Dr Srivastava, very academic question. We are yet to decode the various physiological signals originating at subcellular level if we need to express it at whole plant level.

Dear Folks

Mechanistically our food system needs to focus on our Health. The organic saying Healthy Soil Healthy Food Healthy People comes to mine. When we look at the mechanism of health which comes from the old German word Hoelth which means becoming complete or whole. If we have incomplete nutrition how can we become whole?

Not since the nutrition comes from the soil it is there where the challenges and opportunities are presented. Do we know the data on a whole gamut of nutritional aspects of our soi?l do we know the critical limitation and the physiological implications? in the plant do we know that status of soil biological life?

We might be concerned with our tomato plant that is displaying physiological rot at the tip of fruit. This so called blossom end rot is traditionally suggested that it is the aggravated by ammoniated fertilizer and fluctuating water availability. Looking toward the mechanism have we checked the presence and level of Boron which is now known to connect with Calcium and pectin. The newest information shows the loss of Calcium sends messages to the plant to respond with defense chemicals which help and the plant are nutritionally beneficial.

In this example of Boron shows how a nutrient which needs are in ppm can govern the content and need of major element. For developing economies it is more likely that we get major leverage for minor elements because they have major effects and can avoid massive effects energetically and environmentally compared to massive major element intervention.

Since plants and animals depend on each other it is wise to developed mixed economies for sustainability and productivity and beneficial impacts over time. The key is get the legume component right, the recycling of animal products into the crop system and keeping the ground covered. When we direct our attention at the symbiotic components Rhizobia and Mycorrhiza we create the nutritional base so they can do the biological operations by their action and we focus on feeding them who in turn feed use.

A single earth worm in one year produces 5 kg of casting which are completely based in their major and minor element composition. If we provide for their habitat and feeding our tillage and nutrient needs are satisfied and our soil improved mitigating global greenhouse gas problems.

While we talk about the major elements did we consider the whole analysis to correct the micronutrient deficiency which holds the critical factors to biological Nitrogen fixation and the role of this to healthy mycorrhizal communities which provide the bulk of soil mobilization of P in over 80% of crop species.

Friends I am more willing to know the very basic question that whether or not a nutrient  acts at gene level. If yes, then how it operates.

Take a look at the acquired systemic resistance response in plants mediated through Calcium with Boron being a co factor. If you instance Phosphate is applied which leaches Calcium in the cell wall and membrane phytoalexins phenolics are triggers eliciting the production of the defensive chemicals this is not a specific response as when an insect, pathogen or a stress occurs any of the insults which attack the integrity of cell wall ring a bell of alarm a biochemical cascade response. First work was initiated by Dr. Kuc at the University of Kentucky there is a lot more information accumulation all the time. This represents Calcium and Boron being signals which turn on the genes activating the defensive phenolic pathway.

I am attaching a model for the attachment of pectin with Calcium and Boron in the cell wall membrane system where this actions occurs. First information for instance my graduate student and I was able to get as good and better rot control with a Calcium bath than with benomyl fungicide. Although I first thought this was purely structural action it is now clear that the plant responds through Calcium and calmodulin system. Fascinating.

Very interesting piece of information Paul , worth reading . Infact  , calcium  amidst big boys of soil fertility ( N,P,K) has taken the back seat , though , this nutrient is considered as secondary messenger in physiological functioning of many enzymes at the subcellular level.  Dr Deka and My Reyahneh , both of you have picked up very pertinent issues . I am waiting for my learned colleagues to interact first.   I am enclosing one PDF relating the calcium as nutrient .

Dr. Anoop Kumar, thank you for asking excellent question on plant nutrition. It is related to fresh our academic knowledge and learning from others; research and experience. I have the following submissions.

1. Each nutrient, besides others has very specific function related to specific parts of a plant. For example Ca is related to cell wall. Deficiency, application or excess will first effect that part but in the long run whole of the plant and many metabolic functions.

