Makalah BMPT

 

MAKALAH BMPT Interaksi Proto-cooperation Mikroba dengan Tanaman 2/8/2016 RIDHO PRATAMA YENDI F1C413042

TITLE                        : INSIDE THE ROOT MICROBIOME: BACTERIAL ROOT

  ENDOPHYTES AND PLANT GROWTH PROMOTION.

AUTHOR                  : JONATHAN R . GAIERO , CRYSTAL A. MCCALL , KAREN A. 

                                      THOMPSON , ICOLA

  J. DAY , ANNA S. BEST , AND KARI E. DUNFIELD.

REVIEWED BY       : Ridho Pratama Yendi. F1C413042. S1- BIOLOGI, FST, UNJA, 2016

What would research be?

Bacterial root endophytes reside in a vast number of plant species as part of their root microbiome, with some being shown to positively infl uence plant growth. Endophyte community structure (species diversity: richness and relative abundances) within the plant is dynamic and is infl uenced by abiotic and biotic factors such as soil conditions, biogeography, plant species, microbes interactions and plant–microbe interactions, both at local and larger scales. Plant-growth-promoting bacterial endophytes (PGPBEs) have been identifi ed, but the predictive success at positively infl uencing plant growth in fi eld conditions has been limited. Concurrent to the development of modern molecular techniques, the goal of predicting an organism’s ability to promote plant growth can perhaps be realized by more thorough examination of endophyte community dynamics. This paper reviews the drivers of endophyte community structure relating to plant growth promotion, the mechanisms of plant growth promotion, and the current and future use of molecular techniques to study these communities.

Why the research should be?

            The interaction between plants and microorganisms in the soil is well recognized. It’s first observed that microorganisms were more abundant in the soil surrounding the plant roots than in soil remote from the root and called this area the Rhizosphere. Plant roots exude many organic compounds that stimulate microbial growth and can have a major impact on the composition of the rhizosphere micro-biome. Recently, research focus has been redirected on the composition of the rhizosphere micro-biome, examining the impact it can have on plant growth and health. The micro-biome within plant roots can differ significantly from that within the rhizosphere, suggesting plants impact the microbial communities found inside their roots. Microorganisms found within plant tissues, termed endophytes, are a subset of the root micro-biome, which also includes the rhizosphere and rhizoid micro-biomes. Extensive research has been done on the potential of root endophytes as plant inoculants for plant growth promotion. However, our understanding of the drivers of endophyte communities is lacking and has hindered our ability to predict the success of endophytes to promote plant growth in the field.

How would focused in this research by?

            The focused of this are endophyte Bacteria and microbes, and about their interaction especially Proto-cooperation, on the term, Proto-cooperation same with mutualism symbion, the differ of them is from the site of cited. Proto-cooperation mean, that one organism before the interacted are 1 after the interacted are same still in 1. Mutualism-symbion mean, between two organism before interacted are 0, then after interacted are 1 and hard for changing one of them cause them still it bound on. All of this, show the same meaning, like a positive interaction all of them still be advantages some of it.

            In the case, mean in this Journals tell what the interacted between microbes and plant still in Rhizosphere., all of part of soils., They are boundary in Endophytes, mean inside of plant sited, especially in root surfaced. This journal still telling about the Endophyte Microbes and Bacteria inside the root surfacing, they told, Endophytes are conventionally defi ned as bacteria or fungi that reside internally in plant tissues, can be isolated from the plant after surface disinfection, and cause no negative effects on plant growth (i.e., they are either beneficial or commensal). Recent molecular advances require that this defi nition be adjusted since an abundance of unculturable endophytes have been sequenced, but not isolated. Furthermore, it appears that certain fungal endophytes can shift between parasitic and mutualistic life strategies, described as a balanced antagonism. Therefore, a more endophytes from the Rhizobiaceae family and their host plants has been the subject of a large amount of research and reviews. The focus of this paper will specifi cally be root-associated bacterial endophytes with plant growth promoting life strategies.

How’s ‘bout the result?

            The result in this shows the describing data are Endophyte distribution within plants depends on a combination of ability to colonize and the allocation of plant resources. Root endophytes often colonize and penetrate the epidermis at sites of lateral root emergence, below the root hair zone, and in root cracks. These colonizers are capable of establishing populations both inter- and intracellularly. After initial colonization, some endophytes can move to other areas of the plant by entering the vascular tissues and spreading systemically. Using endophytes

labeled with green-fl uorescent-protein (GFP), it’s demonstrated the transport of the endophytes

from seeds into plant roots and tissues, and endophytes injected into stems moved into the roots and rhizosphere, suggesting that there may be a continuing movement of organisms throughout the root microbiome. The second factor infl uencing distribution is the allocation of resources throughout the plant. Different plant tissues can harbor compositionally distinct endophyte communities. For example, found that Pseudomonas spp. Were more common in the stems than in the roots of potatoes ( Solanum tuberosum ) after 1 mo of growth. It’s speculated that the higher endophyte concentration within carrot ( Daucus carota ) crowns compared with that in the

metaxylem tissues was due to higher concentrations of photosynthate in crown regions, supplying more resources for a larger community to proliferate. While molecular studies can identify an observable distribution pattern of endophytes within plant s, the mechanisms behind the establishment of the distribution patterns is not clear, and is a promising area for new research. Experiments characterizing transcriptome dynamics of endophytes and their host plants offer promising methods to discover some of the drivers of the plant–endophyte interactions.

