野火能減少植被林冠和地面覆蓋,，并改變到達(dá)地面的陽光的光譜和強(qiáng)度。許多植物通過煙或熱激發(fā)的種子發(fā)芽從而在火后環(huán)境的資源競爭減少中獲益,。
karrikins是一種存在于野火煙中的化合物，已知能夠刺激種子發(fā)芽,。煙中這種成分可能通過誘發(fā)種子感光從而促進(jìn)植物生長,。Steven Smith及其同事分析了karrikins對(duì)植物的作用，顯示其影響植物種子發(fā)芽和成苗的光依賴過程,。
這組作者說,，與沒有接觸karrikins的植物相比，karrikins促進(jìn)了低光照度下的種子發(fā)芽,，而且增強(qiáng)了新出現(xiàn)的幼苗莖的光感受,，或許引發(fā)了接觸到煙的植株感受到土壤表面火災(zāi)引發(fā)的陽光的變化。這組科學(xué)家還發(fā)現(xiàn),，這種化合物影響了萵苣和蕪青的光調(diào)控生長,，這是另外兩種已知對(duì)光高度敏感的植物。
這項(xiàng)研究增加了當(dāng)前對(duì)植物的karrikin信號(hào)傳導(dǎo)機(jī)制的理解,，而且可能有助于科學(xué)家發(fā)現(xiàn)這種化合物對(duì)于植物發(fā)芽的影響,。(生物谷Bioon.com)
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.0911635107
Karrikins enhance light responses during germination and seedling development in Arabidopsis thaliana
David C. Nelsona, Gavin R. Flemattib, Julie-Anne Riseborougha,c, Emilio L. Ghisalbertib, Kingsley W. Dixonc,d, and Steven M. Smitha,b,1
Karrikins are a class of seed germination stimulants identified in smoke from wildfires. Microarray analysis of imbibed Arabidopsis thaliana seeds was performed to identify transcriptional responses to KAR1 before germination. A small set of genes that are regulated by KAR1, even when germination is prevented by the absence of gibberellin biosynthesis or light, were identified. Light-induced genes, putative HY5-binding targets, and ABRE-like promoter motifs were overrepresented among KAR1-up-regulated genes. KAR1 transiently induced the light signal transduction transcription factor genes HY5 and HYH. Germination of afterripened Arabidopsis seed was triggered at lower fluences of red light when treated with KAR1. Light-dependent cotyledon expansion and inhibition of hypocotyl elongation were enhanced in the presence of germination-active karrikins. HY5 is important for the Arabidopsis hypocotyl elongation, but not seed germination, response to karrikins. These results reveal a role for karrikins in priming light responses in the emerging seedling, and suggest that the influence of karrikins on postfire ecology may not be limited to germination recruitment.
