Use of Plant Auxins Produced by Bacteria in Plant Tissue Culture and Seed Pre-treatment; A Possibility of Replacement of Synthetic Auxins

Phyto-hormones or plant growth regulators are organic substances synthesized in defined organs of the plant that can be translocated to the other sites, where it triggers specific biochemical, physiological and morphological responses (Vamil, 2011). Today, the synthetic plant growth regulators are available commercially. If these chemicals are applied in specific quantity, enhance the plant growth (Naeem, 2004). There are five different types of plant growth promoting substances produced in plants. Out of this IAA, IBA are important as having major growth promoting activity. Many investigations showed that presowing treatment of growth regulators to the seeds could lead to increase in tissue hydration, redistribution of nutrient reserves, higher respiratory activities and enhancement of seedling growth, dry matter production, early flowering and yield. (Vamil, 2011). IAA exerts influence on plant growth by enlarging leaves and increasing photosynthetic activities in plants (Naeem, 2004). IAA also activates the translocation of carbohydrates during their
synthesis (Naeem, 2004; Ritenour, 1996). It has been observed that IAA in combination with Kinetin caused a decrease in length and number of internodes, expansion of main stem diameter and increases the number and area of leaves (Naeem, 2004). In nature the microorganisms present in the rhizosphere of plant roots, help the plant by producing these plant growth promoting substances. Many of them are known to produce compounds like IAA, IBA, NAA (Naphthalene acetic acid) (Ali, 2007). Commercially available Phyto-hormones like IAA, IBA and NAA are commonly used in plant tissue culture. But bacterial Phytohormones have not been evaluated to replace these commercial synthetic preparations. Secondly, pre-treatment of seeds with bacterial IAA and/ IBA along with Rhizobium has not been evaluated for growth response of the plant. Chick pea is third most important legume in the world. In India no plant growth regulator is used in Chick pea growth. India is world leader in Chick pea production.

Bacterial production of IAA and its effect on plant growth has been reported by many researchers (Mohite, 2013; Ali, 2009). The main objective of the present study is to investigate the possible use of bacterial IAA, IBA in plant tissue culture as well as pretreatment of legume, especially Chick pea with or without Rhizobium.

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