In vitro flowering in Bambusa bambos (L.) Voss, an anatomical perspective.

Bamboo [Bambusa bambos (L.) Voss (Syn. Bambusa arundinacea Retz.)] is an important arborescent grass with immense socio economic implications. The plant exhibits unique biological and growth characteristics including a distinct monocarpic gregarious flowering behavior. Studies on in vitro flowering in bamboo are not uncommon. The present study focuses on effect of different growth regulators on in vitro flowering in B. bambos and analyzes the morphological and developmental changes accompanying the process. Multiple shoots were raised from B. bambos seeds on MS medium supplemented with 10 µM BAP. Anatomical sections showed intense mitotic activity in the apical meristem of the main shoot and formation of additional shoot buds along the margins. For multiplication, propagules of 7-9 shoots were transferred to maintenance medium containing 5 µM BAP. Longitudinal sections of propagules showed prolific cell divisions and formation of meristemoids, which continuously gave rise to new shoots upon subculture. In vitro induction of flowering in cultures was observed in multiple shoots after 8 weeks. Transfer of multiple shoots to MS basal medium containing 10 µM NAA resulted in rooting and proliferation of inflorescences. On medium supplemented with 10 µM 2,4-D callusing and development of shoot buds and somatic embryos was followed by development of inflorescences. The report outlines a protocol that can be used to raise and proliferate flowering cultures in B. bambos.

Identification of genes involved in spontaneous leaf color variation in Pseudosasa japonica.

Spontaneous leaf color variation in bamboo provides the opportunity to study the mechanisms of leaf color formation and the breeding of ornamental bamboos. Despite the fact that many genes are known to be involved in leaf color variation in model plants, molecular mechanisms governing natural leaf color variation in bamboo have remained obscure. This study aimed to identify the genes responsible for the occurrence of such phenomena in bamboo using the suppression subtractive hybridization (SSH) method between green and albino leaves in Pseudosasa japonica f. A total of 1062 and 1004 differentially expressed transcripts were obtained from the forward and reverse SSH libraries, respectively. Subsequently, 59 differentially expressed unigenes with potential roles in leaf color formation, predicted via computational analysis of their functional relevance, were selected for further analysis using qPCR. Ten genes, involved in photosynthesis, plastid development, and cation signal transduction, showed 2-fold changes in expression levels between green and albino leaves. Further expression pattern analyses of these genes at three developmental stages revealed much lower expression abundance of Lhca1-encoded chlorophyll a/b binding protein in the albino leaves than in the green leaves. Our results suggest that, together with the concatenated negative pressure for subsequent photosynthetic processes, the albino phenotype is at least partly attributable to chloroplast inner membrane damage or to the impairment of photosynthetic pigment accumulation, which results from low Lhca1 expression.

Parametric and non-parametric species delimitation methods result in the recognition of two new Neotropical woody bamboo species.

The Neotropical woody bamboo genus Otatea is one of five genera in the subtribe Guaduinae. Of the eight described Otatea species, seven are endemic to Mexico and one is also distributed in Central and South America. Otatea acuminata has the widest geographical distribution of the eight species, and two of its recently collected populations do not match the known species morphologically. Parametric and non-parametric methods were used to delimit the species in Otatea using five chloroplast markers, one nuclear marker, and morphological characters. The parametric coalescent method and the non-parametric analysis supported the recognition of two distinct evolutionary lineages. Molecular clock estimates were used to estimate divergence times in Otatea. The results for divergence time in Otatea estimated the origin of the speciation events from the Late Miocene to Late Pleistocene. The species delimitation analyses (parametric and non-parametric) identified that the two populations of O. acuminata from Chiapas and Hidalgo are from two separate evolutionary lineages and these new species have morphological characters that separate them from O. acuminata s.s. The geological activity of the Trans-Mexican Volcanic Belt and the Isthmus of Tehuantepec may have isolated populations and limited the gene flow between Otatea species, driving speciation. Based on the results found here, I describe Otatea rzedowskiorum and Otatea victoriae as two new species, morphologically different from O. acuminata.

Assessment of genetic diversity of landraces of Dendrocalamus hamiltonii using AFLP markers and association with biochemical traits.

