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Current Biology：植物適應(yīng)環(huán)境變化的機(jī)理
畢業(yè)論文
生物谷：在植物的生命周期諸如發(fā)芽期或開花期，植物完全可以根據(jù)外界環(huán)境條件的變化，調(diào)節(jié)自己的生長狀況。而當(dāng)環(huán)境不適合時(shí)，它們甚至可以暫時(shí)抑制自己的生長。那么，植物是如何1步步實(shí)現(xiàn)這種能力的呢？日前，世界著名的植物分子生物學(xué)實(shí)驗(yàn)室———約翰艾因斯中心的科學(xué)家在《當(dāng)代生物期刊》上，宣稱發(fā)現(xiàn)了植物是怎樣在進(jìn)化過程中逐漸獲得適應(yīng)環(huán)境與氣候變化的能力的。
赤霉素是植物生長的重要激素。研究者通過多種植物在赤霉素信號(hào)傳導(dǎo)途徑中基因的變化情況來了解植物的進(jìn)化過程。最先進(jìn)化的陸生植物是地錢類、金魚藻類和原始地衣類等苔蘚植物，這些物種大多數(shù)今天依然存在。它們可以復(fù)制自己的基因，但其本身的蛋白質(zhì)卻不具備互相交換信息的功能，也不具備抑制自我生長的能力。
40億年前，石松類植物開始進(jìn)化，并具有了植物維管組織，從而具有了在植物體內(nèi)輸送水分和營養(yǎng)物的功能，體內(nèi)蛋白質(zhì)也具有了互相交換信息的能力。然而它們尚不能抑制自我生長。直到30億年前，裸子植物（開花植物）體內(nèi)結(jié)構(gòu)的變化允許蛋白質(zhì)相互交換信息，并相應(yīng)地調(diào)整基因的分布，最終在進(jìn)化中獲得了抑制自我生長的能力，因此裸子植物成為在當(dāng)時(shí)占主導(dǎo)并且在今天種群依然龐大的物種。（科技日報(bào)）
原始出處:
Current Biology, Vol 17, 1225-1230, 17 July 2007
Report
Step-by-Step Acquisition of the Gibberellin-DELLA Growth-Regulatory Mechanism during Land-Plant Evolution
1 John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom
Corresponding author
Nicholas P. Harberd
nicholas.harberd@bbsrc.ac.uk
Angiosperms (flowering plants) evolved relatively recently and are substantially diverged from early land plants (bryophytes, lycophytes, and others [1]). The phytohormone gibberellin (GA) adaptively regulates angiosperm growth via the GA-DELLA signaling mechanism [2, 3, 4, 5, 6, 7]. GA binds to GA receptors (GID1s), thus stimulating interactions between GID1s and the growth-repressing DELLAs [8, 9, 10, 11, 12]. Subsequent 26S proteasome-mediated destruction of the DELLAs promotes growth [13, 14, 15, 16, 17]. Here we outline the evolution of the GA-DELLA mechanism. We show that the interaction between GID1 and DELLA components from Selaginella kraussiana (a lycophyte) is GA stimulated. In contrast, GID1-like (GLP1) and DELLA components from Physcomitrella patens (a bryophyte) do not interact, suggesting that GA-stimulated GID1-DELLA interactions arose in the land-plant lineage after the bryophyte divergence (430 million years ago [1]). We further show that a DELLA-deficient P. patens mutant strain lacks the derepressed growth characteristic of DELLA-deficient angiosperms, and that both S.kraussiana and P. patens lack detectable growth responses to GA. These observations indicate that early land-plant DELLAs do not repress growth in situ. However, S. kraussiana and P. patens DELLAs function as growth-repressors when expressed in the angiosperm Arabidopsis thaliana. We conclude that the GA-DELLA growth-regulatory mechanism arose during land-plant evolution and via independent stepwise recruitment of GA-stimulated GID1-DELLA interaction and DELLA growth-repression functions.
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