2. We assess the responses to the whole plant due to its ease and less technological requirements as well as because of our targeted end product.

3. We do not have knowledge up to that detail that how and up to what extent nutrients will effect on sub-cellular and gene level, though it may exist. With development of knowledge and technology, we are finding these details slowly but regularly.

4. The research is a dynamic and rigorous phenomenon and we are travellin on this road to find and understand the facts we are observing. 

Dr Srivastava , very thoughtful question . We usually evaluate the response of a nutrient on the basis of whole plant , simply due to easiness . Often , we evaluate on the basis of response on consumable part of the plants. I strongly feel , nutrients do act at cellular or subcellular level.

Traditional plant nutrition studies look at nutrient efficiency mainly at whole plant level.Although  useful,  studies with whole plants cannot provide sufficient insights into the genetic nature and its specific modification of the nutritional processes. Recent progress in plant molecular biology has provided the means to tackle complex plant nutritional problems through genomics , transcriptomics , proteomics and metabolomics approaches. all these approaches , together with phenotypic analyses , will enable us to elucidate the functions and interactions of plant nutrients at the molecular , cellular , organ , and whole plant level.  These are the reasons , the concept of Nutriomics was introduced . This is a new frontiers of plant biology .

What is your opinion about the nutrient efficient plant type and nutrient inefficient plant type ?. is this not a character of gene pool ?. How a plant coordinates its all necessary physiological functions under nutrient stress conditions. Under such nutrient stress conditions , whether a plant leaves certain metabolic functions?

How a plant adopts to a soil  facing multiple nutrient deficiencies compared to soil having mono nutrient deficiency or soil with high fertility. Any information about plant function?

Reyhaneh Eslamikah

The answer is a unanimous yes.

The natural state is designed to communicate and interact and increase. It is under genetic control but it is beyond genetics. It has no randomness in it at all it is designed.

 Please take a look at how legume plants interact with the Rhizobia bacteria as a case in point.

When the legume is lacking in Nitrogen it sends out flavonoid compounds. These stimulate the bacteria to swim toward the root hair which embraces the bacteria. Then the plant and bacteria form an infection tube where the DNA of the bacteria fuse with that of plant to form a nodule. The plant provides for the home for the bacteria and the nutrients needed for thenutrients needed. The plant in exchange for its graciousness as host gives the plant all the Nitrogen it could need in exchange. No randomness it was planned.

The presence of the power team invite the mycorrhizal fungus in but only when soil conditions are low in Phosphorus. The tripartite team allows for luxuriant growth with a scarce environment. But wait the fungus produces a protective coating of glycoprotein which cements the soil into soil aggregates which favors the plant. By design not by chance.

When the plant is favored the residuals favor the earthworms and soil fauna that recycle the nutrients back into the soil and in the case of earthworms their casting is the exact size and fertility that favors the plant. By randomness not at all.

I believe this is a divine dance that is beyond human comprehension our goal then becomes to work with it and not against it.

If we look to Greeks men of the mind they foresaw four elements Fire, Water, Air and Earth. They sensed that there was a fifth element they called Quintessence the firth essence. What is that element?  I believe it is the creative essence of Love.

We can only do so much as men and women of the mind alone and to go beyond we need to be in higher thought through love. We need to think with our hearts.

I salute your love for the heart to search the soil for  truth and ask for blessing on your house and hope you remain grounded in all your pursuits.

Thank you for the opportunity to share my heart.

No doubt we evaluate nutrient response on the basis of whole plant response but often response is erroneously received especially when evaluated for change in edible part. Can any one tell how identify the most nutrient responsive plant part ?

Thank you Dr. Anoop for describing the new innovations in plant nutrient studies. Let us hear something from our other learned researchers as well.

