Parallelismic homoplasy of leaf and stipule phenotypes among genetic variants of Pisum sativum and Medicago truncatula and some taxa of Papilionoideae, Caesalpinioideae and Mimosoideae subfamilies of the Leguminosae flora of Delhi

The leguminous flora of Delhi comprises 78 Papilionoideae, 24 Caesalpinioideae and 24 Mimosoideae species; 80 of them are perennials. Five types of imparipinnate and two types of paripinnate compound leaves were observed in the species. The paripinnate leaves are bipinnate in 25 species (mostly mimosoid) and bifoliate in two species. The imparipinnate leaves were trifoliate or multifoliate in 59 papilionoid species and multifoliate in 16 caesalpinioid species; four of the papilionoid species produced leafletted and tendrilled unipinnate leaves. Leaves were bifacially simple in 22 species, simple with ectopic terminal growth in one species and simple tendril in one species. Twenty-one species (mostly mimosoid) were devoid of stipules. In 82 species stipules were small and free. Stipules were large and lobed in 17 species and large and adnate in four species. Two species of Caesalpinioideae produce compound leaf-like stipules. All four stipule phenotypes of 126 species corresponded with stipular phenotypes observed in wild type, coch, st and coch st genotypes of the model legume P. sativum. The seven leaf phenotypes observed in 126 species corresponded with phenotypes expected among combinations of uni (uni-tac), af, ins, mfp and tl mutants of P. sativum and sgl1, cfl1, slm1 and palm1 mutants of M. truncatula, also an IRL model legume. All the variation in leaf and stipule morphologies observed in the leguminous flora of Delhi could be explained in terms of the gene regulatory networks already revealed in P. sativum and M. truncatula. It is hypothesized that the ancestral gene regulatory networks for leaves and stipules produced in Leguminosae were like that prevalent in P. sativum.     

New allele of the <Emphasis Type="Italic">COCHLEATA</Emphasis> gene in pea <Emphasis Type="Italic">Pisum sativum</Emphasis> L.

Analysis with the polymerase chain reaction showed that the Khlorofill-4 pea Pisum sativum chlorophyll-deficient mutant with reduced stipules has an altered structure of the COCHLEATA (COCH) gene, carrying a new mutant COCH allele. The phenotype of the mutant was described in comparison with another form having reduced stipules (stipules reduced) and the control. Leaves of the coch mutant are smaller and have other proportions than in the control; stipules are absent from leaves of the first nodes and are narrow, bandlike, or spoonlike at later ontogenetic stages. It was concluded that the cell number in the stipule epidermis is reduced in the st and coch mutants compared to the wild type.     

Leaf and Flower Development in Pea (Pisum sativum L.): Mutants cochleata andunifoliata

The stipule mutant cochleata(coch) and the simple-leaf mutantunifoliata(uni) are utilized to increase understanding of the controlof compound leaf and flower development in pea. The phenotypeof the coch mutant, which affects the basal stipules of thepea leaf, is described in detail. Mutant coch flowers have supernumeraryorgans, abnormal fusing of flower parts, mosaic organs and partialmale and female sterility. The wild-type Coch gene is shownto have a role in inflorescence development, floral organ identityand in the positioning of leaf parts. Changes in meristem sizemay be related to changes in leaf morphology. In the coch mutant,stipule primordia are small and their development is retardedin comparison with that of the first leaflet primordia. Thediameter of the shoot apical meristem of the uni mutant is approx.25% less than that of its wild-type siblings. This is the firsttime that a significant difference in apical meristem size hasbeen observed in a pea leaf mutant. Genetic controls in thebasal part of the leaf are illustrated by interactions betweencoch and other mutants. The mutantcoch gene is shown to changestipules into a more ‘compound leaf-like’ identitywhich is not affected by thestipules reduced mutation. The interactionof coch and tendril-less(tl) genes reveals that the expressionof the wild-type Tl gene is reduced at the base of the leaf,supporting the theories of gradients of gene action. Copyright2001 Annals of Botany Company Pisum sativum, garden pea, leaf morphogenesis, compound leaf, leaf mutants, flower morphology     

Pisum sativum wild-type and mutant stipules and those induced by an auxin transport inhibitor demonstrate the entire diversity of laminated stipules observed in angiosperms

