The leucaena genes for drought tolerancebe can be identified from a tracriptome sequence library on the basis of partial similarities with stress-related genes from other plants. The expression of the putative genes for drought tolerance can be determined by microarray and quantitative PCR.

To identify traits and genes associated to these traits, you must expose your plants to water stress in pots in the glasshouse and in field conditions; you can start measuring leaf survival to drought, dry matter accumulation, phenology, etc

Hello Md,

 I wrote in response to a previous, almost identical question,, I repeat the answer here. The answer is not dependant on plant species. It applies to plants grown in isolated volumes of soil but actually applies also to plants growing in the field but there the experimental analysis is much more difficult to do.  

Regards

David Lawlor

Dear Ahmed,

There are NO GENES responsible for "drought tolerance" as there is no single factor which can be identified as responsible for improved growth and production of plants under water-deficient conditions, which can be considered to be drought tolerance. . So drought tolerance depends on many factors and therefore is multi-genetic. As Sasan says decreasing water loss is probably the primary mechanisms for surviving in dry environments - he focusses on stomata.  But leaf area is probably as, or more important , than stomata. Better said both are of the greatest importance.

I have dealt with aspects in

D W Lawlor J Exp Bot. 2013 Jan;64(1):83-108. doi: 10.1093/jxb/ers326. Epub 2012 Nov 16.Genetic engineering to improve plant performance under drought: physiological evaluation of achievements, limitations, and possibilities.AbstractFully drought-resistant crop plants would be beneficial, but selection breeding has not produced them. Genetic modification of species by introduction of very many genes is claimed, predominantly, to have given drought resistance. This review analyses the physiological responses of genetically modified (GM) plants to water deficits, the mechanisms, and the consequences. The GM literature neglects physiology and is unspecific in definitions, which are considered here, together with methods of assessment and the type of drought resistance resulting. Experiments in soil with cessation of watering demonstrate drought resistance in GM plants as later stress development than in wild-type (WT) plants. This is caused by slower total water loss from the GM plants which have (or may have-morphology is often poorly defined) smaller total leaf area (LA) and/or decreased stomatal conductance (g (s)), associated with thicker laminae (denser mesophyll and smaller cells). Non-linear soil water characteristics result in extreme stress symptoms in WT before GM plants. Then, WT and GM plants are rewatered: faster and better recovery of GM plants is taken to show their greater drought resistance. Mechanisms targeted in genetic modification are then, incorrectly, considered responsible for the drought resistance. However, this is not valid as the initial conditions in WT and GM plants are not comparable. GM plants exhibit a form of 'drought resistance' for which the term 'delayed stress onset' is introduced. Claims that specific alterations to metabolism give drought resistance [for which the term 'constitutive metabolic dehydration tolerance' (CMDT) is suggested] are not critically demonstrated, and experimental tests are suggested. Small LA and g (s) may not decrease productivity in well-watered plants under laboratory conditions but may in the field. Optimization of GM traits to environment has not been analysed critically and is required in field trials, for example of recently released oilseed rape and maize which show 'drought resistance', probably due to delayed stress onset. Current evidence is that GM plants may not be better able to cope with drought than selection-bred cultivars.PMID:23162116[PubMed - indexed for MEDLINE]

A free full text is available under David W Lawlor on Research Gate or via MEDLINE

The simplifications offered by genetic modification/engineering should be treated very carefully.

Regards

David Lawlor

Thank you very much Dear David Lawlor.

I would like to provide stress in vitro in Leucaena plant and after that I would like to check their gene expression pattern via qPCR. For that, I need to develop primer related to drought and their reference genes. This is the ultimate objective of my question. Could you help me Dear David Lawlor.