It is often debated , nutrient use efficiency is whether an acquired trait or an essentially a genetic trait . for example, zinc uptake is mediated by two overlapping processes , one called as high velocity ; low affinity system , and another class called  as low velocity ; high affinity system  ( operates under low Zn conditions ).Zn absorption is facilitated by the presence of Zn transporters into the root symplasm .These Zn transporters are mostly proteinous in nature , which participate in long distance transport of Zn through xylem . While , phloem mobility of Zn is low , since Zn is not mobilised from older leaves under low Zn concentration . Hence  , Zn -influx has been hypothesized as free Zn2+ ions as well as Zn complexes with non-protein amino acid  . called phytosiderophores or phytometallophores.

The potential mechanisms incuding root Zn uptake and translocation , Zn sequestration in leaves and biochemical utilisation of Zn , are often claimed to be either root specific trait or shoot specific trait under genetic control at the sub-cellular level.  Under such transport , Zn is much better mediated through complexation as part of carbonic anhydrase ( Metalloenzyme) and dismutase-controlled ( Cu/Zn-SOD ) under Zn-surplus conditions .  That is even today , the Zn like most of the micronutrients absorption linked Zn-efficiency  is considered  as trait term of the plant where root configuration has a strong impetus on the utilisation of Zn at the plant organ/tissue level. Zinc efficiency of a plant is also considered as shoot mediated trait ( In addition to root mediated trait )  through subcellular Zn compartmentation for cytoplasm Zn and biochemical utilisation of cellular Zn incorporating Zn as a cofactor of Zn requiring enzymes  under low Zn , is usually operational  . This is one of the micronutrients , so widely deficient worldover . The physiology and biochemistry of Zn-nutrition will surely unravel many of the mysteries associated with sub-optimum nutrition .  

For me the most responsive part of the plant is the system of roots. Much reglected for the lack of easy direct observation. When a lot of soluble nutrients are provided to the plant the symbiosis of the plant and its associated microorganisms is curtainled. When the plant is comfortable with a lot of Nitrogen it does not produce the key flavonoid compounds with start the Rhizobium swarming to them. A similar situation works in Phosphorus for plant susceptibility and action for mycorrhizal fungi. These symbioses are synergistiic in improving plant health and wholeness while minimizing external inputs and maximizing results. For this reason we need to look to nutritional balance in the context of optimizing the productivity of the smbionts and look to farming system and soil to optimize roots. Ironically the intensified system stressing everything dwart usually also dwarves the root system which makes the system less sustainable. 

My favorite plant organ is the root and my favorite organ in my body is my brain and that can be problematic also. 

Paul, I am tempted to ask if that is the case then why do we evaluate the nutrient response at whole plant level or edible plant parts having marketability. Do you think nutrient response is invariably translated via all the physiological signals from roots. Or roots are the epicentre of all the physiological signals of higher yield and quality.

A lot of information shows that Calcium targeted at the developing fruit causes fruits more resistant to bruising from the strengthened cell walls. These fruits also keep better. As you know Calcium is transported upward through the xylem as such the greatest benefit theoretically is from a root or mycorrhizal absorption and not from a foliar response. In ginger you can foliarly apply Calcium and still have deficiency in the rhizome. The signal for plants to accept Rhizobia or mycorrhizal fungi all come from the plant to the organism and back. If we are to be good plant doctors we want to make sure at first course as in Hippocratic Oath Do no Harm. The healthy plant is a function of a health root system and the root system should be a replica in size and shape of aboveground plant. If we have stimuli of rampant aboveground growth and sacrifice the roots which can happen with ammoniated fertilizer we disrupt the balance and signaling. I believe signaling is mainly from the roots because it is from the roots and soil that plants get the majority of their nutrition even when they are fertilized. 

You are very right Dr. Paul, roots are the first plant directly facing good, favorable and stressed conditions. Hence, roots are affected first of all and respond according to prevailing situation. Then these effects are translated to other parts of the plant. The ease is the only reason we are studying whole plant or its aerial parts otherwise roots tell a lot. Roots studies are of equal importance.  

