Exploring phylogenetic relationships within the subgenera of Bambusa based on DNA barcodes and morphological characteristics.

The genus Bambusa belongs to the subtribe Bambusinae and the subfamily Bambusoideae. The subgenera of Bambusa has not been satisfactorily circumscribed, and this remains a major taxonomic issue. Simultaneously, genera such as Dendrocalamus and Gigantochloa have not been confidently assigned to Bambusa. Here, the phylogenetic relationships among subgenera were investigated using five chloroplast DNA markers (rpl32-trnL, rpl16, matK, rbcL, and trnH-psbA) for a sample of 50 ingroup and 16 outgroup species. A total of 186 key morphological descriptors were studied for the 50 ingroup species. The results indicated that five chloroplast DNA markers were possible to distinguish Bambusa species from other species and divide them into several clusters. Phylogenetic analyses conducted using morphological descriptors and a combined marker (rpl32-trnL+rpl16) revealed three and five distinct lineages, respectively, among the currently recognized Bambusa species. The branching pattern of the dendrogram was not completely consistent with the classical taxonomic classification of Bambusa. In addition, not all varieties and cultivars were clustered with McClure classifications. As the maximum parsimony topology and morphological analyses were inconsistent, some clustering results overlapped. Overall, the results obtained here do not support the current classification of the Bambusa subgenera.

Nitrogen addition and clonal integration alleviate water stress of dependent ramets of Indocalamus decorus under heterogeneous soil water environment.

Water and nitrogen are two of the most important factors for plant growth and development. However, little is known about effects of N on water translocation between connected bamboo ramets. We performed experiment connected Indocalamus decorus ramets in adjacent pots with different soil water contents and three N levels. We determined antioxidase activities, concentration of osmotic adjustment products, O2·-, MDA and photosynthetic pigments, and electrolyte leakage rate in paired unit. When N supply to supporting ramets increased, their electrolyte leakage rates and contents of O2·- and MDA significantly increased, while antioxidase activities and contents of osmotic adjustment products and photosynthetic pigments in connected dependent ramets increased markedly as their electrolyte leakage rates and contents of O2·- and MDA decreased greatly. When N addition to dependent ramets increased, antioxidant enzyme activity and contents of osmotic adjustment products and photosynthetic pigments decreased in both ramets, but electrolyte leakage rates and O2·- and MDA contents increased significantly. Therefore, N addition to either supporting or dependent ramets can improve water integration among I. decorus ramets. N addition to supporting ramets promotes water translocation and alleviates water stress of dependent ramets, but N addition to dependent ramets exacerbates drought stress damage to dependent ramets.