人類的過度開發(fā)和不合理的資源利用造成生物多樣性的嚴(yán)重喪失，尤其是在物種多樣性非常豐富的熱帶雨林地區(qū),。在各地森林遭受強(qiáng)烈破壞和片斷化的情況下,，許多樟科種類生境惡化,、傳播和更新受到很大影響，生存受到嚴(yán)重威脅,。中科院西雙版納熱帶植物園李捷研究員帶領(lǐng)的植物系統(tǒng)與保護(hù)生物學(xué)研究組利用三年的時間對樟科瀕危植物思茅木姜子開展了保護(hù)遺傳學(xué)方面的研究,，并取得了重要進(jìn)展。
思茅木姜子（Litsea szemaois(Liou)J. Li et H. W. Li）,，是分布于我國云南西雙版納熱帶季雨林的高大木本植物,，屬于狹域分布的瀕危物種。過去將其處理為樟科木姜子屬（Litsea）越南木姜子的一個變種（Litsea pierrei Lec. var. szemois Liou）,。通過對野外調(diào)查時所采集眾多標(biāo)本的觀察,，以及室內(nèi)對模式標(biāo)本的對比研究，李捷研究員等提出思茅木姜子和越南木姜子在雌雄蕊與葉形等形態(tài)特征及分布范圍等方面存在極大差別,，應(yīng)作為獨(dú)立的一個種,，并命名為Litsea szemaois(Liou) J . Li et H.W. Li。該課題組利用AFLP和ISSR兩種分子標(biāo)記對該瀕危種進(jìn)行了遺傳多樣性和遺傳結(jié)構(gòu)的研究,，結(jié)果顯示出較高水平的遺傳多樣性和一定程度的遺傳分化,。并據(jù)此提出了物種的現(xiàn)狀除了與西雙版納地區(qū)生境的破碎化有關(guān),，還與物種自身的生物學(xué)特性相關(guān)，如多年生,、雌雄異株,、木本、蟲媒,、果實(shí)主要靠重力傳播等,。在研究過程中，采集200多株不同居群的幼苗植入西雙版納植物園苗圃,，建立了一個較大的遷地保護(hù)居群,。
通過此項(xiàng)目研究不僅對瀕危的思茅木姜子提出理論上的保護(hù)依據(jù)，為其遷地保護(hù)提出了科學(xué)的保護(hù)策略和措施,，具有重要的現(xiàn)實(shí)意義,，而且以此研究為基礎(chǔ)，深入了解樟科物種（已發(fā)現(xiàn)報(bào)道一樟科植物新屬—孔藥楠屬Sinopora J. Li,，N.H. Xia & H.W. Li）,，在今后樟科的其它稀有瀕危植物的保護(hù)生物學(xué)研究中發(fā)揮重要的指導(dǎo)性作用。該研究的一系列研究論文發(fā)表在《植物分類學(xué)與進(jìn)化》（Plant Systematics and Evolution）,、“Novon”,、《生物多樣性》《云南植物研究》等國內(nèi)外重要期刊。（生物谷Bioon.com）
生物谷推薦原始出處：
Plant Systematics and Evolution,，doi：10.1007/s00606-008-0012-4,，Xiu-qin Ci，Jie Li
AFLP and ISSR analysis reveals high genetic variation and inter-population differentiation in fragmented populations of the endangered Litsea szemaois (Lauraceae) from Southwest China
Xiu-qin Ci1, 2, Jun-qiu Chen1, 2, Qiao-ming Li1 and Jie Li1, 3
(1) Laboratory of Plant Phylogenetics and Conservation Biology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, 650223 Yunnan, People’s Republic of China
(2) The Graduate School of the Chinese Academy of Sciences, 100039 Beijing, People’s Republic of China
(3) 88 Xuefu Rd., Kunming, 650223 Yunnan, People’s Republic of China
Received: 25 October 2007 Accepted: 23 January 2008 Published online: 27 May 2008
Abstract Litsea szemaois (Lauraceae) is an endemic and endangered species from the tropical rain forests of Xishuangbanna, southern Yunnan, SW China, but habitat fragmentation, especially exacerbated by rubber planting, has caused a decline in population size of the species. AFLP and ISSR were used to investigate the genetic diversity and population structure of eight populations from across its known distribution. Three AFLP and ten ISSR primer combinations produced a total of 203 and 77 unambiguous and repeatable bands respectively, of which 164 (80.8%) and 67 (87.0%) were polymorphic for the two markers. These two markers showed that Litsea szemaois exhibits comparatively high genetic diversity at species level (heterozygosity (hs) = 0.2109) relative to some other Lauraceae. Most of the genetic variation was partitioned within populations, but genetic differentiation between populations was significant and relatively high (Φ st = 0.2420, θB = 0.1986) compared with other tropical plants. The genetic characteristics of L. szemaois may be related to its outbreeding system, insect pollination and fragmented distribution. Because L. szemaois is dioecious and slow to mature, ex situ conservation across its genetic diversity is unlikely to succeed, although seedlings grow well under cultivation. Thus, in situ conservation is very important for this endangered species, especially as only 133 adult individuals are known in the wild. In particular, the Nabanhe and Mandian populations should be given a high conservation priority due to their higher genetic diversity, larger population size and better field condition, but wider sampling is required across all populations to determine additional areas with significant genetic conservation value.