Biochemical communication of plants is not an exception it is the norm. In the case of natural conditions the root systems of plants of the same species can fuse and become grafted together as a type of colony. In the issues with Dutch Elm Disease unless the neighboring tests were root trenched the contagion would move down the urban tree line. In a prairie or meadow the root systems of diverse species are interwoven together.

When a tree is attacked by an insect the tree will give off volatiles which communicate to nearby trees. The neighbors response to the volatiles by producing inhibitory substances which reduce the spread of damage in a biochemical conflict of sort.

When we look to cellular level the cell walls and membranes seem to be active sites. Calcium pectin and boron seem to be very important as a line of defense and signaling. Many of the rot fungi need exudated substances to grow and cause pathogenic damage. In the case Pythium fungus the damage is contingent on the exudation. When you have Boron deficiency and in stress conditions the exudation can be greatly increased predisposes plants to critical disease. When Calcium levels are being reduced that is signaling event for defensive metabolism. When Phosphate buffer is applied to plants the binding of plant Calcium with start the defensive cascade.

The rhizobium symbiosis is very fascinating because plant flavonoids are stimulants for swarming of rhizobia to the root hair but also the development of the infection thread ends up with the bacterial genetic material incorporated into the root cells that form a distinctive nodule with is a interspecific super organism in some sense.

Another interesting idea is some workers have shown my variability of plants when under toxicities of manganese and aluminum this would need to some adaptation to that condition working on a genetic level.

In response to the point raised by Dr Deka , I agree with Dr Hepperly an d Dr Nazir , the major control station of different physiological  and biological signals emanate from roots only . Why am I saying this , it is the variety of root transporters for different nutrients  embedded into the plasmalema of cell walls. However , it remains  to be seen , whether or not , different kinds of transporters or what kind of transporters   really  operate at the subcellular level according to nature of cations or anions. Probably , this is the reason , rhizosphere properties hold so much of importance in the context of plant physiology and biochemistry at any level of plant functionality  , whether nutrient stress or surplus conditions.  

We observed that AM-seeedlings displayed significantly higher shoot morphological properties (plant height, stem diameter,and leaf number),biomass production(shoot and root fresh weight and leaf RWC,regardless of soil water status.AM inoculation significantly increased CaM and soluble protein on centrations and CAT activity,where as significantly decreased O•−2 and H2O2 concentration under both well water and drought Stress conditions. The AM seedlings also exhibited significantly higher Cu/Zn-SOD and Mn-SOD activities than the non-AM seedlings under drought stress but not under well water,which are triggered by higher Ca M levels ( Calmodulin as an acidic protein , best characterized by Ca-receptors)  in AM plants on the basis of correlation studies. Further, the negative correlation ofCu/Zn-SOD and Mn-SOD activities with O•−2 and H2O2 concentration showed the DS-induced ROS scavenging ability of CaM mediated SOD s under mycorrhization.Our results demonstrated that AM-inoculation elevated the synthesis of CaM in leaves and up-regulated activities of the antioxidant enzymes, thereby, repairing the possible oxidative damage to plants by lowering the ROS accumulation under drought stress condition. These studies lend strong support , how rhizosphere -associated roots function in tandem with plant canopy.

How do you characterize the plant rhizosphere sensitive / responsive to above ground physiological demand. Whether these rhizosphere properties will differ from one plant species to another.

Dr Deka  you have raised a very burning in issue in the context of the whole discussion . Dr Hepperly could supplement better response , since he is more equipped person with his scientific  prowess. I am looking forward to his another piece of marvel.

I was going through the research paper by Rien Aerts on  NUTRIENT USE EFFICIENCY IN EVERGREEN AND DECIDUOUS SPECIES FROM HEALTHLANDS ( PDF enclosed ). It is claimed that due to evolutionary trade-offs, genotypically  determined plant characteristics  which lead to a high growth rate are inversely correlated with those which reduce nutrient losses.  The low potential growth rate of plant species from low-nutrient habitats is probably the consequence of their nutrient conserving strategy rather than a feature on which direct selection takes place in these habitats.  The paper further supplies an excellent account of how roots coordinate with shoots in transferring the required physiological signals.

