Partnering crops with root-associated microbes for soil health and agricultural sustainability

Increasing global demand for food presents a significant challenge to maintaining soil health and sustainable production of agricultural crops. As plant root-associated microbial fitness is greatly impacted by community growth, development, and nutrient acquisition, the cultivation of functional assembly of root-associated microbes may provide solutions for achieving food security while maintaining healthy soils. Here, we propose a four-part strategy to promote soil health and agricultural productivity by partnering crops with root-associated microbes.

植物有益伯克霍尔德氏菌的研究进展及其在农业中的应用

伯克霍尔德氏菌属是一类革兰氏阴性细菌,其具有广泛的地理及生态位分布。近年来,随着对植物相关的伯克霍尔德氏菌的研究增加,越来越多的证据表明,伯克霍尔德氏菌是一类重要的植物相关的有益微生物。伯克霍尔德氏菌能够通过生物固氮、解磷作用,促进植物对氮、磷的吸收;还能够产生吲哚乙酸等植物激素、分泌抗菌物质抑制病原菌的生长,因此,伯克霍尔德氏菌在促进植物生长和维持植物健康方面具有较大的应用潜力。本文对近些年来关于植物有益的伯克霍尔德氏菌的研究进展进行了综述,并讨论了其在农业上的应用前景。

甘蔗联合固氮的研究进展及应用潜力

在农业生产中,化学氮肥的投入大幅度增加了粮食产量,然而过量或不合理的施肥措施对农业生态环境造成了严重破坏。因此,挖掘植物自身的生物学特性,寻求其他有效的氮素来源,对农业减肥增效至关重要。其中,植物与微生物之间的生物固氮作用,能为宿主提供大量的清洁氮源,在农业生产中发挥着不可替代的作用。本文以甘蔗为代表,综述了植物联合固氮的研究进展和应用潜力,包括联合固氮作用的提出、联合固氮菌的筛选、侵染机制及功能研究,并总结了联合固氮复合菌在甘蔗生产中的应用,以期为作物养分高效的品种改良及推动生物固氮作用在农业生产中的实践提供理论依据和参考。

Functional assembly of root-associated microbial consortia improves nutrient efficiency and yield in soybean

Root-associated microbes are critical for plant growth and nutrient acquisition. However, scant information exists on optimizing communities of beneficial root-associated microbes or the mechanisms underlying their interactions with host plants. In this report, we demonstrate that rootassociated microbes are critical influencers of host plant growth and nutrient acquisition. Three synthetic communities(SynComs) were constructed based on functional screening of 1,893 microbial strains isolated from root-associated compartments of soybean plants. Functional assemblage of SynComs promoted significant plant growth and nutrient acquisition under both N/P nutrient deficiency and sufficiency conditions.Field trials further revealed that application of SynComs stably and significantly promoted plant growth, facilitated N and P acquisition, and subsequently increased soybean yield. Among the tested communities, SynCom1 exhibited the greatest promotion effect, with yield increases of up to 36.1% observed in two field sites. Further RNA-seq implied that SynCom application systemically regulates N and P signaling networks at the transcriptional level, which leads to increased representation of important growth pathways, especially those related to auxin responses. Overall,this study details a promising strategy for constructing SynComs based on functional screening,which are capable of enhancing nutrient acquisition and crop yield through the activities of beneficial root-associated microbes.

Pyramiding of the dep1-1 and NAL1NJ6 alleles achieves sustainable improvements in nitrogen-use efficiency and grain yield in japonica rice breeding

Rice is one of the most important cereal crops in the world, and a substantial increase in grain yield is necessary for food security. However, high yields of semidwarf modern rice varieties are heavily dependent on the application of mineral nitrogenous fertilizer (Tilman et al., 2002;Sun et al., 2014). Nitrogen (N)-insensitive sponses associated with reduced N-use efficiency (NUE) is a major characteristic of the green revolution varieties (GRVs), in which the growth-inhibiting protein SLENDER RICE1 (SLR1) accumulates (Li et al., 2018). Unfortunately, increasing the level of N fertilizer use to reach the full yield potential of GRVs is subject to diminishing returns, quite apart from its deleterious effect on the environments (Rahn et al., 2009;Liu et al., 2015). Therefore, there is an urgent need to develop new rice GRVs that increase NUE while maintaining their high yields. Recently, several genes (e.g., DEP1, OsNRTl.lB, OsNRT2.3b, ARE1 and GRF4) responsible for improved NUE have been identified in rice (Sun et al.. 2014;Hu et al., 2015;Fan et al., 2016;Wang et al., 2018;Li et al., 2018). More importantly, boosting the activity of the transcription factor GRF4 overcomes the ability of SLR1 to prevent the GRF4-GIF1 interaction, which in turn promotes the coordinated expression of the genes involved in N assimilation and carbon fixation and consequently enhances the NUE of rice GRVs, thereby improving our ability to grow crops sustainably (Li et al., 2018). However, current understanding of the genetic basis for improving NUE remains at the level of identification of a number of quantitative trait loci (QTLs), without any understanding of the nature of the gene products.

INTERCROPPING TEA PLANTATIONS WITH SOYBEAN AND RAPESEED ENHANCES NITROGEN FIXATION THROUGH SHIFTS IN SOIL MICROBIAL COMMUNITIES

Intercropping with eco-friendly crops is a well-known strategy for improving agriculture sustainability with benefits throughout the soil community,though the range of crop impacts on soil microbiota and extent of feedbacks to crops remain largely unclear.This study evaluated the impacts of different intercropping systems on soil bacterial community composition,diversity,and potential functions in tea gardens.Intercropping systems were found to be significantly influenced soil microbiota.Within the three tested intercropping systems(tea-soybean,tea-rapeseed and tea-soybean-rapeseed),the teasoybean-rapeseed intercropping system had the most dramatic influence on soil microbiota,with increases in richness accompanied by shifts in the structure of tea garden soil bacterial networks.Specifically,relative abundance of potentially beneficial bacteria associated with essential mineral nutrient cycling increased significantly in the tea-soybean-rapeseed intercropping system.In addition,soil microbial functions related to nutrient cycling functions were significantly enhanced.This was in accordance with increasing relative abundance of nitrogen cycling bacteria,including Burkholderia spp.and Rhodanobacter spp.Based on these results,it is proposed that intercropping tea plantation with soybean and rapeseed may benefit soil microbiota,and thereby promises to be an important strategy for improving soil health in ecologically sound tea production systems.