Regulation of flowering time via miR172-mediated APETALA2-like expression in ornamental gloxinia (Sinningia speciosa).

We investigated the microRNA172 (miR172)-mediated regulatory network for the perception of changes in external and endogenous signals to identify a universally applicable floral regulation system in ornamental plants, manipulation of which could be economically beneficial. Transgenic gloxinia plants, in which miR172 was either overexpressed or suppressed, were generated using Agrobacterium-mediated transformation. They were used to study the effect of altering the expression of this miRNA on time of flowering and to identify its mRNA target. Early or late flowering was observed in transgenic plants in which miR172 was overexpressed or suppressed, respectively. A full-length complementary DNA (cDNA) of gloxinia (Sinningia speciosa) APETALA2-like (SsAP2-like) was identified as a target of miR172. The altered expression levels of miR172 caused up- or down-regulation of SsAP2-like during flower development, which affected the time of flowering. Quantitative real-time reverse transcription PCR analysis of different gloxinia tissues revealed that the accumulation of SsAP2-like was negatively correlated with the expression of miR172a, whereas the expression pattern of miR172a was negatively correlated with that of miR156a. Our results suggest that transgenic manipulation of miR172 could be used as a universal strategy for regulating time of flowering in ornamental plants.

[Calcium sensors and their stress signaling pathways in plants].

Calcium (Ca2+) signals are a core regulator of plant growth and development and responses to environmental cues and thus highlighted in plant physiological and stress biology. External stimuli trigger specifically intracellular spatial and temporal [Ca2+]cyt variations in plant cells. This [Ca2+]cyt variations will be sensed and decoded by calcium sensors and, in turn, calcium sensor interacting proteins transmit resulting signals to the downstream effectors to activate the expression of early response genes or promote ion channel activities, finally leading to specific stress responses. How the plant cell distinguishes different types or intensity of external stimuli through sensing intracellular spatial and temporal variations of Ca2+ signals is a scientific issue recently highlighted by plant biologists. This review summarized recent advances in the research field of plant calcium sensors, including the structural characteristics, functional roles, and stress signaling path-ways of calcium-dependent protein kinases (CDPKs), calmodulins (CaMs), calmodulin-like proteins (CMLs), and cal-cineurin B-like proteins (CBLs) and their interacting kinases (CIPKs), and moreover provided new insights and perspectives.

Root border cell development is a temperature-insensitive and Al-sensitive process in barley.

In vivo and in vitro experiments showed that border cell (BC) survival was dependent on root tip mucigel in barley (Hordeum vulgare L. cv. Hang 981). In aeroponic culture, BC development was an induced process in barley, whereas in hydroponic culture, it was a kinetic equilibrium process during which 300-400 BCs were released into water daily. The response of root elongation to temperatures (10-35 degrees C) was very sensitive but temperature changes had no great effect on barley BC development. At 35 degrees C, the root elongation ceased whereas BC production still continued, indicating that the two processes might be regulated independently under high temperature (35 degrees C) stress. Fifty microM Al could inhibit significantly BC development by inhibiting pectin methylesterase activity in the root cap of cv. 2000-2 (Al-sensitive) and cv. Humai 16 (Al-tolerant), but 20 microM Al could not block BC development in cv. Humai 16. BCs and their mucigel of barley had a limited role in the protection of Al-induced inhibition of root elongation, but played a significant role in the prevention of Al from diffusing into the meristems of the root tip and the root cap. Together, these results suggested that BC development was a temperature-insensitive but Al-sensitive process, and that BCs and their mucigel played an important role in the protection of root tip and root cap meristems from Al toxicity.

[Discussion of learning and instructional strategies on genetics teaching].

This paper attempts to explore learning and teaching strategies, such as, attention, classification, organization, provoke-thinking,problem-solving,and learning-based task analysis and programmed teaching strategies in genetics teaching on the basis of the concept of lifelong education and struggle for existence. It aims at teaching students how to study and at the same time improve teaching efficiency.