Ms Reyaneh , you have put up a very genuine quarry . Let me respond to it . Root transporters are basically proteinous in nature , have great diversity in choosing a definite nutrient to perch them into the xylem cells . Root transporters remain embedded in plasma membrane  of cell wall.  I am enclosing two excellent PDFs to throw more lights on behaviour of root transporters.  These root- based nutrient transporters functionality is affected by water and nutrient availability , stress level etc. within the growing medium.

I am still waiting for some responses on the suitable  properties which can effectively describe the environment in the rhizosphere. How they influence the vascular connection between roots and shoots.

Dr Deka ,  number of  properties describing plant rhizosphere are frequently used to describe the rhizosphere health vis-a-vis plant health. These soil respiration , labile pool of organic carbon ,  microbial biomass , microbial biomass nutrients,  soil enzymes, redox potential , water transmission properties, etc  , depending upon the  sensitivity of crop .

Let me flag off another very important issue. The role of nutrients as regulatory molecules is now a  well established fact , whether unicellular or multicellular organisms.  for example, carbon and nitrogen metabolism  must be tightly coordinated to sustain the growth and development of plants. Half of transcriptome is regulated by C,N or C-N combination . distinct bioassays have demonstrated putative nitrate transporter (NTR2.1)  , putative glutamate receptor ( GLR1.1) and putative nitrite transporter (NTR 2.2) have important fundamental contributions. in C:N balance and consequent phenotypic characterization through C/N balance signalling . ( Zheng Z-L 2009,. plant Signal Behaviour  4(7) : 584-591) . Likewise , sugar signalling ha sbeen largely focussed on gene expression , however , little is known  about the actual transcriptional machinery underlying growth and developmental responses. however , role of calcium in sugar signalling is suggested by the isolation of sugar-induced plasma membrane -associated calcium dependent protein kinase . Calmodulin inhibitors provide additional evidence for involvement of calcium signalling in sugar induction . Find below a PDF explaining , how the C_ baalnce is regulated at subcellular level and expressed at whole plant level in form of various phenotypic expression s.

In our schooling we are taught a Carbon cycle, a Nitrogen cycle, a water cycle etc.

In reality these are simplified conception used for the purpose of coming to an understanding based on dissection and simplification.  Like a child we do not understand it so we take it about.

In reality these cycles are inter-twined. Very difficult to have a water cycle without photosynthesis but we do not teach their interconnected. In fact an over looked reality is our resource of soil carbon is the stored treasure for its ability to retain, conserve and recirculate water.

Sometimes we look in a Liebig limiting factor sense and look for a way to optimize Nitrogen alone. Yet the global agricultural system is most constrained by water.  If we resolve one another will replace maybe one we did not know about.

Because the mycorrhizal fungi can extend the functional root systems by thousands of times its role in signaling and sensing as part of the team cannot be underestimated. Yet will all this importance and contribution it is something of an unsung hero by being both understudied and probably appreciated.

The deep truth of science is that the more we know the more we know how incomplete our best understanding is. Einstein talking about his theory of relativity said I knew it was true because it was some simple and beautiful.

Colleagues seek the beauty as you ponder the complexity.

The study of biogeochemical soil cycles will need to be better taught to help our future generations prosper.

When we talk about communications being initiated in the root systems these messages are traveling up and out into the plant. Many of you are aware of rhizosphere the zone which is a haven for bacteria growth based on the exudation of plant compounds which comprise about 20% of the photosynthetate.

The other idea is the mycorrhizae are stimulating a much richer total soil effect through their interaction. The term mycorhizosphere comes in being. The signaling of rhizobium to plant has been seen as a tripartite 3 part symbiosis I would add the rhizosphere bacteria quadra partite and wait the earth worms quinta partite symbiosis.

