological data revealed a possible trend in grass evolution encompassing the chloridoid-panicoid groups and provided insights into the phylogenetic affinities of the bambusoid and oryzoid grasses. The results also underscored the heterogeneity of the taxa within the Pooideae.     

The complete chloroplast genome of tall fescue (Lolium arundinaceum; Poaceae) and comparison of whole plastomes from the family Poaceae

In this paper, we describe the complete chloroplast genome of Lolium arundinaceum. This sequence is the culmination of a long-term project completed by >400 undergraduates who took general genetics at Middle Tennessee State University from 2004-2007. It was undertaken in an attempt to introduce these students to an open-ended experiential/exploratory lesson to produce and analyze novel data. The data they produced should provide the necessary information for both phylogenetic comparisons and plastome engineering of tall fescue. The fescue plastome (GenBank FJ466687) is 136048 bp with a typical quadripartite structure and a gene order similar to other grasses; 56% of the plastome is coding region comprised of 75 protein-coding genes, 29 tRNAs, four rRNAs, and one hypothetical coding region (ycf). Comparisons of Poaceae plastomes reveal size differences between the PACC (subfamilies Panicoideae, Arundinoideae, Centothecoideae, and Chloridoideae) and BOP (subfamilies Bambusoideae, Oryzoideae, and Pooideae) clades. Alignment analysis suggests that several potentially conserved large deletions in previously identified intergenic length polymorphic regions are responsible for the majority of the size discrepancy. Phylogenetic analysis using whole plastome data suggests that fescue closely aligns with Lolium perenne. Some unique features as well as phylogenetic branch length calculations, however, suggest that a number of changes have occurred since these species diverged.     

Phylogenetic structure in the grass family (Poaceae): evidence from the nuclear gene phytochrome B

Phylogenetic analyses of partial phytochrome B (PHYB) nuclear DNA sequences provide unambiguous resolution of evolutionary relationships within Poaceae. Analysis of PHYB nucleotides from 51 taxa representing seven traditionally recognized subfamilies clearly distinguishes three early-diverging herbaceous "bambusoid" lineages. First and most basal are Anomochloa and Streptochaeta, second is Pharus, and third is Puelia. The remaining grasses occur in two principal, highly supported clades. The first comprises bambusoid, oryzoid, and pooid genera (the BOP clade); the second comprises panicoid, arundinoid, chloridoid, and centothecoid genera (the PACC clade). The PHYB phylogeny is the first nuclear gene tree to address comprehensively phylogenetic relationships among grasses. It corroborates several inferences made from chloroplast gene trees, including the PACC clade, and the basal position of the herbaceous bamboos Anomochloa, Streptochaeta, and Pharus. However, the clear resolution of the sister group relationship among bambusoids, oryzoids, and pooids in the PHYB tree is novel; the relationship is only weakly supported in ndhF trees and is nonexistent in rbcL and plastid restriction site trees. Nuclear PHYB data support Anomochlooideae, Pharoideae, Pooideae sensu lato, Oryzoideae, Panicoideae, and Chloridoideae, and concur in the polyphyly of both Arundinoideae and Bambusoideae.     

Anthocyanins of grasses

The anthocyanin content of 23 grass species (Poaceae) belonging to five subfamilies has been determined. Altogether 11 anthocyanins were identified; the 3-(6″-malonylglucosides) and 3-glucosides of cyanidin, peonidin and delphinidin, the 3-(3″,6″-dimalonylglucoside), 3-(6″-rhamnosylglucoside) and 3-(6″-glucosylglucoside) of cyanidin, in addition to peonidin 3-(dimalonylglucoside) and delphinidin 3-(6″-rhamnosylglucoside). Anthocyanins acylated with one and/or two malonic acid moieties dominated the anthocyanin profiles of all the species in the subfamilies Pooideae and Panicoideae. On the other hand, the 3-glucoside and 3-rutinoside of cyanidin were the major anthocyanins in Sinarundinaria murielae (subfamily Bambusoideae) and Molinia caerulea (subfamily Arundinoideae), while the 3-glucosides of cyanidin and peonidin were the principal anthocyanins in rice, Oryza sativum (subfamily Oryzoideae). Pelargonidin derivatives and free anthocyanidins have previously been reported to occur in several Poaceae species, however, not identified in any of the species included in this survey.     

