茶树‘湘妃翠’黄化枝光合生理与组织学

Photosynthetic Physiological and Histology in Novel Etiolated Branch of the’Xiangfeicui’ Tea Plant(Camellia sinensis)

黄化突变是茶树叶色变异中的一个重要分支,研究其光合生理特征及生理结构变化规律对于揭示黄化茶树对环境的响应机理具有重要意义。在湖南农业大学‘湘妃翠’茶树母本园中,发现一株茶树上生长出数枝黄化枝条。通过对黄化单株黄化叶(YPEL)、黄化单株正常叶(YPNL)以及正常株正常叶(NPNL)的叶绿体色素含量、超微结构、叶绿素荧光参数及解剖结构进行研究。结果表明:YPEL叶绿素、类胡萝卜素含量极显著低于YPNL和NPNL;YPEL叶绿体面积与基粒片层有效堆叠明显少于NPNL,YPEL叶绿体中出现淀粉粒、嗜锇颗粒和囊状小泡异常增多现象;YPEL叶绿素荧光参数Fm、Fv/Fm、Fv/Fo、qP、qN值极显著低于YPNL和NPNL,而Fo、NPQ值则极显著高于YPNL和NPNL;黄化叶主脉厚度极显著小于NPNL(15.96%),栅栏组织厚度/海绵组织厚度显著高于NPNL(37.09%),YPEL茎髓细胞面积极显著小于NPNL(43.86%)。研究表明,‘湘妃翠’黄化单株叶色黄化的直接原因可能是因为叶绿体结构瓦解,导致叶绿素及类胡萝卜素的生物合成受阻;而叶绿体结构瓦解也严重影响了黄化叶的光合作用,导致黄化叶受到光抑制与光氧化。黄化枝通过改变叶与茎的生理结构比例,减少养分消耗并增强营养物质的储存能力,从而保证其正常发育与生长。

Etiolated mutation is an essential branch of color variation in tea plant,it is crucial to research its photosynthetic physiological characteristics and change regulation of histos structure to reveal the mechanism of etiolated tea plant response environment.A tea cultivars(Camellia sinensis cv.Xiangfeicui)with some etiolated branches was discovered in a local tea plantation in Hunan Agricultural University,Changsha,China.We researched the chloroplast pigment content,ultrastructure,chlorophyll fluorescence parameters and anatomical structure of YPEL,YPNL and NPNL.The results showed that etiolated leaves on these special branches had extremely low chlorophyll a,chlorophyll b and carotenoid contents,with chloroplast areas,valid grana lamellar stacking of etiolated leaves were extremely less than normal leaves,starch granules abnormal soared in chloroplast,and a large number of osmium granules and saccular vesicles emerge.The chlorophyll fluorescence parameters including Fm,Fv/Fm,Fv/Fo,q P,qN were extremely lower contrast with control leaves,the Fo,NPQ were extremely higher than control leaves.The thickness of main vein of etiolated leaves was extremely less than normal leaves(15.96%),the thickness of palisade tissue spongy tissue was extremely higher than normal leaves(37.09%),and the acreage of pith-cell of etiolated stem was extremely smaller than normal stems(43.86%).We speculate the immediate cause of etiolated is the disrupted of chloroplast structure,which hinders the biosynthesis of chlorophyll and carotenoids.The disrupted chloroplast structure also seriously affected the photosynthesis of etiolated leaves,resulting in photoinhibition and photooxidation.By changing the proportion of physiological structure between leaf and stem,etiolated branches can reduce nutrient consumption and enhance nutrient storage capacity,so as to ensure its normal development and growth.