玉米/花生间作对根际优势功能微生物的影响及其改善作物铁营养的生物学机制

Peanut/maize intercropping is a sustainable and effective agroecosystem that evidently enhances the iron nutrition of peanuts in calcareous soils in the North of China. Significant progress has been made in Fe improvement of peanut intercropped with maize in last decade, our results indicated that rhizosphere interaction of maize and peanut significantly played a key role in improving the Fe nutrition of intercropped peanut at the molecular and ecological level. In our recent study, our results suggested that intercropping changed the microbial community structure and increased the percentage of the siderophore-secreting microbes in the rhizosphere of peanut intercropped with maize, and we identified microorganism of Pseudomonas sp.IP1 and Achromobacter sp.IP1. These results imply that the microbial community structure and siderophore-secreting microbes may play an important role in improvement iron nutrition of crops. The objective of the present study will investigate how intercropping of maize and peanut shows efffects on iron nutrition and the microbial community structure and siderophore-secreting microbes in the rihzospher of two crops at different growth stages in calcareous soil. Moreover, the study will illustrate how root exudates from crops in different cropping system to regulate iron uptake and siderophore-secreting microbes at molecular and physiological level. We will also investigate the effects of Pseudomonas sp.IP1 and Achromobacter sp.IP1 on iron nutrition of crops. Finally, Our study will illustrate the function of rhizo-biome in iron improvement and resources efficiency of intercropping of maize and peanut at molecular, physiological and ecological level. Our results will confirm the ecological significance of functional rhizo-biome of intercropping for improving the adaptation of plants to environmental stress and the regulation mechanism of intercropping improvement in iron nutrition of crops. Our study would also provide scientific and technical evidence for improvement resources efficiency and high crop production and food security through plant- plant and plant -microorganism interaction in the rhizosphere of intercropping systems.

以华北平原生产中间作优势明显的玉米/花生间作能改善花生铁营养的生态现象为主题，十多年系统研究表明植物间互作互惠对改善作物铁营养具有重要的分子生态调控作用。最新研究初步发现间作使花生根际能产生铁载体的优势微生物明显增加并获得两个功能性微生物假单胞菌（Pseudomonas sp.IP1）和无色杆菌（Achromobacter sp.IP1）菌株, 进一步从分子、生理和生态水平阐明间作根际效应对不同生育期玉米和花生根际微生物群落结构和能够分泌铁载体的微生物的影响及其变化规律，解析玉米花生根系分泌物对能够分泌铁载体的微生物的影响及其与改善作物铁营养的调控作用，明确分泌铁载体的微生物对植物吸收利用铁的影响及其分子生态机制和间作对其功能发挥的影响，阐明该体系利用作物-微生物互作互惠提高铁营养的生物学调控机制，为通过调控根际益生微生物功能发挥，实现养分资源高效和绿色农业发展提供重要依据。

以华北平原生产中间作优势明显的玉米/花生间作能改善花生铁营养的生态现象为主题，二十多年系统研究表明石灰性土壤上植物间互作对改善作物铁营养具有重要的分子生态调控作用，然而，该体系中有关微生物对改善作物铁营养的作用却知之甚少。本项目系统深入研究结果表明间作明显招募和富集能够高效产生铁载体的功能微生物并对改善花生铁营养发挥了重要作用。通过16SrDNA高通量测序表明，间作显著改变了花生、玉米根际微生物多样性及群落结构，尤其是玉米根系分泌物通过间作在花生根际招募和富集了高效产生微生物铁载体的功能微生物并对改善花生铁营养发挥了重要的作用；在田间和盆栽试验条件下，筛选获得功能菌荧光假单胞菌Pseudomonas sp.IP1、无色杆菌Achromobacter sp.1604IPR-02和芽孢杆菌Bacillus sp.1603IPR-02以及分泌的铁载体能够有效的改善花生铁营养和提高产量和籽粒中铁锌含量；玉米分泌的植物铁载体类似物PDMA能够有效改善花生缺铁黄化并实现产量和品质同步提升，这为研发功能微生物肥料和新型微量元素螯合剂促进作物生长提供了重要的理论技术支撑和资源；克隆并验证了花生根系的AhFRDL1基因同时具有调控铁从根系向地上部转移和抗铝毒的生物学功能，根系铁运输基因AhNRAMP1兼备转运Mn和Zn的生物学功能，为通过分子育种培育抗铝和耐缺铁作物品种提供了重要的理论和技术依据。总之，本项目进一步从分子、生理和生态水平多层次阐明间作体系作物-微生物-作物互作互惠对提高养分高效利用和粮食安全发挥了重要作用，也为通过调控根际有益生微生物功能发挥和研发新型功能微生物肥料，提升土壤-作物健康和农业绿色发展提供了创新的理论和技术途径，应用前景十分广阔。