Photoperiod in plants is perceived by leaves and in many species influences the transition to reproductive growth through long-distance signaling. CONSTANS (CO) is implicated as a mediator between photoperiod perception and the transition to flowering in Arabidopsis. To test the role of CO in long-distance signaling, CO was expressed from a promoter specific to the companion cells of the smalle...

Some potato species require a short-day (SD) photoperiod for tuberization, a process that is negatively affected by gibberellins (GAs). Here we report the isolation of StGA3ox2, a gene encoding a GA 3-oxidase, whose expression is increased in the aerial parts and is repressed in the stolons after transfer of photoperiod-dependent potato plants to SD conditions. Over-expression of StGA3ox2 under...

Effect of light intensity and photoperiod on growth, indoleamines and carotenoid production was studied in unicellular green algae D. bardawil. Maximum biomass and carotenoid contents were found when cultures were grown in light (intensity of 2.0 Klux) at a photoperiod of 16/8h light and dark cycle. There was a profound influence of tested photoperiod conditions of light:dark viz. 8:16, 10:14, ...

Under natural conditions the vole (Microtus agrestis) breeds in the spring and summer but not in the autumn and winter. This seasonal change was attributed by Baker & Ranson (1933) to the influence of hours of sunshine, and in the laboratory it has been shown that photoperiod affects the growth ofgonads and maintenance of their activity (Baker & Ranson, 1932; Clarke & Kennedy, 1967; Breed & Cla...

Forty-four soybean genotypes with different photoperiod response were selected after screening of 1000 soybean accessions under artificial condition and were profiled using 40 SSR and 5 AFLP primer pairs. The average polymorphism information content (PIC) for SSR and AFLP marker systems was 0.507 and 0.120, respectively. Clustering of genotypes was done using UPGMA method for SSR and AFLP and c...

In plants, flowering is a major biological phenomenon, which is regulated by an array of interactions occurring between biotic and abiotic factors. In our study, we have compared the expression profiles of flowering genes involved in the flowering pathway, which are influenced by conditions like photoperiod and temperature from seedling to heading developmental stages in two Oryza sativa indica...

For 17 cultivars of winter wheat (Triticum aestivum L.) different vernalisation and photoperiod responses were detected. The effect of photoperiod sensitivity was not significantly changed by vernalisation; different vernalisation responses were probably due to the presence of multiple alleles at Vrn loci. The delay in heading depended on the vernalisation deficit exponentially: y = parameter (...

Seasonal variation in immune function putatively maximizes survival and reproductive success. Day length (photoperiod) is the most potent signal for time of year. Animals typically organize breeding, growth, and behavior to adapt to spatial and temporal niches. Outside the tropics individuals monitor photoperiod to support adaptations favoring survival and reproductive success. Changes in day l...

Photoperiod induced dormancy for 14 North American strains of Aedes albopictus were determined at 21, 26 and 29 degrees C. Strains tested at 21 degrees C and intermediate temperatures of 25-27 degrees C demonstrated clear photoperiodic responses whereas temperatures of 29 degrees C and above, greatly reduced or negated diapause incidence. A suboptimal larval diet increased the percentage diapau...

This study investigated the effect of different photoperiods (14L: 10D, 12L:12D and 10L:14D) on the gonadal development and GtH mRNA expression in the pituitary of damselfish. The results showed that gonadosomatic index (GSI) was significantly lower in shot photoperiod (10L:14D), in comparison with other photoperiodic group during the spawning season. After 60 days treatment, histological analy...