Leaf senescence is the terminal phase of leaf development that involves massive programmed cell death and nutrient remobilization. The senescence process is highly coordinated and tightly regulated by genetic program, involves differential expression of thousands of senescence associated genes (SAGs). It has great impact on crop production by altering photosynthesis duration, and by affecting the nutrient remobilization efficiency. This research work is designed to decipher the underlying molecular and genetic mechanism of leaf senescence in the model plant Arabidopsis and agronomic crop tobacco. The main aim of the research work is to identify genes involved in regulation of leaf senescence and to device strategies for senescence induction systems in an agricultural setting. Two experimental projects have been designed to accomplish the desired goals that include;1) Screening of Arabidopsis T-DNA insertion accessions for identification of leucine-rich repeat receptor-like kinase (LRR-RLK) genes regulating leaf senescence. Receptor like kinases play important roles in plant development and defense. LRR-RLKs represent the largest subfamily of putative RLKs in plants. However, few members in this subfamily have been identified for their role in leaf senescence. In this study, reverse genetic approach was employed to identify homozygous Arabidopsis accessions for T-DNA insertion. PCR based genotyping was performed and 26 mutants were confirmed for homozygous T-DNA insertion. Arabidopsis lines with T-DNA insertions within coding regions of 48 LRR-RLK genes were screened for leaf senescence phenotypes. Six novel LRR-RLK genes were identified in which loss of function displayed altered leaf senescence phenotypes. Two individual T-DNA mutants have been identified and isolated where knock out mutation displayed delay leaf senescence. These genes were named Senescence-associated Receptor like Kinase i.e., SRK1 (At4g08850) and SRK2 (At2g37050). Leaf senescence in two T-DNA insertion lines of SRK2gene is significantly delayed. While no obvious alteration in the overall developmental process was observed, such as the timing of leaf emergence and growth. srk-2 retained chlorophyll contents for longer period than Col-0. For gain of function analysis, SRK1 and SRK2 gene isolated from cDNA and cloned in over-expression vector pCHF3. After sequence analysis, Agrobacterium mediated Arabidopsis thaliana (Col-o) was transformed and T0 seeds were collected. RNA is extracted at four different leaf senescence stages (young, fully expanded, early and late senescence) from plants of Col-0 background and srk1 and srk2 mutants for expression analysis. Functional analysis of these genes in leaf senescence will further be confirmed by gain of function and complementary tests.2) Inducible gene expression system for leaf senescence regulation in tobacco. Inducible systems offer researchers the possibility to deregulate gene expression levels at particular stages of plant development and in particular tissues of interest. NAP is a transcription factor gene and a universal regulator of leaf senescence. Its sequence homologues exist in various plant species. NAP (from Arabidopsis / tobacco cDNA) genes were isolated and cloned. For ethanol inducible system, cloning constructs consists of a small shuttle vector containing the AlcA promoter followed by a MCS and terminator (pBJ36_AlcA) and a binary vector containing the 35S promoter driving the AlcR gene (pMLBART_AlcR). It contains Spectinomycin resistance for selection in bacteria, BASTA (glufosinate ammonium) resistance for selection in plants, as well as a unique NotI cloning site between the RB and LB. The NAP genes were cloned into MCS of pBJ36_AlcA. Agrobacterium mediated transformation of tobacco (Nicotiana tabaccum cv Hongda) was conducted with the inducible gene expression constructs. Induction of T0 plants was carried out with 2-5％ethanol in controlled conditions as well as in green house. Leaf senescence initiated after 5-10 days of induction and whole plant senescence occurred after 20 days. Homozygous transgenic lines will be generated for further studies.