云南松苗木生长对氮磷配施的响应规律及其分子调控机制

Pinus yunnanensis Franch. forest is an important tree species in the southwest of China. However, it grew slowly in the seedling stage, which restrict the economic and ecological benefits of young forests. Therefore, the fast seedling growth and the strong seedling cultivation were the key issues for P. yunnanensis development of the forestry industry. Fertilization is often used to promote seedling growth in practice. But the previous research was limited to reveal the relationship between fertilization and seedling growth. The promotion mechanism of seedling growth is not yet completely understood. Furthermore, the utilization of nitrogen and phosphorus of plants is a complicated process driven by multiple genes and multiple steps. And the appropriate amount of nitrogen and phosphorus and their proportions are especially important for the seedling cultivation. Therefore, the fertilization of nitrogen and phosphorus will be carried out by using 3×3 regression design. The response regularity of seedling growth on the external nitrogen and phosphorus addition will be analyzed based on the measurement of the morphological traits such as growth, biomass, architecture characteristics of root systems. The nutrient regulation characteristics of response regularity of seedling growth on the external nitrogen and phosphorus addition will be studied. Transcriptome and proteome will be sequenced, and the bioinformatic method will be used to screen the difference of gene expression in order to search the key genes. The relationship will be revealed between the gene expression and the external nitrogen and phosphorus addition. The response regularity and molecular regulation mechansim of the seedling growth on the application of nitrogen and phosphorus in P. yunnanensis will be explored. Based on this research, the regressive relations will be established between seedling growth and the application of nitrogen and phosphorus, seedling growth and nutrients content. The correlations will be also showed among the application of nitrogen and phosphorus, nutrients content, gene expression and morphological traits. The response regularity and molecular regulation mechansim of the seedling growth on the application of nitrogen and phosphorus in P. yunnanensis will be revealed deeply and systematically. Meanwhile, the research findings will provide reference for the best option of the balanced fertilization to promote seedling growth.

云南松是我国西南地区重要的造林树种，但苗期生长缓慢，制约了幼林经济和生态效益的发挥。因此，加速苗木生长、开展壮苗培育是云南松产业发展急需解决的问题，生产中常采用施肥实现苗木促成培育。然而，相关研究仅局限于施肥与苗木生长的因果关系，对其调控机制尚不清楚，但植物的氮、磷利用是多基因调控的复杂过程，且适宜的氮、磷用量及其比例对苗木的促成培育尤为关键。鉴于此，该项目基于3×3回归试验设计进行氮、磷配施试验；通过生长量、生物量及根系构型等表型性状测定，分析苗木生长对氮磷配施的响应规律；通过土壤及植株体内养分含量的测定，阐明苗木生长对氮磷配施响应规律的养分调控特征；通过转录组和蛋白组测序，结合生物信息学分析，寻找差异基因与关键基因，揭示基因表达与氮磷配施间的关系，探讨云南松苗木生长对氮磷配施响应规律的分子调控机制。通过研究，构建苗木生长与氮磷用量及其比例、苗木生长与土壤及植株体内养分含量之间的回归关系；建立氮磷配施-养分含量-基因表达-表型性状之间的联系，较为深入系统揭示云南松苗木生长对氮磷配施的响应规律及其分子调控机制，并为云南松促成培育配方施肥最佳方案的选择提供参考。

云南松（Pinus yunnanensis）作为我国西南地区的典型代表树种，在其分布区的林业生产和生态系统的可持续发展中发挥着重要作用。然而，云南松苗期生长缓慢，进而影响造林成效，如何加速幼苗生长是云南松产业急需解决的问题之一。氮磷作为植物生长的必需营养元素和生态系统的重要限制元素，对其开展苗木促成培育应用较多。目前关于云南松苗木氮磷处理的研究多集中在生长评价方面，缺乏系统的研究。鉴于以上情况，本项目以云南松苗木为研究对象，采用氮、磷2因素3水平的3×3试验设计开展氮磷配施，揭示氮磷处理后对云南松苗木生长、生理、养分间的相互关系与因果关系，探讨苗木的养分需求及分配特征，综合分析云南松苗木生长对外源氮磷配施的响应。结果表明：（1）氮、磷处理对促进云南松苗木的苗高、地径生长量效果显著，氮肥的添加一定程度促进苗高、地径的生长，同时随着磷肥的增加均呈先增加后降低的趋势，单施高浓度的氮肥或磷肥对苗高、地径生长会有抑制作用。（2）不同氮、磷处理对云南松苗木生物量积累和分配影响不同，根、茎、叶、地上、单株生物量最大的处理为处理5（N2P2）和处理9（N3P3），单施氮或磷肥对生物量的增加有一定作用。氮、磷处理对根系形态特征各指标的影响不显著，除根表面积主要受氮肥影响外，其他指标的生长主要受磷肥的影响。（3）氮、磷处理改变了云南松的根、茎、叶中的养分积累，施肥后提高了云南松苗木各器官的营养元素含量。苗木各器官的N:P化学计量受氮磷处理影响，氮肥处理能增加N:P，同时氮肥和磷肥对营养元素的吸收能相互促进。（4）氮、磷处理改变了苗木与土壤的相关关系，使苗木与土壤的相关关系由负相关或不相关转变为正相关关系，且这种相关关系存在明显的时间变异，随着时间的延长，相关性逐渐增强。（5）氮、磷处理下云南松苗木的基因表达与蛋白质表达均发生改变，与对照相比，在二萜生物合成、亚油酸代谢、单萜类生物合成、苯丙烷类生物合成、氨基糖和核苷酸糖代谢中均表现为上调基因表达。进一步分析表明差异蛋白主要富集在次生代谢产物的生物合成、萜类主链生物合成、光合作用等通路。研究结果为系统揭示云南松苗木生长的分子调控奠定基础，为苗木促成培育氮磷用量和配比的选择提供参考，同时也为同类树种的养分高效利用与管理提供借鉴。