Nuclear DNA variation, chromosome numbers and polyploidy in the endemic and indigenous grass flora of New Zealand

BACKGROUND AND AIMS: Little information is available on DNA C-values for the New Zealand flora. Nearly 85 % of the named species of the native vascular flora are endemic, including 157 species of Poaceae, the second most species-rich plant family in New Zealand. Few C-values have been published for New Zealand native grasses, and chromosome numbers have previously been reported for fewer than half of the species. The aim of this research was to determine C-values and chromosome numbers for most of the endemic and indigenous Poaceae from New Zealand. SCOPE: To analyse DNA C-values from 155 species and chromosome numbers from 55 species of the endemic and indigenous grass flora of New Zealand. KEY RESULTS: The new C-values increase significantly the number of such measurements for Poaceae worldwide. New chromosome numbers were determined from 55 species. Variation in C-value and percentage polyploidy were analysed in relation to plant distribution. No clear relationship could be demonstrated between these variables. CONCLUSIONS: A wide range of C-values was found in the New Zealand endemic and indigenous grasses. This variation can be related to the phylogenetic position of the genera, plants in the BOP (Bambusoideae, Oryzoideae, Pooideae) clade in general having higher C-values than those in the PACC (Panicoideae, Arundinoideae, Chloridoideae + Centothecoideae) clade. Within genera, polyploids typically have smaller genome sizes (C-value divided by ploidy level) than diploids and there is commonly a progressive decrease with increasing ploidy level. The high frequency of polyploidy in the New Zealand grasses was confirmed by our additional counts, with only approximately 10 % being diploid. No clear relationship between C-value, polyploidy and rarity was evident.     

Phylogeny of the grass family (Poaceae) from rpl16 intron sequence data

DNA sequence data from the chloroplast noncoding rpl16 intron are used to address phylogenetic relationships among the major lineages of the grass family, with particular emphasis on the highly heterogeneous subfamily Bambusoideae and the basal lineages. Thirty-five grass sequences representing all six currently recognized major groups of the family and one outgroup sequence were analyzed using both parsimony and distance methods. The phylogenetic analyses indicated: (1) Puelia, a traditionally isolated bambusoid genus, is the most basal lineage in the BOP clade (Bambusoideae, Oryzoideae, and Pooideae); (2) the bambusoid clade is a sister group to the pooid clade; and (3) the monophyletic oryzoid clade is well separated from the bambusoid clade. The study further confirmed the recognition of two primary groups in the grass family: the BOP clade and the PACC clade (Panicoideae, Arundinoideae, Chloridoideae, and Centothecoideae); it also provided further evidence that the traditional subfamily Bambusoideae is highly heterogeneous and phylogenetically unacceptable. The data support Streptochaeteae, Anomochloeae, and Phareae as the most basal lineages among the extant grasses. Within the BOP clade, oryzoids and pooids are confirmed as two monophyletic clades, but the bambusoid clade, including only the woody bamboo tribe Bambuseae and the herbaceous bamboo tribe Olyreae, is relatively weakly supported. The study also indicated that the chloroplast noncoding region sequence data could be useful in phylogenetic analysis at relatively high taxonomic levels.     

Phylogenetics and character evolution in the grass family (Poaceae): Simultaneous analysis of morphological and Chloroplast DNA restriction site character sets