Fermented bamboo shoots are popular traditional food items of various ethnic groups of the northeastern India, especially in Manipur State. Dendrocalamus hamiltonii is an economically important bamboo species used to produce fermented bamboo shoots. We studied genetic variability of this bamboo species in Chandel and Imphal-East (commercial production districts), using AFLP molecular markers. Each of the selected primers detected polymorphisms and 1614 (95.8%) were found to be polymorphic. Cluster analysis based on Dice similarity coefficients using UPGMA differentiated the populations into two major groups. Principal coordinate analysis based on the AFLP data clearly separated the populations according to their genetic diversity and antioxidant activity. Four primers were tested through multiple regression analysis to identify marker-trait association between AFLP data and biochemical attributes, i.e., antioxidant activity and total cyanide content. The 273 bp generated by EcoRI-AAG(Joe)/MseI-CTC showed high positive correlation with antioxidant activity (r = 0.729, P < 0.01). The 396 bp generated by EcoRI-AAC(Ned)/MseI-CTG were negatively correlated with cyanide content (r = -0.694, P < 0.01). Thus, we found association of DNA markers with antioxidant activities and total cyanide content. These results could be of use for the identification of superior genotypes with desirable traits.

Direct and indirect effects of understorey bamboo shape tree regeneration niches in a mixed temperate forest.

Plant cover plays a major role in shaping the nature of recruitment microsites through direct (resource mediated) and indirect (consumer mediated) interactions. Understorey plants may differentially affect seedling establishment, thus contributing to regeneration-niche separation among canopy tree species. We examined patterns of early tree seedling survival resulting from interactive effects of understorey bamboo (Chusquea culeou) and resident consumers in a mixed temperate Patagonian forest, Argentina. Newly germinated seedlings of Nothofagus dombeyi and Austrocedrus chilensis were planted in bamboo thickets and non-bamboo patches, with or without small-vertebrate exclosures. We found species-specific patterns of seedling survival in relation to bamboo cover. Nothofagus survival was generally low but increased under bamboo, irrespective of cage treatment. Desiccation stress accounted for most Nothofagus mortality in open, non-bamboo areas. In contrast, Austrocedrus survival was highest in non-bamboo microsites, as most seedlings beneath bamboo were killed by small vertebrates through direct consumption or non-trophic physical damage. There was little evidence for a negative impact of bamboo on tree seedling survival attributable to resource competition. The balance of simultaneous positive and negative interactions implied that bamboo presence facilitated Nothofagus early establishment but inhibited Austrocedrus recruitment via apparent competition. These results illustrate the potential for dominant understorey plants to promote microsite segregation during early stages of recruitment between tree seedlings having different susceptibilities to water stress and herbivory. We recognise, however, that patterns of bamboo-seedling interactions may be conditional on moisture levels and consumer activity during establishment. Hence, both biotic and abiotic heterogeneity in understorey environments should be incorporated into conceptual models of regeneration dynamics and tree coexistence in forest communities.

Morphological and molecular characterization of Bambusa tulda with a note on flowering.

BACKGROUND AND AIMS: Flowering incidence in Bambusa tulda has a high socio-economic impact. The aim of the present study was to describe the species for morphological characters (vegetative and reproductive) as well as molecular markers in order to enable species identification at various stages of the life cycle. METHODS: Thirty-two key morphological characters (15 culm and 17 culm-sheath) were studied along with detailed inflorescence and floral characters. Incidence of sporadic flowering was recorded. Genomic DNA was isolated from leaves collected from 17 eco-geographical locations and RAPD profiles were generated. KEY RESULTS: The description of culm, culm-sheath, inflorescence and floral morphology are in agreement with the prior taxonomic description by Gamble in 1896, but in this communication a more detailed description and illustrations are presented. No seed set was recorded following sporadic flowering, probably due to prezygoting isolating mechanisms (herkogamy or protandry). All 17 populations surveyed generated identical RAPD profiles. CONCLUSIONS: Sporadic flowering may occur in B. tulda, but may not necessarily be followed by gregarious flowering, and does not result in seed production.