About a quarter of angiosperm species are stipulate. They produce stipule pairs at stem nodes in association with leaves. Stipule morphology is treated as a species-specific characteristic. Many species bear stipules as laminated organs in a variety of configurations, including laterally free large foliaceous, small, or wholly leaf-like stipules, and as fused intrapetiolar, opposite, ochreate or interpetiolar stipules. In Pisum sativum, the wild-type and stipule-reduced and cochleata mutants are known to form free large, small, and leaf-like stipules, respectively. Auxin controls initiation and development of plant organs and perturbations in its availability and distribution in the meristems, caused by auxin transport inhibitor(s) (ATIs), lead to aberrations in leaf development. The effect(s) of ATI(s) on stipule development are unexplored. To study the effect of the ATI 1-N-naphthylphthalamic acid (NPA) on stipule morphogenesis, P. sativum explants were grown in vitro in presence of a sublethal concentration of NPA. The NPA-treated shoots produced fused stipules of all the different types described in angiosperms. The observations indicate that (a) the gene sets for stipule differentiation may be common in angiosperms and (b) the interspecies stipule architectural differences are due to mutations, affecting gene expression or activity that got selected in the course of evolution.     

Genetic interaction and mapping studies on the leaflet development (lld) mutant in Pisum sativum

In Pisum sativum, the completely penetrant leaflet development (lld) mutation is known to sporadically abort pinnae suborgans in the unipinnate compound leaf. Here, the frequency and morphology of abortion was studied in each of the leaf suborgans in 36 genotypes and in presence of auxin and gibberellin, and their antagonists. Various lld genotypes were constructed by multifariously recombining lld with a coch homeotic stipule mutation and with af, ins, mare, mfp, tl and uni-tac leaf morphology mutations. It was observed that the suborgans at all levels of pinna subdivisions underwent lld-led abortion events at different stages of development. As in leafblades, lld aborted the pinnae in leaf-like compound coch stipules. The lld mutation interacted with mfp synergistically and with other leaf mutations additively. The rod-shaped and trumpet-shaped aborted pea leaf suborgans mimicked the phenotype of aborted leaves in HD-ZIP-III-deficient Arabidopsis thaliana mutants. Suborganwise aborted morphologies in lld gnotypes were in agreement with basipetal differentiation of leaflets and acropetal differentiation in tendrils. Altogether, the observations suggested that LLD was the master regulator of pinna development. On the basis of molecular markers found linked to lld, its locus was positioned on the linkage group III of the P. sativum genetic map.     

Croton dissectistipulatus, a new species of Euphorbiaceae from Amazonian Brazil

A new species ofCroton,C. dissectistipulatus, is described from Amazonian Brazil. This species is superficially similar toC. timandroides from northeastern and southeastern Brazil, but differs in having petiolate leaves with glandular margins, persistent stipules, conspicuous racemose inflorescences, staminate flowers having externally glabrous sepals and 3 stamens, and pedicellate pistillate flowers. The systematic position ofC. dissectistipulatus relative to the sections ofCroton is discussed.     

NODULE ROOT and COCHLEATA Maintain Nodule Development and Are Legume Orthologs of Arabidopsis BLADE-ON-PETIOLE Genes

During their symbiotic interaction with rhizobia, legume plants develop symbiosis-specific organs on their roots, called nodules, that house nitrogen-fixing bacteria. The molecular mechanisms governing the identity and maintenance of these organs are unknown. Using Medicago truncatula nodule root (noot) mutants and pea (Pisum sativum) cochleata (coch) mutants, which are characterized by the abnormal development of roots from the nodule, we identified the NOOT and COCH genes as being necessary for the robust maintenance of nodule identity throughout the nodule developmental program. NOOT and COCH are Arabidopsis thaliana BLADE-ON-PETIOLE orthologs, and we have shown that their functions in leaf and flower development are conserved in M. truncatula and pea. The identification of these two genes defines a clade in the BTB/POZ-ankyrin domain proteins that shares conserved functions in eudicot organ development and suggests that NOOT and COCH were recruited to repress root identity in the legume symbiotic organ.     

Pea Compound Leaf Architecture Is Regulated by Interactions among the Genes UNIFOLIATA, COCHLEATA, AFILA, and TENDRIL-LESS

The compound leaf primordium of pea represents a marginal blastozone that initiates organ primordia, in an acropetal manner, from its growing distal region. The UNIFOLIATA (UNI) gene is important in marginal blastozone maintenance because loss or reduction of its function results in uni mutant leaves of reduced complexity. In this study, we show that UNI is expressed in the leaf blastozone over the period in which organ primordia are initiated and is downregulated at the time of leaf primordium determination. Prolonged UNI expression was associated with increased blastozone activity in the complex leaves of afila (af), cochleata (coch), and afila tendril-less (af tl) mutant plants. Our analysis suggests that UNI expression is negatively regulated by COCH in stipule primordia, by AF in proximal leaflet primordia, and by AF and TL in distal and terminal tendril primordia. We propose that the control of UNI expression by AF, TL, and COCH is important in the regulation of blastozone activity and pattern formation in the compound leaf primordium of the pea.     

