多倍性（或稱(chēng)整基因組復(fù)制）是植物中常見(jiàn)的一種演化創(chuàng)新,。幾種主要作物（包括小麥、棉花和油菜）是異源多倍體,，含有兩個(gè)或多個(gè)趨異的基因組,，而且一些植物也以種內(nèi)和種間雜交體的形式存在。這樣的植物會(huì)有旺盛的生長(zhǎng)現(xiàn)象,。
美國(guó)得克薩斯大學(xué)與中國(guó)農(nóng)業(yè)大學(xué)的研究小組通過(guò)對(duì)兩種擬南芥植物（Arabidopsis thaliana 和 A. arenosa.）的雜交體所做的一項(xiàng)研究為了解雜交體生長(zhǎng)能力增強(qiáng)的機(jī)制基礎(chǔ)提供了線(xiàn)索,。研究表明，生物節(jié)律時(shí)鐘的表觀(guān)基因調(diào)制在異源多倍體中調(diào)節(jié)光合作用通道及淀粉代謝通道中的基因表達(dá),。因此,，它們比其父輩積累更多葉綠素，產(chǎn)生更多淀粉,，而且長(zhǎng)得更大,。所以，雜交體和異源多倍體植物似乎能通過(guò)可逆調(diào)整生物節(jié)律時(shí)鐘調(diào)控因子而從生理及代謝通道的控制中獲得優(yōu)勢(shì),，以更好利用白天的時(shí)間,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 457, 327-331 (15 January 2009) | doi:10.1038/nature07523
Altered circadian rhythms regulate growth vigour in hybrids and allopolyploids
Zhongfu Ni1,6,7, Eun-Deok Kim1,6, Misook Ha1,2,3, Erika Lackey1, Jianxin Liu1, Yirong Zhang1,7, Qixin Sun5 & Z. Jeffrey Chen1,2,3,4
1 Section of Molecular Cell and Developmental Biology,
2 Institute for Cellular and Molecular Biology,
3 Center for Computational Biology and Bioinformatics, and,
4 Section of Integrative Biology, The University of Texas at Austin, One University Station, A-4800, Austin, Texas 78712, USA
5 Department of Plant Genetics and Breeding, China Agricultural University, Yuanmingyuan Xilu No. 2, Beijing, 100094, China
6 These authors contributed equally to this work.
Segregating hybrids and stable allopolyploids display morphological vigour1, 2, 3, and Arabidopsis allotetraploids are larger than the parents Arabidopsis thaliana and Arabidopsis arenosa 1, 4—the mechanisms for this are unknown. Circadian clocks mediate metabolic pathways and increase fitness in animals and plants5, 6, 7, 8. Here we report that epigenetic modifications of the circadian clock genes CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY)9, 10, 11 and their reciprocal regulators TIMING OF CAB EXPRESSION 1 (TOC1) and GIGANTEA (GI)10, 12, 13 mediate expression changes in downstream genes and pathways. During the day, epigenetic repression of CCA1 and LHY induced the expression of TOC1, GI and downstream genes containing evening elements14 in chlorophyll and starch metabolic pathways in allotetraploids and F1 hybrids, which produced more chlorophyll and starch than the parents in the same environment. Mutations in cca1 and cca1 lhy and the daily repression of cca1 by RNA interference (RNAi) in TOC1::cca1(RNAi) transgenic plants increased the expression of downstream genes and increased chlorophyll and starch content, whereas constitutively expressing CCA1 or ectopically expressing TOC1::CCA1 had the opposite effect. The causal effects of CCA1 on output traits suggest that hybrids and allopolyploids gain advantages from the control of circadian-mediated physiological and metabolic pathways, leading to growth vigour and increased biomass.