Then, Plant-growth-promoting bacterial endophytes (PGPBEs) facilitate plant growth via three interrelated mechanisms: phytostimulation, biofertilization, and biocontrol. Plant-growth-promoting bacterial endophytes (PGPBEs) facilitate plant growth via three interrelated mechanisms: phytostimulation, biofertilization, and biocontrol. Phytostimulation, Phytostimulation is the direct promotion of plant growth through the production of phytohormones. The most highly studied example of phytostimulation involves lowering plant hormone ethylene levels by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Several endophytes that release ACC deaminase have been shown to increase plant growth, including Arthrobacter spp. and Bacillus spp. in pepper plants ( Capsicum annuum), as well as Pseudomonas putida and Rhodococcus spp. in peas ( Pisum sativum). The mechanism of plant growth promotion is unknown; however, ACC deaminase production may reduce abiotic stress by balancing plant ethylene-level production, because elevated ethylene levels inhibit cell division, DNA synthesis, and root/shoot growth ( Burg, 1973 ). The production of other plant hormones including indole-3-acetic acid, jasmonates, and abscisic acid by bacterial strains may

also stimulate plant growth. Biofertilization, The promotion of plant growth by increasing the accessibility or supply of major nutrients is termed biofertilization ( Bashan, 1998 ). A well-studied form of biofertilization is nitrogen fixation, which is the conversion of atmospheric nitrogen to ammonia. Several PGPBEs have been studied extensively for their ability to fix nitrogen including Azospirillum spp. ( Hill and Crossman, 1983 ), Pantoea agglomerans ( Verma et al., 2001 ), and Azoarcus spp. ( Hurek et al., 2002 ). Some PGPBEs can increase phosphorus availability to the plant through phosphorus solubilization. The release of low molecular weight acids can allow the chelation of the metal cation attached to phosphorus, making it more accessible to plants. It’s isolated, characterized, and quantified the phosphate solubilization abilities of endophytes in sunfl ower ( Helianthus annuus ), identifying Achromobacter xiloxidans and Bacillus pumilus as having the highest chelating capabilities. Yazdani and Bahmanyar (2009) showed that the use of PGPBEs in fertilizer treatments for corn ( Zea mays ) reduced the need for phosphorus application by 50% without significant loss in grain yield. Biocontrol, The promotion of plant growth through protection from phytopathogens is known as biocontrol. Several mechanisms may be involved, including the production of siderophores or antibiotics. Siderophores, such as pyochelin and salicylic acid, chelate iron and can indirectly contribute to disease control by competing with phytopathogens for trace metals. Antimicrobial metabolites produced by PGPBEs, such as 2,4-diacetylphloroglucinol (DAPG), can enhance disease suppression in plants. For example, eggplant wilt caused by Ralstonia solanacearum was reduced by 70% after seeds were inoculated with DAPG-producing endophytic isolates.

Importance of endophytes

The potential of PGPBEs to improve plant health has led to a great number of studies examine their applied use as inoculants, primarily in agricultural crops. The potential for microbial inoculants to reduce the need for chemicals such as pesticides and fertilizers makes them important in the development of sustainable agricultural practices. In the following sections, we will review drivers that determine endophyte community structure and factors that will need to be considered for applied use of PGPBEs in a field setting.

What would conclusion state in cited?

The ubiquity of beneficial and non beneficial, naturally occurring bacterial endophytes in plant roots is undisputed. It is less clear what determines absolutely whether the endophytes will be benefi cial for the host plant or not, the external factors or cues involved, and what shapes the dynamics of the plant–endophyte relationship. Endophytes tested in isolation may indicate different life strategies and plant-growth-promoting characteristics compared to similar species or co-inoculating multiple strains. In a similar vein, external factors may contribute to altered life strategies of endophytes, such as the conditions imposed upon them via the host plant including soil and geographic factors, and anthropogenic management of the crops. These factors drive the overall structure and function in the root interior microbiome. As with all species assemblages, the internal root microbiome is dynamic and determined by many interacting abiotic and biotic factors that occur at various spatial and temporal scales. Endophyte community dynamics remain an important area of future research. Researchers now have the tools to more fully explore the interactions of abiotic and biotic factors that infl uence these communities and the subsequent impact of these changes on plant health. A particularly relevant question is how these populations will be affected in an environment that is under the infl uence of climate change. Novel molecular methods have highlighted the limitations of the past, increased our overall understanding of the nature of plant–microbe and microbe– interactions, and have helped outline new questions for the future. Future application of this research in combination may lead to the development of an optimal PGPBE inoculants strain that is robust, such that slight variations in external environmental factors and in the plant will not affect the efficacy of plant growth promotion.