Studies in Brazilian Passifloraceae III. A new species of Passiflora

A new species ofPassiflora from Minas Gerais, Brazil, is described and namedP. saccoi. This species belongs to subgenusPassiflora seriesLobatae harms because of its lobed leaves, foliaceous, semi-ovate to semi-oblong stipules that are attached on one side above base and, hence, often appear sub-reniform, and foliaceous, verticillate bracts borne near the apex of the peduncle.     

Origin and variation of polymerous gynoecia in Fabaceae: evidence from floral mutants of pea (Pisum sativum L.)

Polymerous gynoecia are normally found in some members of Fabaceae, although the vast majority of this family is characterized by a gynoecium consisting of a single carpel. Summarizing the variation of gynoecium features in these species together with analysis of floral structure and ontogeny in mutants of pea (Pisum sativum L.) suggests to propose two different ways of gynoecium polymerization in legumes. The first is homeotic replacement of the stamens into carpels observed in stp mutants of pea and possibly causing the multicarpellate habit in mimosoids. The second deals with flower fusion within an inflorescence, a transformation observed in fasciated forms of pea together with the mutants coch and det. Similar processes might contribute to formation of the bicarpellate flowers of some swartzioid legumes. The polymerous gynoecium evolved in Fabaceae at least twice independently.     

Three new species of Dendropanax (Araliaceae) from Bahia, Brazil

Three new species of BrazilianDendropanax from the rain forests of Bahia state are described and illustrated.Dendropanax amorimii, endemic to the rain forests near Boa Nova, in southern Bahia, is characterized by compound umbellate inflorescences with elongated primary branches each having a proximal whorl of bracts, and by leaves with well-developed tertiary venation.Dendropanax bahiensis, endemic to the Atlantic rain forests of southern Bahia, is distinguished by its large and membranous leaves with reddish schizogenous glands on the abaxial surface and by the reduced and branched inflorescences with short-pedicellate flowers and large fruits.Dendropanax geniculatus, an endemic species from the “matas de grotão” of Serra da Chapadinha, Chapada Diamantina, is characterized by simple and usually geniculate inflorescences bearing long-pedicellate flowers and fruits.     

The morphology of stipules and inflorescences in <Emphasis Type="Italic">Geissois sensu stricto</Emphasis> (<Emphasis Type="Italic">Cunoniaceae</Emphasis>)

Summary   Geissois sensu stricto (i.e. excluding the Australian species of this genus) has 19 species restricted to islands in the south-west Pacific and is the sole group in Cunoniaceae in which the stipules are intrapetiolar (axillary) in the adult foliage. In apical buds, paired opposite stipules are coherent round their margins and are either clearly intrapetiolar in relation to the most distal pair of developed leaves (Type I, most species), or they appear interpetiolar due to the abortion of the pair of leaves associated with them and the failure of the internode proximal to them to elongate (Type II, a few species). Stipules are often accrescent and the largest in the family occur in this group, reaching 10 cm long in some species. The ornithophilous racemose inflorescences of members of this group normally consist of either axillary triads (G. hirsuta only) or apparently simple, unbranched racemes which are ramiflorous or occasionally axillary. However, bract scars on the axes proximal to the flowers show that both types of inflorescence module usually consist of two metamers. The structure of the inflorescences and stipules in Geissois sensu stricto supports the distinction between this group and the Australian species traditionally included in Geissois sensu lato.     