The ancient Greek idea of 4 substances fire water earth and air non scientific. We see these in the synthesis or making through light photosynthesis the earth is the soil, the water is the soil water, the air is our Carbon dioxide and the fire is our sunlight the basic components needed for photosynthesis.

But they also looked for the fifth substance the glue to how it all  interesting that in the components brought up they are quintessence. As we ponder we will come to wonder and start the search for the Greeks fifth substance.

Is our Universe the result of randomness? I think not.

Very Interesting Paul. How the signalling for nutrient demand by the host plant is imposed on the AM under mycorrhizosphere? Is it through formation of CMN between host plants and AMs.

I feel nutrient efficiency we have to define at subcellular level, it is simply the compartmentalisation of different physiological signalling for various plant functions. And the transcriptional level of different signals is again dependent on the level of plant organisation that is growth stage?

Take a look at Wang et al 2012 signaling process promote mycorrhizal colonization through increased branching and proliferation.

The plant derived hormones are stimulative to mycorrhizal fungal branching and are derived from the plant carotenoids are called strigolcactones.

Maillet et 2011 Fungal chitolipogliosaccharides Nature 469:58-63 shows the fungal symbiont stimulates the infection and growth of the plant. Genes have been identified in the host that promote the mycorrhizal infection and inhibit it when they are defective.

Since in the case of legumes with soil nitrogen and mycorrhizae with Phosphorus the mineral status is used by the plant to turn susceptibility for the symbiosis on or off, respectively. This in some way is almost like an intelligence to be engaged only as it is necessary.

While the subcellular levels are important,  the application needs accurate information at subcellular, cellular, plant, population and at the level of farming systems.  

Why have we so candidly failed to develop early warning system to  identify the nutrient constraints on real time basis , if such a coordinated sequel of signal system operates at subcellular level and eventually expressed at whole plant level. 

Perhaps decoding these physioligical and biochemical signals originating at gene level , we are not able to decode them?

Sir,

Physiological and biological signals are based on codons. Let me give some basics here.

A codon is a trinucleotide sequence of DNA or RNA. The cell reads the sequence of the gene in groups of three bases. There are 64 different codons: 61 specific amino acids while the remaining three are used as stop signals. Biological decoding is accomplished by the ribosome.  Synthesis of any compound in the system needs signals and codons.

Pl see :

The Molecular and Hormonal Basis of Plant-Growth Regulation

By Ya' Acov Leshem

Page 56-58

Different systems are explained  in page 56

Thanks

Responding to Dr. Srivastava I believe we need to continue to look at what happens related to leakage and repair mechanisms in relation to an early warning system.

I believe the signals are being recognized at the cell wall and membrane level. They are transmitted into Nucleus and nucleic containing organelles and it is the that machinery which then produces the biochemical cascades of responses.

If we look to cell wall a primary function is selective permeability. When nutrition is optimized this mechanism works well. however under assault and poor nutrition this mechanism fails which will show itself as leakage.

Our genetic machinery will age but when we are not nourished our ability to repair these mechanisms are hampered and at some point it just collapses.

The role of our nutrition is to keep the selective semi-permeability intact to keep the good stuff coming in and the bad stuff out. Anything that we do nutritionally will stimulate the preservation in addition of genetic repair mechanisms which will prevent damage and maintain all repair mechanism.

Exudations and leakages can tell us a lot more than we currently are using. Genetic microarray analysis is breaking new ground on what genes are being switched on and off.

When I first studied these areas we worked on the one gene for one protein model. The first estimates were that the human genome would possess more than 100,000 genes. When the data came this was not the case. The number of genes appears more like some 20,000 and the hypothesis now is one gene is multiple tasking and have diverse roles.

The way how Dr. Paul tried to relate the ancient Greek Philosophy with science is very interesting.

Nutrients are simply the part and parcel of plant immune system. Plant supplied with low nutrient status will be more vulnerable to diseases .