磷高效湿加松无性系的不定根发育特性研究

The hybrid between slash pine (Pinus elliottii) and Caribbean pine (Pinus caribaea) is one of the important fast-growing plantation species in South China. Low phosphorus (P) availability is a major constraint to the growth of the hybrid pines. Genotypic differences in phosphorus uptake and use efficiency were detected in plants and the important roles of root morphology and root system architecture were found as well. The developmental characteristics of adventitious roots, which are the root type for cuttings, might be closely related to the P efficiency of the hybrid pine cuttings. The proposed research involves the theories and methods of root biology and plant nutrition. The P efficiency of the hybrid pine clones will be evaluated and classified, and the adaptive responses of root architecture and morphology to low P stress will be studied. The proposed research will facilitate generating P-efficient hybrid pines through root breeding and molecular breeding.

湿加松是南方重要的速生丰产林树种之一，土壤缺磷是当前限制湿加松推广的重要因素。研究发现，植物对磷的吸收利用效率存在基因型差异，而根系的形态构型在其中扮演着重要角色。不定根是林木扦插苗的根系来源，因此不定根的发育特性与湿加松无性繁育苗木的磷效率密切相关。本项目综合应用根系生物学和植物营养学等研究手段，对湿加松无性系材料的磷效率进行评价与分类，研究其根系构型和形态对缺磷的适应性反应，初步探讨湿加松不定根发育与磷效率的关系及其内部机理。本项目的开展为下一步通过根系育种和分子育种等方法进行湿加松磷效率的遗传改良奠定重要基础。

本项目以自主培育的50个湿加松无性系为材料，设置了磷丰缺处理的盆栽试验和大田试验，对无性系的磷效率进行分类。通过成活率、株高增量、地径增量、表型等分析其差异表现，从中筛选获得磷高效无性系4个、磷低效无性系2个。优良无性系在缺磷条件下的存活率比群体提高8~13个百分点，株高增加34%~62%，地径增加39%~119%。进而，在不同生长介质中设置扦插苗期试验，浇灌高低磷营养液，以分析50个无性系的根系性状表现，结果表明，与其它物种相似的是，湿加松磷高效无性系的总根长与根系表面积显著性高于磷低效无性系，而与作物不同的是，湿加松细根的长度与比例与磷效率无明显关系。另外，通过色谱-质谱联用技术（GC-MS），对筛选获得的优良无性系H1进行初步的代谢物分析，从而获得木糖醇、反丁烯二酸等13个差异表达代谢物，为进一步研究磷高效性状的形成机制奠定了重要的基础。