A phylogenetic analysis of the grass family (Poaceae) was conducted using two character sets, one representing variation in 364 mapped and cladistically informative restriction sites from all regions of the chloroplast genome, the other representing variation in 42 informative “structural characters.” The structural character set includes morphological, anatomical, chromosomal, and biochemical features, plus structural features of the chloroplast genome. The taxon sample comprises 75 exemplar taxa, including 72 representatives of Poaceae and one representative of each of three related families (Flagellariaceae, Restionaceae, and Join-villeaceae);Flagellaria served as the outgroup for the purpose of cladogram rooting. Among the grasses, 24 tribes and all 16 subfamilies of grasses recognized by various modern authors were sampled. Transformations of structural characters are mapped onto the phylogenetic hypotheses generated by the analysis, and interpreted with respect to biogeography and the evolution of wind pollination in the grass family. A major goal of the study was to test the monophyly of several putatively natural groups, including Bambusoideae, Pooideae, Arundinoideae, and the “PACC clade” (the latter comprising subfamilies Panicoideae, Arundinoideae, Chloridoideae, and Centothecoideae), as well as to analyze the phylogenetic structure within these groups and others. Several genera of controversial placement (Amphipogon, Anisopogon, Anomochloa, Brachyelytrum, Diarrhena, Eremitis, Ehrharta, Lithachne, Lygeum, Nardus, Olyra, Pharus, andStreptochaeta) also were included, with the goal of determining their phylogenetic affinities. The two character sets were analyzed separately, and a simultaneous analysis of the combined matrices also was conducted. The combined data set also was analyzed using homoplasy-implied weights. Among major results of the combined unweighted analysis were resolution of a sister-group relationship betweenJoinvillea and Poaceae; resolution of a clade comprisingAnomochloa andStreptochaeta as the sister of all other grasses, withPharus the next group to diverge from the lineage that includes all remaining grasses; and resolution of other taxa often assigned to Bambusoideae s.l. (includingEhrharta and Oryzeae, and excluding a few other taxa as noted) as a paraphyletic assemblage, within which is nested a clade that consists ofBrachyelytrum, the PACC clade (includingAmphipogon), and Pooideae (including Brachypodieae, Stipeae,Anisopogon, Diarrhena, Lygeum, andNardus). Within the PACC clade,Aristida is identified as the sister of all other elements of the group; Chloridoideae, Centothecoideae, and Panicoideae are each resolved as monophyletic, the latter two being sister-groups; and the remaining Arundinoid elements constitute a paraphyletic group within which are nested these three subfamilies. Within the Pooideae, four “core tribes” (Bromeae, Hordeeae [i.e., Triticeae], Agrostideae [i.e., Aveneae], andPoeae, the latter includingSesleria) are resolved as a monophyletic group that is nested among the remaining elements of the subfamily (Brachypodieae, Meliceae, Stipeae,Anisopogon, Diarrhena, Lygeum, andNardus). A second principal goal of the analysis was to identify structural synapomorphies of clades. Among the synapomorphies identified for some of the major clades are the following: gain of a 6.4 kb inversion in the chloroplast genome inJoinvillea and the grasses; reduction to 1 ovule per pistil, gain of a lateral “grass-type” embryo, and gain of an inversion around the gene trnT in the chloroplast genome in the grasses; loss of arm cells in the clade that consists ofBrachyelytrum, Pooideae, and the PACC clade; loss of the epiblast and gain of an elongate mesocotyl internode in the PACC clade; gain of proximal female-sterile florets in female-fertile spikelets, gain of overlapping embryonic leaf margins, and gain ofPanicum- type endosperm starch grains in the clade that comprises Centothecoideae and Panicoideae; and loss of the scutellar tail of the embryo in Pooideae (in one of two alternative placements of Pooideae among other groups). These findings are consistent with an origin and early diversification of grasses as forest understory herbs, followed by one or more radiations into open habitats, concomitant with multiple origins of C₄ photosynthesis and specialization for wind pollination.     

A worldwide phylogenetic classification of the Poaceae (Gramineae) III: An update

We present an updated worldwide phylogenetic classification of Poaceae with 11 783 species in 12 subfamilies, 7 supertribes, 54 tribes, 5 super subtribes, 109 subtribes, and 789 accepted genera. The subfamilies (in descending order based on the number of species) are Pooideae with 4126 species in 219 genera, 15 tribes, and 34 subtribes; Panicoideae with 3325 species in 242 genera, 14 tribes, and 24 subtribes; Bambusoideae with 1698 species in 136 genera, 3 tribes, and 19 subtribes; Chloridoideae with 1603 species in 121 genera, 5 tribes, and 30 subtribes; Aristidoideae with 367 species in three generaand one tribe; Danthonioideae with 292 species in 19 generaand 1 tribe; Micrairoideae with 192 species in nine generaand three tribes; Oryzoideae with 117 species in 19 genera, 4 tribes, and 2 subtribes; Arundinoideae with 36 species in 14 genera and 3 tribes; Pharoideae with 12 species in three generaand one tribe; Puelioideae with 11 species in two generaand two tribes; and the Anomochlooideae with four species in two generaand two tribes. Two new tribes and 22 new or resurrected subtribes are recognized. Forty-five new (28) and resurrected (17) genera are accepted, and 24 previously accepted genera are placed in synonymy. We also provide an updated list of all accepted genera including common synonyms, genus authors, number of species in each accepted genus, and subfamily affiliation. We propose Locajonoa, a new name and rank with a new combination, L. coerulescens. The following seven new combinations are made in Lorenzochloa: L. bomanii, L. henrardiana, L. mucronata, L. obtusa, L. orurensis, L. rigidiseta, and L. venusta.     

Distribution of the tryptophan pathway-derived defensive secondary metabolites gramine and benzoxazinones in Poaceae

The Poaceae is a large taxonomic group consisting of approximately 12,000 species and is classified into 12 subfamilies. Gramine and benzoxazinones (Bxs), which are biosynthesized from the tryptophan pathway, are well-known defensive secondary metabolites in the Poaceae. We analyzed the presence or absence of garamine and Bxs in 64 species in the Poaceae by LC-MS/MS. We found that Hordeum brachyantherum and Hakonechloa macra accumulated gramine, but the presence of gramine was limited to small groups of species. We also detected Bxs in four species in the Pooideae and six species in the Panicoideae. In particular, four species in the Paniceae tribe in Panicoideae accumulaed Bxs, indicating that this tribe is a center of the Bx distribution. Bxs were absent in the subfamilies other than Pooideae and Panicoideae. These findings provide an overview of biased distribution of gramine and Bxs in Poaceae species.