Evolving phyllody resistant mutant(s) in sesame (Sesamum indicum L.) through marker validation and phytochemical quantification

Sesame (Sesamum indicum L.) is one of the most important oilseed crops in India. Among the various factors affecting the productivity of sesame, phyllody caused by phytoplasma and transmitted by Orosius albisinctus is a major disease which will reduce the yield up to 80 %. As sesame phyllody is a vector bone disease it is very difficult to control this disease and evolving resistant/tolerant variety may be one of the low-cost solutions. With the objective of evolving a high yielding phyllody resistant sesame variety through mutation, this research was executed. About 100 handpicked good quality seeds of sesame varieties viz. TMV 7, CO 1 and VRI 3 were subjected to irradiation at Atomic Power Station, Kalpakkam (IGCAR) on 18th September 2020. Three doses of gamma irradiation viz., 30 kR, 40 kR and 50 kR were fixed for our mutation studies. The M1 generation was raised at Agricultural Research Station, Vaigai Dam on 21.09.2020 by following Randomized Block Design (RBD) with three replications. At the time of flowering, selfing was carried out to ensure self-pollination in the mutants and the selfed seeds of the M1 generation were used to raise the M2 generation. In the M2 generation 132 phyllody-free sesame plants were identified at the time of maturity and forwarded as families to M3 generation. In the M3 generation a total number of eighteen families were identified as phyllody free families and forwarded to M4 generation. Among the eighteen families of the M4 generation, one family i.e. PR 375 is recorded as the phyllody tolerant species with the score of 16.06a. While screening for phyllody resistance none of the plant protective measures were carried out. From these families, seven phyllody resistant mutants (PR 375-1, PR 375-2, PR 375-3, PR 375-4, PR 375-5, PR 375-6 and PR 375-7 were identified. The resistance for phyllody in the PR 375 family was confirmed by the nested polymerase chain reaction (PCR) assay by using the universal primer pairs P1/P7 and R16F2n / R16 R2 as marker and quantification of secondary metabolites viz. phenols, tannin, alkaloids and flavonoids. The progeny of PR 375 will be forwarded to subsequent generations for further evaluation.