Inflorescence architecture: A developmental genetics approach

We are characterizing a suiteof Pisum sativum mutants that alter inflorescence architecture to construct a model for the genetic regulation of inflorescence development in a plant with a compound raceme. Such a model, when compared with those created forAntirrhinum majus andArabidopsis thaliana, both of which have simple racemes, should provide insight into the evolution of the development of inflorescence architecture. The highly conserved nature of cloned genes that regulate reproductive development in plants and the morphological similarities among our mutants and those identified inA. majus andA. thaliana enhance the probability that a developmental genetics approach will be fruitful. Here we describe sixP. sativum mutants that affect morphologically and architecturally distinct aspects of the inflorescence, and we analyze interactions among these genes. Both vegetative and inflorescence growth of the primary axis is affected byUNIFOLIA TA, which is necessary for the function ofDETERMINATE (DET).DET maintains indeterminacy in the first-order axis. In its absence, the meristem differentiates as a stub covered with epidermal hairs.DET interacts withVEGETATIVE1 (VEG1).VEG1 appears essential for second-order inflorescence (I₂) development.veg1 mutants fail to flower or differentiate the I₂ meristem into a rudimentary stub,det veg1 double mutants produce true terminal flowers with no stubs, indicating that two genes must be eliminated for terminal flower formation inP. sativum, whereas elimination of a single gene accomplishes this inA. thaliana andA. majus. NEPTUNE also affects I₂ development by limiting to two the number of flowers produced prior to stub formation. Its role is independent ofDET, as indicated by the additive nature of the double mutantdet nep. UNI, BROC, and PIM all play roles in assigning floral meristem identity to the third-order branch.pim mutants continue to produce inflorescence branches, resulting in a highly complex architecture and aberrant flowers.uni mutants initiate a whorl of sepals, but floral organogenesis is aberrant beyond that developmental point, and the double mutantuni pim lacks identifiable floral organs. A wild-type phenotype is observed inbroc plants, butbroc enhancesthe pim phenotype in the double mutant, producing inflorescences that resemble broccoli. Collectively these genes ensure that only the third-order meristem, not higher- or lower-order meristems, generates floral organs, thus precisely regulating the overall architecture of the plant. Gene symbols used in this article: For clarity a common symbolization is used for genes of all species discussed in this article. Genes are symbolized with italicized capital letters. Mutant alleles are represented by lowercase, italicized letters. In both cases, the number immediately following the gene symbol differentiates among genes with the same symbol. If there are multiple alleles, a hyphen followed by a number is used to distinguish alleles. Protein products are represented by capital letters without italics.     

A new species of “sangre de drago” (Croton section Cyclostigma, Euphorbiaceae) from coastal Ecuador

Croton churutensis is described as a new species ofCroton sectionCyclostigma endemic to lowland deciduous forests in coastal Ecuador. Its red latex is used locally in Guayas Province to treat wounds, stomach ulcers, and some skin conditions caused by fungal infections. The new species differs from its closest apparent relative,Croton hibiscifolius, in its arching-pendent inflorescences, short-pedicellate female flowers with quadrifid stigmas, more numerous stamens, laciniate stipules, and lower elevation habitat.     

Synchronized protandry and hermaphroditism in a tropical secondary forest tree, Schefflera heptaphylla (Araliaceae)

Selection favoring avoidance of stigma clogging, pollen discounting, self-fertilization, and other negative effects of self-pollination can produce intricate patterns of intra- and interfloral dichogamy in plants bearing numerous flowers. Here we report an extensive study of the relationships among dichogamy, floral sex allocation (pollen-to-ovule ratios), nectar production, floral visitors, mating system, and fruit set in natural populations of Schefflera heptaphylla, a widespread paleotropical secondary forest tree that produces thousands of flowers in a blooming season. Each tree produces 15?C30 sequentially blooming, paniculate, compound inflorescences. Each compound inflorescence has up to three orders of umbellets, which also bloom sequentially. While hand-pollinations showed that S. heptaphylla was capable of self-fertilization, our observations of thousands of flowers showed that strong intra- and interfloral protandry severely restricts both autogamous and geitonogamous self-pollination. All flowers were bisexual, thus the sexual system of the populations we studied was hermaphroditism. The pollen-to-ovule (P/O) ratios were characteristic of outcrossing species, and P/O ratios of flowers in the last-maturing (third order) umbellets were significantly higher than those in earlier-maturing (first and second order) umbellets. Floral visitors were primarily flies (Chrysomya sp. and Syrphinae sp.) and wasps (Vespula sp. and Eumenes sp.). Flowers produced nectar during both the male (pollen presentation) and female (stigma receptivity) stages of their development, and the volume of nectar production was higher in the female stage. Nevertheless, flowers received fewer visits in the female stage than they did in the male stage, and natural fruit set was low, especially in first and third order umbellets. Fruit set from hand cross- and self-pollinations was significantly higher than natural fruit set, indicating pollen limitation of fruit set. Schefflera heptaphylla has also been reported to be andromonoecious. Both hermaphroditism and andromonoecy are consistent with theoretical predictions for variation in sex allocation among sequentially maturing flowers in protandrous species. Further studies comparing hermaphroditic and andromonoecious populations of S. heptaphylla could elucidate the selective factors affecting sex expression, nectar production, and fruit set in species with numerous flowers displaying both intra- and interfloral dichogamy.     

Regulation of stipule development by <Emphasis Type="Italic">COCHLEATA</Emphasis> and <Emphasis Type="Italic">STIPULE</Emphasis>-<Emphasis Type="Italic">REDUCED</Emphasis> genes in pea <Emphasis Type="Italic">Pisum sativum</Emphasis>

Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.