RESEARCH COMMUNICATIONS CURRENT SCIENCE, VOL. 81, NO. 8, 25 OCTOBER 2001 1109 *For correspondence. (e-mail: sushil2000_01@yahoo.co.in) The floral androcarpel organ (ACO) mutation permits high alkaloid yields in opium poppy Papaver somniferum Seema Prajapati † , Suphla Bajpai † , M. M. Gupta † and Sushil Kumar †,#, * † Central Institute of Medicinal and Aromatic Plants, Lucknow 226 015, India # National Centre for Plant Genome Research, JNU Campus, New Delhi 110 067, India Isolation of a recessive aco (androcarpel organ) mu- tation in opium poppy Papaver somniferum, is de- scribed. The aco (aco aco) mutant plants form androcarpels in place of inner whorl stamens in their flowers. The abnormal flowers are self-fertile, as stamens in the outer whorl are normal. In aco mu- tant the calyx, corolla and syncarpous gynoecium are formed like in the wild type ACO plants. The andro- carpel walls of aco plants synthesize and accumulate alkaloids like the main carpel walls. The aco muta- tion provides a means for improving carpel wall husk mass and thereby the yield of alkaloids. THE opium poppy plant, Papaver somniferum, synthe- sizes more than 40 alkaloids in its root, stem, leaf and/ or fruit (capsule), some of which have high biological– pharmacological activities and economic importance. The demand for poppy alkaloids, especially for mor- phine and related compounds used for suppressing pain and cough, has been growing and is estimated as 75 tonnes; it was about 10 tonnes in 1983 and 55 tonnes in 1997 (ref. 1). The poppy plant is harvested in two ways to produce raw material for alkaloid production. The growing capsule at the advanced stage of development is lanced and the latex that oozes out and forms opium after coagulation on the capsule wall is collected. Alter- natively, the dried capsule and part of peduncle are har- vested and threshed to collect the husk after separation of seeds. The alkaloids are chemically extracted from the opium or capsule/peduncle husk. Under the 1988 United Nations (UN) Convention, while a few countries have been permitted to grow opium poppy for capsule husk, India has been permitted to cultivate poppy for obtaining opium, to meet the international requirements of opium alkaloids and to control their illicit traffic 2 . Poppy crops are cultivated by identified farmers, of se- lected districts in Uttar Pradesh, Madhya Pradesh and Rajasthan, who are licenced by the Narcotics Commis- sioner of the Government of India to grow opium poppy in small fields, for the production of opium all of which is purchased by the Narcotics Commissioner. UN con- vention requires India to develop new cultivars and processing technique(s) that will increase alkaloid pro- duction, reduce the area of poppy cultivation and further check any illicit traffic of opium poppy products 2 . To meet these requirements, one of the objectives of the opium poppy plant breeding programme is to develop cultivars that accumulate higher levels of morphine, codeine, thebaine, narcotine and/or papaverine in cap- sule husk for industrial extraction 3 . Under dense planting conditions of cultivation, indi- vidual P. somniferum poppy plants produce 1–3 cap- sules from equal number of flowers 3 . The poppy flower has four kinds of organs arranged in concentric whorls, two sepals in two outermost whorls, four petals ar- ranged in two whorls, inner to sepals, several whorls of stamens and a gynoecium comprising many fused car- pels. The gynoecium has a stigmatic plate, a very short style and an ovary. Each carpel of syncarpous unilocu- lar ovary on the inside bears a placenta, the two sides of which bear the ovules. The ovary (capsule) wall has a vast network of laticiferous vessels which are the prin- ciple site of synthesis and accumulation of alkaloids 4,5 . Apparently to breed high alkaloid-yielding opium poppy genotypes, one of the strategies will be to in- crease the number of carpel organs and thereby capsule wall volume. In angiosperms, differential activities of homeotic genes in different regions of a developing flower are responsible for the specification of organ identities in flower 6 . Three classes of floral homeotic genes that function in overlapping domains determine the identity of sepals, petals, stamens and carpels in such flowers 7 . In Arabidopsis, the A-class genes, APETALA 1 and APETALA 2, act to specify sepal and petal development. The B-class genes, APETALA 3 (AP3) and PISTILLATA (PI), act to specify petal and stamen development and the C-class gene(s) AGAMOUS (AG) acts to specify stamen and carpel development. The floral homeotic genes have been highly conserved among angiosperm plant species. It has been shown that the orthologous genes are involved in the development of corresponding organs in Antirrhinum and Petunia 7–9 . Mutations in the homeotic genes are known to change identities of the organs of different floral whorls. For example in ap2 mutant of Arabidopsis, sepals and petals become carpels and stamens, respectively 10 . Here, we describe isolation of a variant (aco aco) from a land race (ACO ACO) in which inner whorls of stamens have become carpels. The presence of many androcarpels in the poppy mutant is shown to increase the yield of carpel husk and thereby alkaloids. In the course of evaluation of the Indian landrace ge- netic resources of P. somniferum, plants were raised of accessions using seeds collected from farmers. The ac- cessions were selfed and progeny populations were screened for variation in morphological features and alkaloid profiles. While the seeds of apparently ho- mogenous selfed plants were pooled accession-wise, the