独脚金内酯的生物合成及其调控

为了解独脚金内酯生物合成最新研究进展，本研究以“独脚金内酯”为关键词，检索了2000—2020年NCBI数据库发表的相关文献资料，综述了近20年来独脚金内酯的生物合成通路和相关基因的功能研究进展，并对独脚金内酯在非生物胁迫作用中的功能以及与其他激素的相互作用进行概括。结果表明:1)独脚金内酯生物合成的通路是保存的，并可能与其他通路有交互作用；2)独脚金内酯的功能是多样的，在植物生长和发育的多个阶段发挥作用；3)独脚金内酯生物合成相关基因不仅是生物合成的关键基因，还可以与其他激素互作参与调控作用。在独脚金内酯生物合成及其调控作用的研究取得了重要突破的基础上，今后着重的研究方向可能是在产量形成机制、形态建成以及激素的调控作用机理等方面的研究。     

OsMAX1a,OsMAX1e通过参与独角金内酯的合成调控水稻分蘖

独角金内酯是调控水稻分蘖的重要激素,在拟南芥中AtMAX1编码细胞色素P450蛋白,是独角金内酯合成途径的重要基因。通过同源序列比对,发现在水稻中有5个MAX1同源基因,包括OsMAX1a、OsMAX1b、OsMAX1c、OsMAX1d和OsMAX1e。分析5个OsMAX1基因的转录水平,发现OsMAX1a和OsMAX1e基因能够在水稻组织中稳定高效表达。对OsMAX1a和OsMAX1e的基因功能进行了验证,在拟南芥中过量表达OsMAX1a和OsMAX1e基因能够使max1突变体多分支表型恢复正常;在水稻中干涉OsMAX1a和OsMAX1e基因的表达能够增加水稻分蘖数。进一步的研究表明,外施GR24能够抑制OsMAX1a和OsMAX1e基因的表达,磷饥饿条件能够提高两个基因的表达水平从而促进独角金内酯的合成。另外,外施生长素和激动素能够显著影响OsMAX1a和OsMAX1e的表达。因此,OsMAX1a和OsMAX1e基因参与了独角金内酯的合成,并且在水稻生长发育中响应植物激素信号的诱导,是调控水稻分蘖的重要基因。     

Synthesis of strigolactones,a strategic account

Strigolactones (SLs) constitute a new class of plant hormones that have received growing interest in recent years. They firstly became known as signalling molecules for host recognition by parasitic plants, and for symbiosis of plants with arbuscular mycorrhizal fungi. Furthermore, they are involved in numerous physiological processes in plants, such as the regulation of plant architecture and the response to abiotic factors. SLs are produced by plants in extremely low quantities, and they may be unstable during the purification process. Therefore, their total synthesis is highly relevant for confirming the structures assigned on the basis of spectroscopic and other physical data. A second important theme in SL research is the design and synthesis of SL analogues that have a simplified structure while still featuring the essential bioproperties. This review summarises the strategy and synthesis of naturally occurring SLs, and the design and synthesis of SL analogues with appreciable bioactivity. © 2015 Society of Chemical Industry     

苜蓿花叶病毒和白三叶草花叶病毒复合侵染对本氏烟中5种激素含量的影响

为探明苜蓿花叶病毒(alfalfa mosaic virus, AMV)和白三叶草花叶病毒(white clover mosaic virus, WCMV)复合侵染的协生作用致病机理,以复合接种AMV+WCMV的本氏烟为处理,分别以单独接种AMV、WCMV、磷酸盐缓冲溶液(pH 7.0, PBS)的本氏烟为对照,采用DAS-ELISA (double-antibody sandwich enzyme-linked immunosorbent assay)方法检测了接种病毒72 h的本氏烟(Nicotiana benthamiana)叶片中的病毒含量及72～720 h内水杨酸(salicylic acid, SA)、茉莉酸(jasmonic acid, JA)、独脚金内酯(strigolactones, SLs)、油菜素内酯(brassinolide, BR)、乙烯(ethylene, ETH) 含量的变化。结果表明：AMV和WCMV 接种比例为3∶1的植株720 h时的发病症状比单独接种一种病毒(AMV或WCMV)明显,主要症状表现为轻花叶、斑驳花叶、重花叶、明脉、皱缩。检测接种72 h时叶片病毒浓度发现,接种比例3∶1的植株中AMV的浓度比单独接种AMV以及AMV和WCMV接种比例为1 ? 1和1 ? 3的处理高,而WCMV的浓度略低于其单独接种WCMV处理,高于AMV和WCMV接种比例为1 ? 1和1 ? 3的处理;接种AMV和WCMV混合液后复合侵染的本氏烟叶片中SA、JA、SLs、BR、ETH含量在一定时间内与单独接种AMV、WCMV及对照之间差异显著(P < 0.05),其中,AMV和WCMV接种比例为3∶1的混合液可在一定时间段内提高本氏烟叶片中SA (216～504 h)、SLs (216～432 h)、BR (216～504 h)、ETH (288～720 h)含量,降低JA (216～504 h)含量,其SA、SLs、BR、ETH含量分别比单独接种AMV、WCMV和健康植株(CK)提高了36.27%以上,JA含量降低了59.09%多。     

籼稻矮化多分蘖突变体gsor23的基因克隆与表达分析

 矮化多分蘖突变体gsor23是籼稻品种Indica9经γ射线辐射后获得的。遗传分析表明其矮化多分蘖表型受一个隐性基因控制,并将突变基因定位在第1染色体长臂上InDel标记C1 WT2与C1 WT4之间。这两个标记之间物理距离为386 kb,其间包含一个抑制植物分枝的基因D10。对gsor23中的D10基因测序发现编码区第404位的碱基C缺失,导致从第135位氨基酸开始移码突变。gsor23的突变位点与已报道的粳稻背景的d10 1和d10 2突变体不一样,是D10基因一个新的等位突变体。D10编码的类胡萝卜素裂解双加氧酶8 (carotenoid cleaving dioxygenase, CCD8),是抑制分枝的新型植物激素独脚金内酯(strigolactones, SLs)合成途径中的关键酶之一。用SLs人工合成类似物GR24处理gsor23,其多分蘖表型受到抑制。实时 RT PCR结果显示D10在水稻根部表达量较高,叶片较低。在突变体gsor23中,参与 SLs合成的基因D10上调表达,而可能参与SLs信号转导的基因D3和D14表达下调。     

Strigolactones--intriguing biologically active compounds: perspectives for deciphering their biological role and for proposing practical application

Strigolactones are a class of bioactive natural metabolites produced by plant roots and released into the rhizosphere. They were discovered as signals indispensable for the induction of germination of seeds of root parasitic weeds, but since then, interestingly, many other biological, physiological and ecological roles have been described. This has suddenly provoked huge scientific interest in these compounds within different research fields. In this short perspective the attention is focused mainly on the ongoing and future research aimed at deciphering the biological roles of strigolactones that could positively affect, more or less directly, the management of parasitic weeds.