柑橘直立枝和斜生枝增粗生长及相关基因的比较分析  

Comparative analysis of secondary growth and its related genes between erect and oblique branches of Citrus

作　　者：韦欣 柳东海 韩晗 罗银 陈欢 刘永忠[1] WEI Xin;LIU Donghai;HAN Han;LUO Yin;CHEN Huan;LIU Yongzhong(College of Horticulture&Forestry Sciences,Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology,Ministry of Education,Wuhan 430070,Hubei,China)

机构地区：[1]华中农业大学园艺林学学院·园艺植物生物学教育部重点实验室,武汉430070

出　　处：《果树学报》2022年第4期509-517,共9页Journal of Fruit Science

基　　金：国家重点研发计划项目(2020YFD1000100);财政部和农业农村部:国家现代农业产业技术体系专项。

摘　　要：【目的】探究柑橘直立枝和斜生枝的粗度差异,阐释导致差异的原因,为调控柑橘枝梢增粗奠定基础。【方法】以枳砧3年生的红心柚和南丰蜜橘的秋梢直立枝(枝梢垂直于地面水平线)和斜生枝(枝梢与地面水平线呈45°~60°)为材料,比较粗度、长度、枝梢解剖结构和枝梢内增粗生长相关基因的相对表达量。【结果】红心柚、南丰蜜橘的直立枝粗度均显著高于斜生枝,解剖分析发现直立枝的形成层细胞层数显著多于斜生枝,且直立枝的木质部横截面积较大,髓细胞较大;34个增粗生长相关基因的定量PCR分析表明,2个品种的直立枝中SND1、WOX4、PXY和MYB46-1的相对表达量均显著高于斜生枝,APL、BRXL2、BES1、HAM4和NAC3的相对表达量则显著低于斜生枝。【结论】柑橘直立枝粗度显著高于斜生枝,与直立枝的形成层层数增加和木质部增厚有关;形成层增加相关基因WOX4、PXY和木质部增厚相关基因SND1的高表达可能是柑橘直立枝梢增粗显著高于斜生枝的重要原因。【Objective】Citrus is an important fruit tree in south China. Because the fruit-bearing shoots of branch are soft, high-yielding trees often require supporting poles to avoid fruit squeezing or branch breaking and to ensure fruit quality and tree health. However, erection of poles needs much labor and it is difficult to finish such work in the current era with labor shortages and aging. Promoting the secondary growth of branches and simplifying tree structure play an important role in removing erection of poles, reducing labor cost and increasing orchard revenue. The present study is to explore the difference in secondary growth between erect and oblique branches of citrus, explain the reasons behind the difference, and lay a foundation for regulating the secondary growth of citrus shoots.【Methods】Three-yearold red pomelo(Citrus grandis‘Hongxinyou’) and Nanfang tangerine(C. reticulata‘Kinokuni’) were used as materials to compare the thickness, length, anatomical structure, and expression of genes related to secondary growth between erect(perpendicular to the ground) and oblique(the shoot is at a 45-60 degree angle to the ground level) shoots.【Results】The thickness of the erect shoots of Nanfeng tangerine and red pomelo was significantly higher than that of the oblique shoots. Moreover, the length of the erect shoots of the two varieties was slightly longer than that of the oblique shoots, but the difference was not significant. The anatomical analysis showed that the primary phloem cell size was larger, the cambium width was significantly larger, and the xylem width was significantly lower in the upper part of erect shoots than in that of the oblique shoots, while in the lower part of shoots, the width of cambium and xylem of the erect shoots was significantly higher than that of oblique shoots. The expression levels of 34 genes related to secondary growth were compared. Of the four genes related to xylem secondary growth, KNAT1 and STM in the erect shoots of Red pomelo were significantly more

关 键 词：柑橘 直立枝 斜生枝 增粗生长 形成层 

分 类 号：S666[农业科学—果树学]